Beginning Movement Load (BML) training is a unique form of light-load training that comprises a lengthening-shortening sequence of muscle actions about multiple degrees of freedom. The purpose of the study was to determine the effectiveness of BML training at improving the performance of old adults on four functional tasks and to identify some of the neuromuscular adaptations that contributed to these gains. Healthy old adults (67.5±5.23 years) were randomly assigned to either a BML training group (n=17) or a control group (n=7). The training group exercised with a 30% of the one repetition-maximum (1-RM) load and performed five to seven sets of 15 repetitions, three times per week for 8 weeks. BML training increased maximal voluntary contraction (MVC) force significantly for the knee extensors (31.6%), but not the elbow flexors (9.8%), and improved the steadiness of isometric contractions (10%, 30%, and 65% MVC forces). Training-associated changes in times for ascending and descending stairs and one-legged balance, but not the chair rise, were predicted by changes in selected combinations of MVC force and steadiness. The attributes of BML training that enabled it to elicit functionally meaningful adaptations in the neuromuscular system of older adults should be explored with more mechanistic studies. © 2012 John Wiley &amp
Sons A/S. Published by John Wiley &amp
Sons Ltd.

Beginning Movement Load (BML) training is a unique form of light-load training that comprises a lengthening-shortening sequence of muscle actions about multiple degrees of freedom. The purpose of the study was to determine the effectiveness of BML training at improving the performance of old adults on four functional tasks and to identify some of the neuromuscular adaptations that contributed to these gains. Healthy old adults (67.5 +/- 5.23 years) were randomly assigned to either a BML training group (n=17) or a control group (n=7). The training group exercised with a 30% of the one repetition-maximum (1-RM) load and performed five to seven sets of 15 repetitions, three times per week for 8 weeks. BML training increased maximal voluntary contraction (MVC) force significantly for the knee extensors (31.6%), but not the elbow flexors (9.8%), and improved the steadiness of isometric contractions (10%, 30%, and 65% MVC forces). Training-associated changes in times for ascending and descending stairs and one-legged balance, but not the chair rise, were predicted by changes in selected combinations of MVC force and steadiness. The attributes of BML training that enabled it to elicit functionally meaningful adaptations in the neuromuscular system of older adults should be explored with more mechanistic studies.

Beginning Movement Load (BML) training is a unique form of light-load training that comprises a lengthening-shortening sequence of muscle actions about multiple degrees of freedom. The purpose of the study was to determine the effectiveness of BML training at improving the performance of old adults on four functional tasks and to identify some of the neuromuscular adaptations that contributed to these gains. Healthy old adults (67.5 +/- 5.23 years) were randomly assigned to either a BML training group (n=17) or a control group (n=7). The training group exercised with a 30% of the one repetition-maximum (1-RM) load and performed five to seven sets of 15 repetitions, three times per week for 8 weeks. BML training increased maximal voluntary contraction (MVC) force significantly for the knee extensors (31.6%), but not the elbow flexors (9.8%), and improved the steadiness of isometric contractions (10%, 30%, and 65% MVC forces). Training-associated changes in times for ascending and descending stairs and one-legged balance, but not the chair rise, were predicted by changes in selected combinations of MVC force and steadiness. The attributes of BML training that enabled it to elicit functionally meaningful adaptations in the neuromuscular system of older adults should be explored with more mechanistic studies.

Beginning Movement Load (BML) training is a unique form of light-load training that comprises a lengthening-shortening sequence of muscle actions about multiple degrees of freedom. The purpose of the study was to determine the effectiveness of BML training at improving the performance of old adults on four functional tasks and to identify some of the neuromuscular adaptations that contributed to these gains. Healthy old adults (67.5 +/- 5.23 years) were randomly assigned to either a BML training group (n=17) or a control group (n=7). The training group exercised with a 30% of the one repetition-maximum (1-RM) load and performed five to seven sets of 15 repetitions, three times per week for 8 weeks. BML training increased maximal voluntary contraction (MVC) force significantly for the knee extensors (31.6%), but not the elbow flexors (9.8%), and improved the steadiness of isometric contractions (10%, 30%, and 65% MVC forces). Training-associated changes in times for ascending and descending stairs and one-legged balance, but not the chair rise, were predicted by changes in selected combinations of MVC force and steadiness. The attributes of BML training that enabled it to elicit functionally meaningful adaptations in the neuromuscular system of older adults should be explored with more mechanistic studies.

We determined the angular range of motion and the relative timing of displacement in the thorax, lumbar spine, and pelvis in the transverse plane during treadmill walking at three velocities. Nine healthy young females walked on a treadmill for three minutes at 0.40, 0.93, and 1.47 m/s. The position of seven reflective markers and three rigs placed on the thorax, lumbar spine, and pelvis were recorded at 200 Hz by an eight-camera motion capture system. As gait velocity increased, stride length increased, cycle time decreased, and angular displacement in the thorax and L1 decreased but increased at the pelvis and L5 (all P < .05). The time of maximal angular rotation occurred in the following sequence: pelvis, L5, L3, L1, and thorax (P < .001). The thorax and L1 and L3 were in-phase for shorter duration as gait velocity increased, and this reduction was especially large, approx. 32% (P < .05), between thorax and pelvis. As gait velocity increased, the pelvis rotated earlier, causing the shortening of in-phase duration between thorax and pelvis. These data suggest that, as gait velocity increases, pelvis rotation dictates trunk rotation in the transverse plane during gait in healthy young females.

We determined the angular range of motion and the relative timing of displacement in the thorax, lumbar spine, and pelvis in the transverse plane during treadmill walking at three velocities. Nine healthy young females walked on a treadmill for three minutes at 0.40, 0.93, and 1.47 m/s. The position of seven reflective markers and three rigs placed on the thorax, lumbar spine, and pelvis were recorded at 200 Hz by an eight-camera motion capture system. As gait velocity increased, stride length increased, cycle time decreased, and angular displacement in the thorax and L1 decreased but increased at the pelvis and L5 (all P &lt
.05). The time of maximal angular rotation occurred in the following sequence: pelvis, L5, L3, L1, and thorax (P &lt
.001). The thorax and L1 and L3 were in-phase for shorter duration as gait velocity increased, and this reduction was especially large, approx. 32% (P &lt
.05), between thorax and pelvis. As gait velocity increased, the pelvis rotated earlier, causing the shortening of in-phase duration between thorax and pelvis. These data suggest that, as gait velocity increases, pelvis rotation dictates trunk rotation in the transverse plane during gait in healthy young females. © 2013 Human Kinetics, Inc.

There is an association between gait performance and spinal alignment in elderly females but it is unclear if this association is gender-dependent and postural changes would also predict gait performance in healthy elderly males. We measured thoracic kyphosis angle (TKA), LLA as indices of spinal alignment and maximal walking speed (WS), timed up and go test (TUG), 10-m obstacle walking time, and 6-min walk distance as indices of gait performance in healthy old males (n = 124, age 73.0 +/- 7.2 years). Knee extensor strength and one-leg standing time with eyes open were measures of physical function. The LLA but not TKA correlated with performance in each of the 4 gait test. Multiple-regression analyses showed that only the combination of knee extensor strength and LLA accounted for significant variation in gait performance. While previous studies showed that spinal alignment is associated with gait performance in elderly women, in healthy elderly males both functional (leg strength) and structural (spinal alignment) factors contribute to gait performance. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

There is an association between gait performance and spinal alignment in elderly females but it is unclear if this association is gender-dependent and postural changes would also predict gait performance in healthy elderly males. We measured thoracic kyphosis angle (TKA), LLA as indices of spinal alignment and maximal walking speed (WS), timed up and go test (TUG), 10-m obstacle walking time, and 6-min walk distance as indices of gait performance in healthy old males (n = 124, age 73.0 +/- 7.2 years). Knee extensor strength and one-leg standing time with eyes open were measures of physical function. The LLA but not TKA correlated with performance in each of the 4 gait test. Multiple-regression analyses showed that only the combination of knee extensor strength and LLA accounted for significant variation in gait performance. While previous studies showed that spinal alignment is associated with gait performance in elderly women, in healthy elderly males both functional (leg strength) and structural (spinal alignment) factors contribute to gait performance. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

There is an association between gait performance and spinal alignment in elderly females but it is unclear if this association is gender-dependent and postural changes would also predict gait performance in healthy elderly males. We measured thoracic kyphosis angle (TKA), LLA as indices of spinal alignment and maximal walking speed (WS), timed up and go test (TUG), 10-m obstacle walking time, and 6-min walk distance as indices of gait performance in healthy old males (n = 124, age 73.0 +/- 7.2 years). Knee extensor strength and one-leg standing time with eyes open were measures of physical function. The LLA but not TKA correlated with performance in each of the 4 gait test. Multiple-regression analyses showed that only the combination of knee extensor strength and LLA accounted for significant variation in gait performance. While previous studies showed that spinal alignment is associated with gait performance in elderly women, in healthy elderly males both functional (leg strength) and structural (spinal alignment) factors contribute to gait performance. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

There is an association between gait performance and spinal alignment in elderly females but it is unclear if this association is gender-dependent and postural changes would also predict gait performance in healthy elderly males. We measured thoracic kyphosis angle (TKA), LLA as indices of spinal alignment and maximal walking speed (WS), timed up and go test (TUG), 10-m obstacle walking time, and 6-min walk distance as indices of gait performance in healthy old males (n = 124, age 73.0 +/- 7.2 years). Knee extensor strength and one-leg standing time with eyes open were measures of physical function. The LLA but not TKA correlated with performance in each of the 4 gait test. Multiple-regression analyses showed that only the combination of knee extensor strength and LLA accounted for significant variation in gait performance. While previous studies showed that spinal alignment is associated with gait performance in elderly women, in healthy elderly males both functional (leg strength) and structural (spinal alignment) factors contribute to gait performance. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

This study was undertaken to elucidate the impact of long-term physical training on the modulation of stretch reflex excitability. To this end, electromyographic activities of the soleus muscle in response to quick toe-up rotation were compared between highly trained endurance runners (n = 8) and non-trained control subjects (n = 9). We specifically focused on the stretch reflex modulation under different voluntary activation levels, from rest to pre-activated conditions (5, 10, 20, and 30% of the maximal). While the two groups showed similar modulation patterns of the stretch reflex responses, the extent of reflex modulation in accordance with the muscle pre-activation level was larger in the trained group. The present results therefore suggest a different modulation pattern of the stretch reflex responses with changing activation level between individuals with different physical background, and the enhancement of the responses in the trained individuals may particularly be advantageous in exerting high level muscle contraction.

This study was undertaken to elucidate the impact of long-term physical training on the modulation of stretch reflex excitability. To this end, electromyographic activities of the soleus muscle in response to quick toe-up rotation were compared between highly trained endurance runners (n = 8) and non-trained control subjects (n = 9). We specifically focused on the stretch reflex modulation under different voluntary activation levels, from rest to pre-activated conditions (5, 10, 20, and 30% of the maximal). While the two groups showed similar modulation patterns of the stretch reflex responses, the extent of reflex modulation in accordance with the muscle pre-activation level was larger in the trained group. The present results therefore suggest a different modulation pattern of the stretch reflex responses with changing activation level between individuals with different physical background, and the enhancement of the responses in the trained individuals may particularly be advantageous in exerting high level muscle contraction.

Despite well-authorized facts regarding asymmetrical architectural changes between different limbs after persistent participation in particular motor training, no studies have addressed the neural aspects to the present. The authors undertook the study to elucidate the possibility of neural adaptation on a limb-by-limb basis after repetitive engagement in a particular motor training routine. We investigated lower leg muscles in endurance-trained track runners who have been trained by routinely running on a track in counterclockwise direction on curved paths. Stretch reflex responses in the plantarflexor muscles (soleus [SOL], medial [MG], and lateral head of the gastrocnemius muscle) were evaluated bilaterally with participants sitting at rest. Comparisons were made between homonymous muscles of the right (corresponding to outside leg for track running) and left leg (inside leg, likewise) and with a group of nontrained controls. The result clearly demonstrated that the responses were prominently different between the legs (thus, asymmetrical) in the MG muscles and partially in the SOL muscles in the trained group. In contrast, no such differences were obtained in the nontrained control group. The result demonstrated that neural adaptation took place asymmetrically and that could be attributable to their repetitive engagement in the stereotypical motor task.

Despite well-authorized facts regarding asymmetrical architectural changes between different limbs after persistent participation in particular motor training, no studies have addressed the neural aspects to the present. The authors undertook the study to elucidate the possibility of neural adaptation on a limb-by-limb basis after repetitive engagement in a particular motor training routine. We investigated lower leg muscles in endurance-trained track runners who have been trained by routinely running on a track in counterclockwise direction on curved paths. Stretch reflex responses in the plantarflexor muscles (soleus [SOL], medial [MG], and lateral head of the gastrocnemius muscle) were evaluated bilaterally with participants sitting at rest. Comparisons were made between homonymous muscles of the right (corresponding to outside leg for track running) and left leg (inside leg, likewise) and with a group of nontrained controls. The result clearly demonstrated that the responses were prominently different between the legs (thus, asymmetrical) in the MG muscles and partially in the SOL muscles in the trained group. In contrast, no such differences were obtained in the nontrained control group. The result demonstrated that neural adaptation took place asymmetrically and that could be attributable to their repetitive engagement in the stereotypical motor task.

In the absence of visual information, humans cannot maintain a straight walking path. We examined the hypothesis that step frequency during walking affects the magnitude of veering in healthy adults. Subject walked at a preferred (1.77 +/- 0.18 Hz), low (0.8 x preferred, 1.41 +/- 0.15 Hz), and high (1.2 x preferred, 2.13 +/- 0.20 Hz) step frequency with and without a blindfold. We compared the absolute differences between estimated and measured points of crossing a target line after 16 m of forward walking at the three step frequencies. There was no significant difference in veering when subjects walked at the different frequencies without a blindfold. However, the magnitude of veering was the smallest at the preferred (mean +/- SE = 91.6 +/- 33.6 cm) compared with the low (204.3 +/- 43.0 cm) and high (112.7 +/- 34.0 cm) frequency gaits with a blindfold. Thus, walking at a preferred step frequency minimizes veering, which occurs in the absence of visual information. This phenomenon may be associated with the previously reported minimization of movement variability, energy cost, and attentional demand while walking at a preferred step frequency. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

In the absence of visual information, humans cannot maintain a straight walking path. We examined the hypothesis that step frequency during walking affects the magnitude of veering in healthy adults. Subject walked at a preferred (1.77 +/- 0.18 Hz), low (0.8 x preferred, 1.41 +/- 0.15 Hz), and high (1.2 x preferred, 2.13 +/- 0.20 Hz) step frequency with and without a blindfold. We compared the absolute differences between estimated and measured points of crossing a target line after 16 m of forward walking at the three step frequencies. There was no significant difference in veering when subjects walked at the different frequencies without a blindfold. However, the magnitude of veering was the smallest at the preferred (mean +/- SE = 91.6 +/- 33.6 cm) compared with the low (204.3 +/- 43.0 cm) and high (112.7 +/- 34.0 cm) frequency gaits with a blindfold. Thus, walking at a preferred step frequency minimizes veering, which occurs in the absence of visual information. This phenomenon may be associated with the previously reported minimization of movement variability, energy cost, and attentional demand while walking at a preferred step frequency. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

In the absence of visual information, humans cannot maintain a straight walking path. We examined the hypothesis that step frequency during walking affects the magnitude of veering in healthy adults. Subject walked at a preferred (1.77 +/- 0.18 Hz), low (0.8 x preferred, 1.41 +/- 0.15 Hz), and high (1.2 x preferred, 2.13 +/- 0.20 Hz) step frequency with and without a blindfold. We compared the absolute differences between estimated and measured points of crossing a target line after 16 m of forward walking at the three step frequencies. There was no significant difference in veering when subjects walked at the different frequencies without a blindfold. However, the magnitude of veering was the smallest at the preferred (mean +/- SE = 91.6 +/- 33.6 cm) compared with the low (204.3 +/- 43.0 cm) and high (112.7 +/- 34.0 cm) frequency gaits with a blindfold. Thus, walking at a preferred step frequency minimizes veering, which occurs in the absence of visual information. This phenomenon may be associated with the previously reported minimization of movement variability, energy cost, and attentional demand while walking at a preferred step frequency. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

In the absence of visual information, humans cannot maintain a straight walking path. We examined the hypothesis that step frequency during walking affects the magnitude of veering in healthy adults. Subject walked at a preferred (1.77 +/- 0.18 Hz), low (0.8 x preferred, 1.41 +/- 0.15 Hz), and high (1.2 x preferred, 2.13 +/- 0.20 Hz) step frequency with and without a blindfold. We compared the absolute differences between estimated and measured points of crossing a target line after 16 m of forward walking at the three step frequencies. There was no significant difference in veering when subjects walked at the different frequencies without a blindfold. However, the magnitude of veering was the smallest at the preferred (mean +/- SE = 91.6 +/- 33.6 cm) compared with the low (204.3 +/- 43.0 cm) and high (112.7 +/- 34.0 cm) frequency gaits with a blindfold. Thus, walking at a preferred step frequency minimizes veering, which occurs in the absence of visual information. This phenomenon may be associated with the previously reported minimization of movement variability, energy cost, and attentional demand while walking at a preferred step frequency. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Introduction: In human movements muscles lengthen and then shorten, or occasionally shorten and then lengthen, but it is unclear whether the nature of neural activation of the initial phase influences the neural state of the subsequent phase. We examined whether contraction history modulates spinal excitability in the healthy human soleus muscle. Methods: Subjects performed six blocks of 10 repetitions of four muscle actions consisting of specific combinations of passive shortening (PAS), and passive lengthening (PAL), shortening contraction (SHO), and lengthening contraction (LEN); that is: (1) SHO+PAL; (2) PAS+LEN; (3) PAS+PAL; and (4) SHO+LEN. Results: Compared with baseline, the H-reflex increased in the block of 300-400 s after SHO+PAL and decreased in the block of 0-100 s after PAS+LEN and SHO+LEN. Conclusions: Our results suggest that spinal excitability is potentiated during a muscle action preceded by muscle shortening, but it becomes depressed during a muscle action preceded by muscle lengthening. Muscle Nerve 43: 851-858, 2011

Introduction: In human movements muscles lengthen and then shorten, or occasionally shorten and then lengthen, but it is unclear whether the nature of neural activation of the initial phase influences the neural state of the subsequent phase. We examined whether contraction history modulates spinal excitability in the healthy human soleus muscle. Methods: Subjects performed six blocks of 10 repetitions of four muscle actions consisting of specific combinations of passive shortening (PAS), and passive lengthening (PAL), shortening contraction (SHO), and lengthening contraction (LEN); that is: (1) SHO+PAL; (2) PAS+LEN; (3) PAS+PAL; and (4) SHO+LEN. Results: Compared with baseline, the H-reflex increased in the block of 300-400 s after SHO+PAL and decreased in the block of 0-100 s after PAS+LEN and SHO+LEN. Conclusions: Our results suggest that spinal excitability is potentiated during a muscle action preceded by muscle shortening, but it becomes depressed during a muscle action preceded by muscle lengthening. Muscle Nerve 43: 851-858, 2011

Unilateral isometric muscle contractions increase motor-evoked potentials (MEPs) produced by transcranial magnetic stimulation not only in the contracting muscle but also in the resting contralateral homologous muscle. Corticospinal excitability in the M1 contralateral to the contracting muscle changes depending on the type of muscle contraction. Here, we investigated the possibility that corticospinal excitability in M1 ipsilateral to the contracting muscle is modulated in a contraction-type-dependent manner. To this end, we evaluated MEPs in the resting left flexor carpi radialis (FCR) during unilateral shortening, lengthening, and isometric muscle contractions of the right wrist flexors at 10, 20, and 30% of maximal isometric contraction force. To compare the effects of different unilateral contractions on MEPs between the contracting and resting sides, MEPs in the right FCR were recorded on two separate days. In a separate experiment, we investigated the contraction specificity of the crossed effect at the spinal level by recording H-reflexes from the resting left FCR during contraction of the right wrist flexors. The results showed that MEPs in the contracting right FCR were the smallest during lengthening contraction. By contrast, MEPs in the resting left FCR were the largest during lengthening contraction, whereas the H-reflex was similar in the resting left FCR during the three types of muscle contraction. These results suggest that different types of unilateral muscle contraction asymmetrically modulate MEP size in the resting contralateral homologous muscle and in the contracting muscle and that this regulation occurs at the supraspinal level.

Unilateral isometric muscle contractions increase motor-evoked potentials (MEPs) produced by transcranial magnetic stimulation not only in the contracting muscle but also in the resting contralateral homologous muscle. Corticospinal excitability in the M1 contralateral to the contracting muscle changes depending on the type of muscle contraction. Here, we investigated the possibility that corticospinal excitability in M1 ipsilateral to the contracting muscle is modulated in a contraction-type-dependent manner. To this end, we evaluated MEPs in the resting left flexor carpi radialis (FCR) during unilateral shortening, lengthening, and isometric muscle contractions of the right wrist flexors at 10, 20, and 30% of maximal isometric contraction force. To compare the effects of different unilateral contractions on MEPs between the contracting and resting sides, MEPs in the right FCR were recorded on two separate days. In a separate experiment, we investigated the contraction specificity of the crossed effect at the spinal level by recording H-reflexes from the resting left FCR during contraction of the right wrist flexors. The results showed that MEPs in the contracting right FCR were the smallest during lengthening contraction. By contrast, MEPs in the resting left FCR were the largest during lengthening contraction, whereas the H-reflex was similar in the resting left FCR during the three types of muscle contraction. These results suggest that different types of unilateral muscle contraction asymmetrically modulate MEP size in the resting contralateral homologous muscle and in the contracting muscle and that this regulation occurs at the supraspinal level.

The aim of the study was to compare the kinematics and the timing and amount of electromyographic (EMG) activity during the lat-pull down exercise performed on machines that afforded one, two, or three degrees of freedom for the movement. Seven healthy men (age 29.4 +/- A 5.6 years) participated in the study. The exercise was performed with a 30% 1-RM load. Three types of machines with varying degrees of freedom were used: Type 1, the conventional device that restricted the movement to a frontal plane; Type 2, the addition of forearm supination-pronation; Type 3, the addition of forearm supination-pronation and horizontal extension-flexion about the shoulder. All exercises involved a technique known as beginning movement load (BML) training in which light loads are lifted with a relaxation-lengthening-shortening sequence of muscle activation. The Type-3 machine showed: (1) the greatest vertical displacement of the wrist (p < 0.05); (2) the greatest abduction-adduction displacement about the shoulder (p < 0.01); (3) the least flexion-extension displacement about the elbow joint (p < 0.01); (4) a peak vertical velocity for the shoulder that preceded (p < 0.01) those for the elbow and then wrist during the pull-down phase; (5) a progressive proximal-to-distal sequence of EMG activation involving the serratus anterior, posterior deltoid, latissimus dorsi, and triceps brachii muscles; (6) a reversal of the roles for biceps and triceps brachii during the pull-down phase. These results suggest that BML exercises with greater degrees of freedom can enhance the association between training actions and functional activities.

The aim of the study was to compare the kinematics and the timing and amount of electromyographic (EMG) activity during the lat-pull down exercise performed on machines that afforded one, two, or three degrees of freedom for the movement. Seven healthy men (age 29.4 +/- A 5.6 years) participated in the study. The exercise was performed with a 30% 1-RM load. Three types of machines with varying degrees of freedom were used: Type 1, the conventional device that restricted the movement to a frontal plane; Type 2, the addition of forearm supination-pronation; Type 3, the addition of forearm supination-pronation and horizontal extension-flexion about the shoulder. All exercises involved a technique known as beginning movement load (BML) training in which light loads are lifted with a relaxation-lengthening-shortening sequence of muscle activation. The Type-3 machine showed: (1) the greatest vertical displacement of the wrist (p < 0.05); (2) the greatest abduction-adduction displacement about the shoulder (p < 0.01); (3) the least flexion-extension displacement about the elbow joint (p < 0.01); (4) a peak vertical velocity for the shoulder that preceded (p < 0.01) those for the elbow and then wrist during the pull-down phase; (5) a progressive proximal-to-distal sequence of EMG activation involving the serratus anterior, posterior deltoid, latissimus dorsi, and triceps brachii muscles; (6) a reversal of the roles for biceps and triceps brachii during the pull-down phase. These results suggest that BML exercises with greater degrees of freedom can enhance the association between training actions and functional activities.

The purpose of this study was to investigate effects of long-term participation to swimming on adaptations of spinal reflex excitability. To this end, mechanically induced stretch reflex (SR) and electrically induced Hoffmann (H-) reflex of the soleus muscle were investigated between swimmers with experience of more than 10 years and non-trained individuals while sitting at rest. The amplitude and the gain (stretch velocity vs. amplitude of the reflex response) of the SR were significantly greater in the swimming group than in the non-trained control group. Similarly, the responses of the H-reflex were also significantly greater in the swimming group than in the non-trained control group. Results of this study demonstrated that the spinal reflex excitability in experienced swimmers was far more enhanced than in non-trained individuals.

The purpose of this study was to investigate effects of long-term participation to swimming on adaptations of spinal reflex excitability. To this end, mechanically induced stretch reflex (SR) and electrically induced Hoffmann (H-) reflex of the soleus muscle were investigated between swimmers with experience of more than 10 years and non-trained individuals while sitting at rest. The amplitude and the gain (stretch velocity vs. amplitude of the reflex response) of the SR were significantly greater in the swimming group than in the non-trained control group. Similarly, the responses of the H-reflex were also significantly greater in the swimming group than in the non-trained control group. Results of this study demonstrated that the spinal reflex excitability in experienced swimmers was far more enhanced than in non-trained individuals.

Original paper

Original paper

Age-related physiological and morphological changes of muscle spindles were examined in rats (male Fischer 344/DuCrj: young, 4-13 months; middle-aged, 20-22 months; old, 28-31 months). Single afferent discharges of the muscle spindles in gastrocnemius muscles were recorded from a finely split dorsal root during ramp-and-hold (amplitude, 2.0 mm; velocity, 2-20 mm s(-1)) or sinusoidal stretch (amplitude, 0.05-1.0 mm; frequency, 0.5-2 Hz). Respective conduction velocities (CVs) were then measured. After electrophysiological experimentation, the muscles were dissected. The silver-impregnated muscle spindles were teased and then analysed using a light microscope. The CV and dynamic response to ramp-and-hold stretch of many endings were widely overlapped in old rats because of the decreased CV and dynamic response of primary endings. Many units in old rats showed slowing of discharge during the release phase under ramp-and-hold stretch and continuous discharge under sinusoidal stretch, similarly to secondary endings in young and middle-aged rats. Morphological studies revealed that primary endings of aged rat muscle spindles were less spiral or non-spiral in appearance, but secondary endings appeared unchanged. These results suggest first that primary muscle spindles in old rats are indistinguishable from secondary endings when determined solely by previously used physiological criteria. Secondly, these physiological results reflect drastic age-related morphological changes in spindle primary endings.

Age-related physiological and morphological changes of muscle spindles were examined in rats (male Fischer 344/DuCrj: young, 4-13 months; middle-aged, 20-22 months; old, 28-31 months). Single afferent discharges of the muscle spindles in gastrocnemius muscles were recorded from a finely split dorsal root during ramp-and-hold (amplitude, 2.0 mm; velocity, 2-20 mm s(-1)) or sinusoidal stretch (amplitude, 0.05-1.0 mm; frequency, 0.5-2 Hz). Respective conduction velocities (CVs) were then measured. After electrophysiological experimentation, the muscles were dissected. The silver-impregnated muscle spindles were teased and then analysed using a light microscope. The CV and dynamic response to ramp-and-hold stretch of many endings were widely overlapped in old rats because of the decreased CV and dynamic response of primary endings. Many units in old rats showed slowing of discharge during the release phase under ramp-and-hold stretch and continuous discharge under sinusoidal stretch, similarly to secondary endings in young and middle-aged rats. Morphological studies revealed that primary endings of aged rat muscle spindles were less spiral or non-spiral in appearance, but secondary endings appeared unchanged. These results suggest first that primary muscle spindles in old rats are indistinguishable from secondary endings when determined solely by previously used physiological criteria. Secondly, these physiological results reflect drastic age-related morphological changes in spindle primary endings.

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 springmass 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. (c) 2007 Elsevier Ireland Ltd. All rights reserved.

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 springmass 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. (c) 2007 Elsevier Ireland Ltd. All rights reserved.

Despite their wide clinical application and success, our understanding of the effects of insoles is relatively limited. The purpose of this study was to assess the biomechanical effects of wearing lateral/medial wedged insoles on subtalar and knee joints during normal walking. Motion analysis was conducted with a 3D motion-analysis system and a ground reaction force analysis using force plate when subjects walked with three different insole conditions : 5-degree medial wedge, no wedge, and 5-degree lateral wedge. Significant differences were found in subtalar or ankle joint motion in coronal and sagittal planes compared with the no-wedge condition. No differences were found in knee joint motion in the coronal and axial planes. The lateral-wedge insole reduced the knee varus moment and increased subtalar pronation moment in mid-stance during walking. At footstrike, however, the lateral wedge increased the knee varus moment and reduced the subtalar supination moment. The medial-wedge insole increased the knee varus moment and decreased subtalar pronation moment during the mid-stance phase. However, the medial wedge reduced the knee varus moment and increased subtalar supination moment at footstrike. The results of this study indicate that the influence of the insoles varied during the stance phase. Therefore, it is requested to select the shape of insole based on the injury mechanism, the location of the pain and the injury prevention.

The aim of this study was to test whether anticipation of upcoming head blow stimuli, which elicit reflex responses in the neck muscle, makes the reflex responses greater or not. In nine healthy subjects the reflex responses were elicited in the sternocleidomastoid (SCM) muscle in the eyes-open (EO) and eyes-closed (EC) conditions, which corresponded to the predictable and unpredictable conditions, respectively. The subjects were instructed not to resist the perturbations after the impact. The results demonstrated that the reflex response of the SCM muscle was significantly smaller in the predictable EO condition than in the unpredictable EC condition (P < 0.05), although no significant differences were observed in either the background EMG activities or the head accelerations. Further, this effect of anticipation was observed only in the later reflex EMG component, which most probably mediated the stretch reflex pathway. In contrast, no significant difference was observed in the early component, which was presumed to be the vestibular-collic reflex. The reduced stretch reflex response was suggested to be functionally relevant to the task requirement, i.e., to let the neck extension movement occur, and not to resist after the impact of the head blow. It was concluded that the anticipation has an effect on reducing the stretch reflex responses in the neck muscle, but does not have any effect on the presumed vestibular-collic reflex under the present experimental paradigm. It is suggested that the gain of the stretch reflex pathway is modulated by anticipatory information of upcoming mechanical event. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

The aim of this study was to test whether anticipation of upcoming head blow stimuli, which elicit reflex responses in the neck muscle, makes the reflex responses greater or not. In nine healthy subjects the reflex responses were elicited in the sternocleidomastoid (SCM) muscle in the eyes-open (EO) and eyes-closed (EC) conditions, which corresponded to the predictable and unpredictable conditions, respectively. The subjects were instructed not to resist the perturbations after the impact. The results demonstrated that the reflex response of the SCM muscle was significantly smaller in the predictable EO condition than in the unpredictable EC condition (P < 0.05), although no significant differences were observed in either the background EMG activities or the head accelerations. Further, this effect of anticipation was observed only in the later reflex EMG component, which most probably mediated the stretch reflex pathway. In contrast, no significant difference was observed in the early component, which was presumed to be the vestibular-collic reflex. The reduced stretch reflex response was suggested to be functionally relevant to the task requirement, i.e., to let the neck extension movement occur, and not to resist after the impact of the head blow. It was concluded that the anticipation has an effect on reducing the stretch reflex responses in the neck muscle, but does not have any effect on the presumed vestibular-collic reflex under the present experimental paradigm. It is suggested that the gain of the stretch reflex pathway is modulated by anticipatory information of upcoming mechanical event. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

The purpose of this study was to investigate how the recruitment properties of the corticospinal pathway are modulated in the soleus muscle of the lower limb during lengthening (LEN) and shortening (SHO) contractions by comparing the shape of the input-output (I/O) relation of the corticospinal pathway. To this end, we investigated the relationship between various stimulus intensities applied via transcranial magnetic stimulation and the size of motor-evoked potentials in 14 healthy subjects during voluntary plantarflexion and dorsiflexion (active lengthening) with a similar background activity (BGA) level. The shape of this relationship was sigmoidal and was characterized by a plateau value, maximum slope and threshold. The plateau value was clearly lower during LEN contractions than during SHO contractions. Likewise, the maximum slope was lower during LEN contractions. However, the threshold did not differ significantly between the two tasks. Since the plateau value and the maximum slope clearly differed between LEN and SHO contractions despite the similarity of their BGA levels. the central nervous system appears to have a different activation strategy for each of these tasks. Namely, the relative balance between excitatory and inhibitory components of the corticospinal volleys, as well as the subliminal fringe of the corticospinal pathway. were reduced during LEN contractions compared with SHO contractions. These strategies may help to avoid reflexive contractions brought about by higher discharge of muscle spindles and enable fine motor actions in voluntary lengthening contractions. (C) 2003 Elsevier Science B.V. All rights reserved.

The purpose of this study was to investigate how the recruitment properties of the corticospinal pathway are modulated in the soleus muscle of the lower limb during lengthening (LEN) and shortening (SHO) contractions by comparing the shape of the input-output (I/O) relation of the corticospinal pathway. To this end, we investigated the relationship between various stimulus intensities applied via transcranial magnetic stimulation and the size of motor-evoked potentials in 14 healthy subjects during voluntary plantarflexion and dorsiflexion (active lengthening) with a similar background activity (BGA) level. The shape of this relationship was sigmoidal and was characterized by a plateau value, maximum slope and threshold. The plateau value was clearly lower during LEN contractions than during SHO contractions. Likewise, the maximum slope was lower during LEN contractions. However, the threshold did not differ significantly between the two tasks. Since the plateau value and the maximum slope clearly differed between LEN and SHO contractions despite the similarity of their BGA levels. the central nervous system appears to have a different activation strategy for each of these tasks. Namely, the relative balance between excitatory and inhibitory components of the corticospinal volleys, as well as the subliminal fringe of the corticospinal pathway. were reduced during LEN contractions compared with SHO contractions. These strategies may help to avoid reflexive contractions brought about by higher discharge of muscle spindles and enable fine motor actions in voluntary lengthening contractions. (C) 2003 Elsevier Science B.V. All rights reserved.

To characterize the electromyographic (EMG) activity, ground reaction forces, and kinematics were used in the running jump with different takeoff angles. Two male long jumpers volunteered to perform running jumps at different approach speeds by varying the number of steps (from 3 to 9) in the run-up. Subject TM achieved a greater vertical velocity of the center of gravity (CG) at takeoff for all approach distances. This jumping strategy was associated with greater backward trunk lean at touchdown and takeoff, a lesser range of motion for the thigh during the support phase, more extended knee and ankle angles at touchdown, and a more flexed knee angle at takeoff. Accompanying these differences in kinematics, TM experienced greater braking impulses and lesser propulsion impulses for the forward-backward component of the ground reaction force. Furthermore, TM activated mainly the rectus femoris, vastus medialis, lateral gastrocnemius, and tibialis anterior, while if rarely activated the biceps femoris from just before contact to roughly the first two-thirds of the support phase. These results indicate that TM used a greater takeoff an le in the running jump because he enabled and sustained a greater blocking effect via the coordination patterns of the muscles relative to the hip, knee, and ankle joints. These findings also suggest that the muscle activities recorded in the present experiment are reflected in kinematics and kinetics. Further, the possible influence of these muscle activities on joint movements in the takeoff leg, and their effect on the vertical and/or horizontal velocity of the jump are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.

To characterize the electromyographic (EMG) activity, ground reaction forces, and kinematics were used in the running jump with different takeoff angles. Two male long jumpers volunteered to perform running jumps at different approach speeds by varying the number of steps (from 3 to 9) in the run-up. Subject TM achieved a greater vertical velocity of the center of gravity (CG) at takeoff for all approach distances. This jumping strategy was associated with greater backward trunk lean at touchdown and takeoff, a lesser range of motion for the thigh during the support phase, more extended knee and ankle angles at touchdown, and a more flexed knee angle at takeoff. Accompanying these differences in kinematics, TM experienced greater braking impulses and lesser propulsion impulses for the forward-backward component of the ground reaction force. Furthermore, TM activated mainly the rectus femoris, vastus medialis, lateral gastrocnemius, and tibialis anterior, while if rarely activated the biceps femoris from just before contact to roughly the first two-thirds of the support phase. These results indicate that TM used a greater takeoff an le in the running jump because he enabled and sustained a greater blocking effect via the coordination patterns of the muscles relative to the hip, knee, and ankle joints. These findings also suggest that the muscle activities recorded in the present experiment are reflected in kinematics and kinetics. Further, the possible influence of these muscle activities on joint movements in the takeoff leg, and their effect on the vertical and/or horizontal velocity of the jump are discussed. (C) 2001 Elsevier Science Ltd. All rights reserved.

太極拳は中国を起源とする武術の型を基礎とし、それに気功、軽絡学、陰陽二元説などの中国古来の理論を取り入れた健身養生術であり、意識と気（呼吸）と動作が一体となり、緩やかな動作（テンシケイ）が主となっている。その内、特に陳式太極拳ではハッケイ（突き）や震脚（シンキャク）と呼ばれる瞬時に完結する激しい動作が含まれる。熟練者では、一度動きが始まると止まるところがなく神経・骨格筋系や内臓の組織が一体となり同調して活動する。また、呼吸を整え身体をゆるめた状態で指、手、四肢、体幹を意識的に集中する動作が特徴であることから大脳認知機能への有用な効果が期待される。これらのことから太極拳を行うことによって肉体的にも精神的にも健康になる。太極拳の効用に関する研究は多数ある。しかし、太極拳の動作そのものに関しては経験的な表現が多く、運動制御とバイオメカニクスの見地から科学的に解明した研究は殆どない。よって、本研究課題として「太極拳、特にハッケイや震脚が含まれる伝統陳式太極拳の動作を科学的に検証すること」とした。陳式太極拳の基本動作形態は合計75の形（金剛搗碓、攬紮衣、六封四閉、単鞭、白鶴亮翅、斜行、掩手肱挙、雲手、巻肱等）がある。これらの演技を最初から終わりまで続けると約20分掛る。昨年度の研究では、熟練者が金剛搗碓の一連の動きを行なったときの身体重心変動を未熟練者と比較・検討した。結果、熟練者は一端動きが始まると腰を落とした状態の姿勢から、重心位置を左右・前後へ円滑に移動し、特に片脚立ちから対側脚への重心移動を行なったときにも片脚のみでバランスを保ちつつ重心を下げながら対側脚に円滑な体重移動を行なう動態をEMG活動と併せて示した。よって本年度は、金剛搗碓の終了時の震脚動作に限定して解析した。被験者は陳式太極拳の熟練者5名（38.8 ± 4.5 yr, 1.69 ± 0.07 m, 69.9 ± 9.9 kg）と初心者4名（40.0 ± 2.2 yrs, 1.69 ± 0.04 m, 68.8 ± 7.2 kg）であった。熟練者の内、1名は中国全国武術選手権大会太極拳部門準優勝者（達人）であった。試技中の動作は3次元動作解析システム(Motion Analysis社製)を 使用し、全身から計34箇所の位置データを記録し、３次元解析した。筋電計はWEB-5500(日本光電社製)を使用し、左右の脊柱起立筋、大腿直筋、外側広筋、大腿二頭筋、前脛骨筋、内・外側腓腹筋の計14ヶ所をテレメータから記録、解析した。地面反力は、キスラー社製の計測装置を用いて2 kHzで測定した。キネマティクスは得られた位置データから上肢、下肢の各関節角度、角速度、角加速度、頭頂、つま先の変位、速度、加速度、身体重心変位、速度、加速度を算出した。結果、熟練者は初心者に比べ、地面反力（鉛直方向成分：7764 ± 624 N vs. 4551 ± 518 N; mean ± SD , p < 0.05）、片脚つま先の床面に到達するまでの最大加速度（31.6 ± 3.7 m/s2 vs. 22.7 ± 5.3 m/s2 ,　p < 0.05）が顕著に大であった。特に達人においては10,719 Nと自体重の15倍を超える力が発揮されていた。このときの達人は、左軸脚外側広筋から大腿直筋、脊柱起立筋、そして反対側の脊柱起立筋、外側広筋、大腿直筋へと時空間的な加重によって爆発的な加速度を産み出し、力発揮の源となったと解釈でき、達人の技の一端が科学的に裏付けられた（研究代表者 成果1）。その他、太極拳動作の特徴として脳の興奮性と呼吸様式が挙げられることから、脳波計測におけるアーチファクトの問題（研究協力者 成果2）、及び呼吸様式の違いを力学的に検討した（連携研究者 成果3）。

本研究は、体育・スポーツの場における走力向上に役立つ写真・動画等を中心とした教材をマルチメディアデータベース化することと、それらをインターネットを介して公開するシステムを構築することであった。我々の研究は、走運動という“動き”を主体とするコンテンツをマルチメディア技術により“理論”と統合化して公開するところがこのシステムの特徴である。 2001年度には、子どもゆめ基金（独立行政法人国立オリンピック記念青少年総合センター）の助成金の交付も受けて「速く走るための動きを科学的に解析してみませんか」を実施し、そこでコンテンツ開発、特に指導法も含めたデータベースを開発し、教材として提供した（研究成果参照）。学校教育において科学的な指導を行う必要性を強く認識し、特に身体運動の基礎となる走運動（ランニング）について、その動き（動画・静止画と解析データ）、地面反力（解析データ）、筋活動（筋活動電位）を示し、ランニングという身体運動が科学的に見てどのような裏付けのもとに成り立っているかの学習素材コンテンツデータベースを開発した（研究成果参照、（http://www.kine.human.waseda.ac.jp/index-j.htm） 2002年度は、本学人間科学部が2003年度から開設の通信教育課程のなかで使用する教材「体育実技II」を制作し、オンデマンド授業を可能とした。学生がインターネット（Waseda-net）のブロードバンド接続によって、自宅に居ながら、いつでも好きな時間に、このオンデマンド型の授業に参加することは画期的な企画であった。2003年度の春学期で提供するデジタルコンテンツの内容は、より健康になるためのランニングおよびストレッチングについての意義と理論、さらに実技をデータ、映像、写真を交えてパワーポイントで解説した（研究成果参照）。

今回我々は、３軸方向の踏力と左右前後に移動する力の作用点(Center of Pressure： C.O.P.)の測定を可能とするペダル踏力測定装置を新しく設計・製作した。フォースペダルは本体をアルミで、軸は鋼材を使用した。表面硬化のためとペダル軸硬化のため、それぞれアルマイト処理と熱処理を施した。センサーには、水晶クオーツを４個取り付けた。出力はX・Y軸成分を合成した後、8軸成分に変換し、接続ケーブルで8chチャージアンプに通した後、パソコンにデータを取り込んだ。フォースペダルから得られるデータは、ペダル踏面に対する鉛直方向成分(Fz)、水平前後方向成分（Fy）、水平左右方向成分（Fx）の力、そして C.O.P.とトルクTz（自由モーメント）であった。　本システムを用いて、２名の被験者に回転数の異なる一定仕事率（125 w）のペダリング運動を行わせ C.O.P.を定量的に測定したところ、すべての条件において踏み込み局面のC.O.P.は内側から外側に移動し、その移動距離は2 cm程度であった。踏み込み局面におけるC.O.P.のX軸座標と膝傾斜角度の関係をみたところ、60 rpm（2.1 kp）、38 rpm（3.3 kp）の条件下では、C.O.P.の外側への移動と膝傾斜角度の外側への傾斜、つまり膝の外反を示す数値の増減が同じ傾向にあることがわかった。一方、低回転・高負荷条件下（25 rpm・5.0 kp）では同じ傾向がみられず、この原因が踏み込み局面での足関節の圧迫によっておこる足部の回内に起因することが示唆された。　以上、今回作製の装置で、正確なC.O.P.と、３軸方向の合成によって描くペダル踏力のベクトルとを対応させながら、さらにペダリング時のキネマティックスを同時に調べることによって自転車駆動中における下肢の機能についてこれまで以上に詳細に解明することが可能となった。研究成果の発表発表年月：1997年6月、早稲田大学大学院人間科学研究科、ヒューマンサイエンスリサーチ論文題目：自転車ペダリング時の踏力作用点と脚キネマティックスの関係Vol.6、1997(131-138)

　本研究は、被験者が筋力トレーニング機器を使って短距離走の模擬動作を行った時の動作のメカニズムについて考察した。被験者は左下肢を充分に伸展させたまま右下肢を屈曲-伸展させる動作を行った。動作は、右下肢の股関節屈曲伸展動作に対する負荷強度（L：40-45回の反復が可能な重量、H：10-15回の反復が可能な重量）、動作速度（F：1 Hz， S：0.17 Hz）、および左下肢の接地位置（中央、20cm 前方、20cm 後方）を変えて行った。EMG活動は、左腓腹筋、左ヒラメ筋、および右大腿直筋から導出した.股関節角度は、ゴニオメータを使って記録した。左下肢の床反力は、鉛直方向（Fz）、水平前後方向（Fy）、水平左右方向（Fx）の力、および力の作用点を計測した。一般的に、右股関節の屈曲-伸展時において右大腿直筋と左腓腹筋のEMG活動は共同活動が相動的に起こり、位相の変わり目はともに活動が弱まった。この間、左ヒラメ筋は、持続的に弱く活動した。軽い負荷強度で速く動作を行った時のFyは、右股関節屈曲開始時では推進方向成分を示したが、屈曲から伸展へ移る時にブレーキ方向成分へと変化した。Fzは、抜重により屈曲から伸展へと移る時に最小値を示し、全体として3相性の波形を示した。軽い負荷強度でゆっくり動作を行った時のFyは、推進方向成分のみとなり、Fzの大きさの変化は少なかった。重い負荷強度で速く動作を行った時のEMG活動は、左腓腹筋と左ヒラメ筋で増大が見られた。Fyは動作中全ての位相で推進方向成分のみとなった。Fzは屈曲-伸展の位相の変わり目での抜重による減少が比較的少なくなった。接地位置を変えたことによる床反力には基本的な違いが見られなかった。以上のことから、トレーニング機器を使って短距離走の模擬動作を行う時には、負荷強度や動作速度の設定に注意しなければならないことが示唆された。