PURPOSE: The purpose of this study was to investigate the relationship between spatiotemporal variables and the muscle activity of the rectus femoris (RF) and biceps femoris (BF) in both legs at various running speeds. METHODS: Eighteen well-trained male athletes (age: 20.7 ± 1.8 yr) were asked to run for 50 m with 7 different "subjective efforts (SE)" (20%, 40%, 60%, 80%, 90%, 95%, and 100% SE). SE scaled relative to the maximal effort running (100%). The spatiotemporal variables (running speed, step frequency, step length) were measured over the distance from 30 to 50 m. The RF and BF muscle activities were obtained from both legs with wireless electromyography (EMG) sensors. We calculated RF and BF onset/offset timings in both legs (e.g., ipsilateral leg RF is "iRF," contralateral leg BF is "cBF"), which were expressed as % of a running cycle. Based on those timings, we obtained the EMG timing variables (%), as Switch1 (iBF offset to iRF onset), Switch2 (iRF offset to iBF onset), Scissors1 (cBF onset to iRF onset), and Scissors2 (iRF offset to cBF offset). RESULTS: running speed was well correlated with the SE, and higher running speed (>9 m·s -1 ) was achieved with higher step frequency (>4.0 Hz). Relative timings of RF and BF onset/offset (%) appeared earlier and later, respectively, with an increase in running speed. The absolute duration of RF activation (s) was elongated with the decrease in absolute running cycle time (increase in running speed). Both Switch and Scissors showed significant negative correlations with running speed and step frequency. CONCLUSIONS: The RF and BF excitation in both legs, as evidenced by changes in both Switch and Scissors, is coordinated for controlling running speed, as well as step frequency.

Transvertebral magnetic stimulation (TVMS) of the human lumbar spinal cord can evoke bilateral rhythmic leg movements, as in walking, supposedly through the activation of spinal locomotor neural circuitry. However, an appropriate stimulus intensity that can effectively drive the human spinal locomotor circuitry to evoke walking-like movements has not been determined. To address this issue, TVMS was delivered over an intervertebral space of the lumbar cord (L1–L3) at different stimulus intensities (10–70% of maximum stimulator output) in healthy human adults. In a stimulus intensity-dependent manner, TVMS evoked two major patterns of rhythmic leg movements in which the left-right movement cycles were coordinated with different phase relationships: hopping-like movements, in which both legs moved in the same direction in phase, and walking-like movements, in which both legs moved alternatively in anti-phase; uncategorized movements were also observed which could not be categorized as either movement type. Even at the same stimulation site, the stimulus-evoked rhythmic movements changed from hopping-like movements to walking-like movements as stimulus intensity was increased. Different leg muscle activation patterns were engaged in the induction of the hopping- and walking-like movements. The magnitude of the evoked hopping- and walking-like movements was positively correlated with stimulus intensity. The human spinal neural circuitry required a higher intensity of magnetic stimulation to produce walking-like leg movements than to produce hopping-like movements. These results suggest that TVMS activates distinct neural modules in the human spinal cord to generate hopping- and walking-like movements.

PURPOSE: We aimed to examine the timing of electromyography activity of the rectus femoris (RF) and biceps femoris (BF) in both legs, as well as spatiotemporal variables (running speed (RS), step frequency (SF), step length (SL)) between the maximal speed (Max) phase (50-70 m) and the deceleration (Dec) phase (80-100 m) of the 100-m dash. METHODS: Nine track and field athletes performed the 100-m dash with maximal effort. Spatiotemporal variables of each 10-m section were measured. A portable wireless data logger was attached to the subject's lower back to record electromyographies. We calculated onset/offset timing (%) of RF and BF in both legs using a Teager-Kaiser Energy Operator filter (e.g., ipsilateral leg RF onset is "iRF-onset," contralateral leg BF onset is "cBF-onset") in a running cycle. RESULTS: The decreased RS in the Dec phase (P < 0.001) was due to a decreased SF (P < 0.001). Moreover, iRF-onset (P = 0.002), iRF-offset (P = 0.008), iBF-offset (P = 0.049), and cBF-offset (P = 0.017) in the Dec phase lagged in the running cycle as compared with the Max phase. Furthermore, the time difference between the swing leg RF activity (iRF-onset) and the contact leg BF activity (cBF-onset; "Scissors1") became bigger in the Dec phase (P = 0.041). Significant negative correlations were found between ΔiRF-onset and ΔSF (P = 0.045), and between ΔiBF-offset and ΔSF (P = 0.036). CONCLUSIONS: The decreased RS and SF in the Dec phase of the 100-m dash would be the delayed timing of the RF and BF activities in the same leg as well as the disturbed interleg muscular coordination.

<jats:p>Purpose: Purpose of this study was to elucidate the differences in sprint performance between two different conditions in the 60 m dash: subjects ran alone (Alone Condition: AC) or two runners competed side-by-side (Competitive Condition: CC). Methods: Subjects were twenty-six male university sprinters. They were asked to perform two 60 m dash, the AC and CC, with maximal effort from crouching start. Running spatiotemporal variables were obtained from video images taken with two digital high-speed cameras. Results: Running speed (AC: 9.34 ± 0.45 mžs-1 vs CC: 9.40 ± 0.43 mžs-1, p = .011) and step length (AC: 2.04 ± 0.12 m vs CC: 2.06 ± 0.10 m, p = .021) in the maximal speed section (30-60m) were significantly increased in the CC. However, there was no significant difference in step frequency (AC: 4.58 ± 0.26 Hz vs CC: 4.57 ± 0.27 Hz, p = .595). There was no significant difference in any variables in the acceleration section (0-30m). Conclusion: These results indicate that running with a competitor improves running speed with increasing step length in the maximal speed section but does not affect performance in the acceleration section. We concluded that competition improves sprint performances in the maximal speed section.</jats:p>

The purpose of this study was to investigate the differences in sprinting movement between children with high and low sprinting ability by using observational evaluation. We analyzed the maximum sprinting speed and sprinting movements of 252 children in the 1st, the 2nd and the 3rd grades of a kindergarten, based on age group and sprinting speed. The main results were as follows:<br>
1. Analysis of variance of sprinting movement scores based on age group and sprinting speed showed that the scores for 3rd grade children were higher than those for 1st and 2nd grade children, and the scores for the groups with medium and high sprinting speed tended to be higher than those for the group with low sprinting speed. This indicates that, although rational sprinting movement can be acquired with increasing age, the better the sprinting ability of children, the more rational the sprinting movement that is acquired.<br>
2. The results for each of the evaluation items suggested that the acquisition of rational sprinting movement progressed to a certain degree with age in the “forward swing range of the elbows”, the “timing of the scissorslike leg motion” and the “foot contact aspect”. However, because some previous studies have indicated that the foot contact aspect may be affected by the overall movement of the lower limb, older children may not necessarily learn to acquire contact on the midfoot or forefoot.<br>
3. While it is expected that the subjects would become more proficient in the “flexion and extension of the elbows” and the “range of the leg motion” with increasing age, the differences among the sprinting speed groups were significant, suggesting that remaining unskilled movements may be a factor in decreasing sprinting speed regardless of age.<br>
These results suggest that the acquisition of basic movement patterns and refinement toward more purposeful movements in sprinting occur simultaneously in early childhood, and that the complex aspect of proficiency is a characteristic feature of infants' sprinting movements.

This research investigated the difference in aspects of gaze control between esports experts (Expert) and players with lower skills (Low Skill) while playing the real-time strategy game called StarCraft. Three versions of this game at different difficulty levels were made with the StarCraft Editor, and the gaze movements of seven Expert and nine Low Skill players were analyzed while they played the games. The gaze of Expert players covered a significantly larger area in the horizontal direction than the gaze of Low Skill players. Furthermore, the magnitude and number of saccadic eye movements were greater, and saccade velocity was faster in the Expert than in the Low Skill players. In conclusion, StarCraft experts have a specific gaze control ability that enables them to quickly and widely take visual information from all over the monitor. This could be one of the factors enabling StarCraft experts to perform better than players with lower skills when playing games that require task-switching ability.

When we have rehearsed a movement using an object, we can reproduce the movement without holding the object. However, the reproduced movement sometimes differs from the movement holding a real object, likely because movement recognition is inaccurate. In the present study, we tested whether the recognition capability was dissociated from the acquisition of motor skill memory. Twelve novices were asked to rotate two balls with their right hand as quickly as possible; they practiced the task for 29 days. To evaluate recognition capability, we calculated the difference in coordination pattern of all five digits between the ball-rotation movement and the reproduced movement without holding balls. The recognition capability did not change within the first day, but improved after one week of practice. On the other hand, performance of the ball rotation significantly improved within the first day. Since improvement of performance is likely associated with acquisition of motor skill memory, we suggest that recognition capability, which reflects the capability to cognitively access motor skill memory, was dissociated from the acquisition of motor skill memory. Therefore, recognition of one's own skilled movement would rely on a hierarchical structure of acquisition of motor skill memory and cognitive access to that memory.

PURPOSE: The purpose of this study was to investigate the relationship between spatiotemporal variables of running and onset/offset timing of rectus femoris (RF) and biceps femoris (BF) muscle activities in both legs. METHODS: Eighteen male well-trained athletes (age = 20.7 ± 1.8 yr) were asked to run 50 m at maximal speed. The spatiotemporal variables (running speed, step frequency, and step length) over the distance from 30 to 50 m were measured. In addition, RF and BF muscle activities were obtained from both legs using wireless EMG sensors. To quantify the onset and offset timing of muscle activity, the band-pass filtered (20-450 Hz) EMG signal was processed using a Teager-Kaiser energy operator filter. We calculated RF and BF onset/offset timings (%) in both legs (e.g., ipsilateral leg RF [iRF] and contralateral leg BF [cBF]) during running cycle. Based on those timings, we obtained the EMG timing variables (%) as follows: "Switch1 (iBF-offset to iRF-onset)," "Switch2 (iRF-offset to iBF-onset)," "Scissors1 (cBF-onset to iRF-onset)," and "Scissors2 (iRF-offset to cBF-offset). RESULTS: We found that "Switch2" had positive (r = 0.495, P = 0.037), "Scissors1" had negative (r = -0.469, P = 0.049), and "Scissors2" had positive (r = 0.574, P = 0.013) correlations with step frequency. However, these variables had no significant correlations with running speed or step length. CONCLUSIONS: These results indicate that higher step frequency would be achieved by smoother switching of the agonist-antagonist muscle activities and earlier iRF activation relative to the cBF activity. To improve sprint performance, athletes and coaches should consider not only muscle activities in one leg but also coordination of muscle activities in both legs.

In bimanual cyclical continuous movements, the relative timing of the most salient movement phase in each movement is a predominant constraint. This is the case for coordination when both movements have a single most salient phase (the relative-salience hypothesis). We tested whether the relative-salience hypothesis could explain results obtained for repetitive discrete movements, utilizing finger tapping. In experiment 1, participants performed unimanual alternate two-finger tapping with the metronome beat (i.e., one finger taps on the beat and the other finger taps off the beat). The stability of the tapping timing relative to the beat, which reflects the extent of salience, was higher in the index finger than the middle finger, and was lower in the ring finger than the middle finger. In experiment 2, participants performed four conditions of repetitive bimanual four-finger tapping (i.e., alternate two-finger tapping in each hand) without external pacing signals. Under all four conditions, a more stable pattern occurred when the timing of the more salient tapping in each hand was simultaneous rather than alternate, regardless of relative direction in the external space or movement coupling of the homologous fingers. The results indicated that bimanual four-finger tapping could be explained by the relative-salience hypothesis.

Short-term motor practice leads to plasticity in the primary motor cortex (M1). The purpose of this study is to investigate the factors that determine the increase in corticospinal tract (CST) excitability after motor practice, with special focus on two factors; “the level of muscle activity” and “the presence/absence of a goal of keeping the activity level constant.” Fifteen healthy subjects performed four types of rapid thumb adduction in separate sessions. In the “comfortable task” (C) and “forceful task” (F), the subjects adducted their thumb using comfortable and strong forces. In the “comfortable with a goal task” (CG) and “forceful with a goal task” (FG), subjects controlled the muscle activity at the same level as in the C and F, respectively, by adjusting the peak electromyographic amplitude within the target ranges. Paired associative stimulation (PAS), which combines peripheral nerve (median nerve) stimulation and transcranial magnetic stimulation (TMS), with an inter-stimulus interval of 25 ms (PAS25) was also done. Before and after the motor tasks and PAS25, TMS was applied to the M1. None of the four tasks showed any temporary changes in behavior, meaning no learning occurred. Motor-evoked potential (MEP) amplitude increased only after the FG and it exhibited a positive correlation with the MEP increase after PAS25, suggesting that FG and PAS25 share at least similar plasticity mechanisms in the M1. Resting motor threshold (RMT) decreased only after FG, suggesting that FG would also be associated with the membrane depolarization of M1 neurons. These results suggest task-dependent plasticity from the synergistic effect of forceful muscle activity and of setting a goal of keeping the activity level constant.

This paper proposes a method that can classify foot strike types using a deep learning model and can extract unknown factors, which enables to evaluate running motions without being influenced by biases of sports experts, using the contribution degree of input values (CDIV). Accelerometers are attached to the runner's body, and when the runner runs, a fixed camera observes the runner and acquires a video sequence synchronously with the accelerometers. To train a deep learning model for classifying foot strikes, we annotate foot strike acceleration data for RFS (Rearfoot strike) or non-RFS objectively by watching the video. To interpret the unknown factors extracted from the learned model, we calculate two CDIVs: the contributions of the resampling time and the accelerometer value to the output (foot strike type). Experiments on classifying unknown runners' foot strikes were conducted. As a common result to sport science, it is confirmed that the CDIVs contribute highly at the time of the right foot strike, and the sensor values corresponding to the right and left tibias contribute highly to classifying the foot strikes. Experimental results show the right tibia is important for classifying foot strikes. This is because many of the training data represent difference between the two foot strikes in the right tibia. As a conclusion, our proposed method could extract unknown factors from the classifier and could interpret the factors that contain similar knowledge to the prior knowledge of experts, as well as new findings that are not included in conventional knowledge.

The effect of the different training regimes and histories on the spatiotemporal characteristics of human running was evaluated in four groups of subjects who had different histories of engagement in running-specific training; sprinters, distance runners, active athletes, and sedentary individuals. Subjects ran at a variety of velocities, ranging from slowest to fastest, over 30 trials in a random order. Group averages of maximal running velocities, ranked from fastest to slowest, were: sprinters, distance runners, active athletes, and sedentary individuals. The velocity-cadence-step length (V-C-S) relationship, made by plotting step length against cadence at each velocity tested, was analyzed with the segmented regression method, utilizing two regression lines. In all subject groups, there was a critical velocity, defined as the inflection point, in the relationship. In the velocity ranges below and above the inflection point (slower and faster velocity ranges), velocity was modulated primarily by altering step length and by altering cadence, respectively. This pattern was commonly observed in all four groups, not only in sprinters and distance runners, as has already been reported, but also in active athletes and sedentary individuals. This pattern may reflect an energy saving strategy. When the data from all groups were combined, there were significant correlations between maximal running velocity and both running velocity and step length at the inflection point. In spite of the wide variety of athletic experience of the subjects, as well as their maximum running velocities, the inflection point appeared at a similar cadence (3.0 ± 0.2 steps/s) and at a similar relative velocity (65-70%Vmax). These results imply that the influence of running-specific training on the inflection point is minimal.

Among tennis coaches and players, the standard volley and drop volley are considered basically similar, but muscles need to be relaxed (deactivation) just at the moment of impact when hitting the drop volley. However, this is not evidence-based. The aim of this study was to clarify racket head trajectory and muscle activity during the drop volley and to compare them with those of the standard volley. We hypothesized that 1) the racket head would move less forward for the drop volley than for the standard volley and 2) the wrist and elbow muscles be relaxed for the drop volley at the time of ball impact. Eleven male college students with sufficient tennis experience volunteered to participate in this study. Wireless EMG sensors recorded activation of the four arm muscles. Each subject performed the standard volley or the drop volley with both a forehand and a backhand from a position near the net. Four high speed video cameras (300 Hz) were set up on the court to measure ball speed and racket head trajectory. Returned ball speed of the drop volley was significantly lower than that of the standard volley (p < 0.05). The racket head moved less forward than in the standard volley, supporting the first hypothesis. Muscle activity of the drop volley, just before and after ball impact for both the forehand and backhand, was lower than that of the standard volley. However, the activity was in the form of a gradual increase as impact time approached, rather than a sudden deactivation (relaxation), which did not support the second hypothesis. For the drop volley, lower muscle activity in the forearm enabled a softer grip and thus allowed a "flip" movement of the racket to diminish the speed of the returned ball.

CONTEXT: Deficits in knee position sense following reconstruction of the anterior cruciate ligament (ACL) can delay an athlete's return to sport participation and increase the risk of reinjury. Deficits in position sense postreconstruction have been evaluated using either a position-reproducing or position-matching task. OBJECTIVE: The aim of our study was to combine both to determine which assessment would be more effective to identify deficits in knee position sense. DESIGN: Longitudinal laboratory-based study. PARTICIPANTS: Eleven athletes (6 men and 5 women; mean age, 20.5 [1.2] y), who had undergone ACL reconstruction with an ipsilateral hamstring autograft, and 12 age-matched controls. INTERVENTIONS: Position sense was evaluated at 6 and 12 months postreconstruction and once for the control group. In addition, peak isokinetic knee extension and flexion strength, at 60°/s and 180°/s, was assessed for the ACL reconstruction group to evaluate possible influences of muscle strength on knee joint position sense. MAIN OUTCOME MEASURES: The variables include the angular differences between the reference limb and indicator limb, and peak torque values of isokinetic knee extension and flexion. RESULTS: Significant matching differences were identified at 6 months postsurgery on the position-matching task, but not at 12 months postsurgery. No significant between-group and within-subject differences were identified on the position-reproducing task. No significant matching errors were identified for the control group. There was no correlation between errors in position sense and maximum isokinetic strength. CONCLUSION: The position-matching task is more sensitive than the position-reproducing task to identify deficits in knee position sense over the first year following ACL reconstruction surgery.

Purpose. This study investigated the relationship between subjective effort (SE) and kinematics/kinetics throughout an entire 50 m sprint. Methods. Fifteen male sprinters performed the 50 m sprint at 3 different levels of SE (100 %SE; maximal-effort, 90 %SE and 80 %SE, sub-maximal efforts). Kinematic and kinetic data were obtained with a digital high speed camera and 50 ground reaction force (GRF) plates placed every 1 m in the running lane. Variables recorded were sprint time, running speed, step frequency, step length, aerial time, contact time, GRF, and ground reaction impulse (GRI). Results & Discussion. Sprint times decreased with increases in SE. However, some subjects ran their fastest 50m at a sub-maximal SE. Thus, the optimal combination of step length & frequency necessary for obtaining maximum speed does not necessarily occur at maximal SE. Indeed, while step frequency significantly increased with an increase in SE, step length was usually the longest at a sub-maximal SE. The vertical GRI in the first half of the ground contact period was significantly greater at sub-maximal SEs. Vertical GRIs and horizontal GRIs in the second half of the ground contact period did not significantly differ among different SEs. Our results suggest that those runners who increase SF too much at maximal SE do so at the cost of decreasing step length (SL). Thus, applying a large force against the ground in the first half of the ground contact period would be effective for improving step length.

Surface electromyography (sEMG) is widely used to analyze human movements, including athletic performance. For baseball pitchers, a very precise movement is required to pitch the ball into the strike zone. The palm muscles appear to play a key role in this movement, and a real-time recording of sEMG from the palm muscle is useful in the analysis of motion during baseball pitching. However, the currently available devices with rigid and bulky electrodes (including connective wires) impede natural movements of the wearer and recording of sEMG from the palm muscles during vigorous action. Here, we describe a skin-contact patch consisting of kirigami-based stretchable wirings and conductive polymer nanosheet-based ultraconformable bioelectrodes, which address the challenge of mechanical mismatch between human skin and electrical devices. The key strategy is a kirigami-inspired wiring design and a mechanical gradient structure from nanosheet-based flexible bioelectrodes to a bulk wearable device. This approach would buffer the mechanical stress applied to the skin-contact bioelectrodes during an arm swing movement. With this patch, we precisely measure sEMG at the abductor pollicis brevis muscle (APBM) in a baseball player during ball pitching. We observe differences in the activity of the APBM between different types of pitches-fastball and curveball. This sEMG measurement system will enable the analysis of motion in unexplored muscle areas, such as on the palm and the sole, leading to a deeper understanding of muscular activity during performance in a wide range of sports and other movements.

This study was performed to devise an instructional program for children who were not good at sprinting and to verify the program’s effectiveness for improvement of sprinting ability and motion.<br>
The participants were 19 upper grade elementary school children who were not good at sprinting. The program included 2 drills with some teaching devices and running on flat markers. The children attended the program for 8 days (2 days per week) and each lesson lasted an hour. In order to validate the program outcome, sprint time (50 m), interval speed (every 10 m), average speed, maximal speed, rate of speed decline, interval and average step frequency and step length were analyzed, and sprint motions were evaluated. The results were as follows:<br>
1) Most of the children’s 50 m times were below the national average. This suggested that their negative feelings toward sprinting resulted from the realization that they were unable to run as fast as other children.<br>
2) The children’s sprint times were improved after the program, and a significant correlation between pre-time and post-pre time was revealed. It was also found that the greater the increase in the children’s step frequency, the faster their sprint times became. These results suggest that sprinting instruction allows low-performing children to increase their step frequency and improve their sprint times.<br>
3) The main aim of the program was to improve children’s sprint motions in the mid sprint phase, and the participants practiced start motions only twice during the program. As a result, speeds from the start to 10 m, 20-50 m, and maximum speed were increased significantly by this practice, suggesting that significant changes of speed led to improvement of the sprint times.<br>
4) Participants became able to swing back their leg under their body and to make contact with the ground with the middle or front of the foot. Therefore it was considered that the drills and running on flat markers with teaching devices were valuable for improving the children’s sprint motions.<br>
5) Although the scissors-like leg motion was not improved by practice with a color board and bells, the kneefolding motion of the swing leg did appear to be improved. Therefore, the children seemed to acquire basic skill in more rapid scissors-like leg motion.<br>
These results suggest that our instructional program was effective in enabling children to improve their sprinting ability and motion. However, additional research focusing on aspects such as the relationship between sprinting ability and sprint motion, or individual feelings and motor competency in the context of sprinting, will be needed.

陸上競技の短距離種目は、他選手と競走する状況で実施される。2009年の世界陸上100m決勝で、ウサイン・ボルトとタイソン・ゲイのステップが無意識のうちに一致した(同調現象)ことで、お互いのパフォーマンスが増長した可能性が示唆されている。そこで本研究では単独走と競走という条件設定の違いが走速度、ピッチ、ストライドに及ぼす影響を調べることを目的とした。被験者は短距離走を専門とする大学生26人とした。被験者はクラウチングスタートから60m走を1人で走る条件（単独走）と2人で走る条件（競走）をランダムに実施した。解析は加速局面(0-30m)と最高走速度局面(30-60m)に分けて行った。最高走速度局面では、走速度およびストライドが競走において有意に大きかった (p<0.01)。一方、加速局面では、走速度が競走において有意に大きかった(p<0.05)。いずれの局面においても「競走する」ことが走速度の向上に貢献する、つまりパフォーマンスの向上に繋がる可能性が示唆された。しかし、競走によるストライドへの影響は加速局面と最高走速度局面とでは異なることが示唆された。

The object of this study was to clarify how the motor imagery of foot muscle relaxation influences corticospinal excitability for the ipsilateral hand. Twelve participants volitionally relaxed their right foot from a dorsiflexed position (actual relaxation), or imaged the same movement (imagery relaxation) in response to an auditory cue. Transcranial magnetic stimulation (TMS) was delivered to the hand area of the left primary motor cortex at different time intervals after an auditory cue. Motor evoked potentials (MEPs) were recorded from the right extensor carpi radialis (ECR) and flexor carpi radialis (FCR). MEP amplitudes of ECR and FCR caused by single-pulse TMS temporarily decreased during both actual relaxation and imagery relaxation as compared with those of the resting control. A correlation of MEP amplitude between actual relaxation and imagery relaxation was observed. Our findings indicate that motor imagery of muscle relaxation of the foot induced a reduction of corticospinal excitability in the ipsilateral hand muscles. This effect is likely produced via the same mechanism that functions during actual muscle relaxation.

© 2018, International Society of Musculoskeletal and Neuronal Interactions. All rights reserved. Objective: Motor-related cortical potentials (MRCP) often compared separated muscle activations; however, MRCP preceding combined contraction onsets and relaxation offsets of one consecutive motor task sequence remain to be elucidated. Methods: Twelve healthy males (27.92±4.33 years, 181.83±7.15 cm, 84.58±7.15 kg) performed 40 submaximal isometric right-limb wrist flexions (i.e. motor task sequences). Each motor task sequence combined timed contractions to and relaxations from distinct torque levels, i.e. 20% and 40% of maximum voluntary contractions (MVC). Synchronized continuous EEG (32 Ag/AgCl-electrodes mounted over motor-related areas) and EMG (i.e. flexor carpi radialis, FCR) recordings served to detect torque level-on/offsets for MRCP analyses. Results: Motor task sequences were accurately maintained with participants’ mean values of FCR muscle activity revealing no signs of fatigue (p > 0.05). Main findings (i.e. readiness potential) were larger amplitudes over frontal electrode sites (p < 0.05) preceding contractions compared to relaxations, whereas amplitudes were larger (i.e. peak) over centro-parietal electrode sites (p < 0.05) preceding 40% compared to 20% MVC. Conclusion: When performed in one consecutive motor task sequence, controlling the production as well as the releasing of force may require similar proprioceptive and visuo-motor processing preceding the same force level (i.e. 20% or 40%); however, this is irrespective of the muscle activation type (i.e. contraction or relaxation).

The effect of cerebellar transcranial direct current stimulation (tDCS) on motor performance remains controversial. Some studies suggest that the effect of tDCS depends upon task-difficulty and individual level of task performance. Here, we investigated whether the effect of cerebellar tDCS on the motor performance depends upon the individual's level of performance. Twenty-four naïve participants practiced dart throwing while receiving a 2-mA cerebellar tDCS for 20 min under three stimulus conditions (anodal-, cathodal-, and sham-tDCS) on separate days with a double-blind, counter-balanced cross-over design. Task performance was assessed by measuring the distance between the center of the bull's eye and the dart's position. Although task performance tended to improve throughout the practice under all stimulus conditions, improvement within a given day was not significant as compared to the first no-stimulus block. In addition, improvement did not differ among stimulation conditions. However, the magnitude of improvement was associated with an individual's level of task performance only under cathodal tDCS condition (p &lt
0.05). This resulted in a significant performance improvement only for the sub-group of participants with lower performance levels as compared to that with sham-tDCS (p &lt
0.05). These findings suggest that the facilitation effect of cerebellar cathodal tDCS on motor skill learning of complex whole-body movements depends on the level of an individual's task performance. Thus, cerebellar tDCS would facilitate learning of a complex motor skill task only in a subset of individuals.

We recently reported that wearing unstable rocker shoes (Masai Barefoot Technology: MBT) may enhance recovery from marathon race-induced fatigue. However, this earlier study only utilized a questionnaire. In this study, we evaluated MBT utilizing objective physiological measures of recovery from marathon-induced muscle damages. Twenty-five university student novice runners were divided into two groups. After running a full marathon, one group wore MBT shoes (MBT group), and the control group (CON) wore ordinary shoes daily for 1 week following the race. We measured maximal isometric joint torque, muscle hardness (real time tissue elastography of the strain ratio) in the lower limb muscles before, immediately after, and 1, 3, and 8 days following the marathon. We calculated the magnitude of recovery by observing the difference in each value between the first measurement and the latter measurements. Results showed that isometric torques in knee flexion recovered at the first day after the race in the MBT group while it did not recover even at the eighth day in the CON group. Muscle hardness in the gastrocnemius and vastus lateralis showed enhanced recovery in the MBT group in comparison with the CON group. Also for muscle hardness in the tibialis anterior and biceps femoris, the timing of recovery was delayed in the CON group. In conclusion, wearing MBT shoes enhanced recovery in lower leg and thigh muscles from muscle damage induced by marathon running.

本研究は、小学生児童における走運動の接地タイプの実態とその接地タイプ（踵接地、水平接地、つま先接地）が最大速度、ステップ頻度指数、ステップ長指数、接地時間、滞空時間にどのように影響するかを明らかにすることを目的とした。小学校で実施される体力テストの50m走に参加した男子児童352名と女子児童334名の走パフォーマンスをカメラで記録した画像から分析した。男女共に踵接地タイプの割合が最も大きく、水平接地タイプ、つま先接地タイプの順に割合は小さくなっていった。男子児童においては、水平接地タイプおよびつま先接地タイプの最大速度の残差とステップ頻度指数はそれぞれ踵接地タイプよりも有意に高かった。女子児童においては、水平接地タイプのステップ頻度指数は踵接地タイプよりも有意に高く、つま先接地タイプのステップ長指数は水平接地タイプおよび踵接地タイプよりも有意に高かった。本研究の結果から、接地タイプによって接地時間や滞空時間が異なることや接地までの脚動作がステップ頻度やステップ長に影響することが示唆された。

<p> 【目的】スプリントにおける股関節筋の筋活動の特徴を明らかにすることを目的とした。【方法】被験者は男子陸上競技短距離選手18名であった。最大努力による50m走中の大腿直筋（RF）と大腿二頭筋（BF）の表面筋電図を取得した。接地からその脚が再び接地する直前までを走の1サイクルとし、測定区間（20m）に要した8～10歩（4～5サイクル）を分析対象とした。筋電データはそれぞれのサイクル時間に合わせて規格化した。そして1サイクルにおけるRFおよびBFの活動タイミングおよび走速度とのピアソンの積率相関係数をそれぞれ算出した。【結果】走速度は9.88 ± 0.6m/s（最大値：10.99 m/s、最小値：9.30 m/s）であった。走速度の高い選手は、離地時にBFの活動が終了するタイミングが早く（r = 0.553）、スウィング期においてRFが活動し始めるタイミング（r = 0.637）とそれが終了するタイミングが早かった（r = 0.527）。さらに、スウィング期後半でBFが活動し始めるタイミングも走速度の高い選手ほど早かった（r = 0.621）。【結論】走速度の高い選手は、1サイクルにおいて股関節筋であるRFおよびBFの活動タイミングが早いことが示唆された。</p>

The object of this study was to clarify whether corticospinal excitability controlling hand muscles changes concurrently with increases in the imagined contraction level of foot dorsiflexion. Twelve participants performed actual and imagined dorsiflexion of their right foot at three different EMG levels (10, 40 or 80% of the maximum voluntary contraction). During isometric actual- or imagined- dorsiflexion, transcranial magnetic stimulation (TMS) was delivered to the right hand area of the left primary motor cortex. Motor evoked potentials (MEPs) were recorded from the right extensor carpi radialis (ECR) and flexor carpi radialis (FCR). During actual contraction, MEP amplitudes of ECR and FCR increased with an increased EMG level of dorsiflexion. Similarly, during imagery contraction, MEP amplitudes of ECR and FCR increased with the intensity of imagery contraction. Furthermore, a correlation between MEP amplitude during actual contraction and imagery contraction was observed for both ECR and FCR. Motor imagery of foot contraction induced an enhancement of corticospinal excitability for hand muscles that was dependent on the imagined contraction levels, just as what was observed when there was an actual contraction.

Background: A better understanding of the neural mechanisms that underlie the development of fear of falling (FoF) in seniors may help to detect potential treatable factors and reduce future falls. We therefore investigate the neural correlates of FoF in older adults using 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET).
Methods: This cohort study included 117 community-dwelling older adults. At baseline, participants were assessed for FoF, psychiatric symptoms, walking speed, global cognition and cerebral glucose metabolism with FDG-PET. The incidence of FoF in the participants who did not report FoF (N-FoF) at baseline was again ascertained 2 years later. FDG uptake was compared between the FoF and non-FoF groups. Logistic regression analyses to examine the predictors of newly developed FoF (D-FoF) using normalized regional FDG uptake were then performed.
Results: At baseline, 50.4% (n = 59) of participants had FoF. The FoF group had significantly decreased glucose metabolism in the left superior frontal gyrus (supplementary motor area, SMA; BA6) compared to the non-FoF group. After 2 years, 19 out of the 58 participants in the non-FoF group developed FoF. Logistic regression analysis revealed that decreased cerebral glucose metabolism in the left SMA at the baseline was a significant predictor of the future development of FoF, independently of psychiatric symptoms and walking speed.
Conclusion: In healthy older adults, hypometabolism in the left SMA, which is involved in motor planning and motor coordination, contributes to the development of FoF. Our result might help elucidate underlying mechanism of the association between deficits in motor control and FoF.

Objective: Low frequency of going outdoors (e.g. being homebound) is associated with depressive mood; however, the underlying neural mechanism of this association is unclear. We therefore investigated the neural substrate involved in the relationship between frequency of going outdoors and depressive mood using positron emission tomography (PET), focusing on the frontal lobe and the limbic system.
Methods: One hundred fifty-eight community-dwelling older adults aged 65-85 years underwent PET with F-18-fluorodeoxyglucose to evaluate regional cerebral metabolic rates of glucose normalized in reference to cerebellar glucose metabolic value (normalized-rCMRglc) in six regions of interest. We also assessed depressive mood, frequency of going outdoors, and potential covariates. Depressive mood was assessed using the Geriatric Depression Scale (GDS).
Results: The proportion of participants who reported low frequency of going outdoors (LG, every 2-3days or less) was 36.1%. The LG group showed significantly higher GDS scores than those who reported high (once a day or more) frequency of going outdoors. A multiple linear regression analysis adjusted for potential covariates showed higher GDS scores were associated with lower normalized-rCMRglc in the ventrolateral prefrontal and orbitofrontal cortices. Adjusting for frequency of going outdoors, the association between GDS score and normalized-rCMRglc in the orbitofrontal cortex was attenuated.
Conclusions: Our results suggest that the orbitofrontal cortex may mediate the relationship between low frequency of going outdoors and depressive mood among community-dwelling older adults. These findings may help disentangle the role of going outdoors in regulating brain function to improve and/ormaintain mental health among community-dwelling older adults. Copyright (C) 2016 John Wiley & Sons, Ltd.

Research on motor behavioural processes preceding voluntary movements often refers to analysing the readiness potential (RP). For this, decades of studies used laboratory setups with controlled sports-related actions. Further, recent applied approaches focus on athlete non-athlete comparisons, omitting possible effects of training history on RP. However, RP preceding real sport-specific movements in accordance to skill acquisition remains to be elucidated.
Therefore, after familiarization 16 right-handed males with no experience in archery volunteered to perform repeated sports-specific movements, i.e. 40 arrow-releasing shots at 60 s rest on a 15 m distant standard target. Continuous, synchronised EEG and right limb EMG recordings during arrow-releasing served to detect movement onsets for RP analyses over distinct cortical motor areas. Based on attained scores on target, archery novices were, a posteriori, subdivided into a skilled and less skilled group. EMG results for mean values revealed no significant changes (all p &gt; 0.05), whereas RP amplitudes and onsets differed between groups but not between motor areas. Arrow-releasing preceded larger RP amplitudes (p &lt; 0.05) and later RP onsets (p &lt; 0.05) in skilled compared to less skilled novices. We suggest this to reflect attentional orienting and greater effort that accompanies central neuronal preparatory states of a sports-specific movement. (C) 2017 Elsevier B.V. All rights reserved.

Motor imagery can be divided into kinesthetic and visual aspects. In the present study, we investigated excitability in the corticospinal tract and primary visual cortex (V1) during kinesthetic and visual motor imagery. To accomplish this, we measured motor evoked potentials (MEPs) and probability of phosphene occurrence during the two types of motor imageries of finger tapping. The MEPs and phosphenes were induced by transcranial magnetic stimulation to the primary motor cortex and V1, respectively. The amplitudes of MEPs and probability of phosphene occurrence during motor imagery were normalized based on the values obtained at rest. Corticospinal excitability increased during both kinesthetic and visual motor imagery, while excitability in V1 was increased only during visual motor imagery. These results imply that modulation of cortical excitability during kinesthetic and visual motor imagery is task dependent. The present finding aids in the understanding of the neural mechanisms underlying motor imagery and provides useful information for the use of motor imagery in rehabilitation or motor imagery training. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

Motor imagery can be divided into kinesthetic and visual aspects. In the present study, we investigated excitability in the corticospinal tract and primary visual cortex (V1) during kinesthetic and visual motor imagery. To accomplish this, we measured motor evoked potentials (MEPs) and probability of phosphene occurrence during the two types of motor imageries of finger tapping. The MEPs and phosphenes were induced by transcranial magnetic stimulation to the primary motor cortex and V1, respectively. The amplitudes of MEPs and probability of phosphene occurrence during motor imagery were normalized based on the values obtained at rest. Corticospinal excitability increased during both kinesthetic and visual motor imagery, while excitability in V1 was increased only during visual motor imagery. These results imply that modulation of cortical excitability during kinesthetic and visual motor imagery is task dependent. The present finding aids in the understanding of the neural mechanisms underlying motor imagery and provides useful information for the use of motor imagery in rehabilitation or motor imagery training. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

We investigated the effects of foot muscle relaxation and contraction on muscle activities in the hand on both ipsilateral and contralateral sides. The subjects sat in an armchair with hands in the pronated position. They were able to freely move their right/left hand and foot. They performed three tasks for both ipsilateral (right hand and right foot) and contralateral limb coordination (left hand and right foot for a total of six tasks). These tasks involved: (1) wrist extension from a flexed (resting) position, (2) wrist extension with simultaneous ankle dorsiflexion from a plantarflexed (resting) position, and (3) wrist extension with simultaneous ankle relaxation from a dorsiflexed position. The subjects performed each task as fast as possible after hearing the start signal. Reaction time for the wrist extensor contraction (i.e. the degree to which it preceded the motor reaction time), as observed in electromyography (EMG), became longer when it was concurrently done with relaxation of the ankle dorsiflexor. Also, the magnitude of EMG activity became smaller, as compared with activity when wrist extensor contraction was done alone or with contraction of the ankle dorsiflexor. These effects were observed not only for the ipsilateral hand, but also for the contralateral hand. Our findings suggest that muscle relaxation in one limb interferes with muscle contraction in both the ipsilateral and contralateral limbs.

Periodic interlimb coordination shows lower performance when the ipsilateral hand and foot (e.g., right hand and right foot) are simultaneously moved than when the contralateral hand and foot (e.g., right hand and left foot) are simultaneously moved. The present study aimed to investigate how brain activity that is related to the dependence of hand-foot coordination on limb combination, using functional magnetic imaging. Twenty-one right-handed subjects performed periodic coordinated movements of the ipsilateral or contralateral hand and foot in the same or opposite direction in the sagittal plane. Kinematic data showed that performance was lower for the ipsilateral hand-foot coordination than for the contralateral one. A comparison of brain activity between the same and opposite directions showed that there was a greater activation of supplementary motor area for ipsilateral hand-foot coordination as compared to that seen during contralateral hand-foot coordination. We speculate that this might reflect a difference in the degree of inhibition of the neural circuit that disrupts opposite directional movements between ipsilateral and contralateral hand-foot coordinated movements.

Periodic interlimb coordination shows lower performance when the ipsilateral hand and foot (e.g., right hand and right foot) are simultaneously moved than when the contralateral hand and foot (e.g., right hand and left foot) are simultaneously moved. The present study aimed to investigate how brain activity that is related to the dependence of hand-foot coordination on limb combination, using functional magnetic imaging. Twenty-one right-handed subjects performed periodic coordinated movements of the ipsilateral or contralateral hand and foot in the same or opposite direction in the sagittal plane. Kinematic data showed that performance was lower for the ipsilateral hand-foot coordination than for the contralateral one. A comparison of brain activity between the same and opposite directions showed that there was a greater activation of supplementary motor area for ipsilateral hand-foot coordination as compared to that seen during contralateral hand-foot coordination. We speculate that this might reflect a difference in the degree of inhibition of the neural circuit that disrupts opposite directional movements between ipsilateral and contralateral hand-foot coordinated movements.

We investigated the effects of foot muscle relaxation and contraction on muscle activities in the hand on both ipsilateral and contralateral sides. The subjects sat in an armchair with hands in the pronated position. They were able to freely move their right/left hand and foot. They performed three tasks for both ipsilateral (right hand and right foot) and contralateral limb coordination (left hand and right foot fora total of six tasks). These tasks involved: (1) wrist extension from a flexed (resting) position, (2) wrist extension with simultaneous ankle dorsiflexion from a plantarflexed (resting) position, and (3) wrist extension with simultaneous ankle relaxation from a dorsiflexed position. The subjects performed each task as fast as possible after hearing the start signal. Reaction time for the wrist extensor contraction (i.e. the degree to which it preceded the motor reaction time), as observed in electromyography (EMG), became longer when it was concurrently done with relaxation of the ankle dorsiflexor. Also, the magnitude of EMG activity became smaller, as compared with activity when wrist extensor contraction was done alone or with contraction of the ankle dorsiflexor. These effects were observed not only for the ipsilateral hand, but also for the contralateral hand. Our findings suggest that muscle relaxation in one limb interferes with muscle contraction in both the ipsilateral and contralateral limbs. (C) 2016 Elsevier Ireland Ltd. All rights reserved.

A growing body of literature indicates that cognitively intact older adults tend to overestimate their physical functioning (e.g., step-over ability), which may lead to fall risk. However, the neural correlates underlying this phenomenon are still unclear. We therefore investigated the neural basis of older adults' self-overestimation of stepping-over ability. A total of 108 well-functioning community dwelling older adults (mean age = 73.9 years) performed step-over tests (SOT) in two ways: self-estimation of step-over ability and an actual step-over task. During the self-estimation task, participants observed a horizontal bar at a distance of 7 m and estimated the maximum height (EH) of successful SOT trials. The actual SOT was then performed to determine the actual maximum height (AH) of successful trials. Participants also underwent positron emission tomography with F-18-fluorodeoxyglucose at rest to assess cerebral neural activity. The SOT showed that 22.2 % of participants overestimated their step-over ability. A regression analysis adjusted for potential covariates showed that increased self-estimation error (difference between EH and AH) was correlated with lower glucose metabolism in the bilateral orbitofrontal cortex (OFC) and left frontal pole. Only the significant correlation between self-estimation error and OFC activity persisted after correcting for multiple comparisons. For well-functioning healthy older adults, overlooking one's own functional decline may be influenced by reduced metabolic activity in the anterior prefrontal cortex, particularly in the OFC. Our findings also suggest that functional decline in the OFC prevents older adults from updating the qualitative/quantitative values of their impaired physical abilities.

Smooth social interactions require a deep understanding of others' intentions and feelings. In the present study, to investigate brain regions that respond to inference of others' effort level, we recorded brain activity during action observation of different effort levels using functional magnetic resonance imaging (fMRI). We used a dumbbell curl movement to depict a movement requiring effort. To dissociate the factors of effort level of the actor and weight of the dumbbell, we used four combinations of dumbbell weight and actor physique: a thin actor or a built actor lifting a heavy or light dumbbell. During observation of dumbbell curls, the bilateral front-parietal action observation network (AON) was activated. This included the premotor cortices, parietal cortices, visual areas 5/superior temporal cortices (STS), amygdalae, hippocampi, right dorsolateral and ventrolateral frontal cortices. When we evaluated brain regions associated with the actor's effort level, activity in the right temporoparietal junction (TPJ) and STS was observed. However, activity in the front-parietal AON was independent of the actor's effort during action observation. This finding suggests that the right TPJ and STS play an important role in the inference of others' effort levels during the observation of others' movements.

The object of this study was to clarify the effects of foot muscle relaxation on activity in the primary motor cortex (M1) of the hand area. Subjects were asked to volitionally relax the right foot from sustained contraction of either the dorsiflexor (tibialis anterior
TA relaxation) or plantarflexor (soleus
SOL relaxation) in response to an auditory stimulus. Single- and paired-pulse transcranial magnetic stimulation (TMS) was delivered to the hand area of the left M1 at different time intervals before and after the onset of TA or SOL relaxation. Motor evoked potentials (MEPs) were recorded from the right extensor carpi radialis (ECR) and flexor carpi radialis (FCR). MEP amplitudes of ECR and FCR caused by single-pulse TMS temporarily decreased after TA and SOL relaxation onset, respectively, d as compared with those of the resting control. Furthermore, short-interval intracortical inhibition (SICI) of ECR evaluated with paired-pulse TMS temporarily increased after TA relaxation onset. Our findings indicate that muscle relaxation of the dorsiflexor reduced corticospinal excitability of the ipsilateral hand muscles. This is most likely caused by an increase in intracortical inhibition.

Although the lift force (F-L) on a spinning baseball has been analyzed in previous studies, no study has analyzed such forces over a wide variety of spins. The purpose of this study was to describe the relationship between F-L and spin for different types of pitches thrown by collegiate pitchers. Four high-speed video cameras were used to record flight trajectory and spin for 7 types of pitches. A total of 75 pitches were analyzed. The linear kinematics of the ball was determined at 0.008-s intervals during the flight, and the resultant fluid force acting on the ball was calculated with an inverse dynamics approach. The initial angular velocity of the ball was determined using a custom-made apparatus. Equations were derived to estimate the F-L using the effective spin parameter (ESp), which is a spin parameter calculated using a component of angular velocity of the ball with the exception of the gyro-component. The results indicate that F-L could be accurately explained from ESp and also that seam orientation (4-seam or 2-seam) did not produce a uniform effect on estimating F-L from ESp.

The contribution of visual information about a pitched ball to the accuracy of baseball-bat contact may vary depending on the part of trajectory seen. The purpose of the present study was to examine the relationship between hitting accuracy and the segment of the trajectory of the flying ball that can be seen by the batter. Ten college baseball field players participated in the study. The systematic error and standardized variability of ball-bat contact on the bat coordinate system and pitcher-to-catcher direction when hitting a ball launched from a pitching machine were measured with or without visual occlusion and analyzed using analysis of variance. The visual occlusion timing included occlusion from 150 milliseconds (ms) after the ball release (R+150), occlusion from 150 ms before the expected arrival of the launched ball at the home plate (A-150), and a condition with no occlusion (NO). Twelve trials in each condition were performed using two ball speeds (31.9 m.s(-1) and 40.3 m.s(-1)). Visual occlusion did not affect the mean location of ball-bat contact in the bat's long axis, short axis, and pitcher-to-catcher directions. Although the magnitude of standardized variability was significantly smaller in the bat's short axis direction than in the bat's long axis and pitcher-to-catcher directions (p &lt; 0.001), additional visible time from the R+150 condition to the A-150 and NO conditions resulted in a further decrease in standardized variability only in the bat's short axis direction (p &lt; 0.05). The results suggested that there is directional specificity in the magnitude of standardized variability with different visible time. The present study also confirmed the limitation to visual information is the later part of the ball trajectory for improving hitting accuracy, which is likely due to visuo-motor delay.

To elucidate the neural substrate associated with capabilities for kinesthetic motor imagery of difficult wholebody movements, we measured brain activity during a trial involving both kinesthetic motor imagery and action observation as well as during a trial with action observation alone. Brain activity was assessed with functional magnetic resonance imaging (fMRI). Nineteen participants imagined three types of whole-body movements with the horizontal bar: the giant swing, kip, and chin-up during action observation. No participant had previously tried to perform the giant swing. The vividness of kinesthetic motor imagery as assessed by questionnaire was highest for the chin-up, less for the kip and lowest for the giant swing. Activity in the primary visual cortex (V1) during kinesthetic motor imagery with action observation minus that during action observation alone was significantly greater in the giant swing condition than in the chin-up condition within participants. Across participants, V1 activity of kinesthetic motor imagery of the kip during action observation minus that during action observation alone was negatively correlated with vividness of the kip imagery. These results suggest that activity in V1 is dependent upon the capability of kinesthetic motor imagery for difficult whole-body movements. Since V1 activity is likely related to the creation of a visual image, we speculate that visual motor imagery is recruited unintentionally for the less vivid kinesthetic motor imagery of difficult whole-body movements. (C) 2015 The Authors. Published by Elsevier Ltd. on behalf of IBRO. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

In this study, we analyzed the kinematic characteristics of various types of baseball pitches by elite baseball pitchers, and tested a null hypothesis that &ldquo;no type of pitch has the same kinematic characteristics as another.&rdquo;<br>  A high-speed video camera was used to record the initial trajectory of the pitched ball thrown by 84 skilled baseball pitchers. Each pitcher was asked to throw all the different types of pitch he would use in competition and practice, and to self-declare the type of pitch used for each throw. The kinematic characteristics of each pitched ball were analyzed as ball speed, the direction of the spin axis, and the spin rate. A custom-made device was used to analyze the direction of the spin axis and the spin rate, and the ball speed was measured with a radar gun. One-way ANOVA with the Games-Howell post hoc test was used to test the hypothesis.<br>  The total of 364 pitches were categorized into 11 self-declared pitch types. Four of 10 pitch types thrown by more than one pitcher - the four-seam fastball, slider, curveball and cutter - had unique kinematic characteristic distinct from all of the other pitch types. No significant differences were found in any of the kinematic parameters between 1) changeup and sinker, 2) forkball and split-fingered fastball, and 3) two-seam fastball and shoot ball. Therefore, the hypothesis was retained for these 3 pairs of pitch types: although they were kinematically similar, the pitchers categorized them as different types.<br>  When the breaking ball was compared with the four-seam fastball, they were classifiable into 3 types: 1) pitches with a slower ball speed and lower spin rate with a different direction of spin axis (changeup, sinker, forkball and split-fingered fastball), 2) pitches with a slower ball speed, different direction of the spin axis and a spin rate comparable to the four-seam fastball (slider, curveball and cutter), and 3) pitches with a comparable ball speed, similar spin axis direction, and lower spin rate (two-seam fastball and shoot ball). These data revealed that the kinematic characteristics of some pitch types are quite different from those described in baseball coaching handbooks.<br>

<p>During coordination of the movement of two limbs, the movements often interfere with each other, i.e., interlimb coordination is constrained. Many movement-related parameters such as movement direction, movement frequency, the coupling of limbs, neural network among limbs, and muscle homology are considered constraints of interlimb coordination, and they are roughly consolidated into two constraints, a neuromuscular constraint, and a perceptual-cognitive constraint. Interlimb coordination is considered to be governed by a coalition of neuromuscular and perceptual-cognitive constraints. On the other hand, spontaneous interlimb coordination is considered purely perceptual in nature. In this review, we focused on an influential study on interlimb coordination published in Nature by Mechsner et al. (2001), which supported the latter psychological approach. Thorough verification of the paper with reference to related studies revealed that no studies have yet proposed decisive contrary evidence against the psychological approach. Rather, investigation of interlimb coordination with perceptual-cognitive perspective has uncovered new findings. As a next psychological approach, the proposal of a unified and predictive explanation for movements is required. In addition, neural mechanisms that connect perceptual-cognitive representation to an appropriate motor command, if any, should be addressed.</p>

<p> 人の自由走行時のステップ長とケイデンスは代謝が最小になるものであると考えられている（Cavanagh et al. 1992）。それらの研究は長距離選手が対象である。長距離選手においては、効率的な動作を獲得した結果、代謝が少ない可能性があり、一般人でも同様かは不明である。そこで、走動作の変化が代謝に及ぼす影響を、ケイデンスを変化させた際の長距離選手と一般人の代謝を比較することで検討した。対象は長距離選手男性10名と、数分間継続して走行できる体力を有する一般男性10名である。測定は1日目にトレッドミルを用いて運動負荷試験を行い、60％ HRreserveになる運動強度を決定した。2日目の測定ではトレッドミルの自由走行に加え、自由走行時のケイデンスから± 10％増減させたケイデンスをメトロノームで指示して走行させた。解析の結果、一般人では自由走行時に最も少ない代謝を示した。長距離選手ではケイデンス減少試行において代謝がより高くなる傾向が見られた。以上の事から一般人においても自分が身に付けている走動作では、自由なケイデンスが最も代謝が低くなると考えられる。</p>

<p> 運動イメージを用いたトレーニングは運動スキルを向上させることできる。運動イメージは筋感覚的運動イメージと視覚的運動イメージに分けることができるが、2種類のイメージ中の第一次運動野と第一次視覚野の興奮性を同時に検討した研究はない。そこで、本研究は14名の被験者を対象に、筋感覚的および視覚的運動イメージ中の第一次視覚野の興奮性を経頭蓋磁気刺激によって誘発されるphospheneの出現確率によって評価した。第一次運動野の興奮性は運動誘発電位の振幅から評価した。イメージする動作は指タッピングとした。その結果、視覚的運動イメージ中には第一次視覚野および第一次運動野の興奮性が安静時と比較して増大した。しかし、筋感覚的運動イメージ中には第一次運動野の興奮性のみしか増大しなかった[交互作用(イメージのモダリティ×脳部位):p<0.05]。これらの結果は、2つのモダリティの運動イメージによって増大する皮質興奮性は非対称的であることを示している。運動イメージ中の神経メカニズムを明らかにすることはより効果的なイメージトレーニング法の開発につながる。</p>

We investigated the weight transferring aspect of gait pattern during treadmill walking and muscle strength of the knee extensors and flexors following unilateral anterior cruciate ligament (ACL) reconstruction surgery. At 6 and 12 postoperative months, 11 patients (six men, five women) walked on a split-belt treadmill with two embedded force plates at their preferred speeds, 20% slower and 20% faster. Seventeen healthy control subjects (nine men, eight women) were also evaluated. Peak values of three components of ground reaction force (vertical, anteroposterior, and mediolateral) were measured bilaterally, and their variabilities were analyzed by coefficients of variation (CVs). The CVs for the anteroposterior forces differed between the reconstructed and contralateral limbs at 6 postoperative months, and this difference disappeared at 12 months. This was not matched by the time course change of quadriceps strength since quadriceps weakness in the reconstructed limb persisted up to 12 months postoperative. These findings suggest that gait alteration in anteroposterior forces may not be caused by quadriceps weakness alone, and the reconstructed and contralateral limbs may compensate for gait execution over the first year following ACL reconstruction surgery.

This paper presents a novel sports training system. We developed a visual real-time feedback system that directly transmits a bird's eye view from a drone camera to a player's eyes. Individual physical ability, experience and intuition is important; however, in team sports such as baseball, football and volleyball, players need to perform spatial cognition such that they immediately understand where they, their teammates and their opponents are on the field as if they could see it from a bird's eye view. The objective is to validate the feasibility of the bird's eye view feedback system. In an experiment, nine participants moved and stood between two experimenters as a cut-off man with or without the system. Using the system produced significantly less error than with no system (p < 0.05). In conclusion, this bird's eye view feedback system can improve human spatial cognition.

The objective of this study was to clarify the temporal change of muscle activity during relaxation of ipsilateral remote muscles. While participants maintained a constant right wrist extensor isometric force, they dorsiflexed the ipsilateral ankle from resting position or relaxed from dorsiflexed position in response to an audio signal. The wrist extensor force magnitude increased in the 0–400 msec period after the onset of foot contraction compared to that of the resting condition (P &lt
 0.05). On the other hand, wrist extensor force magnitude and electromyographic (EMG) activity decreased in the 0–400 msec period after the onset of ankle dorsiflexion compared to that of the resting condition (P &lt
 0.05). Our findings suggest that foot muscle relaxation induces temporal reduction in hand muscle EMG activity and force magnitude.

We investigated how corticospinal excitability of the resting digit muscles was modulated by the digit movement in the ipsilateral limb. Subjects performed cyclical extension-flexion movements of either the right toes or fingers. To determine whether corticospinal excitability of the resting digit muscles was modulated on the basis of movement direction or action coupling between ipsilateral digits, the right forearm was maintained in either the pronated or supinated position. During the movement, the motor evoked potential (MEP) elicited by transcranial magnetic stimulation (TMS) was measured from either the resting right finger extensor and flexor, or toe extensor and flexor. For both finger and toe muscles, independent of forearm position. MEP amplitude of the flexor was greater during ipsilateral digit flexion as compared to extension, and MEP amplitude of the extensor was greater during ipsilateral digit extension as compared to flexion. An exception was that MEP amplitude of the toe flexor with the supinated forearm did not differ between during finger extension and flexion. These findings suggest that digit movement modulates corticospinal excitability of the digits of the ipsilateral limb such that the same action is preferred. Our results provide evidence for a better understanding of neural interactions between ipsilateral limbs, and may thus contribute to neurorehabilitation after a stroke or incomplete spinal cord injury.

It has been speculated that the control of core temperature is modulated by physiological demands. We could not prove the modulation because we did not have a good method to evaluate the control. In the present study, the control of core temperature in mice was assessed by exposing them to various ambient temperatures (T-a), and the influence of circadian rhythm and feeding condition was evaluated. Male ICR mice (n=20) were placed in a box where T-a was increased or decreased from 27 degrees C to 40 degrees C or to -4 degrees C (0.15 degrees C/min) at 0800 and 2000 (daytime and nighttime, respectively). Intra-abdominal temperature (T-core) was monitored by telemetry. The relationship between T-core and T-a was assessed. The range of T-a where T-core was relatively stable (range of normothermia, RNT) and T-core corresponding to the RNT median (regulated T-core) were estimated by model analysis. In fed mice, the regression slope within the RNT was smaller in the nighttime than in the daytime (0.02 and 0.06, respectively), and the regulated T-core was higher in the nighttime than in the daytime (37.5 degrees C and 36.0 degrees C, respectively). In the fasted mice, the slope remained unchanged, and the regulated T-core decreased in the nighttime (0.05 and 35.9 degrees C, respectively), while the slopes in the daytime became greater (0.13). Without the estimating individual thermoregulatory response such as metabolic heat production and skin vasodilation, the analysis of the T-a-T-core relationship could describe the character of the core temperature control. The present results show that the character of the system changes depending on time of day and feeding conditions. (C) 2015 Elsevier Ltd. All rights reserved.

In a variety of sports activities and in our daily lives, we utilize locomotory movements such as walking and running. It is well understood that maintaining and improving their function can be of major significance in the acquisition of a better sports performances and a more fulfilling life. To facilitate appropriate changes in performance, it is essential to know the basic mechanisms underlying them. In the case of the basiclocomotory movements, their neuronal control mechanisms are predominantly automatic and quite different from those that underlie voluntarily-induced movements. A number of studies in the last several decades have described the characteristic features and responsible mechanisms in both animals and humans. On the basis of the knowledgeobtainedin these studies, this chapter will review the recently acquired knowledge to elucidate the neural mechanisms underlying execution of locomotion movements and provide information for construction of possible intervention for improvement in their performance.

When performing intra- or inter-person coordination of cyclical movements of two joints, there is a perceptual-cognitive constraint based on spatial information for performing such coordination. However, bimanual coordination of the index finger flexion-extension is an exception in which the constraint occurs based on motoric information, which might be peculiar to digits. In order to investigate whether intra- and inter-person coordination of fingers and toes were constrained based on spatial or motoric information, coordinated movements were performed in one of two modes, flexing fingers concomitant with either toe flexion or toe extension, with the forearm either in the pronated or supinated position. In intra-person coordination, both the relative direction of movement and activation coupling influenced the stability of coordination toa similar extent. In inter-person coordination, the coordination with alternate activation of the corresponding muscles of fingers and toes in the opposite direction was less stable as compared to other coordination modes. These findings suggest that both spatial and motoric information are utilized in intra-person coordination of the fingersand toes, whereas either spatial or motoric information is utilized in inter-person coordination to meet a specific requirement for each task.

The aim of this study was to clarify the relationship between maximal running speed, step frequency, step frequency index, step length, step length index, foot contact time, and aerial time during sprinting in elementary school children. The participants were 335 girls and 352 boys (age: 6 to 12 years) who ran a 50-m sprint race as part of their school fitness test in 2013. Their maximal running speed, step frequency, and step length were calculated from images captured by video cameras (60 frames/second) located at the sides of the lanes. Contact time and aerial time over the distance from 20 m to 30 m were calculated from images captured by high-speed video cameras (300 frames/second) located at the side of the 25-m mark for the lanes. Two-way ANOVA with the Games-Howell procedure was used to test differences among all grades. Two-way ANCOVA was used to test interaction and the main effect of gender and grade on maximal running speed. The Pearson product-moment correlation coefficient (r) and partial correlation coefficient (pr) were calculated to analyze the relationship between maximal running speed, step frequency, stride length, foot contact time, and aerial time. Step length (which was strongly correlated with maximal running speed) showed a strong partial correlation (controlled for age) with maximal running speed. Therefore, it is suggested that step length contributes to not only the increase in running speed with growth, but also individual differences in running speed among the children at the same age. There were slight tendencies for step frequency and foot contact time to increase with growth. However, these factors showed a significant partial correlation (controlled for age) with running speed. Therefore, it was suggested that these factors contribute to individual differences in running speed. The absence of a negative impact of a shorter foot contact time on stride length suggests that the running performance of school children could be improved by decreasing their foot contact time. In order to establish effective methods for augmenting the development of running ability in children, it will be necessary to consider foot contact time and aerial time in addition to step frequency and step length.<br>

In this study, we utilized functional magnetic resonance imaging (fMRI) to measure blood oxygenation level-dependent (BOLD) signals. This allowed us to evaluate the relationship between brain activity and imagined force level. Subjects performed motor imagery of repetitive right hand grasping with three different levels of contractile force; 10%, 30%, and 60% of their maximum voluntary contraction (MVC). We observed a common activation among each condition in the following brain regions; the dorsolateral prefrontal cortex (DLPFC), ventrolateral prefrontal cortex (VLPFC), supplementary motor area (SMA), premotor area (PM), insula, and inferior parietal lobule (IPL). In addition, the BOLD signal changes were significantly larger at 60% MVC than at 10% MVC in the right PM, the right IPL, and the primary somatosensory cortex (SI). These findings indicate that during motor imagery right fronto-parietal activity increases as the imagined contractile force level is intensified. The present finding that the right brain activity during motor imagery is clearly altered depending on the imagined force level suggests that it may be possible to decode intended force level during the motor imagery of patients or healthy subjects.

We utilized functional magnetic resonance imaging (fMRI) to evaluate the common brain region of motor imagery for the right and left upper and lower limbs. The subjects were instructed to repeatedly imagined extension and flexion of the right or left hands/ankles. Brain regions, which included the supplemental motor area (SMA), premotor cortex and parietal cortex, were activated during motor imagery. Conjunction analysis revealed that the left SMA and inferior frontal gyrus (IFG)/ventral premotor cortex (vPM) were commonly activated with motor imagery of the right hand, left hand, right foot, and left foot. This result suggests that these brain regions are activated during motor imagery in an effector independent manner. (C) 2014 Elsevier Ireland Ltd. All rights reserved.

In ball games, players have to pay close attention to visual information in order to predict the movements of both the opponents and the ball. Previous studies have indicated that players primarily utilise cues concerning the ball and opponents' body motion. The information acquired must be effective for observing players to select the subsequent action. The present study evaluated the effects of changes in the video replay speed on the spatial visual search strategy and ability to predict free throw success. We compared eye movements made while observing a basketball free throw by novices and experienced basketball players. Correct response rates were close to chance (50%) at all video speeds for the novices. The correct response rate of experienced players was significantly above chance (and significantly above that of the novices) at the normal speed, but was not different from chance at both slow and fast speeds. Experienced players gazed more on the lower part of the player's body when viewing a normal speed video than the novices. The players likely detected critical visual information to predict shot success by properly moving their gaze according to the shooter's movements. This pattern did not change when the video speed was decreased, but changed when it was increased. These findings suggest that temporal information is important for predicting action outcomes and that such outcomes are sensitive to video speed.

The effectiveness of fastballs of equivalent speed can differ; for example, one element of this difference could be due to the effect of rate and orientation of ball spin on launched ball trajectory. In the present experiment, baseball batters' accuracy in hitting fastballs with different backspin rates at a constant ball velocity of 36 m/s was examined. Thirteen skilled baseball players (professionals, semiprofessionals, and college varsity players) participated in the study. The movements of bat and ball were recorded using two synchronized high-speed video cameras. The Pearson product-moment correlation coefficient (r) was calculated and used to analyze the relationship between ball backspin rate and the vertical distance between ball center and sweet spot at the moment of ball-bat impact. Ball backspin rate was positively correlated with increases in the distance from the optimal contact point of the swung bat (sweet spot) to the actual point of contact (r = .38, P &lt; .001). Batters were most effective at the usual backspin rate for the ball velocity used. The decrease in accuracy of the batter's swing that was observed when the fastball's backspin deviated from the usual rate likely occurred because experienced batters predict ball trajectory from perceived ball speed.

Understanding the degree of leg stiffness during human movement would provide important information that may be used for injury prevention. In the current study, we investigated bilateral differences in leg stiffness during one-legged hopping. Ten male participants performed one-legged hopping in place, matching metronome beats at 1.5, 2.2, and 3.0 Hz. Based on a spring-mass model, we calculated leg stiffness, which is defined as the ratio of maximal ground reaction force to maximum center of mass displacement at the middle of the stance phase, measured from vertical ground reaction force. In all hopping frequency settings, there was no significant difference in leg stiffness between legs. Although not statistically significant, asymmetry was the greatest at 1.5 Hz, followed by 2.2 and 3.0 Hz for all dependent variables. Furthermore, the number of subjects with an asymmetry greater than the 10% criterion was larger at 1.5 Hz than those at 2.2 and 3.0 Hz. These results will assist in the formulation of treatment-specific training regimes and rehabilitation programs for lower extremity injuries. © 2013 Human Kinetics, Inc.

The effectiveness of fastballs of equivalent speed can differ
for example, one element of this difference could be due to the effect of rate and orientation of ball spin on launched ball trajectory. In the present experiment, baseball batters' accuracy in hitting fastballs with different backspin rates at a constant ball velocity of 36 m/s was examined. Thirteen skilled baseball players (professionals, semiprofessionals, and college varsity players) participated in the study. The movements of bat and ball were recorded using two synchronized high-speed video cameras. The Pearson product-moment correlation coefficient (r) was calculated and used to analyze the relationship between ball backspin rate and the vertical distance between ball center and sweet spot at the moment of ball-bat impact. Ball backspin rate was positively correlated with increases in the distance from the optimal contact point of the swung bat (sweet spot) to the actual point of contact (r = .38, P &lt
.001). Batters were most effective at the usual backspin rate for the ball velocity used. The decrease in accuracy of the batter's swing that was observed when the fastball's backspin deviated from the usual rate likely occurred because experienced batters predict ball trajectory from perceived ball speed. © 2013 Human Kinetics, Inc.

In a previous study, we investigated the contribution of the surface of the face, chest, abdomen, and thigh to thermal comfort by applying local temperature stimulation during whole-body exposure to mild heat or cold. In hot conditions, humans prefer a cool face, and in cold they prefer a warm abdomen. In this study, we extended investigation of regional differences in thermal comfort to the neck, hand, soles, abdomen (Experiment 1), the upper and lower back, upper arm, and abdomen (Experiment 2). The methodology was similar to that used in the previous study. To compare the results of each experiment, we utilized the abdomen as the reference area in these experiments. Thermal comfort feelings were not particularly strong for the limbs and extremities, in spite of the fact that changes in skin temperature induced by local temperature stimulation of the limbs and extremities were always larger than changes that were induced in the more proximal body parts. For the trunk areas, a significant difference in thermal comfort was not observed among the abdomen, and upper and lower back. An exception involved local cooling during whole-body mild cold exposure, wherein the most dominant preference was for a warmer temperature of the abdomen. As for the neck and abdomen, clear differences were observed during local cooling, while no significant difference was observed during local warming. We combined the results for the current and the previous study, and characterized regional differences in thermal comfort and thermal preference for the whole-body surface.

Excitability of the corticospinal pathway increases during observation of an action. However, how corticospinal excitability changes during observation of sequential actions in the course of acquiring novel skills (observational learning) remains unexplored. To investigate this, we used a previously unpracticed sequence of ten hand postures. Participants were asked to repeat observation and replication of the sequence. This block of observation and replication was repeated 5 times. During observation of a given hand posture (OK sign), motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation were recorded from hand muscles. In experiment 1, the OK sign appeared in the 9th position of the sequence. Almost all participants could replicate the OK sign only at the 5th block of the experiment. MEP amplitude was greater than that in the control, and decreased with the stages. This suggested that during observational learning of sequential hand postures MEP changed with the progress of the learning. To evaluate this idea, we performed two additional experiments. In experiment 2, the OK sign appeared in the 2nd position. Almost all participants replicated the OK sign even in the 1st block. The MEP amplitude did not change across stages. In experiment 3, the OK sign appeared in the 9th position, but the order of other signs was randomized in every stage. Many participants were not able to replicate the OK sign even during the 5th block of the experiment. The MEP amplitude did not change across stages. These results suggest that: (1) During observational learning modulation of corticospinal excitability is associated with the learning process. (2) Corticospinal excitability decreases as learning progresses.

Our previous studies showed that corticospinal excitability during imagery of squeezing a foam ball was enhanced by somatosensory input generated by passively holding the ball. In the present study, using the same experimental model, we investigated whether corticospinal excitability was influenced by holding the object with the hand opposite to the imagined hand. Corticospinal excitability was assessed by monitoring motor evoked potentials (MEPs) in the first dorsal interosseous muscle following transcranial magnetic stimulation over the motor cortex during motor imagery. Subjects were asked to imagine squeezing a foam ball with the right hand (experiment 1) or the left hand (experiment 2), while either holding nothing (Null condition), a ball in the right hand (Right condition) or a ball in the left hand (Left condition). The MEPs amplitude during motor imagery was increased, only when the holding hand and the imagined hand were on the same side. These results suggest that performance improvement and rehabilitation exercises will be more effective when somatosensory stimulation and motor imagery are done on the same side. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

In the present review, we summarized, how to measure motor imagery ability, brain activity during motor imagery, the benefits of motor imagery practice, and the influence of sensory inputs on motor imagery. First, we explain the classification of motor imagery. Many methods have been utilized to evaluate motor imagery ability. For example, questionnaires, mental chronometry, and mental rotation tasks have been used in the psychological approach. Brain activity has been measured utilizing transcranial magnetic stimulation (TMS), functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and electroencephalography (EEG). Brain regions working in motor execution show activation during motor imagery. This includes the supplementary motor area (SMA), the premotor cortex (PM) and the parietal cortex: Although motor imagery is done without movement or muscle contraction, sensory input from the periphery interacts with motor imagery. Brain activation during imagery of an action, as assessed by TMS, is stronger when sensory inputs resemble to those present during the actual execution of the action. Many studies have provided evidence of the effects of motor imagery practice on basic motor skills and sport performance. Most elite athletes (70 - 90 %) report that they use motor imagery to improve performance, and professional players,as compared to amateurs, utilized imagery practice more often. Many studies have confirmed that motor imagery practice can also be useful not only in sports, but also for improving performance in patient rehabilitation programs.

NAGAMI, T., J. MOROHOSHI, T. HIGUCHI, H. NAKATA, S. NAITO, and K. KANOSUE. Spin on Fastballs Thrown by Elite Baseball Pitchers. Med. Sci. Sports Exerc., Vol. 43, No. 12, pp. 2321-2327, 2011. Purpose: In this study, we analyzed the direction of the spin axis angles and the spin rate of baseballs pitched by elite collegiate and professional pitchers. Method: The video image of a ball being pitched was taken from the period just before release until 200 ms after release with a high-speed video camera at a rate of 1000 frames per second. A custom-made device was used to analyze the spin axis angle and the spin rate. Results and Conclusion: There were no significant differences in the direction of the spin axis angles or the spin rate between collegiate and professional pitchers. A significant correlation was obtained between spin rate and ball speed; that is, the higher the ball speed, the greater the spin rate. In addition, the spin rate deviated more across subjects than did ball speed. For all subjects, the azimuth and elevation of spin axis were 19 degrees +/- 14 degrees and -32 degrees +/- 9 degrees, respectively. Some of the pitchers were able to put a characteristic spin on their fastball; the nature of this spin could be related to their pitching success.

Despite the fact that a stiffer leg spring is prerequisite for achieving a better performance during sports activities, effects of various types of warm-up on the leg stiffness is not well-known. The purpose of this study was to determine if static stretching influences the leg stiffness during two-legged hopping. Fourteen male subjects performed two-legged hopping at 2.2 Hz before and after a 3-min passive stretching of the triceps surae (dorsiflexion of 30 degrees). Based on a spring-mass model, we calculated leg stiffness, which is defined as the ratio of maximal ground reaction force to maximum center of mass displacement at the middle of the stance phase. It was found that there was no significant difference in leg stiffness after passive static stretching. These results suggest that 3-min passive static stretching does not affect the leg-spring behavior and stiffness regulation during two-legged hopping. Finally, possible explanations for the invariant leg stiffness after the passive stretching are discussed.

Identifying the major determinant of leg stiffness during hopping would be helpful in the development of more effective training methods. Despite the fact that overall leg stiffness depends on a combination of the joint stiffness, it is unclear how the major determinants of leg stiffness are influenced by hopping frequency. The purpose of this study was to identify the major determinant of leg stiffness over a wide range of hopping frequencies. Fourteen well-trained male athletes performed in a place hopping on two legs, at three frequencies (1.5, 2.2 and 3.0 Hz). We determined leg and joint stiffness of the hip, knee and ankle from kinetic and kinematic data. Multiple linear regression analysis revealed that knee stiffness could explain more of the variance of leg stiffness than could ankle or hip stiffness at 1.5 Hz hopping. Further, only ankle stiffness was significantly correlated with leg stiffness at both 2.2 and 3.0 Hz, and the standardized regression coefficient of ankle stiffness was higher than that of knee and hip stiffness. The results of the present study suggest that the major determinant of leg stiffness during hopping switches from knee stiffness to ankle stiffness when the hopping frequency is increased.

We would like to emphasize about the system involved with homeostatic maintenance of body temperature. First, the primary mission of the thermoregulatory system is to defend core temperature (T (core)) against changes in ambient temperature (T (a)), the most frequently encountered disturbance for the system. T (a) should be treated as a feedforward input to the system, which has not been adequately recognized by thermal physiologists. Second, homeostatic demands from outside the thermoregulatory system may require or produce an altered T (core), such as fever (demand from the immune system). There are also conditions where some thermoregulatory effectors might be better not recruited due to demands from other homeostatic systems, such as during dehydration or fasting. Third, many experiments have supported the original assertion of Satinoff that multiple thermoregulatory effectors are controlled by different and relatively independent neuronal circuits. However, it would also be of value to be able to characterize strictly regulatory properties of the entire system by providing a clear definition for the level of regulation. Based on the assumption that T (core) is the regulated variable of the thermoregulatory system, regulated T (core) is defined as the T (core) that pertains within the range of normothermic T (a) (Gordon in temperature and toxicology: an integrative, comparative, and environmental approach, CRC Press, Boca Raton, 2005), i.e., the T (a) range in which an animal maintains a stable T (core). The proposed approach would facilitate the categorization and evaluation of how normal biological alterations, physiological stressors, and pathological conditions modify temperature regulation. In any case, of overriding importance is to recognize the means by which an alteration in T (core) (and modification of associated effector activities) increases the overall viability of the organism.

The purpose of the present study was to determine how humans adjust leg stiffness over a range of hopping frequencies. Ten male subjects performed in place hopping on two legs, at three frequencies (1.5, 2.2, and 3.0 Hz). Leg stiffness, joint stiffness and touchdown joint angles were calculated from kinetic and/or kinematics data. Electromyographic activity (EMG) was recorded from six leg muscles. Leg stiffness increased with an increase in hopping frequency. Hip and knee stiffnesses were significantly greater at 3.0 Hz than at 1.5 Hz. There was no significant difference in ankle stiffness among the three hopping frequencies. Although there were significant differences in EMG activity among the three hopping frequencies, the largest was the 1.5 Hz, followed by the 2.2 Hz and then 3.0 Hz. The subjects landed with a straighter leg (both hip and knee were extended more) with increased hopping frequency. These results suggest that over the range of hopping frequencies we evaluated, humans adjust leg stiffness by altering hip and knee stiffness. This is accomplished by extending the touchdown joint angles rather than by altering neural activity. (C) 2009 Elsevier Ltd. All rights reserved.

The present study investigated whether combining observation and imagery of an action increased corticospinal excitability over the effects of either manipulation performed alone. Corticospinal excitability was assessed by motor-evoked potentials in the biceps brachii muscle following transcranial magnetic stimulation over the motor cortex during observation, imagery or both. The action utilized was repetitive elbow flexion/extension. Simultaneous observation and imagery of the elbow action facilitated corticospinal excitability as compared to that recorded during observation or imagery alone. However, facilitation due to the combination of observation and imagery was not obtained when the participants imagined the action pattern while they observed the same action presented out of phase. These findings suggest that a combination of observation and imagery can enhance corticospinal excitability. This enhancement depends on phase consistency between the observed and imagined actions. (C) 2009 Elsevier Ireland Ltd and the Japan Neuroscience Society. Ail rights reserved.

Understanding stiffness of the lower extremities during human movement may provide important information for developing more effective training methods during sports activities. It has been reported that leg stiffness during submaximal hopping depends primarily on ankle stiffness, but the way stiffness is regulated in maximal hopping is unknown. The goal of this study was to examine the hypothesis that knee stiffness is a major determinant of leg stiffness during the maximal hopping. Ten well-trained male athletes performed two-legged hopping in place with a maximal effort. We determined leg and joint stiffness of the hip, knee, and ankle from kinetic and kinematic data. Knee stiffness was significantly higher than ankle and hip stiffness. Further, the regression model revealed that only knee stiffness was significantly correlated with leg stiffness. The results of the present study suggest that the knee stiffness, rather than those of the ankle or hip, is the major determinant of leg stiffness during maximal hopping. (C) 2009 Elsevier Ltd. All rights reserved.

We investigated whether corticospinal excitability during the imagery of an action involving an external object was influenced by actually touching the object. Corticospinal excitability was assessed by monitoring motor evoked potentials (MEPs) in the first dorsal interosseous muscle following transcranial magnetic stimulation over the motor cortex during imagery of squeezing a ball-with or without passively holding the ball. The MEPs amplitude during imagery when the ball was held was larger than that when the ball was not held. The MEPs amplitude was not modulated just by holding the ball. In the same experimental condition, the somatosensory evoked potentials (SEPs) in response to the stimulation of median nerve were not modulated by motor imagery or by holding the ball. These results suggest that the corticospinal excitability during imagery of squeezing a ball is enhanced with the real touch of the ball, and the enhancement would be caused by some changes along the corticospinal pathway itself and not by the change in responsiveness along the afferent pathway to the primary somatosensory cortex.

Sensations evoked by thermal stimulation (temperature-related sensations) can be divided into two categories, "temperature sensation" and "thermal comfort."Although several studies have investigated regional differences in temperature sensation, less is known about the sensitivity differences in thermal comfort for the various body regions. In the present study, we examined regional differences in temperature-related sensations with special attention to thermal comfort. Healthy male subjects sitting in an environment of mild heat or cold were locally cooled or warmed with water-perfused stimulators. Areas stimulated were the face, chest, abdomen, and thigh. Temperature sensation and thermal comfort of the stimulated areas were reported by the subjects, as was whole body thermal comfort. During mild heat exposure, facial cooling was most comfortable and facial warming was most uncomfortable. On the other hand, during mild cold exposure, neither warming nor cooling of the face had a major effect. The chest and abdomen had characteristics opposite to those of the face. Local warming of the chest and abdomen did produce a strong comfort sensation during whole body cold exposure. The thermal comfort seen in this study suggests that if given the chance, humans would preferentially cool the head in the heat, and they would maintain the warmth of the trunk areas in the cold. The qualitative differences seen in thermal comfort for the various areas cannot be explained solely by the density or properties of the peripheral thermal receptors and thus must reflect processing mechanisms in the central nervous system.

We investigated the effects of alcohol on thermoregulatory responses and thermal sensations during cold exposure in humans. Eight healthy men (mean age 22.3 +/- 0.7 year) participated in this study. Experiments were conducted twice for each subject at a room temperature of 18 degrees C. After a 30-min resting period, the subject drank either 15% alcohol at a dose of 0.36 g/kg body weight (alcohol session) or an equal volume of distilled water (control session), and remained in a sitting position for another 60 min. Mean skin temperature continued to decrease and was similar in control and alcohol sessions. Metabolic rate was lower in the alcohol session, but the difference did not affect core temperature, which decreased in a similar manner in both alcohol and control sessions (from 36.9 +/- 0.1 degrees C to 36.6 +/- 0.1 degrees C. Whole body sensations of cold and thermal discomfort became successively stronger in the control session, whereas these sensations were both greatly diminished after drinking alcohol. In a previous study we performed in the heat, using a similar protocol, alcohol produced a definite, coordinated effect on all autonomic and sentient heat loss effectors. In the current study in the cold, as compared to responses in the heat, alcohol intake was followed by lesser alterations in autonomic effector responses, but increased changes in sensations of temperature and thermal discomfort. Overall, our results indicate that although alcohol influences thermoregulation in the cold as well as in the heat, detailed aspects of the influence are quite different. (c) 2008 Elsevier Inc. All rights reserved.

Understanding the leg and joint stiffness during human movement would provide important information that could be utilized for evaluating sports performance and for injury prevention. In the present study, we examined the determinants of the difference in the leg stiffness between the endurance- trained and power-trained athletes. Seven distance runners and seven power-trained athletes performed in-place hopping, matching metronome beats at 3.0 and 1.5 Hz. Leg and joint stiffness were calculated from kinetic and kinematics data. Electromyographic activity (EMG) was recorded from six leg muscles. At both hopping frequencies, the power-trained athletes demonstrated significantly higher leg stiffness than the distance runners. Hip, knee, and ankle joints were analyzed for stiffness and touchdown angles. Ankle stiffness was significantly greater in the power-trained athletes than the distance runners at 3.0 Hz as was knee stiffness at 1.5 Hz. There was no significant difference in touchdown angle between the DR and PT groups at either hopping frequencies. When significant difference in EMG activity existed between two groups, it was always greater in the distance runners than the power-rained athletes. These results suggest that (1) the difference in leg stiffness between endurance-trained and power-trained athletes is best attributed to increased joint stiffness, and (2) the difference in joint stiffness between the two groups may be attributed to a lack of similarity in the intrinsic stiffness of the muscle-tendon complex rather than in altered neural activity. (c) 2007 Elsevier Ltd. All rights reserved.

Analysis of actually pitched ball movement is important in various sports scenes such as amusement, science, and skill up for the pitching. We have been studying a method of spin detection of the pitched ball from image streams obtained by high speed camera. Our algorithm employs a set of linear equations composed by image coordinate of feature points that are corresponding between successive frame. In this paper, methods of ball radius estimation and feature points detection are described in detail, since the both are significantly affects on the performance of the algorithm.

The authors have recently developed a system for analyzing the spin on a baseball (Koseki et al., 2007). In the present study we analyzed the spin pitched by a professional pitcher. He pitched eight different pitches, each twice, from official pitching mound. The image of ball in the period from just before to 500 ms after the ball release was taken with a high speed video camera at 1000 fps. English alphabets E, M, A, and I were marked on the ball for image processing. Feature points from the image stream were assembled into a set of linear equations that represents orientation change between consecutive two frames by rotation matrix R, and the direction of spin axis and spin rate were obtained. Both values varied considerably depending on pitches. The recording of spin was suggested to be valuable for training if the data could be combined with those of motion analysis.

Background/Aims: The effects of muscle cooling on the stiffness of the human gastrocnemius muscle (GAS) were examined in vivo. Methods: The knee joint was passively extended from 90 to 0 degrees (0 degrees = full knee extended position) with a constant ankle angle of 10 degrees dorsiflexed position (0 degrees = the sole of the foot is approximately perpendicular to the anterior margin of the shaft of the tibia) in a control condition (room temperature of 18-23 degrees C) and a cooling condition (muscle temperature decreased by 5.8 +/- 8 1.7 degrees C after cooling using a cold water bath at a temperature of 5-8 degrees C for 60 min). The change in passive Achilles tendon force, muscle fascicle length of GAS and muscle temperature were measured (n = 6) during the motion. Results and Conclusion: GAS stiffness was significantly greater in the cooling condition (20 +/- 8 N/mm) than the control condition (18 +/- 8 N/mm). There was no cooling effect on the muscle slack length, beyond which passive muscle force arises. The maximum passive Achilles tendon force significantly increased by 19 +/- 20% after cooling. These results suggested that cooling increased the passive muscle force due to the increase in the muscle stiffness rather than the shift of the muscle slack length. Copyright (C) 2007 S. Karger AG, Basel.

While the spring-like leg behavior of legs in mammalian locomotion has been well documented, its neural basis remains ambiguous. The purpose of the present study was to examine leg stiffness control during hopping. Seven male subjects performed in place two-legged hopping at their preferred frequency with two different contact times of the stance phase, preferred and short ones (PCT and SCT, respectively). Based on a spring-mass model, leg stiffness was calculated from the subjects' body mass, ground contact and flight times. Surface electromyographic (EMG) activities of the medial gastrocnemius (MG), soleus (SOL) and tibialis anterior (TA) muscles were recorded. Leg stiffness was higher in the SCT condition than in the PCT condition. The SCT condition was characterized by high EMG activity of MG and SOL at both pre- and post-landing phases, which peaked at about 50 ms. On the other hand, the activity of TA was low throughout the contact phase as compared with those of MG and SOL, and its peak value around 50 ms after landing was significantly lower for the SCT condition than for the PCT condition. We conclude that (1) the leg stiffness is regulated by a change in centrally programmed muscle preactivation and probably also by a concomitant change in the short-latency stretch reflex response of the triceps surae muscles, and (2) the co-contraction of antagonistic TA does not play a major role in leg stiffness control.

For improvement of pitching skill in baseball, it is important to understand the behavior of the pitched ball itself. This paper presents a method of detecting rotation of the pitched ball from image streams obtained by high speed camera. The ball was marked previously for helping image processing. Feature points from the image stream assemble into a set of linear equations that represents orientation change between consecutive two frames by rotation matrix R. The results from live pitching data are shown.

Systemic salt loading has been reported to facilitate operant heat-escape/cold-seeking behavior. In the present study, we hypothesized that the median preoptic nucleus (MnPO) would be involved in this mechanism. Rats were divided into two groups (n = 6 each): one group had the MnPO lesion with ibotenic acid (4.0 mu g) and the other was the vehicle control. After subcutaneous injection (10 ml/kg) of either isotonic-(154 mM) or hypertonic-saline (2,500 mM), each rat was placed in a behavior box, where the ambient temperature was changed to 26 degrees C, 35 degrees C, and 40 degrees C every 1 h. The position of a rat in the box and the body core temperature (T(core)) were monitored. A rat could trigger 0 C air for 45 s in the 35 degrees C and 40 C heat when moved in a specific area in the box (operant behavior). In the control group, counts of the operant behavior were greater (P &lt; 0.05) in the hypertonic-than in the isotonic-saline injection (17 +/- 2 and 10 +/- 2 at 35 degrees C, 24 +/- 2 and 18 +/- 1 at 40 degrees C). Tcore remained unchanged throughout the exposure, although the level was lower (P &lt; 0.05) in the hypertonic-than in the isotonic-saline trial (36.6 +/- 0.2 degrees C and 37.4 +/- 0.1 degrees C at 26 degrees C and 36.9 +/- 0.2 degrees C and 37.4 +/- 0.1 degrees C at 40 C, respectively). However, in the MnPO-lesion group, counts of the behavior were similar between the hypertonic-and isotonic-saline injection trials (10 +/- 2 and 8 +/- 1 at 35 degrees C, and 17 +/- 1 and 16 +/- 1 at 40 degrees C, respectively). Tcore increased (P &lt; 0.05) in the heat in both trials (36.8 +/- 0.1 degrees C and 37.4 +/- 0.1 degrees C at 2 degrees C and 37.4 +/- 0.2 degrees C and 37.8 +/- 0.2 degrees C at 40 degrees C in the hypertonic-and isotonic-saline injection trials, respectively). These results may suggest that, at least in part, the MnPO is involved in the facilitation of heat-escape/cold-seeking behavior during osmotic stimulation.

We report a new system for monitoring sensations of many body parts as well as comprehensively showing the distribution of overall skin temperature (T-sk) and temperature-related sensations. The system consists of a console with 52 levers to report temperature-related sensations and software that facilitates the visualization of the distribution of T-sk and temperature-related sensations by displaying them on a model of the human body. The system's utility was demonstrated with a physiological experiment involving three males and three females. They were exposed to step changes of ambient temperature from 23 degrees C to 33 degrees C. We measured T-sk at 50 points, and the subjects concurrently provided estimates of local temperature sensation and thermal comfort/discomfoq at 25 loci. This system greatly facilitates the perception and analysis of spatial relationships and differences in temperature and sensation in various areas of the body.

Athletes have been instructed to refrain from taking carbonated beverages in the sports world, but the mechanism has not been clear. The purpose of this study was to clarify how physiological and biochemical evaluation are affected by taking a 10% CHO carbonated beverage after cycle ergometer (60 min, 60% V̇O 2max). Seven subjects consumed a carbonated or noncarbonated (10% carbohydrate) beverage after exercise. No differences were observed in concentration of glucose, insulin, free fatty acids, K and Na in serum from carbonated beverage compared with noncarbonated beverage intakes after exercise. These results indicate that carbonated beverage did not affect the changes of physiological and biochemical parameter after prolonged exercise, and it could be more refreshing and stimulate taste rather than noncarbonated beverage, but seemed to be hard to drink immediately after exercise because it made subjects feel as if having drunk more than they did.

The nature of muscle efferent fibre activation during whole body cooling was investigated in urethane-anaesthetized rats. Multiunit efferent activity to the gastrocnemius muscle was detected when the trunk skin was cooled by a water-perfused jacket to below 36.0 +/- 0.7 degrees C. That efferent activity was not blocked by hexamethonium (50 mg kg(-1), i.v.) and was not associated with movement or electromyographic activity. Cold-induced efferent activity enhanced the discharge of afferent filaments from the isotonically stretched gastrocnemius muscle, demonstrating that it was fusimotor. Fusimotor neurons were activated by falls in trunk skin temperature, but that activity ceased when the skin was rewarmed, regardless of how low core temperature had fallen. While low core temperature alone was ineffective, a high core temperature could inhibit the fusimotor response to skin cooling. Fusimotor activation by skin cooling was often accompanied by desynchronization of the frontal electroencephalogram (EEG), but was not a simple consequence of cortical arousal, in that warming the scrotum desynchronized the EEG without activating fusimotor fibres. Inhibition of neurons in the rostral medullary raphe by microinjections of glycine (0.5 M, 120-180 nl) reduced the fusimotor response to skin cooling by 95 +/- 3%, but did not prevent the EEG response. These results are interpreted as showing a novel thermoregulatory reflex that is triggered by cold exposure. It may underlie the increased muscle tone that precedes overt shivering, and could also serve to amplify shivering. Like several other cold-defence responses, this reflex depends upon neurons in the rostral medullary raphe.

We investigated the effects of alcohol on thermoregulatory responses and thermal sensations during mild heat exposure in humans. Eight healthy men participated in this study. Experiments were conducted twice for each subject at a room temperature of 33 degrees C. After a 30-min resting period, the subject drank either 15% alcohol (alcohol session) at a dose of 0.36 g/kg body weight or equal volume of water (control session). Skin blood flow and chest sweat rate in the alcohol session significantly increased over those in controls 10 min after drinking. Deep body temperature in the alcohol session started to decrease 20 min after the onset of sweating and eventually fell 0.3 degrees C lower than in the controls. Whole body hot sensation transiently increased after alcohol drinking, whereas it changed little after water drinking. The increased "hot" sensation would presumably cause cool-seeking behavior, if permitted. Thus, alcohol influences thermoreaulation so that body core temperature is lowered not only by automatic mechanisms (sweating and skin vasodilation) but also behaviorally. These results suggest that decreases in body temperature after alcohol drinking are not secondary to skin vasodilation, a well-known effect of alcohol, but rather result from a decrease in the regulated body temperature evidenced by the coordinated modulation of various effectors of thermoregulation and sensation. (c) 2005 Elsevier Inc. All rights reserved.

The purpose of the present study was to examine the influence of muscle cooling on the passive mechanical properties of the human gastrocnemius muscle (GAS) in vivo. In a thermoneutral (a room temperature of 18-23°C) and a local cooling (placing the right lower leg into cold water with a temperature of 5-8°C for 60 min) conditions, the change in passive plantarflexion force (F), which is produced only by the GAS length change, was taken in five subjects during passive knee extension from 90° to 0° with a constant ankle joint angle of 10° dorsiflexion. To evaluate an elastic component of the passive plantarflexion force of GAS, the subject held full knee extended position for 1 min (i.e. relaxation period). Skin and muscle temperature of GAS were also measured using a core temperature thermistor. The peak value of F (Fve) that was measured at the end of the knee extension phase, the decrease of F (ΔF) during the relaxation period, and the F at the end of the relaxation period (Fe) were measured in the two conditions. Muscle cooling decreased the skin and muscle temperature by 6.7 ± 1.1°C and 8.1 ± 2.5°C, respectively. Fve increased by 24% ± 22% by muscle cooling. ΔF in the thermoneutral and local cooling conditions were 11.5 ± 4.9 N and 12.5 ± 2.9 N, respectively. Fe increased by 28% ± 21% by muscle cooling. These results suggested that muscle cooling increased an elastic component of the passive force arisen from GAS and seemed not to affect its viscous component. © 2005 IEEE.

The criptochrome genes (Cry1 and Cry2) are involved in the molecular mechanism that controls the circadian clock, and mice lacking these genes ( Cry1(-/-)/ Cry2(-/-)) are behaviorally arrhythmic. It has been speculated that the circadian clock modulates the characteristics of thermoregulation, resulting in body temperature (T-b) rhythm. However, there is no direct evidence proving this speculation. We show here that T-b and heat production in Cry1(-/-)/Cry2(-/-) mice are arrhythmic under constant darkness. In contrast, both rhythms occur under a light-dark cycle and/or periodical food restriction linked with spontaneous activity and/or eating, although they are not robust as those in wild-type mice. The relationship between heat production and T-b in Cry1(-/-)/Cry2(-/-) mice is linear and identical under any conditions, indicating that their T-b rhythm is determined by heat production rhythm associated with activity and eating. However, T-b in wild-type mice is maintained at a relatively higher level in the active phase than the inactive phase regardless of the heat production level. These results indicate that the thermoregulatory responses are modulated according to the circadian phase, and the Cry genes are involved in this mechanism.

The purpose of this study was to examine the differences in the geometric and elastic properties of the Achilles tendon between right and left ankles in kendo (japanese fencing) athletes, who engaged in kendo training for years, and matched controls. The subjects were twelve kendo athletes and nine controls (21 and 20 yrs, 65 and 60 kg, and 172 and 171 cm, respectively). While the subjects developed maximum voluntary isometric plantarflexion (MVIP) torque (TQ), the tendon displacement and ankle joint rotation was determined using a B-mode ultrasonograph and a goniometer, respectively. The tendon force (F) was calculated from TQ and the moment arm of the Achilles tendon. The elongation of the Achilles tendon (ΔX) was obtained from the tendon displacement and ankle joint rotation. The cross-sectional area of the Achilles tendon (CSA) was measured using a B-mode ultrasonography. The Achilles tendon stiffness (k) was defined as F divided by ΔX, stress (σ) as F divided by CSA, strain (ε) at MVIP as ΔX divided by the Achilles tendon length at rest (Lr), and Young's modulus (E) as σ divided by ε. The results showed that there were no significant differences in TQ, F, σ, Lr, ΔX, ε, k, and E between right and left ankles for both control and kendo athlete subjects, and between control and kendo athlete subjects. CSA of kendo athletes' right ankles was significantly greater than that of kendo athletes' left ankles (p=0.03). It was suggested that a long-term kendo training did not affect the elastic properties of the Achilles tendon and resulted in smaller Achilles tendon CSA in left ankles.

The hypothalamus, especially the preoptic area, plays a crucial role in thermoregulation, and our previous studies showed that the periaqueductal gray matter is important for transmitting efferent signals to thermoregulatory effectors in rats. Neurons responsible for skin vasodilation are located in the lateral portion of the rostral periaqueductal gray matter, and neurons that mediate non-shivering thermogenesis are located in the ventrolateral part of the caudal periaqueductal gray matter. We investigated the distribution of neurons in the rat hypothalamus that are activated by exposure to neutral (26 degrees C), warm (33 degrees C), or cold (10 degrees C) ambient temperature and project to the rostral periaqueductal gray matter or caudal periaqueductal gray matter, by using the immunohistochemical analysis of Fos and a retrograde tracer, cholera toxin-b. When cholera toxin-b was injected into the rostral periaqueductal gray matter, many double-labeled cells were observed in the median preoptic nucleus in warm-exposed rats, but few were seen in cold-exposed rats. On the other hand, when cholera toxin-b was injected into the caudal periaqueductal gray matter, many double-labeled cells were seen in a cell group extending from the dorsomedial nucleus through the dorsal hypothalamic area in cold-exposed rats but few were seen in warm-exposed rats. These results suggest that the rostral periaqueductal gray matter receives input from the median preoptic nucleus neurons activated by warm exposure, and the caudal periaqueductal gray matter receives input from neurons in the dorsomedial nucleus/dorsal hypothalamic area region activated by cold exposure. These efferent pathways provide a substrate for thermoregulatory skin vasomotor response and non-shivering thermogenes is, respectively. (c) 2005 IBRO. Published by Elsevier Ltd. All rights reserved.

Sensations evoked by innocuous thermal stimulation can be divided into two categories. One is "temperature sensation" in a narrow sense, which is directed towards an object outside the body. The other is the "thermal comfort/discomfort" of the body that is important for thermoregulation. We recently reported rCBF changes in the amygdala which correlated with thermal comfort during whole body cooling (Kanosue et al., 2000). In the present study we investigated the region of brain that is activated by local thermal stimulation of the hand. Eight healthy subjects were recruited and gave written informed consent to participate in the study. Warm (39 degrees C) or cold (25 degrees C) stimuli was applied to the right or left hand for 30 s by using a water circulating tube that covered the whole hand. Each subject reported the magnitude of the stimulus intensity of temperature sensation using a scale from 1 (very cold) to 9 (very hot). All subjects reported hot or cold sensations and not pain. We examined the correlation between the rating scores and regional activity over the entire brain with a 3 Tesla MR imagers (VP, General Electrics, Milwaukee, US). Activation was observed in the contralateral secondary somatosensory cortex in response to both warm and cold stimulation of the hand. No activation was observed in the amygdala. This suggests that temperature sensation and thermal comfort might be generated by completely different structures of the brain.

This study examined two factors that are important for baseball batting, (1) swing speed and (2) ability to repeat the same swing (repeatability). Twenty male subjects participated in the study; eight beginners, five active players from a university baseball club (players), and another seven who played baseball at a high school or university but are not active now (experienced). Each subject hit a ball on a batting tee fifteen times. Swing speed was measured by a custom-made machine using laser position detectors. The motion of the bat head was also recorded by a high speed video camera (250 flames/s). Swing speed was 82.6km/h, 108.2km/h, and 97.2km/h, for the beginner, player, and experienced groups, respectively. Repeatability of the swing was evaluated by utilizing the standard deviation (SD) of the bat head position in the vertical plane when it hit the ball. The SD was 2.1cm for the beginners and 1.1 cm for the player and experienced groups. There were significant differences in both swing speed and repeatability between the beginners and the player or experienced groups. These data suggest that both swing speed and repeatability improve with practice.

We surveyed the neural substrata for behavioral thermoregulation with immunohistochemical analysis of the expression of Fos protein in the rat brain. We used an operant system in which a rat exposed to heat ( 40 degreesC) could get cold air ( 0 degreesC) for 30 s when it moved into the reward area. Rats moved in and out of the reward area of the system periodically and thus maintained their body temperature at a normal level. In the rats performing heat escape behavior ( active group), strong Fos immunoreactivity (Fos-IR) was found in the median preoptic nucleus (MnPO), parastrial nucleus ( PS), and dorsomedial hypothalamus (DMH) compared with the controls. Another group of rats ( passive group) were given the same temperature changes, regardless of the rat's movement, as those obtained by rats of the active group. Fos-IR in the MnPO was also seen in this group. The present results suggest that the PS and DMH play an important role in the genesis of thermoregulatory behavior, whereas the MnPO may be important for detecting changes in ambient and/or body temperatures.

The major effector organ for thermogenesis during inflammation or experimental pyrogen-induced fever in rodents is the brown adipose tissue (BAT). Prostaglandin E2 (PGE(2)) microinjection into the medial preoptic area (POA) of rats leads to hyperthermia through an increase in BAT thermogenesis and induces pyrogenic signal transmission towards the raphe pallidus nucleus (RPa), a brainstem nucleus known to contain sympathetic premotor neurons for BAT control. The medial POA has a high expression of prostaglandin E receptor subtype EP3 (EP3R) on POA neurons, suggesting that these EP3R are main central targets of PGE(2) to mediate BAT thermogenesis. To reveal central command neurons that contain EP3R and polysynaptically project to the BAT, we combined EP3R immunohistochemistry with the detection of transneuronally labelled neurons that were infected after injection of pseudorabies virus into the BAT. Neurons double-labelled with EP3R and viral surface antigens were particularly numerous in two brain regions, the medial POA and the RPa. Of all medial POA neurons that became virally infected 71 h after BAT inoculation, about 40% expressed the EP3R. This subpopulation of POA neurons is the origin of a complete neuronal chain that connects potential PGE(2)-sensitive POA neurons with the BAT. As for the efferent pathway of pyrogenic signal transmission, we hypothesize that neurons of this subpopulation of EP3R expressing POA neurons convey their pyrogenic signals towards the BAT via the RPa. We additionally observed that two-thirds of those RPa neurons that polysynaptically project to the interscapular BAT also expressed the EP3R, suggesting that RPa neurons themselves might possess prostaglandin sensitivity that is able to modulate BAT thermogenesis under febrile conditions.

To investigate the mechanism involved in the reduction of body core temperature (T-core) during fasting in rats, which is selective in the light phase, we measured T-core, surface temperature, and oxygen consumption rate in fed control animals and in fasted animals on day 3 of fasting and day 4 of recovery at an ambient temperature (T-a) of 23 degreesC by biotelemetry, infrared thermography, and indirect calorimetry, respectively. On the fasting day, 1) T-core in the light phase decreased (P &lt; 0.05) from the control; however, T-core in the dark phase was unchanged, 2) tail temperature fell from the control (P &lt; 0.05, from 30.7 +/- 0.1 to 23.9 +/- 0.1 degreesC in the dark phase and from 29.4 +/- 0.1 to 25.2 +/- 0.2 degreesC in the light phase), 3) oxygen consumption rate decreased from the control ( P &lt; 0.05, from 24.37 +/- 1.06 to 16.24 +/- 0.69 ml . min(-1) . kg body wt(-0.75) in the dark phase and from 18.91 +/- 0.64 to 14.00 +/- 0.41 ml . min(-1) . kg body wt(-0.75) in the light phase). All these values returned to the control levels on the recovery day. The results suggest that, in the fasting condition, T-core in the dark phase was maintained by suppression of the heat loss mechanism, despite the reduction of metabolic heat production. In contrast, the response was weakened in the light phase, decreasing T-core greatly. Moreover, the change in the regulation of tail blood flow was a likely mechanism to suppress heat loss.

To investigate the involvement of the periaqueductal gray (PAG) in the control of non-shivering thermogenesis, we tested the effects of electrical or chemical stimulation of the PAG on thermogenesis of brown adipose tissue (BAT) in urethane anesthetized rats. Electrical stimulation (0.1 mA, 33 Hz, 0.5 ms) or application of D,L-homocysteic acid (0.5 mM, 0.3 mul) into the lateral region of the caudal PAG (cPAG) elicited BAT thermogenesis, measured as a rise in the local temperature of interscapular BAT. These results suggest that neurons in the cPAG send excitatory efferent signals for BAT thermogenesis. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

We investigated the thermoregulatory responses of sympathetic fibres supplying the tail in urethane-anaesthetised rats. When skin and rectal temperatures were kept above 39degreesC, tail sympathetic fibre activity was low or absent. When the trunk skin was cooled episodically by 2-7degreesC by a water jacket, tail sympathetic activity increased in a graded fashion below a threshold skin temperature of 37.8 +/- 0.6degreesC, whether or not core (rectal) temperature changed. Repeated cooling episodes lowered body core temperature by 1.3-3.1degreesC, and this independently activated tail sympathetic fibre activity, in a graded fashion, below a threshold rectal temperature of 38.4 +/- 0.2degreesC. Tail blood flow showed corresponding graded vasoconstrictor responses to skin and core cooling, albeit over a limited range. Tail sympathetic activity was more sensitive to core than to trunk skin cooling by a factor that varied widely (24-fold) between animals. Combined skin and core cooling gave additive or facilitatory responses near threshold but occlusive interactions with stronger stimuli. Unilateral warming of the preoptic area reversibly inhibited tail sympathetic activity. This was true for activity generated by either skin or core cooling. Single tail sympathetic units behaved homogeneously. Their sensitivity to trunk skin cooling was 0.3 +/- 0.08 spikes s(-1) degreesC(-1) and to core cooling was 2.2 +/- 0.5 spikes s(-1) degreesC(-1). Their maximum sustained firing rate in the cold was 1.82 +/- 0.35 spikes s(-1).

Regional activation of the brain was studied in humans using functional magnetic resonance imaging during whole body cooling that produced thermal comfort/discomfort. Eight normal male subjects lay in a sleeping bag through which air was blown, exposing subjects to cold air (8degreesC) for 22 min. Each subject scored their degree of thermal comfort and discomfort every min. As the subjects reported more discomfort the blood oxygen level dependent response in the bilateral amygdala increased. There was no activation in the thalamus, somatosensory, cingulate, or insula cortices. This result suggests that the amygdala plays a role in the genesis of thermal discomfort due to cold. (C) 2002 Published by Elsevier Science Ireland Ltd.

To investigate the involvement of the medullary raphe in thermoregulatory vasomotor control, we chemically manipulated raphe neuronal activity while monitoring the tail vasomotor response to preoptic warming. For comparison, neuronal activity in the rostral ventrolateral medulla (RVLM) was manipulated in similar experiments. Injections Of D,L-homocysteic acid (DLH; 0.5 mm, 0.3 mul) into a restricted region of the ventral medullary raphe suppressed the tail vasodilatation normally elicited by warming the preoptic area to 42degreesC. DLH injection into the RVLM also suppressed the vasodilatation elicited by preoptic warming. Injection of bicuculline (0.5 mm, 0.3 mul) into the same raphe region suppressed the vasodilatation elicited by preoptic warming. Bicuculline injection into the RVLM did not suppress tail vasodilatation. These results suggest that neurones in both the medullary raphe and the RVLM are vasoconstrictor to the tail, but only those in the raphe receive inhibitory input from the preoptic area. That input might be direct and/or indirect (e.g. via the periaqueductal grey matter).

The preoptic area (POA) occupies a crucial position among the structures participating in thermoregulation, but we know little about its efferent projections for controlling various effector responses. In this study, we used an immunohistochemical analysis of Fos expression during local warming of the preoptic area. To avoid the effects of anesthesia or stress, which are known to elicit Fos induction in various brain regions, we used a novel thermode specifically designed for chronic warming of discrete brain structures in freely moving rats. At an ambient temperature of 22 degreesC, local POA warming increased Fos immunoreactivity in the supraoptic nucleus (SON) and the periaqueductal gray matter (PAG). Exposure of animals to an ambient temperature of 5 degreesC induced Fos immunoreactivity in the magnocellular paraventricular nucleus (mPVN) and the dorsomedial region of the hypothalamus (DMH). Concurrent warming of the POA suppressed Fos expression in these areas. These findings suggest that thermal information from the preoptic area sends excitatory signals to the SON and the PAG, and inhibitory signals to the mPVN and the DMH. (C) 2002 Elsevier Science BV All rights reserved.

We examined body core and skin temperatures and thermal comfort in young Japanese women suffering from unusual coldness (C, n=6). They were selected by interview asking whether they often felt severe coldness even in an air-conditioned environment (20-26degreesC) and compared with women not suffering from coldness (N, n=6). Experiments were conducted twice for each subject: 120-min exposure at 23.5degreesC or 29.5degreesC after a 40-min baseline at 29.5degreesC. Mean skin temperature decreased (P&lt;0.05) from 33.6&PLUSMN;0.1&DEG;C (mean &PLUSMN; SE) to 31.1&PLUSMN;0.1&DEG;C and from 33.5&PLUSMN;0.1&DEG;C to 31.1&PLUSMN;0.1&DEG;C in C and N during the 23.5&DEG;C exposure. Fingertip temperature in C decreased more than in N (P&lt;0.05; from 35.2+/-0.1degreesC to 23.6+/-0.2degreesC and from 35.5+/-0.1degreesC to 25.6+/-0.6degreesC). Those temperatures during the 29.5degreesC exposure remained at the baseline levels. Rectal temperature during the 23.5degreesC exposure was maintained at the baseline level in both groups (from 36.9+/-0.2degreesC to 36.8+/-0.1degreesC and 37.1+/-0.1degreesC to 37.0+/-0.1degreesC in C and N). The rating scores of cold discomfort for both the body and extremities were greater (P&lt;0.05) in C than in N. Thus the augmented thermal sensitivity of the body to cold and activated vasoconstriction of the extremities during cold exposure could be the mechanism for the severe coldness felt in C.

Recently we found that food-deprived rats kept under a light-dark cycle showed a progressive reduction in body temperature during the light phase on each subsequent day while body temperature in the dark phase did not differ from baseline values. In this study, we investigated the effect of lesioning the hypothalamic suprachiasmatic nucleus (SCN) on body temperature modulation by food deprivation. In the SCN-lesioned rats in which daily rhythms of body temperature and activity were abolished, body temperature was unchanged by food deprivation. We also examined the effect of food deprivation on the daily changes in Fos expression in the SCN. Under normal fed conditions the number of SCN cells expressing Fos is high during the day and low at night. Food deprivation attenuated the amplitude of this daily change in Fos expression in the SCN. This tendency was prominent in the dorsal part of the SCN. while the ventral part showed no effect of food deprivation. These findings suggest that the SCN plays some role in body temperature modulation due to food deprivation. (C) 2002 Elsevier Science B.V. All rights reserved.

Salt loading decreases body core temperature (T(core)) at neutral ambient temperature (26 degrees C) and increases heat-escape/cold-seeking behaviour in desalivated rats. In this study, we tested the hypothesis that brain angiotensin II (AII) and arginine vasopressin (AVP) are associated with these responses. Surgically desalivated rats (n = 28) were administered an injection (S.C., 10 ml kg(-1)) of either normal saline (154 mM, NS) or hypertonic saline (2500 mM, HS) following an intracerebroventricular injection (10 microl kg(-1)) of an AII AT(1)-receptor antagonist (candesartan, 5 microg microl(-1)), an AVP V(1)-receptor antagonist ((beta-mercapto-beta, beta-cyclopenta-methylene propionyl(1), O-Me-Tyr(2), Arg(8))-vasopressin, 0.5 microg microl(-1)), or normal saline (154 mM). Each rat was placed in a behaviour box, first at 26 degrees C for 1 h to allow the measurement of baseline T(core) and movement. The ambient temperature was then elevated to 40 degrees C for the next 2 h, during which time the rat was able to trigger a 0 degrees C air reward for 30 s by moving into a specific area of the box (operant behaviour). The S.C. HS significantly decreased baseline T(core) at 26 degrees C (36.5 +/- 0.1 degrees C) and increased counts of operant behaviour at 40 degrees C (57 +/- 3) compared with results obtained following S.C. NS injection (37.4 +/- 0.1 degrees C and 42 +/- 1, respectively). These responses to s.c. HS were inhibited by the intracerebroventricular injection of AT(1) (37.3 +/- 0.1 degrees C and 43 +/- 2, respectively; P < 0.05) and V(1) antagonists (37.2 +/- 0.2 degrees C and 42 +/- 2, respectively; P < 0.05), although administration of both antagonists with S.C. NS had no effect. These results suggest that brain AII and AVP are involved in the decrease in T(core) observed at neutral ambient temperature and the increase in heat-escape/cold-seeking behaviour in response to osmotic stimulation, via the central AT(1) and V(1) receptors, respectively

Although the posterior part of the hypothalamus has long, been considered important for thermoregulatory shivering, it is unknown whether the neurons there or the passing fibers are implicated in the response. Exposure of urethane-anesthetized rats to cold (15-21 degreesC) elicits shivering. An injection of muscimol (0.5 mm), a GABA(A) receptor agonist, into the medial part of the hypothalamus, including the dorsomedial and posterior nuclei, suppressed the cold-induced shivering. This result suggests that neurons having an excitatory effect on shivering are in this region of the hypothalamus.

Effects of estrogen on thermoregulatory vasomotion and heat-escape behavior were investigated in ovariectomized female rats supplemented with estrogen (replaced estrogen rats) or control saline (low estrogen rats). First, we measured tail temperature of freely moving rats at ambient temperatures (T-a) between 13 and 31 degreesC. Tail temperature of the low estrogen rats was higher than that of the replaced estrogen rats at T-a between 19 and 25 degreesC, indicating that the low estrogen rats exhibit more skin vasodilation than the replaced estrogen rats. There was no significant difference in oxygen consumption and core temperature between the two groups. Second, we analyzed heat-escape behaviors in a hot chamber where rats could obtain cold air by moving in and out of a reward area. The low estrogen rats kept Ta at a lower level than did the replaced estrogen rats. These results imply that the lack of estrogen facilitates heat dissipation both by skin vasodilation and by heat-escape behavior. Ovariectomized rats may mimic climacteric hot flushes not only for autonomic skin vasomotor activity but also for thermoregulatory behavior.

We examined the effect of hypertonic saline injection on heat-escape/cold-seeking behavior in desalivated rats. Rats were exposed to 40 degreesC heat after normal (154 mM NaCl, control) or hypertonic saline (2,500 mM NaCl) injection (1 ml/100 g body wt). The rats received a 0 degreesC air for 30 s when they entered a specific area in an experimental box. Core temperature (T(c)) surpassed 40 degreesC in both conditions when 0 degreesC air was not available. Hypertonic saline injection produced a lower baseline T(c) than control [36.9 +/- 0.2 and 37.9 +/- 0.2 degreesC (means +/- SE), P &lt; 0.05] and a greater number of 0&lt;degrees&gt;C air rewards during the 2-h heat with lower T(c) at the end (48 +/- 1 and 34 +/- 2, 37.6 +/- 0.1, and 37.3 +/- 0.1 degreesC in the control and hypertonic saline injection trial, respectively, P &lt; 0.05, n = 6). However, T(c) was similar (37.7 +/- 0.2 and 37.6 +/- 0.4&lt;degrees&gt;C in the control and hypertonic saline injection trial, n = 5) when 0 degreesC air was automatically and intermittently (35 times) given during the heat. Rats augment heat-defense mechanisms in response to osmotic stress by lowering the baseline T(c) and increasing heat-escape/cold-seeking behavior.

1. We investigated the mechanism of starvation-induced hypothermia in rats.
2. Threshold core temperatures (T-cor) for tail skin vasodilatation and cold-induced thermogenesis were determined after a 3 day starvation using a chronically implanted intravenous thermode. Food deprivation significantly lowered the threshold T-cor for heat production, but did not affect the heat loss threshold. 3. Thermogenic response to a fall in T-cor below its threshold was enhanced by starvation.
4. Preferred ambient temperatures (T-pref) and T-cor were measured before and during a 3 day starvation in a thermal gradient. The 3 day starvation significantly lowered T-cor only in the light phase of the day. The level of hypothermia was the same throughout the fasting period, while T-pref gradually increased during the 3 days of starvation.
5. When rats were starved at a constant ambient temperature of 25 degrees C (no thermal gradient), their T-cor levels were comparable with those of the rats kept in the thermal gradient.
6. The results suggest that, in rats, hypothermia caused by starvation ws not due to a decrement in thermogenic capability, but was due to a decrease in the threshold for the activation of thermogenesis.

Homeothermic animals regulate body temperature (Tb) by using both autonomic and behavioral mechanisms. In the latter process, animals seek out cooler or warmer places when they are exposed to excessively hot or cold environments. Thermoregulation is affected by the state of energy reserves in the body. In the present study, we examine the effects of 4-day food deprivation on circadian changes in Tb and on cold-escape and heat-escape behaviors in rats. Continuous measurement of Tb during food deprivation indicated that the peak Tb amplitude was not different from baseline values, but the trough amplitude continuously decreased after the onset of food deprivation. Cold-escape behavior was facilitated by food deprivation, whereas heat-escape behavior was unchanged. After the termination of food deprivation, the lowered Tb returned to normal on the first day. However, cold-escape behavior was still facilitated on the third day after food reintroduction. Autonomic and behavioral thermoregulatory effecters are modulated in the face of food shortage so as to maintain optimal performance during the active period, whereas increasing energy conservation occurs during the quiescent phase.

Warming one side of a rat's preoptic area and anterior hypothalamus (POAH) suppresses shivering on both sides of the body, and the present study evaluated the extent to which signals mediating this suppression cross the midline within and below the POAH. Hind paw shivering during unilateral POAH thermal stimulation was measured for rats in which the POAH had been midsagittally transected and for rats in which one side of the hypothalamus had been coronally transected just caudal to the POAH. In midsagittally transected rats, unilateral warming on either side of the POAH suppressed shivering equally on both sides of the body. In unilaterally transected rats, POAH warming on the transected side did not affect shivering, but warming the intact side suppressed shivering equally on both sides of the body. When a unilateral transection of only the lateral part of the hypothalamus included the medial forebrain bundle, the effect was the same as that of a unilateral transection of the whole hypothalamus. These results indicate that no information controlling shivering is exchanged between the left and right POAH and that efferent signals from the POAH, descending through the medial forebrain bundle, cross the midline somewhere below the hypothalamus to innervate both sides of the body equally.

Warming one side of a rat's preoptic area and anterior hypothalamus (POAH) causes skin vasodilation on both sides of the body, and the present study evaluated the extent to which signals mediating this vasodilation cross the midline within and below the POAH. Hind paw vasomotion during unilateral POAH thermal or electrical stimulation was measured for rats in which the POAH had been midsagittally transected and for rats in which one side of the hypothalamus had been coronally transected just below the POAH. In midsagittally transected rats, unilateral POAH thermal or electrical stimulation produced bilateral paw vasodilation, but the ipsilateral dilation occurred at a hypothalamic temperature lower than that at which contralateral dilation occurred. In the unilaterally transected rats, unilateral POAH warming produced bilateral vasodilation and, regardless of which side of the POAH was warmed, the threshold stimulus temperature was always lower for vasodilation on the intact side. Unilateral transection of a part of the hypothalamus that included the medial forebrain bundle had the same effect as did unilateral transection of the whole hypothalamus. Information controlling thermoregulatory vasomotion thus crosses the midline both within and below the POAH. Although efferent signals descending through the medial forebrain bundle innervate skin blood vessels on both sides of the body, this innervation is stronger on the ipsilateral side.

Subcutaneous and intracerebroventricular (icv) injections of indomethacin were used to test whether prostaglandin synthesis is essential for the exercise-induced increase in a rat's body temperature. At an air temperature of 24°C , male Wistar rats ran on a treadmill at 10-15 m/min 20 min after 300-μg icv injection or 60 min after 15-mg/kg sc injection of indomethacin or of control vehicle. The rectal temperature (T(re)) of control rats in 17 control experiments increased by 1.0°C during exercise, whereas the T(re) of the rats pretreated with intracerebroventricular indomethacin increased by only 0.4°C. Threshold T(re) for tail vasodilation was significantly lower in rats pretreated with indomethacin than the control rats (38.4 ± 0.1 vs. 38.9 ± 0.1°C), but O2 uptake did not differ between indomethacin-pretreated and control rats. Subcutaneous injection of indomethacin did not affect the body temperature, tail vasomotor activity, or O2 uptake of exercising rats. Intracerebroventricular indomethacin did not affect T(re) or tail vasomotor activity of rats resting at ambient temperatures of 24 and 28°C. Present results suggest that prostaglandin synthesis is required for the vasoconstrictive effect of exercise on skin blood vessels and thus for the exercise-induced elevation of body temperature.

The present study explored the laterality of central nervous thermoregulatory control in anesthetized rats by measuring paw skin vasomotor activity and cold-induced shivering in hind leg muscles during unilateral preoptic area and anterior hypothalamus (POAH) warming and electrical stimulation or during unilateral thermal stimulation of abdominal skin. Unilateral POAH warming produced vasodilation on both sides of the body, but vasodilation on the ipsilateral side always either occurred at a lower threshold hypothalamic temperature or was stronger than on the contralateral side. In a cold environment (5-degrees-C), shivering was suppressed simultaneously in both hind legs when one side of the POAH was warmed, and shivering reappeared simultaneously on both sides when POAH warming stopped. These results suggest that different thermoregulatory effectors are regulated in a different way by each side of the POAH. Unilateral thermal stimulation of the abdominal skin, on the other hand, affected vasomotor activity and shivering equally on both sides of the body, as previously reported for its influence on salivary secretion. Skin thermal signals from both sides of the body therefore seem to converge before they act on different thermoregulatory effector systems.

1. At neutral (24-degrees-C) and at hot (40-degrees-C) ambient temperatures (T(a)) salivary secretion from the submandibular gland of freely moving rats was recorded, together with simultaneous observation of saliva-spreading behaviour (grooming).
2. At a T(a) of 24-degrees-C, basal salivary flow was less than 2-mu-l/min. When rats were first placed in the experimental chamber, brief grooming bouts often occurred. Transient secretion at more than 10-mu-l/min was associated with this grooming, and the rate of salivary flow was positively correlated with the duration of grooming activity.
3. At a Ta of 40-degrees-C, grooming appeared frequently and salivary secretion at more than 20-mu-l/min continued even between grooming bouts. Threshold rectal temperatures (T(re)) for thermally induced grooming (38.2 +/- 0.2-degrees-C) and for salivary secretion (38.2 +/- 0.1-degrees-C) were similar, and for eleven of sixteen rats the two thresholds coincided.
4. At the threshold T(re) both the rate of salivary secretion and the duration of grooming increased in a stepwise fashion. Above the threshold, there was no correlation between the duration of grooming and the rate of salivary flow.
5. Thermally induced salivary secretion and grooming behaviour appear to be controlled by independent mechanisms.