The intrinsic and extrinsic muscles are considered to stabilize the foot and contribute to propulsion during walking. This study aimed to clarify the functional relationship between intrinsic and extrinsic muscles during walking. Thirteen healthy men participated in this study. The muscle activities of the intrinsic muscles (quadratus plantae and abductor hallucis), and the extrinsic muscles (flexor hallucis longus, flexor digitorum longus, and tibialis posterior) were measured using fine-wire and surface electromyography during walking. The muscle onset timing after foot contact was calculated and compared among muscles using the one-way ANOVA. The stance phase was divided into early and late braking, and early and late propulsion phases. Muscle activity among phases was compared using repeated-measures ANOVA. The onset time of the abductor hallucis was significantly earlier than those of the flexor digitorum longus and tibialis posterior. The quadratus plantae demonstrated significantly earlier onset than that of the tibialis posterior. In the late propulsion phase, the activity of extrinsic muscles decreased, whereas intrinsic muscles were continuously active. Early activation of the intrinsic muscles may stabilize the foot for efficient torque production by the extrinsic muscles. Furthermore, the intrinsic muscles may contribute to the final push-off after the deactivation of extrinsic muscles.

PURPOSE: This study aimed to compare the repositioning error (RE) of patients with unilateral sacroiliac joint pain (SIJP) to that of patients with low back pain (LBP) and a healthy control (HC) group. Differences between the symptomatic and asymptomatic sides were also investigated. METHODS: Sixty-six patients with SIJP, LBP, and HC were included in this study. An active straight leg-raising repositioning test (ASLR-Rt) was performed. ASLR was performed three times each on the left and right sides, targeting a set base angle. RE was calculated as the difference between the base angle and the participant's attempt to adjust the target angle. RE was expressed as constant error (CE) and absolute error (AE). RESULTS: The CE of the SIJP group (median [interquartile range]) (6.9 [4.6‒10.4]) was significantly higher than that in the LBP group (3.2 [1.3‒7.1]) and the HC group (2.7 [0.3‒4.6]) (P = 0.009, d = 0.91, P < 0.001, d = 1.30). The AE of the SIJP group (7.3[5.0‒10.4]) was also significantly higher than that in the LBP (3.7[2.8‒7.1]) and HC groups (3.0[1.9‒4.2]) (P = 0.003, d = 1.04; P = 0.001, d = 1.57). Comparing the symptomatic and asymptomatic sides in the SIJP group, the symptomatic side (8.0[6.0‒10.6]) was significantly higher than the asymptomatic side (5.7[3.6‒8.1]) in terms of CE (P = 0.05, d = 0.51). CONCLUSION: Patients with SIJP increased RE during ASLR, which may be related to impaired proprioception and decreased motor control.

BACKGROUND: Shoulder pain, known as swimmer's shoulder, is the most common injury for swimmers. Studies that have analyzed muscle activity have focused on the shoulder joint. However, the whole-body muscle coordination of swimmers with swimmer's shoulder is not clear, although swimming requires movements of the upper limbs, trunk, and lower limbs to obtain propulsive force. This study investigated differences in muscle coordination between swimmers with and without swimmer's shoulder during the front crawl and backstroke using muscle synergy analysis. HYPOTHESIS: Swimmers with swimmer's shoulder have muscle synergies differing from those without it. STUDY DESIGN: Case-control study. LEVEL OF EVIDENCE: Level 4. METHODS: A total of 20 elite swimmers who regularly swam front crawl and backstroke were included (swimmer's shoulder, n = 8; control, n = 12). Muscle synergy data were analyzed using the nonnegative matrix factorization method and compared between groups. RESULTS: For both front crawl and backstroke, there were 2 synergies in the control group and 3 synergies in the swimmer's shoulder group. During recovery, the control group showed coordinated triceps brachii, serratus anterior, upper trapezius, lower trapezius, internal oblique, and external oblique muscles activities; however, in the swimmer's shoulder group, the contribution of the upper limbs decreased and only that of the trunk muscles increased. CONCLUSION: A comparison of muscle coordination during the front crawl and backstroke performed by swimmers with and without swimmer's shoulder revealed that coordination differed during the recovery phase. During both front crawl and backstroke, the swimmer's shoulder group could not maintain coordination with the upper limb when the trunk rolled, and split synergy was formed between the upper limbs and trunk. CLINICAL RELEVANCE: Because coordination of the upper limbs and trunk is important during the recovery phase of front crawl and backstroke, swimmer's shoulder rehabilitation should introduce exercises to improve their coordination between the upper limbs and the trunk.

BACKGROUND: A high prevalence of lower back pain has been observed in competitive divers. Hyperextension of the lumbar vertebrae during water entry is considered the main mechanism behind the incidence of lower back pain in divers. Therefore, this study aimed to investigate the influence of the shoulder angle on the entry alignment. METHODS: Posture angles of 13 male drivers (age: 16.8±2.9 years) who were invited to the national training camp in 2012 by Japan Swimming were recorded at the time of water entry via 201B using a high-speed camera. RESULTS: A negative correlation was observed between shoulder joint flexion and trunk extension angles on water entry. In addition, the trunk angle was significantly different between groups. For the lower back pain group, 210.4±5.7°, and in the non-lower back pain group, 199.9±9.0°, angles were observed with a larger extension of the trunk on water entry in the lower back pain group. CONCLUSIONS: The alignment on water entry was associated with the occurrence of lower back pain. Which suggested that enough shoulder flexibility can prevent the incidence of lower back pain.

BACKGROUND: Sacroiliac joint (SIJ) dysfunction in athletes affects competitiveness. However, the pathology and imaging features have not been clarified. OBJECTIVE: To clarify the association between SIJ pain and MRI findings in high-performance athletes. METHODS: Fifty-two Japanese high-performance athletes with or without SIJ pain were recruited. MRI short tau inversion recovery (STIR) semi-coronal and semi-axial images of their SIJs were taken. The relationships between high-signal changes in MRI-STIR and SIJ pain and pain duration were investigated. Six athletes with continuous SIJ pain were prospectively followed. RESULTS: The proportion of athletes with high-signal changes in the SIJ was significantly higher among athletes with SIJ pain for one month or more (76.9%, 10/13) than among athletes with SIJ pain for less than one month (18.2%, 2/11) and among athletes without SIJ pain (28.6%, 8/28). High-signal changes on painful SIJs were most often present in the sacrum. In three of the six athletes who were prospectively followed, the high-signal area and intensity on MRI both diminished as their symptoms improved. CONCLUSIONS: High-signal changes of the SIJ on MRI-STIR images in high-performance athletes may reflect their SIJ pain.

BACKGROUND: The KOJI AWARENESS� screening test is a self-administered screening tool for assessment of mobility, stability, and strength. It provides corrective exercises corresponding to the individual's answers to the KOJI AWARENESS� test questions. However, there is no evidence of the effectiveness of corrective exercises in improving KOJI AWARENESS� screening test scores and activity-related pain. METHODS: Twenty-six healthy subjects (11 female and 15 male ; age 20?50 years) were selected for participation. In a controlled laboratory setting, subjects were administered the KOJI AWARENESS� test and were provided with individualized exercise programs based on the results of this first test. KOJI AWARENESS� results were checked on the first day immediately after the first exercise session, and then again after the two-week program. Pain intensity was also assessed during daily training using a numerical rating scale. RESULTS: Compared to pre-intervention, KOJI AWARENESS� scores were significantly higher immediately after the first corrective exercise session and after 2 weeks of intervention (p<0.001). Moreover, pain intensity was significantly lower after 2 weeks of intervention (p<0.001). CONCLUSIONS: Individualized KOJI AWARENESS� corrective exercises were effective immediately on the first day and also after the two-week program in improving the KOJI AWARENESS� score and reducing pain intensity during daily training. J. Med. Invest. 70 : 208-212, February, 2023.

Objective

This study aimed to validate the KOJI AWARENESS™, a self-screening movement test, and compare it with the Functional Movement Screen (FMS).

Methods

Fifty-seven healthy participants completed the KOJI AWARENESS™ and functional movement screening. Pearson’s correlation coefficients were used to assess the validity of the test. Subsequently, partial correlation analysis was used to determine the associations between age, sex, body mass index, and sports level as control variables and motor function.

Results

Correlation and partial correlation analyses showed a strong positive correlation between the functional movement screening and the KOJI AWARENESS™ scores.

Conclusion

This study found that the KOJI AWARENESS™ test is valid and comparable to functional movement screening. It can be used for self-screening of movement.

Abstract

Perturbation exercises enhance lower limb and trunk muscles, and adding swing perturbation while loading during exercise might improve muscle activation or strength. This study aimed to check variations in trunk and lower limb muscle activity during conventional isometric squats, and whether it will change with or without swing using the Hammerobics-synchronized squat method. Twelve healthy men participated in this study. Activities for the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, rectus femoris, biceps femoris long head, semitendinosus, gluteus maximus, multifidus, and internal oblique muscles were measured using surface electromyography during a Hammerobics-synchronized squat and conventional isometric squat. Muscle activities were statistically compared between squat methods. Hammerobics-synchronized squats significantly activated the abductor hallucis, tibialis anterior, tibialis posterior, peroneus longus, semitendinosus, and multifidus muscles, in both phases, compared with the conventional isometric squats. The Hammerobics-synchronized squat exercise can be considered for trunk and foot stability exercise.

<title>Abstract</title><sec>
<title>Background</title>
Medial tibial stress syndrome is a common sports related injury. Altered foot kinematics can be a risk factor for the injury. Since foot segments can move independently, intersegment coordination is important for proper foot function. This study aimed to compare the foot intersegmental coordination pattern and single segment kinematics between female lacrosse players with and without a history of medial tibial stress syndrome during drop jump.


</sec><sec>
<title>Methods</title>
Twelve players with a medial tibial stress syndrome history and 12 players with no history were enrolled. Foot kinematics, including angle at landing and peak angle and excursion at the rearfoot, midfoot, and forefoot during single-leg drop jumps were analysed. Each segment motion data from landing to leaping was time-scaled to 100% to analyse the intersegmental coordination with a modified vector coding technique. Instant intersegmental coordination of every 1% was classified into four patterns (in-phase, two segments rotate in the same direction with similar amplitudes; anti-phase, two segments rotate in opposite directions; proximal phase, proximal segment dominantly rotates in the same direction compared to the distal segment; and distal phase, distal segment dominantly rotates in the same direction compared to the proximal segment). The percentage of intersegmental coordination pattern and kinematics in each segment were compared between the groups using the Student’s t test.


</sec><sec>
<title>Results</title>
Groups with a history of medial stress syndrome showed a significantly higher percentage of proximal phase between the rearfoot and midfoot in the sagittal (Mean ± SD; history, 52.2 ± 17.9%, no history, 29.3 ± 16.7%; <italic>p</italic> = 0.004) and coronal planes (history, 40.3 ± 22.0%, no history, 15.9 ± 9.1%; <italic>p</italic> = 0.004). Dorsiflexion excursion (history, 34.5 ± 4.5°, no history, 29.6 ± 2.1°; <italic>p</italic> = 0.003) were significantly larger in a history of medial tibial stress syndrome group compared to no history group.


</sec><sec>
<title>Conclusions</title>
Rearfoot dominant motion pattern relative to the midfoot may be related to medial tibial stress syndrome. Intersegmental coordination analysis may be useful for detecting abnormal foot coordination patterns. Also, stabilization for the rearfoot may be required rather than the midfoot for intervention.


</sec>

Abstract

This study aimed to clarify the differences in the onset of trunk muscle activity with and without anticipation of the movement starting time during rapid shoulder movements. Ten healthy men in a relaxed upright position performed rapid 135° flexion, 135° abduction, and 45° extension of the shoulder on the dominant hand side with and without anticipation of the movement starting time. They moved their shoulder joints following a 3-s countdown and a light stimulus in the anticipation and non-anticipation conditions, respectively. Electromyography of the anterior and posterior quadratus lumborum, transversus abdominis, internal oblique, external oblique, rectus abdominis, lumbar multifidus, lumbar erector spinae on the non-dominant hand side, and the middle deltoid on the dominant hand side were measured. The onset of activity of each trunk muscle relative to the onset of the middle deltoid was calculated. Two-way analysis of variance (eight trunk muscles × two anticipation conditions) was used to compare the onset of electromyographic activity of the trunk muscles in each direction of the shoulder movement. There were significant interactions between the muscles and anticipation conditions during shoulder abduction and extension. The onset of activity in the anterior and posterior quadratus lumborum, transversus abdominis, and internal oblique occurred earlier with anticipation of the movement starting time than without anticipation during shoulder abduction and extension. The anticipation of movement starting time may contribute to a reliable center of mass control within the support base and improve lumbar spine stability by hastening the onset of activity of the deep trunk muscles.

Background:

Improvements in motor control of the scapular muscles are important for the prevention and rehabilitation of shoulder and elbow injuries in overhead athletes.

Purpose:

To clarify scapular muscle activity during multijoint compound movement exercises using fine-wire and surface electrodes.

Study Design:

Descriptive laboratory study.

Methods:

Sixteen healthy men performed 5 types of exercises (cat and dog, trunk rotation, A-exercise, T-exercise, and Y-exercise). Muscle activity was measured as percentage of maximum voluntary isometric contraction (%MVIC) by using fine-wire electrodes in the rhomboid major (Rhom) and using surface electrodes in the upper (UT), middle (MT), and lower (LT) trapezius and serratus anterior (SA) muscles. The Rhom/UT, MT/UT, LT/UT, and SA/UT muscle activity ratios were calculated. One-way analysis of variance was used to compare the %MVIC and muscle activity ratios between exercises.

Results:

There was no significant difference in Rhom activity between the exercises (34.6-54.2%MVIC; P = .25). LT activity was significantly greater in the trunk rotation (58.0 ± 24.6%MVIC) and Y-exercise (63.2 ± 40.1%MVIC) than in the cat and dog scapular retraction (19.6 ± 9.3%MVIC) and A-exercise (28.2 ± 14.2%MVIC) ( P &lt; .05). SA activity was significantly greater in the cat and dog scapular protraction (26.7 ± 11.0%MVIC) and Y-exercise (25.6 ± 19.3%MVIC) than in the other exercises ( P &lt; .05). The SA/UT activity ratio in the cat and dog scapular protraction exercise (9.64 ± 8.48) was significantly higher than in the other exercises ( P &lt; .05).

Conclusion:

All the exercises were effective for activating the Rhom. The trunk rotation and Y-exercise were effective for activating the LT, and the cat and dog scapular protraction exercise was effective for activating the SA while suppressing the UT.

Clinical Relevance:

These results enable exercise selection based on muscle activity characteristics (moderate [20%-50%MVIC] and high [&gt;50%MVIC] levels contribute to muscle activation) to prevent and rehabilitate shoulder and elbow injuries.

Abstract

This study aimed to investigate whether muscle synergy differs between swimmers with and without swimmer's shoulder in the butterfly technique. Muscle synergies, which can assess muscle coordination, were analyzed using surface electromyography. Twenty elite swimmers were included in this study (swimmer's shoulder: n = 8; control: n = 12). The motions involved in executing the butterfly technique were classified into the early pull-through, late pull-through, and recovery phases. Muscle synergy data analyzed using the nonnegative matrix factorization method were compared between the two groups.

The swimming velocities were 1.66 ± 0.09 m・s ⁻¹ and 1.69 ± 0.06 m・s ⁻¹ for the control and swimmer's shoulder groups, respectively. Four muscle synergies in both groups were identified: synergy #1, which was involved in the early pull; synergy #2, involved in the late pull; synergy #3, involved in the early recovery; and synergy #4, involved in pre- and posthand entry. Compared to the control group, the swimmer's shoulder group had a small contribution from the pectoralis major (p = 0.032) and a high contribution from the rectus femoris during the early pull phase (p = 0.036). In the late pull phase, the contribution of the lower trapezius muscle in the swimmer's shoulder group was low (p = 0.033), while the contribution of the upper trapezius muscle in the pre- and postentry phases was high (p = 0.032). In the rehabilitation of athletes with swimmer's shoulder, it is therefore important to introduce targeted muscle rehabilitation in each phase.

OBJECTIVES: To examine the incidence and survival rates of sudden cardiac arrest that were documented during school organized sports in Japan. DESIGN: Retrospective cohort study. METHODS: Insurance claim data of cardiac events (sudden cardiac death and sudden cardiac arrest with resultant disabilities) that occurred during Japanese high school organized sports between 2009 and 2018 were retrieved. Participation data from All Japan High School Athletic Federation and Japan High School Baseball Federation were used for incidence rate calculations. Incidence rate ratios with 95 % confidence interval were calculated to compare the risk by sports and sex. The survival rate was calculated with the proportion of resuscitated cases to total number of cardiac events in this dataset. RESULTS: A total of 55 cardiac events (25 survivors and 30 deceased) were identified in the dataset. The majority affected male student-athletes (92.7 %). The frequency and incidence rate of cardiac events were highest in male baseball (n = 16 [29.1 %], incidence rate: 0.91 per 100,000 athlete-years). Incidence rate ratio revealed that male basketball (2.19, 95 % confidence interval: 1.04-4.60), male baseball (2.31, 95 % confidence interval: 1.32-4.03), and first-year male baseball (4.11, 95 % confidence interval: 2.10-8.07) had significantly higher risk of cardiac events, compared to the overall incidence rate (0.38 per 100,000 athlete-years). The survival rates were 37.5 % in the first half (2009-2013) and 56.5 % in the latter half (2014-2018) of the study period. CONCLUSIONS: The risk of cardiac events was highest in male, baseball, first-year student-athletes. Rapid AED application by bystanders should be advocated to enhance better survival.

Draw-in is a promising intervention for regaining isolated control of the transverse abdominis (TrA). Exercises to stimulate isolated contractions are needed; however, the appropriate methods are unclear. The objectives of this study were to examine how the muscle activity and muscle activity ratio of abdominal muscles change with various verbal instructions and to determine the onset of the abdominal muscles during drawin. The participants were 21 healthy men. TrA electromyography was performed using fine-wire electrodes, and the internal oblique (IO), external oblique (EO), and rectus abdominis (RA) were determined using surface electrodes. The participants performed seven abdominal exercises according to verbal instructions and isolated voluntary contraction of the TrA for more than 5 sec. The TrA showed higher activity in bracing. IO and EO activities were highest in bracing, whereas RA showed the highest activity in maximum bracing. TrA/IO and TrA/EO were not significantly different between conditions. The results of the onset activity analysis of the abdominal muscles during the draw-in maneuver showed that the TrA was significantly earlier than the other muscles. The activity ratios of TrA to IO and EO were highly individualized and did not differ according to the verbal instruction. Maximum draw-in showed more significant IO activity, and bracing showed co-contraction of the superficial and deep abdominal muscles. During draw-in, the TrA initiated the earliest activity among the abdominal muscles and then isolated activity for 1.1 sec.

BACKGROUND: Trunk muscle activity during isometric exercise is altered by external-focus instruction. OBJECTIVE: To check alterations in trunk muscle activity during side plank exercise both with and without instructions to refrain from crushing an item (external-focus instruction method). METHODS: Twenty-one healthy men aged 20–49 participated in this study. Ten trunk muscle activities were measured using surface electromyography during side plank exercises both with and without external-focus instruction. The unpaired t-test or Mann–Whitney U test was used to compare differences between exercise tasks and between sides. RESULTS: Side plank exercise with external-focus instruction increased activity of the upper trapezius, lower trapezius, latissimus dorsi, medial head of the triceps, and internal oblique on the supported side when compared with that without external-focus instruction (p&lt; 0.05 for all). On the unsupported side, side plank exercise with external-focus instruction significantly increased activity of the upper trapezius, lower trapezius, latissimus dorsi, medial head of the triceps, clavicular part of the pectoralis major serratus anterior, external oblique, rectus abdominis, internal oblique, and multifidus when compared with that without external-focus instruction (p&lt; 0.001 for all). CONCLUSIONS: Adding the external-focus instruction method to the conventional side plank exercise may be effective in increasing the trunk muscles’ activity.

BACKGROUND: External focus isometric exercises using a paper balloon can change trunk muscle activation in the chest squeeze; however, it is unknown whether this method affects muscle activities in conventional exercises. OBJECTIVE: To check variations of trunk muscle activity during front plank (static task) and shoulder press (dynamic task) both with and without instruction to avoid crushing an object. METHODS: Twenty-six healthy adult males aged 19–49 were recruited. Ten trunk muscle activities were measured using surface electromyography during a front plank and dynamic shoulder press exercises, both with and without external-focus instruction. RESULTS: Adding the external-focus using the paper balloon to the front plank significantly activated 8 out of the 10 muscles. In the downward shoulder press, 5 out of 10 muscles with 50% 1 RM, 2 out of 10 muscles with 100% 1 RM were significantly activated. CONCLUSIONS: Adding external-focus instruction using paper-balloon increases trunk muscles in front plank and shoulder press while possibly improving trunk stability. Novel exercises using paper balloon may efficiently activate specific muscles without external loading thus possibly reducing the stress on the involved joints during exercise.

BACKGROUND: Osgood-Schlatter disease (OSD) is an apophysitis of the tibial tubercle caused by repeated traction of the patellar tendon during adolescence. Although OSD is associated more with sports such as soccer, it remains unclear whether the kicking motion itself is related to OSD onset. PURPOSE: To prospectively evaluate the kicking motion in adolescent soccer players who later developed OSD. STUDY DESIGN: Case-control study. METHODS: The authors observed 47 Japanese adolescent male soccer players (mean age, 12 years) over 6 months in 2018-2019; none of the participants had OSD at study onset. The players underwent tibial tubercle ultrasound at baseline, and their kicking motion was evaluated using 3-dimensional (3D) motion analysis with 65 reflective markers. The 3D angle of the lumbar spine, thorax, and pelvis and the angular velocity of the hips, knees, and ankles were calculated for the support leg. The kicking motion was divided into 8 phases, and ball speed, kicking time, and positions of the support (nonkicking) leg and center of mass (COM) from the ball were calculated for each phase. Six months later, the players underwent another ultrasound and were divided into 2 groups: those diagnosed with OSD in the support leg (OSD group) and those without OSD (normal [NRL] group). All factors calculated using the kicking motion analysis at the baseline were compared between groups. RESULTS: There were 19 players in the OSD group and 28 players in the NRL group. Anthropometric measurements, ball speed, and kicking time were similar between the 2 groups. The forward translation of the COM and the support leg, the flexion angle of the thorax, and the rotation angle of the pelvis before impact with the ball were all significantly smaller in the OSD group than in the NRL group (P < .05). Moreover, the knee extension angular velocity of the support leg was significantly larger in the OSD group (P < .05) at ball impact. CONCLUSION: A kicking motion with small COM translation, small thoracic flexion, and small pelvic rotation before ball impact, as well as large knee extension angular velocity of the support leg at ball impact, may be associated with OSD onset.

This study aimed to clarify the changes in the activity of the trunk and lower limb muscles during 2000-m rowing. Ten male rowers performed a 2000-m race simulation on a rowing ergometer. Electromyography results of the abdominal muscles, back muscles, gluteus maximus (GMax), biceps femoris (BF), and rectus femoris (RF) were recorded. The electromyographic activity during the three strokes after the start (initial stage), at 1000m (middle stage), and before the end (final stage) were analyzed. From the handle position, the rowing motion was divided into five phases (early-drive, middle-drive, late-drive, early-recovery, and late-recovery). The peak activities of the abdominal muscles, back muscles, GMax, and BF in each stroke of the rowing motion were delayed at the middle and final stages compared to the initial stage (P<0.05). The peak activity of the RF was observed in the late-drive phase at the initial stage, whereas a high RF activity was observed in the middle-drive phase at the middle and final stages (P<0.05). Considering the results of the activity of the back muscles and RF, RF muscular endurance enhancement may lead to a decrease in the load on the back muscles and help prevent muscular low back pain in rowers. J. Med. Invest. 69 : 45-50, February, 2022.

Background : Various musculoskeletal screening and functional performance tests are used to evaluate physical condition. However, validated analysis tools that can identify gaps in pain knowledge during athletes' daily training are lacking. This study aimed to investigate the relationship between pain intensity in athletes during their daily training and the KOJI AWARENESS™ test in order to determine whether body dysfunction is related to pain among athletes. Methods : This cross-sectional study was conducted in a fitness center at the authors' affiliated institution. Thirty-five athletes (17 women and 18 men) aged 20-40 years were selected for study participation. KOJI AWARENESS™ self-evaluated test scores and pain intensity during daily training, as assessed on the numerical rating scale (NRS), were recorded. Results : The KOJI AWARENESS™ score showed a strong negative correlation with the NRS score for pain intensity during daily training (r = -0.640, P < 0.001). There was a significant negative correlation between KOJI AWARENESS™ and NRS scores, even when body mass index, sex, and age were entered as control variables. Conclusions : KOJI AWARENESS™ was highly accurate in detecting pain in athletes during their training. J. Med. Invest. 69 : 204-216, August, 2022.

The purpose of this study was to investigate the activation of the hip flexor and abdominal muscles during an active straight leg raise (ASLR) to end range of hip flexion. Data were recorded from nine healthy men. Fine-wire electromyography (EMG) electrodes were inserted into psoas major (PM), and surface electrodes were placed over rectus femoris (RF), rectus abdominis, obliquus externus abdominis (OE), and obliquus internus abdominis/transversus abdominis (OI/TrA). EMG and kinematic data were obtained during concentric, hold (at end range) and eccentric phases of an ASLR. Concentric and eccentric movements were divided into three phases (early, mid, and late). Onsets of EMG relative to the onset of the ALSR movement and EMG amplitudes in each phase were compared between muscles. Onsets of the PM (–33 ± 245 ms) and RF (-3 ± 119 ms) EMG prior to leg elevation were significantly earlier than those of the OE and OI/TrA. PM EMG showed highest activation in the late concentric, hold, early eccentric phase, and was significantly higher than RF EMG. OI/TrA EMG was significantly greater in mid and late concentric, hold, and early eccentric phase than other phases. During the ASLR, unlike RF, PM EMG continues to increase towards the end range of hip flexion. Activation of OI/TrA muscle may be involved in control trunk and pelvic movement.

This study aimed to clarify the differences in electromyographic activity between the quadratus lumborum anterior (QL-a) and posterior layers (QL-p), and the relationship among trunk muscles and gluteus medius (GMed) activities during forward landing. Thirteen healthy men performed double-leg and single-leg (ipsilateral or contralateral sides as the electromyography measurement of trunk muscles) forward landings from a 30 cm-height-box. The onset of electromyographic activity in pre-landing and the electromyographic amplitude of the unilateral QL-a, QL-p, abdominal muscles, lumbar multifidus (LMF), erector spinae (LES), and bilateral GMed were recorded. Two-way ANOVA was used to compare the onset of electromyographic activity (3 landing leg conditions × 10 muscles) and electromyographic amplitude among (3 landing leg conditions × 2 phases). The onset of QL-p was significantly earlier in contralateral-leg landing than in the double-leg and ipsilateral-leg landings. The onset of LMF and LES was significantly earlier than that of the abdominal muscles in contralateral-leg landing. QL-p activity and GMed activity on the contralateral leg side in the pre-landing were significantly higher in contralateral-leg landing than in the other leg landings. To prepare for pelvic and trunk movements after ground contact, LMF, LES, QL-p on non-support leg side, and GMed on support leg side showed early or high feedforward activation before ground contact during single-leg forward landing.

CONTEXT: The range of shoulder rotation is associated with shoulder pain in young male and female swimmers. However, the association between shoulder pain and shoulder complex mobility of the scapulothoracic and acromioclavicular joints has not yet been examined. Moreover, shoulder pain occurs more frequently in females than in males, but only a few studies have examined the relationship between shoulder pain and sex as a risk factor. This study aims to determine the association between shoulder complex mobility and shoulder pain in young male and female swimmers. DESIGN: Prospective cohort design. METHODS: The participants were competitive swimmers (n = 76; 37 males and 39 females) with a mean age of 14 years in Japan. The shoulder rotation width, which was the index of shoulder complex mobility, shoulder internal and external rotation range, and middle finger distance of the back-scratch test were measured. An examiner regularly visited the swimming clubs to evaluate the development of shoulder pain and swimming distance. Logistic regression analysis was used to determine the physical characteristics related to the overall development of shoulder pain in both female and male swimmers. The cutoff value was calculated using receiver operating characteristic curves. RESULTS: Sixteen participants, composed of 8 males and 8 females, developed shoulder pain. The overall swimming distance of the male (odds ratio [OR]: 1.0007, P = .01) and female (OR: 1.0018, P = .02) swimmers and the shoulder rotation width of the male (OR: 1.0952, P = .04) and female (OR: 0.888, P = .03) swimmers were identified as risk factors for shoulder pain. The cutoff value for swimming distance was 6000 m. Shoulder rotation width was more than 88 cm in males and <54 cm in females. CONCLUSIONS: Hypomobility and hypermobility of the shoulder complex were identified as risk factors for shoulder pain in male and female swimmers, respectively.

Limited literature has investigated epidemiology of sports-related fatalities during high school organizes sports in Japan. Therefore, the purposes of this study are to determine the frequency and incidence rate of sports-related fatalities in Japanese high schools by cause and sports, and to examine the type of on-site first responder. Insurance claim data of sports-related fatalities in Japanese high schools reported to Japan Sports Council Injury and Accident Mutual Aid Benefit System between 2009 and 2018 were retrieved as the primary data source. All fatalities were classified into direct or indirect type by the reported etiology and further categorized into cardiac-related, head and neck injury, exertional heat stroke (EHS), or other. Frequency and incidence rate were calculated by cause of death and sports, and incidence rates were expressed per 100,000 athlete-years (AY) with 95% confidence interval (CI). Information regarding first responder to the incident was also retrieved and examined by frequency. A total of 63 sports-related fatalities were analyzed. The overall incidence rate was 0.45 (95%CI = 0.25–0.65) per 100,000AY. The incidence rates of direct and indirect fatalities declined from 0.36 and 0.50 per 100,000AY to 0.28 and 0.00 per 100,000AY, respectively. The leading cause of deaths was cardiac-related (n = 30/63, 47.6%), followed by head and neck injury (n = 15/63, 23.8%) and EHS (n = 14/63, 22.2%). The number of fatalities was highest in male baseball (n = 12/63, 19.0%) and the incidence rate was highest in male judo (4.79 per 100,000 AY, 95%CI: 0.68–8.15). Coach was the most frequently reported first responder onsite (n = 52/63, 82.5%). Medically trained personnel were involved in onsite care in two cases (3.2%). In conclusion, the occurrence of sports-related fatalities has declined over time from 2009 to 2018. To deliver appropriate medical care onsite for better survival, employment of medically trained personnel should be promoted in high school sports setting in Japan.

The purpose of this study was to clarify the coordination between the trunk and lower limb muscles during sidestep and to compare this coordination before and after fatigue intervention. The intervention was lateral jump until exhaustion. Nonnegative matrix factorization (NMF) was used to extract muscle synergies from electromyography. Subsequently, to compare the muscle synergies, a scalar product that evaluates the coincidence of synergies was calculated. Three muscle synergies were extracted before and after the intervention from the NMF analysis. In accordance with the evaluation of the scalar product, these synergies were the same before and after the intervention. One of these synergies that engaged the internal oblique/transversus abdominis, rectus femoris, and adductor muscle was activated from before landing to midstance during sidestep motion
therefore, this synergy is thought to suppress excessive hip abduction. However, the activation timing of this synergy was delayed after the intervention (P=0.028, effect size: 0.54, Wilcoxon test). This delay is considered to decrease hip stability. Thus, this change may induce a reduction in hip control function.

&lt;p&gt;Trunk stabilization exercises improve injury prevention and performance, but the effect of deep trunk muscle training for underwater competitive performance and posture has not been clarified. If trunk stability can be obtained immediately after trunk stabilization exercises, such exercises may lead to performance improvements during underwater swimming and improve lumbar lordosis alignment during swim motions. The purpose of this study was to clarify the immediate effects of deep trunk muscle training on lumbar lordosis angle and swimming speed in underwater motion. The trial examined underwater motion before and after two different types and intensities of trunk stabilization exercises (low-intensity and high-intensity). Underwater motion was observed with an underwater high-speed camera placed 7.5 m from the pool wall, while lumbar lordosis angle was measured from the angle formed by markers affixed to the Th12, L3, and S1. During the glide swim, dolphin kick, and flutter kick trials, the maximum lumbar lordosis angle was calculated. Lumbar lordosis angle and swimming speed were calculated before and after two different intensities of trunk exercise interventions. There were significant differences in lumbar lordosis angle after both exercises during all three underwater motions. The high-intensity intervention elicited a significantly lower lumbar lordosis angle during glide swim, dolphin kick, and flutter kick, while swimming velocity was also improved during glide swim and flutter kick (&lt;i&gt;P&lt;/i&gt;&lt;0.05). Performing trunk exercise before practice or competition may help improve competition performance by reducing underwater resistance.&lt;/p&gt;

仙腸関節障害は画像で診断することが困難なため，理学所見や徒手検査の機能的診断による評価が必要となる．特に，one finger testや仙腸関節の疼痛誘発テストは仙腸関節障害の推察に役立つ．仙腸関節障害の病態はnutation type, counter-nutation type, instability typeの3つに分類することができ，それぞれのタイプに適した徒手療法や腹横筋，大殿筋を賦活化する運動療法が治療には重要である．

© 2018 The Society of Physical Therapy Science. [Purpose] To measure electromyographic activity of the piriformis using fine-wire electrodes during 7 hip movements. [Subjects and Methods] Eleven healthy men, without severe low back pain or lower limb injury, participated in this study. Fine-wire electrodes were inserted into the piriformis and surface electrodes were attached to the muscles in the hip region and the trunk muscles on the dominant arm side. Electromyographic signal amplitude was measured during 7 hip movements: side-lying external rotation in hip neutral position, side-lying abduction in hip neutral position, side-lying abduction in hip external rotation, side-lying abduction in hip internal rotation, prone extension in hip neutral position, prone extension in hip external rotation, and prone extension in hip internal rotation. Repeated-measures one-way analysis of variance was used to examine electromyographic activity in each of the 7 hip movements. [Results] Piriformis electromyographic activity was highest during prone hip extension in external rotation. Both the superior and inferior portions of the gluteus maximus were also highly activated during prone hip extension in external rotation. [Conclusion] Prone hip extension in external rotation induced high electromyographic activity in the piriformis and superior and inferior gluteus maximus muscles.

STUDY DESIGN: Controlled laboratory study, with a pretest-posttest design.
BACKGROUND: Diffusion-weighted imaging is a noninvasive magnetic resonance imaging technique that can be used to assess the recruitment of the psoas major (PM) and quadratus lumborum (QL). The recruitment of these muscles during trunk exercises has not been evaluated.
OBJECTIVE: To evaluate the diffusion of water movement in several trunk muscles using diffusion-weighted imaging before and after specific trunk exercises and thereby to understand the level of recruitment of each muscle during each exercise.
METHODS: Nine healthy male participants performed the right side bridge, knee raise, and 3 front bridges, including the hand-knee, elbow-knee, and elbow-toe bridges. Diffusion-weighted imaging was performed before and after each exercise. After scanning, the apparent diffusion coefficient (ADC) map was constructed, and ADC values of the rectus abdominis, lateral abdominal muscles, QL, PM, and back muscles were calculated.
RESULTS: The right PM following the elbow-toe bridge demonstrated the largest increase in ADC values, a change significantly greater than that demonstrated by the hand-knee bridge (P&lt;.001) and side bridge (P =.002) exercises. The ADC change in the right QL following the side bridge exercise was significantly larger than that of other exercises (P&lt;.008).
CONCLUSION: Of the 5 exercises investigated, the elbow-toe bridge and side bridge exercises elicit the greatest recruitment of the PM and QL, respectively.

<p>【はじめに，目的】</p><p></p><p>腰痛の原因の1つに仙腸関節由来の腰痛があるが，その診断方法は確立されておらず，MRI，CTでも特異的な画像所見が得られないため，見逃される例が多い。仙腸関節は，仙骨が両寛骨間を矢状面において回旋する前屈，後屈挙動を有している。先行研究において寛骨の傾斜が重心動揺面積や重心位置に影響を与える事が報告されている。しかし，寛骨の傾斜と重心偏位の関係性は明らかにされていない。寛骨傾斜の方向と重心偏位の関係性が明らかとなると，仙腸関節運動評価の一助になりうると考える。本研究は，寛骨を傾斜させる介入により寛骨傾斜角と重心（足圧）にどのような影響を与えるのか明らかにすることを目的とした。</p><p></p><p>【方法】</p><p></p><p>対象は，健常男性5名（平均年齢24.0±1.7歳）とした。</p><p></p><p>重心は，重心動揺計グラビコーダGR-31を2つ使用し，各重心動揺計に片脚ずつ乗せた両脚立位にて，左右の足圧を測定した。（重心動揺計は足圧中心を算出するため，重心を足圧と表記する）</p><p></p><p>寛骨傾斜誘導方法は，膝関節抵抗運動により生じる寛骨の代償運動を利用した。</p><p></p><p>寛骨前方傾斜（前傾）は，被検者を腹臥位とし，膝関節最大伸展位から90度まで屈曲する運動に対して徒手的抵抗運動を10回行わせた。寛骨後方傾斜（後傾）は，床に足底がつかない状態の端座位とし，膝関節90度から最大伸展位まで伸展する運動に対して徒手的抵抗運動を10回行わせた。</p><p></p><p>プロトコールは，足圧測定，右側寛骨後傾誘導介入，足圧測定，左側寛骨前傾誘導介入，足圧測定の順で実施した。足圧測定時に，上前腸骨棘，上後腸骨棘にマーカーを貼付け，矢状面から静止画撮影をした。静止画をもとに，画像解析ソフトimageJを用い，寛骨傾斜角を測定した。なお，寛骨傾斜角は，上前腸骨棘と上後腸骨棘を結ぶ線と床への垂線がなす角とした。</p><p></p><p>寛骨誘導介入前後の寛骨傾斜，足圧偏移の変化量の比較をt検定にて行った。有意水準は5％未満とした。</p><p></p><p>【結果】</p><p></p><p>寛骨傾斜角は，開始肢位の寛骨傾斜角を基準とし，正の変化を前傾，負の変化を後傾とした。左寛骨は前傾誘導介入により，92.65°から95.11°と2.46°前傾し，有意差を認めた。右寛骨は後傾誘導介入により，95.09°から93.91°と1.18°後傾したが，有意差を認めなかった。</p><p></p><p>足圧は，開始肢位の足圧中心を基準とし，正の変化を前方偏位，負の変化を後方偏位とした。左寛骨前傾誘導介入後は，左足圧が－2.42cmから－1.06cmと1.36cm前方偏移し，有意差を認めた。右寛骨後傾誘導介入後は，右足圧が－1.44cmから－1.6cmと0.16cm後方偏移したが，有意差を認めなかった。</p><p></p><p>【結論】</p><p></p><p>今回，介入による寛骨前傾に伴い，同側の足圧は有意な前方偏位を認めた。しかし，介入による寛骨後傾の効果は認めず，この場合，同側の足圧は偏位を認めなかった。この結果から，寛骨傾斜と足圧偏位には関係性があることが示唆された。そのため，足圧偏位の方向が仙腸関節運動を捉える一つの指標になり得ると考えた。</p>

[Purpose] The purpose of the study was to assess the muscle activity change of the tibialis posterior, flexor digitorum longus, and peroneus longus during gait with orthoses. [Subjects and Methods] Sixteen healthy males participated in this study. Activity of each muscle was measured by using fine-wire and surface electromyography. Gait task was performed by the participants barefoot, with footwear and with orthoses. The electromyography data from a stance phase of each gait trial were used for analysis. The stance phase was divided into contact, midstance, and propulsion phases. The data from ten participants were extracted for final analysis, as electromyography measurements were unsuccessful for the other six. [Results] The results demonstrated that orthoses significantly reduced the tibialis posterior muscle activity in the propulsion phase compared to that in the barefoot condition. Although there was a significant difference in the midstance phase, post hoc analysis did not indicate significant differences among the phases. No significant electromyography amplitude change was detected in flexor digitorum longus and peroneus longus. [Conclusion] Orthothes reduced the tibialis posterior activity level during gait. This result may be beneficial for patients with injuries related to excessive activity of tibialis posterior.

Background Injury and illness surveillance in the aquatic disciplines has been conducted during the FINA World Championships and Olympic Games. The development of an aquatic-specific injury and illness surveillance system will improve the quality of the data collected and the development of preventive measures. Our ultimate objective is to enhance aquatic athlete health and performance.
Objective The objective was to refine the injury and illness surveillance protocols to develop aquatic-specific definitions of injury and illness; define aquatic-specific injury location and causation; better describe overuse injuries; regard pre-existing and recurrent injuries; more accurately define aquatic athlete exposures and develop a protocol to capture out-of-competition aquatic athlete health parameters.
Methods FINA compiled an Injury and Illness Surveillance Expert Working Group comprised of international experts to review the scientific literature in the field. A consensus meeting was convened to provide an opportunity for debate, following which recommendations were collated.
Results Aquatic-specific injury and illness surveillance protocols covering both the in-competition and out-of-competition time periods were developed. Definitions for all relevant variables were outlined, and documentation forms for athletes and for clinicians were proposed. Recommendations for the implementation of an injury and illness surveillance system for FINA are presented.
Conclusion The FINA consensus authors recommend ongoing in-competition and out-of-competition surveillance to determine injury and illness trends over time. The implementation of the definitions and methodology outlined in this paper will improve the accuracy and value of injury and illness surveillance, and provide important information for injury prevention.

Objectives: To ascertain the dynamic stretch effects of flexibility of the hamstrings on lumbar spine and pelvic kinematics. Background: Tight hamstrings are positively correlated with low back pain. However, it is unclear how flexibility of the hamstrings affects spino-pelvic rhythm. Methods: Twelve healthy men participated in the study. The straight leg raising (SLR) angle, finger floor distance (FFD), and spino-pelvic rhythm was measured before and after the 6-week stretching protocol. The forward bending task was divided into 4 phases. The paired t-test was used to determine significant differences before and after the FFD, SLR angle, lumbar motion, and pelvic motion, and spino-pelvic rhythm in each phase (p 0.05). Results: After 6 weeks of stretching, significant improvements were seen in the FFD with maximum forward bending and in the SLR angle. Total pelvic rotation was also significantly increased in contrast to total lumbar flexion. A decreased spino-pelvic ratio was seen in the final phase. Conclusion: Dynamic stretching could change the spino-pelvic rhythm to a pelvis-dominant motion, indicating that flexible hamstrings are important for preventing low back pain.

© 2016 the American Physiological Society. Despite numerous attempts to discover genetic variants associated with elite athletic performance, injury predisposition, and elite/world-class athletic status, there has been limited progress to date. Past reliance on candidate gene studies predominantly focusing on genotyping a limited number of single nucleotide polymorphisms or the insertion/deletion variants in small, often heterogeneous cohorts (i.e., made up of athletes of quite different sport specialties) have not generated the kind of results that could offer solid opportunities to bridge the gap between basic research in exercise sciences and deliverables in biomedicine. A retrospective view of genetic association studies with complex disease traits indicates that transition to hypothesis-free genome-wide approaches will be more fruitful. In studies of complex disease, it is well recognized that the magnitude of genetic association is often smaller than initially anticipated, and, as such, large sample sizes are required to identify the gene effects robustly. A symposium was held in Athens and on the Greek island of Santorini from 14 -17 May 2015 to review the main findings in exercise genetics and genomics and to explore promising trends and possibilities. The symposium also offered a forum for the development of a position stand (the Santorini Declaration). Among the participants, many were involved in ongoing collaborative studies (e.g., ELITE, GAMES, Gene SMART, GENESIS, and POWERGENE). A consensus emerged among participants that it would be advantageous to bring together all current studies and those recently launched into one new large collaborative initiative, which was subsequently named the Athlome Project Consortium.

The aim of this study was to investigate the immediate effects of trunk stabilization exercise (SE) and conventional trunk exercise (CE) programs on jump performance. 13 adolescent male soccer players performed 2 kinds of jump testing before and immediate after 3 experimental conditions: SE, CE, and non-exercise (NE). The SE program consisted of the elbow-toe, hand-knee, and back bridge, and the CE program consisted of the sit-up, sit-up with trunk rotation and back extension. Testing of a countermovement jump (CMJ) and rebound jump (RJ) were performed to assess jump performance. Jump height of the CMJ and RJ-index, contact time, and jump height of the RJ were analyzed. The RJ index was improved significantly only after SE (p=0.017). However, contact time and jump height did not improve significantly in the SE condition. Moreover, no significant interaction or main effects of time or group were observed in the CMJ. Consequently, this study showed the different immediate effect on the RJ between the SE and CE, and suggested the possibility that the SE used in this study is useful as a warm-up program to improve the explosive movements.

【はじめに，目的】水球競技は，2m以上の水深がある足がつかない水中環境において行われ，投球動作，泳動作のみではなく，水中での激しい身体接触が多く，数あるスポーツの中でも1試合あたりのエネルギー消費量が最も多いと言われるほど過酷な競技である。それ故，身体のリコンディショニングのみではなく，外傷への対応など，トレーナーが対応するべき局面は幅広い。今回，2015年7月26日から8月5日にロシア・カザン にて開催された第16回世界水泳選手権大会の水球日本代表チーム（男・女）にトレーナーとして帯同する機会を得た。そこで，今回は上記大会期間中の傷害状況とトレーナーサポートについて報告する。【方法】2015年7月26日から8月5日の試合期間中に，トレーナーが対応した件数（試合中の対応は除く），選手の主訴部位，トレーナー対応方法を集計した。【結果】延べ対応件数は166件（男子87件，女子79件）だった。主訴・傷害部位（重複あり，全225件）としては，肩関節周囲が66件と最も多く，次いで腰部46件，肘関節37件，股関節周囲24件，全身20件，その他32件となっていた。これらの傷害のなかで，明らかな外傷に起因していたものは2例13件であり，その他は今大会前からの有症状部位や疲労の蓄積に起因すると考えられる症状であった。トレーナー対応方法は徒手的対応が68件，テーピング46件，物理療法機器（超音波治療器，ラジオ波治療器）41件，アイシング39件，エクササイズ28件，創処置3件だった。外傷に起因していた1例を紹介する。試合中に相手選手の巻き足が前脛部に当たり，徐々に足関節背屈時の疼痛および背屈困難感を自覚した。試合中はアイシングで対応しながら試合終了までプレーを続行した。試合終了時には前脛部の腫脹があり，背屈困難，歩行困難な状態だった。医師によって下腿打撲と診断され，消炎鎮痛剤が処方された。トレーナーとしては，RICE処置を継続しながら，患部への超音波治療，電気治療，歩行時の背屈補助を目的としたテーピングを実施した。受傷2日目，3日目にも同様の対応を実施し，疼痛緩和が得られ，背屈困難感は解消し歩行も可能となったが，泳動作（キック）時の疼痛が残存したため，底屈制限を目的としたテーピングを実施し，試合に出場した。【結論】水球競技における傷害は肩関節，腰部に多く，投球動作，泳動作による負担が多いことに起因すると考えられる。試合期間中，負荷が高まることが背景にあるが，日常から肩関節や腰部のコンディショニングの意識を高める必要がある。また，外傷による問題も少なからず発生することから，トレーナーは外傷への対応力を習得する必要がある。

【はじめに，目的】飛込競技は高さ1m・3mの弾力性のある飛板，あるいは5m・7m・10mの固定台から飛込む採点競技である。傷害発生に関する先行研究では，入水時に腰痛が多く発生し，その腰痛発症には肩甲帯の柔軟性が関与していることが明らかにされた。そこで，2014年ナショナルジュニア合宿参加者の1年間の傷害発生状況および肩甲帯の柔軟性（肩回旋幅）を測定し，現役選手の傷害予防策を講じるための一助とした。【方法】対象は2014年飛込競技ナショナルジュニア合宿に参加した男性14名，女性8名，計22名とした。傷害発生状況を把握するため合宿参加前1年間の傷害調査を実施した。傷害の定義は，飛込競技によって生じ，練習を1日以上休んだものとした。肩甲帯の柔軟性の指標として肩回旋幅（cm）の測定を行った。2回測定し平均値を肩回旋幅とした。肩回旋幅の結果を2014年参加者と2003～2010年参加者（男性60名，女性56名，計116名）の結果を参考とし，比較検討を行った。肩回旋幅は対応のないt検定を用い，肩回旋幅の平均値を全選手（男女），男性選手，女性選手間で比較した。有意水準は5%とした。【結果】合宿参加前1年間の傷害発生状況：2014年合宿参加者20名中，過去1年間に傷害を経験した選手は10名（50.0%）であった。また，傷害総数は12件であり全体の50%が腰部であった。2003～2010年合宿参加者92名中，過去1年間に傷害を経験した選手は43名（46.7%）であった。また，傷害総数は49件であり全体の49%が腰部であった。2014年群の参加者は，過去群の合宿参加者と同様に腰痛を抱えながら競技を行っている選手が多い結果となった 肩回旋幅：全選手（男女）の肩回旋幅は，2014年は55.5±19.5cm，2003～2010年は39.6±19.6cmであり，肩甲帯の柔軟性は有意に低下していた。女性選手の肩回旋幅は2014年では46.3±8.8cm，2003～2010年は26.3±15.6cmであり，肩甲帯の柔軟性は有意に低下していた。また，男性選手の肩回旋幅は2014年では60.8±22.0cm，2003～2010年は52.0±14.1cmであり，肩甲帯の柔軟性は低下傾向であった。【結論】2014年合宿参加者の肩甲帯柔軟性は全選手（男女），女性選手において，2003～2010年合宿参加者よりも有意に低下していた。傷害調査の結果から，2014年合宿参加者は，2003～2010年と同様に腰痛を抱えながら競技を行っている選手が多い結果となった。2003～2010年に対して2014年の腰痛者の割合が減少していないのは，肩甲帯の柔軟性が低下しているためだと考える。そのため今後，練習内容の検討や適切なストレッチ指導を行い肩甲帯の柔軟性を改善する必要があると考える。また，頻回にメディカルチェックを実施することで筋の柔軟性の変化について早期に対処することが重要であるという報告があるため，飛込競技も同様に柔軟性に対する項目を継続して実施する必要があると考える。

【はじめに，目的】着地動作は多くのスポーツに含まれる動作であり，適切に遂行するために多くの筋が協調して活動している。特に後脛骨筋や，長腓骨筋，中殿筋はそれぞれ足関節周囲，股関節周囲の安定性を担っており，動作や姿勢保持に重要な役割を果たしている。姿勢保持のためにそれぞれの筋が協調的に活動し，お互いの機能を補完し合っているとの報告は散見されるが，着地動作中の筋の筋活動開始時間を比較した研究はみられない。本研究の目的は，着地動作中の後脛骨筋，長腓骨筋，中殿筋の筋活動開始時間を比較検討することである。【方法】対象は健常成人男性6名（平均年齢20.6±1.6歳）とした。除外基準は下肢に外傷や疼痛があり，着地動作を行えないものとした。実験試技は片脚着地動作として，高さ30cmの台上で右脚片脚立位をとった姿勢から，台の30cm前方に設置したフォースプレート上に飛び降り，右脚で着地するように行った。試技は5回行い，そのうち3回の成功試技を記録した。被験筋は後脛骨筋，長腓骨筋，中殿筋として着地動作中の筋活動を測定した。後脛骨筋の筋活動測定にはワイヤ筋電図を用いた。ワイヤ電極の刺入は下腿内側近位1/3の位置にて，超音波エコーで筋を描出しながら行った。長腓骨筋と中殿筋の測定は表面筋電図を用いた。筋電図のフィルタ設定はhigh pass 20Hz，low pass 500Hzとし，得られた筋活動データに対して全波整流処理を行った。一連の着地動作のうち身体が宙空にある接地200msec前から接地までの期間を解析し，各筋の筋活動開始時間をintegrated profile methodに基づいて算出した。3回の試技の平均値を各筋の筋活動開始時間として，接地の何msec前から活動を開始したか記録とした。統計解析には一元配置分散分析を使用し，post hoc testとしてBonferroni法を用いた。有意水準は5％未満とした。【結果】各筋の筋活動開始時間は，後脛骨筋が-59.7±28.6msec，長腓骨筋が-70.9±26.6msec，中殿筋が-116.8±22.7msecであった。統計解析の結果，中殿筋の筋活動開始時間は，後脛骨筋，長腓骨筋と比較して有意に早いものであった（p＜0.05）。後脛骨筋と長腓骨筋の筋活動開始時間に有意差はみられなかった。【結論】本研究の結果より，着地動作において中殿筋が後脛骨筋，長腓骨筋よりも早期に活動を開始することが示された。中殿筋の機能が不十分だと片脚立位時の足圧中心偏位量が増加するとされている。また，中殿筋の疲労が起こると着地時に長腓骨筋の筋活動量が増加し，筋活動開始時間も早くなるとの報告もある。それらのことからも，身体重心に近い中殿筋から筋活動を開始し，近位部分を安定化させることで，下肢全体の安定性を向上させていると考えられる。臨床的にも，足部の安定性改善を図る場合，中殿筋などの股関節周囲筋も含めた運動が行われているが，その理論的な根拠の一つとなる結果が示唆された。

【はじめに，目的】変形性膝関節症の進行に，歩行や階段昇降の立脚初期における膝関節側方動揺の大きさが関与するといわれており，この膝関節側方動揺の因子を抽出することは意義深い。階段昇降は膝関節側方動揺，疼痛が出現しやすく，痛みにより階段昇降が困難な患者が，手すりを用いることで痛みが軽減することを経験する。しかし，手すりを用いた階段昇降時の膝関節側方動揺は定量的に捉えられておらず，膝関節側方動揺の大きさと痛みの関係は明らかでない。本研究の目的は，健常者の階段降段時に，手すりの使用が膝関節側方動揺にどの様に影響するかを検証し，階段降段時の膝関節負荷の基礎的資料とすることである。【方法】対象は膝関節に既往歴のない，健常男性3名（身長171.7±7.4cm，体重56.3±1.5kg，年齢23.0±1.73歳）女性3名（身長164.2±9.9cm，体重60.0±8.7kg，年齢20±0.0歳）の計6名とした。計測は，対象者の右腓骨頭に3軸無線加速度計（ワイヤレステクノロジ―社製）を非伸縮テープ（ニチバン社製）で装着し，算出された加速度を膝の動揺とする直接計測法で行った。加速度計のサンプリング周波数は1000Hzとした。測定試技は，10段の階段を110step/secの速さで降りることとし，手すりを使わない通常の階段降段動作（以下，通常降段）と，手すりを用いる階段降段動作（以下，手すり有り降段）の2種類の試技を行った。手すり有り降段では，計測肢である右足が接地する前に左手で手すりを把持する様に指示した。踵接地時の衝撃として計測波形の上方加速度を観察することにより右足接地期を同定した。解析は4，6，8歩目の右脚接地期の最も大きな側方加速度を算出し，その平均値を算出した。その最大側方加速度を，通常降段時と手すり有り降段時で対応のあるt検定を用いて比較した。【結果】膝関節側方加速度ピーク値の平均は，通常降段で1421.7±510.3mG，手すり有り降段で2001.9±735.4mGであり，手すり有り降段が，通常降段と比較し，有意に外側方向に大きな加速度を有していた。【結論】階段降段時の手すり使用により，手すりを使用しない時よりも膝関節側方動揺が大きくなった。今回の試技は，速さや手すりの使用方法を規定されたものに合わせるという課題であり，運動が不安定となり，右足接地期の膝関節側方動揺が大きくなったと考える。また，手すりを用いて上肢での体重支持を行うことで，右脚で体重を支持する筋出力が減少し，膝関節側方動揺が大きくなったのではないかと考える。今回，階段降段時の手すり使用による膝関節の痛みの軽減は，関節側方動揺の大きさは関与していない可能性が示唆された。また，手すりの使用が必ずしも膝関節の安定性を向上させない事が示唆された事から，特に手すりの使用に慣れていない膝関節疾患の術後や急性期の患者においては，膝関節側方動揺にも着目して指導を行う必要があると考える。今後は，手すりの使用方法や形状による違い，変形性膝関節症患者での検討が課題である。

<p>Background: Pelvic tilting is performed to improve lumbopelvic flexibility or retrain the motor control of local muscles. However, few studies investigated the activity of local muscles during pelvic tilting. Purpose: The purpose of this study was to investigate muscle activity during anterior and posterior pelvic tilting. Method: Twelve healthy males (age, 22.6 ± 1.4 years) participated. Fine-wire electrodes were inserted into the bilateral lumbar multifidus (MF) and transversus abdominis (TrA). Surface electrodes were used to record activity of the bilateral rectus abdominis, external oblique, and erector spinae (ES), and the unilateral right latissimus dorsi, gluteus maximus, semitendinosus, and rectus femoris muscles. The electromyographic activities during anterior and posterior pelvic tilting in a standing position were recorded and expressed as a percentage of the maximum voluntary contraction (%MVC) for each muscle. Results: The activities of the bilateral MF (right: 23.9 ± 15.9 %MVC, left: 23.9 ± 15.1 %MVC) and right ES (19.0 ± 13.3 %MVC) were significantly greater than those of the other muscles during anterior pelvic tilting. The activity of the left TrA (14.8 ± 16.4 %MVC) was significantly greater than that of the other muscles during posterior pelvic tilting. Conclusions: The results suggested that the MF and ES are related to anterior pelvic tilting. The activity of the TrA, which was classified as a local muscle, was greater during posterior pelvic tilting. This study indicated that local muscles such as the MF and TrA may be related to pelvic tilting.</p>

Objectives: To ascertain the dynamic stretch effects of flexibility of the hamstrings on lumbar spine and pelvic kinematics. Background: Tight hamstrings are positively correlated with low back pain. However, it is unclear how flexibility of the hamstrings affects spino-pelvic rhythm. Methods: Twelve healthy men participated in the study. The straight leg raising (SLR) angle, finger floor distance (FFD), and spino-pelvic rhythm was measured before and after the 6-week stretching protocol. The forward bending task was divided into 4 phases. The paired t-test was used to determine significant differences before and after the FFD, SLR angle, lumbar motion, and pelvic motion, and spino-pelvic rhythm in each phase (p&lt;0.05). Results: After 6 weeks of stretching, significant improvements were seen in the FFD with maximum forward bending and in the SLR angle. Total pelvic rotation was also significantly increased in contrast to total lumbar flexion. A decreased spino-pelvic ratio was seen in the final phase. Conclusion: Dynamic stretching could change the spino-pelvic rhythm to a pelvis-dominant motion, indicating that flexible hamstrings are important for preventing low back pain. J. Med.

Purpose: We evaluated trunk muscle recruitment in abdominal and back exercises with magnetic resonance (MR) diffusion-weighted imaging.
Methods: Twelve men performed bent-knee sit-up, crunch, trunk lateral flexion, and trunk extension exercises. We obtained axial diffusion-weighted images of the trunk before and after each exercise using a 1.5-tesla MR system, calculated apparent diffusion coefficient (ADC) values from the right and left rectus abdominis, lateral abdominal, psoas major, quadratus lumborum, and intrinsic back muscles to evaluate the activity of these muscles during each exercise, and compared ADC values before and after exercise using a paired t-test.
Results: The ADCs of the rectus abdominis (right, +19.1%; left, +11.7%), lateral abdominal (right, +15.5%; left, +14.1%), and psoas major (right, +14.8%; left, +15.9%) muscles on both sides increased after the bent-knee sit-up (P &lt; 0.01). The ADCs of the rectus abdominis (right, +16.8%; left, +10.2%) and lateral abdominal (right, +8.4%; left, +7.0%) muscles on both sides increased after the crunch exercise (P &lt; 0.01). Trunk lateral flexion resulted in increased ADC on only the right side of all of the muscles (rectus abdominis, +12.3%; lateral abdominal muscles, +20.3%; quadratus lumborum, +17.1%; intrinsic back muscles, +12.0%; psoas major, +15.4%) (P &lt;0.01). The ADCs of the lateral abdominal (right, +5.2%; left, +5.6%), quadratus lumborum (right, +6.0%; left, +3.0%), and intrinsic back (right, +13.2%; left, +14.6%) muscles on both sides were elevated after trunk extension (right lateral abdominal muscles and left quadratus lumborum, P &lt; 0.05; other muscles, P &lt; 0.01).
Conclusion: Diffusion-weighted imaging reveals the recruitment patterns of superficial and deep trunk muscles in abdominal and back exercises through exercise-induced activation in intramuscular water movement.

Background/Aim During competitive diving, divers jump up from 1 to 3 m springboards or 5 to 10 m platforms and dive into the water. The impact forces are very large in the water entry phase, and, as such, microtraumatic injuries are common due to the tremendous physical stress placed on the diver. Low-back pain (LBP) is the most frequently reported symptom in divers. This study aimed to extract possible risk factors related to LBP from physical and technical characteristics in Japanese elite junior divers.
Methods Eighty-three elite junior divers (42 men and 41 women) in Japan were included in this study. LBP was assessed by a questionnaire, interview and physical examination during a national training camp. Morphological data, physical fitness and diving skills were also evaluated. The factors related to LBP were extracted by using logistic-regression analysis and the forward-selection method (likelihood ratio).
Results A total of 37.3% (31 reports) of back pain occurred in the lumbar region. Shoulder flexibility (OR 0.919; 95% CI 0.851 to 0.992) and age (OR 0.441; 95% CI 0.239 to 0.814) were recognised as factors related to LBP in male-elite junior divers, whereas only age (OR 0.536; 95% CI 0.335 to 0.856) was a factor in female-elite junior divers.
Conclusions Our results suggest that shoulder flexibility is important for preventing LBP in elite-male junior divers, since they require full shoulder flexion during the water entry phase. Limited shoulder flexibility could cause lumbar hyperextension when adjusting for the angle of water entry.

様々な運動器疾患に対し水中運動療法が行われている中で,水中大股歩行が近年注目され実施されている。そこで本研究では,大股歩行を水中と陸上で行った際の体幹・下肢筋活動を測定し,水中大股歩行の有効性を検討した。健常男性6名に対し,水中および陸上で大股歩行を行わせた際の筋電図および画像データを収集した。1歩行周期を立脚期,遊脚期,二重支持期にphase分けし,各phaseにおける筋活動量を比較した。その結果,歩行周期全体を通して,体幹・下肢の筋活動量は水中大股歩行で有意に小さかった。特に,水中大股歩行において,脊柱起立筋および大腿二頭筋は二重支持期で,大腿直筋は遠心性収縮の活動様式である遊脚後期で活動量が有意に小さかった。本結果より,水中歩行は陸上歩行よりも筋活動量が少なくなり,荷重負荷とともに筋への負荷が少ない運動であることが示唆された。

PURPOSE/BACKGROUND:Trunk exercises, such as trunk stabilization exercises (SE) and conventional trunk exercises (CE), are performed to improve static or dynamic balance. Recently, trunk exercises have also been often used as part of warm-up programs. A few studies have demonstrated the immediate effects of SE and CE on static balance. However, immediate effects on dynamic balance are not yet known. Therefore, the purpose of this study was to compare the immediate effect of SE with that of CE on the Star Excursion Balance Test (SEBT).;METHODS:Eleven adolescent male soccer players (17.9 ± 0.3 years, 168.5 ± 5.4 cm, and 60.1 ± 5.1 kg) participated in this study. A crossover design was used, and each participant completed three kinds of testing sessions: SE, CE, and non-exercise (NE). Experiments took place for three weeks with three testing sessions, and a 1-week interval was provided between different conditions. Each testing session consisted of three steps: pretest, intervention, and posttest. To assess dynamic balance, the SEBT score in the anterior, posteromedial, and posterolateral directions was measured before and 5 minutes after each intervention program. The data of reach distance were normalized with the leg length to exclude the influence of the leg length on the analysis.;RESULTS:The SEBT composite score was significantly improved after the SE (p < 0.05) but did not change after the CE and NE (p > 0.05). Furthermore, in the SE condition, SEBT scores of the posterolateral and posteromedial directions were significantly improved at the posttest, compared with those at the pretest (p < 0.05).;CONCLUSIONS:This study demonstrated the immediate improvements in the posteromedial and posterolateral directions of the SEBT only after the SE. This result suggests that the SE used in this study is effective in immediately improving dynamic balance.;LEVELS OF EVIDENCE:3b.

BACKGROUND AND OBJECTIVE: Sitting posture may often place large burden on trunk muscles, while trunk muscle activities in the sitting posture have not been well clarified. In this study, a difference in trunk muscle activity between two kinds of sitting postures was evaluated, focusing on low back pain induced by posture holding.
MATERIAL AND METHODS: An experiment was conducted on the subjects sitting on a stable-seat and on an unstable-seat, with the pelvis inclined forward, backward, rightward, and leftward.
RESULTS: With the pelvis inclined forward, rightward and leftward, muscle activities were significantly increased in a stable-seat sitting posture. In contrast, no significant increase in muscle activity was observed with the pelvis inclined in every direction in an unstable-seat sitting posture.
CONCLUSIONS: With the pelvis inclined in the stable-seat sitting posture, muscle activities were imbalanced, while with the pelvis inclined in the unstable-seat sitting posture, muscle activities were not imbalanced. Thus, it is suggested that with the pelvis inclined to the maximum extent in the stable-seat sitting posture, low back pain may be induced by imbalanced muscle activities.

PURPOSE/BACKGROUND:Many athletes perform trunk stabilization exercises (SE) and conventional trunk exercises (CE) to enhance trunk stability and strength. However, evidence regarding the specific training effects of SE and CE is lacking and there have been no studies for youth athletes. Therefore, the purpose of this study was to investigate the training effects of SE and CE on balance and athletic performance in youth soccer players.;METHODS:Twenty-seven male youth soccer players were assigned randomly to either an SE group (n = 13) or CE group (n = 14). Data from nineteen players who completed all training sessions were used for statistical analyses (SE, n = 10; CE, n = 9). Before and after the 12-week intervention program, pre- and post-testing comprised of a static balance test, Star Excursion Balance Test (SEBT), Cooper's test, sprint, the Step 50, vertical jump, and rebound jump were performed. After pre-testing, players performed the SE or CE program three times per week for 12 weeks. A two-way repeated-measures ANOVA was used to assess the changes over time, and differences between the groups. Within-group changes from pre-testing to post-testing were determined using paired t-tests. Statistical significance was inferred from p < 0.05.;RESULTS:There were significant group-by-time interactions for posterolateral (p = 0.022) and posteromedial (p < 0.001) directions of the SEBT. Paired t-tests revealed significant improvements of the posterolateral and posteromedial directions in the SE group. Although other measurements did not find group-by-time interactions, within-group changes were detected indicating significant improvements in the static balance test, Cooper's test, and rebound jump in the only SE group (p < 0.05). Vertical jump and sprint were improved significantly in both groups (p < 0.05), but the Step 50 was not improved in either group (p > 0.05).;CONCLUSIONS:Results suggested that the SE has specific training effects that enhance static and dynamic balance, Cooper's test, and rebound jump.;LEVEL OF EVIDENCE:3b.

The aim of this study was to clarify the prevalence and distribution of disc degeneration in collegiate rowers and investigate the relationship between disc degeneration progression and low back pain (LBP). In this cross-sectional study, 68 collegiate rowers were evaluated for lumbar disc degeneration using the Pfirrmann classification based on T2-weighted magnetic resonance imaging (MRI). After 2 years, 20 participants underwent follow-up MRI. Injury surveillance to check LBP was conducted between the first examination and follow-up study. The relationship between symptoms and disc degeneration was investigated. Thirty-one (45.6%) rowers had disc degeneration: 48.8% of male rowers and 40.0% of female rowers. After 2 years, disc degeneration progression was observed in 5 (25%) rowers. During the 2 years, 6 rowers reported LBP. In the LBP group, disc degeneration progression was observed in 4 (66.7%) rowers. Significantly more participants in the LBP group than in the non-LBP group (7.1%) (p = 0.014) showed disc degeneration progression. The prevalence of disc degeneration among collegiate rowers was 45.6%, high at the level of the lower lumbar spine. Progression of lumbar disc degeneration was observed in significantly more LBP than non-LBP rowers during the longitudinal study.

BACKGROUND AND OBJECTIVE: Sitting posture may often place large burden on trunk muscles, while trunk muscle activities in the sitting posture have not been well clarified. In this study, a difference in trunk muscle activity between two kinds of sitting postures was evaluated, focusing on low back pain induced by posture holding.
MATERIAL AND METHODS: An experiment was conducted on the subjects sitting on a stable-seat and on an unstable-seat, with the pelvis inclined forward, backward, rightward, and leftward.
RESULTS: With the pelvis inclined forward, rightward and leftward, muscle activities were significantly increased in a stable-seat sitting posture. In contrast, no significant increase in muscle activity was observed with the pelvis inclined in every direction in an unstable-seat sitting posture.
CONCLUSIONS: With the pelvis inclined in the stable-seat sitting posture, muscle activities were imbalanced, while with the pelvis inclined in the unstable-seat sitting posture, muscle activities were not imbalanced. Thus, it is suggested that with the pelvis inclined to the maximum extent in the stable-seat sitting posture, low back pain may be induced by imbalanced muscle activities.

PURPOSE: Polymorphic variation in the angiotensin-converting enzyme (ACE) and α-actinin-3 (ACTN3) genes has been reported to be associated with endurance and/or power-related human performance. Our aim was to investigate whether polymorphisms in ACE and ACTN3 are associated with elite swimmer status in Caucasian and East Asian populations. METHODS: ACE I/D and ACTN3 R577X genotyping was carried out for 200 elite Caucasian swimmers from European, Commonwealth, Russian, and American cohorts (short and middle distance, ≤400 m, n = 130; long distance, >400 m, n = 70) and 326 elite Japanese and Taiwanese swimmers (short distance, ≤100 m, n = 166; middle distance, 200-400 m, n = 160). Genetic associations were evaluated by logistic regression and other tests accommodating multiple testing adjustment. RESULTS: ACE I/D was associated with swimmer status in Caucasians, with the D allele being overrepresented in short-and-middle-distance swimmers under both additive and I-allele-dominant models (permutation test P = 0.003 and P = 0.0005, respectively). ACE I/D was also associated with swimmer status in East Asians. In this group, however, the I allele was overrepresented in the short-distance swimmer group (permutation test P = 0.041 and P = 0.0098 under the additive and the D-allele-dominant models, respectively). ACTN3 R577X was not significantly associated with swimmer status in either Caucasians or East Asians. CONCLUSIONS: ACE I/D associations were observed in these elite swimmer cohorts, with different risk alleles responsible for the associations in swimmers of different ethnicities. The functional ACTN3 R577X polymorphism did not show any significant association with elite swimmer status, despite numerous previous reports of associations with "power/sprint" performance in other sports.

Objective To determine trunk muscle activity when lifting an object of greater weight than expected, which may contribute to the development of low back pain.
Design Electromyographic evaluation of trunk muscle activity.
Setting University of Tsukuba, Spine laboratory.
Participants Eleven healthy men with a mean age of 24 (SD 2) years.
Interventions Trunk muscle activity was measured when subjects lifted an object with their right arm in immediate response to a light stimulus. Surface and wire electrodes were used to measure the activity of the rectus abdominis, external oblique and erector spinae muscles, and the transversus abdominis and lumbar multifidus muscles, respectively. The lifting tests were performed in three different settings: lifting an expected 1-kg object, lifting an unexpected 4-kg object (erroneously expected to weigh 1 kg), and lifting an expected 4-kg object.
Main outcome measures The muscle activity induced when subjects lifted objects of different weights was compared by calculating the root mean square (RMS) of muscle activity at rest and % maximum voluntary contraction.
Results When the subjects were aware of the weight of the object to be lifted, the activity of the external oblique, transversus abdominis, erector spinae and lumbar multifidus muscles increased immediately after lifting. When the subjects were not aware of the weight of the object to be lifted, the increase in muscle activity was delayed (P &lt; 0.05).
Conclusions Trunk muscles may not be able to function appropriately when individuals lift an object that is much heavier than expected. (C) 2011 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

【はじめに、目的】倒立は体操や飛込競技の演技で頻繁に行われる動作であり，高い点数を得るためには身体を一直線に保つ能力が必要とされる．倒立は上肢で体重を支持しながら重心をコントロールするため，立位姿勢とは異なった筋活動様式を示すと考えられる．そこで本研究では，体操選手の倒立姿勢と立位姿勢保持時の筋活動量を比較し，倒立姿勢時の筋活動様式を明らかにすることを目的とした．【方法】対象は体操競技経験10 年以上の大学男子体操選手7 名とした．マット上で直立立位および倒立姿勢を3 秒間保持させた際の筋電図を測定した．倒立姿勢は実際の演技を想定し，できる限り身体を一直線にして静止させた．被験筋は右側の腹直筋，外腹斜筋，内腹斜筋，胸部脊柱起立筋（第9 胸椎レベル），腰部脊柱起立筋（第3 腰椎レベル），大腿直筋，上腕三頭筋，広背筋であり，表面電極を貼付した．立位，倒立ともに姿勢が安定した1 秒間の筋活動量を，等尺性最大随意収縮時の活動量で正期化した%MVCを算出した．各筋において，立位と倒立時の筋活動量をWilcoxonの符号付順位検定を用いて比較した．なお，有意水準は5%とした．【倫理的配慮、説明と同意】本研究はヘルシンキ宣言に基づいた倫理的配慮の下行った。被験者には口頭にて，実験の概要，方法，研究による危険性とその対処法，自由意志による同意であること，同意を示された方でもいかなる場合においても理由を問われることなく実験への同意を撤回することができること，個人の人権を擁護することを説明し，実験参加の同意を得られた後，実験を行った．【結果】腹直筋（立位：0.3 ± 0.1%MVC，倒立：6.5 ± 4.2"%MVC），外腹斜筋（立位：1.0 ± 0.4%MVC，倒立：6.4 ± 5.1"%MVC），大腿直筋（立位：0.6 ± 0.2%MVC，倒立：3.5 ± 2.2"%MVC），上腕三頭筋（立位：0.6 ± 1.0%MVC，倒立：13.5 ± 7.0"%MVC），広背筋（立位：0.5 ± 0.4%MVC，倒立：1.9 ± 1.3"%MVC）は倒立時の活動量が立位時よりも有意に大きかった．腰部脊柱起立筋（立位：4.7 ± 3.6%MVC，倒立：1.6 ± 1.2"%MVC）は立位時の活動量が倒立時よりも有意に大きかった．内腹斜筋，胸部脊柱起立筋に有意差は認めなかった．【考察】本結果より，倒立時には腹直筋，外腹斜筋，大腿直筋，上腕三頭筋，広背筋の活動量が大きかった．倒立時には上肢で体重を支持するため手関節および肩関節のトルクが大きくなることが報告されており（Kerwin DG and Trewartha G,2001），上腕三頭筋や広背筋など上肢筋の活動量が大きくなったと考える．また，倒立姿勢の重心をコントロールするために体幹・股関節の運動制御が必要とされ，腹直筋，外腹斜筋，大腿直筋の活動量が大きくなったと考える．上級者の倒立は初心者よりも股関節伸展方向への角度変位量が少ないことが示されていることから（Gautier G et al., 2009），体幹・股関節屈筋群を活動させて，安定した倒立姿勢を維持している可能性が示唆された．一方，腰部脊柱起立筋は有意に立位で活動量が大きく，胸部脊柱起立筋も有意差は認めなかったが，立位で活動量が大きかった（立位：2.6 ± 0.8%MVC，倒立：1.7 ± 1.1"%MVC）．脊柱起立筋群は立位姿勢においては抗重力筋として活動するが，倒立姿勢では抗重力作用を必要としないため活動量が減少する可能性が示唆された．以上から，体幹筋群において立位では体幹背面筋群が活動し，倒立では体幹前面筋群の活動量が大きくなる傾向を示した．今後は，重心位置やアライメントを計測し，抗重力作用と筋活動との関連を明らかにしながら，身体を一直線に維持するための倒立技術を解明する必要がある．【理学療法学研究としての意義】倒立は体操競技だけでなく様々な競技のトレーニング現場で用いられている．本研究では一流体操選手の倒立筋活動を明らかにしたことから，スポーツ現場において倒立パフォーマンスを向上させるための有用な情報になると考える．

STUDY DESIGN: Experimental laboratory study. OBJECTIVES: To measure the activation patterns (onset and magnitude) of the abdominal muscles during a standing long jump using wire and surface electromyography. BACKGROUND: Activation patterns of the abdominal muscles, especially the deep muscles such as the transversus abdominis (TrA), have yet to be examined during full-body movements such as jumping. METHODS: Thirteen healthy men participated. Wire electrodes were inserted into the TrA with the guidance of ultrasonography, and surface electrodes were attached to the skin overlying the rectus abdominis (RA) and external oblique (EO). Electromyographic signals and video images were recorded while each subject performed a standing long jump. The jump task was divided into 3 phases: preparation, push-off, and float. For each muscle, activation onset relative to the onset of the RA and normalized muscle activation levels (percent maximum voluntary contraction) were analyzed during each phase. Comparisons between muscles and phases were assessed using 2-way analyses of variance. RESULTS: The onset times of the TrA and EO relative to the onset of the RA were -0.13 ± 0.17 seconds and -0.02 ± 0.07 seconds, respectively. Onset of TrA activation was earlier than that of the EO. The activation levels of all 3 muscles were significantly greater during the push-off phase than during the preparation and float phases. CONCLUSION: Consistent with previously published trunk-perturbation studies in healthy persons, the TrA was activated prior to the RA and EO. Additionally, the highest muscle activation levels were observed during the push-off phase. Copyright © 2013 Journal of Orthopaedic &amp
Sports Physical Therapy®. All rights reserved.

The study investigated age-related changes in the thickness of the deep and superficial abdominal muscles of 103 healthy women who could walk independently The participants were classified into five age groups: young (n = 26; 20-24 years), young adult (n = 26; 25-44 years), middle-aged (n = 16; 45-64 years), young-old (n = 16; 65-74 years), and old-old (n = 19; 75-85 years). The muscle thicknesses of the right rectus abdominis, external oblique, internal oblique, and transversus abdominis were measured using ultrasound imaging. The rectus abdominis was significantly thicker in the young group compared with the young adult, middle-aged, young-old, and old-old groups (p &lt; 0.05). The external oblique and internal oblique muscles were significantly thicker in the young group compared with the middle-aged, young-old, and old-old groups (p &lt; 0.05). However, there were no significant differences in the thickness of the transversus abdominis between groups. The results suggest that age-related muscle atrophy occurs from an early age in superficial abdominal muscles, such as rectus abdominis, and that age-related atrophy is less in deep abdominal muscles such as the transversus abdominis. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

〔目的〕飛込競技男子選手の腰痛発生要因を明らかにするため，ジュニア選手の成長期における身体特性の変化を3年間の縦断調査から検討した．〔対象〕1998～2010年に飛込競技男子ジュニア強化選手に選抜された119名のうち13-15歳の経過を追跡できた13名．〔方法〕形態，瞬発力，体幹筋力，柔軟性，競技特性を評価した11項目のうち，13-15歳の各年齢間の変化を一元配置分散分析にて解析した．〔結果〕有意な変化を認めたのは，身長，体重，立幅跳，垂直跳，30秒上体起こし，背筋力，倒立持続時間であった．柔軟性の項目に有意な変化は認めなかった．〔結語〕15歳以降の体重の増加，背筋と腹筋の比が低値であることが，腰痛発生に関わっていると考えられた．

[Purpose] It has been reported that chronic low-back pain (CLBP) patients exhibit asymmetric atrophy of the lumbar multifidus muscle. However, studies focusing on the abdominal muscles have not yet been conducted. The purpose of this study was to determine abdominal muscle thickness and symmetry in CLBP patients and healthy subjects. [Subjects and Methods] Data were obtained from 50 healthy subjects (30.2 +/- 6.1 years) and 50 CLBP patients (31.5 +/- 8.7 years). The thicknesses of the rectus abdominis (RA), external oblique (EO), internal oblique (10), and transversus abdominis (TrA) were measured by ultrasonography. We calculated the mean thicknesses of both sides. In addition, we calculated the asymmetry ratio as a percentage of the difference between the sides. The differences in muscle thickness between the CLBP patients and healthy subjects were analyzed using the t-test. [Results] We found that the TrA thickness was significantly smaller in CLBP patients (3.7 +/- 0.8 mm) than in healthy subjects (4.2 +/- 1.2 mm). Similarly, the TrA asymmetry ratio was significantly different between the healthy subjects (8.4 +/- 7.5%) and CLBP patients (16.4 +/- 12.1%). [Conclusion] The TrA muscle of CLBP patients was thinner and more asymmetric than that of healthy subjects.

[Purpose] Therapeutic exercise for chronic low back pain is one of the most important conservative treatments. Recently, lumbar stabilization exercise focused on deep trunk muscles has attracted considerable attention. This study investigated the effectiveness of lumbar stabilization exercises for treating CLBP. [Subjects] The subjects were 18 patients with CLBP. CLBP was defined as pain that persisted for more than 3 months. [Methods] The therapeutic exercises involved the abdominal drawing-in maneuver (hereafter referred to as "drawing-in") and prone kneeling (hereafter referred to as "hand-knee"). The exercises were performed during a 3-month intervention period. Pain was evaluated using a Visual Analog Scale (hereafter referred to as "VAS"), while quality-of-life (hereafter referred to as "QOL") was estimated using the Japanese Orthopaedic Association Back Pain Examination Questionnaire (hereafter referred to as "JOABPEQ"). Pain and QOL were assessed prior to the intervention (TO), and at one (T1), three (T3), and six months (T6) after the intervention. The Steel-Dwass test was used to investigate differences between values prior to and after performance of the therapeutic exercise regime. Significance was defined as p&lt;0.05. [Results] The median low back pain value was significantly improved at T3 and T6 compared to TO. At T1, patients reported significant improvement in the lumbar functions score in comparison with TO. This change was still observed at T3 and T6. At T3, scores of all items had significantly increased. At T6, the changes in low back pain score and walking ability score were no longer significant, however their tendencies remained. [Conclusions] These results suggest that performance of lumbar stabilization exercises is an effective method for improving comfort and QOL of patients with CLBP.

本研究では慢性腰痛患者を対象に運動療法を指導し,自宅での自主トレーニングを行わせ,腰痛および体幹筋の筋厚の変化について調査した.対象者は18名(男性4名,女性14名)で,3ヵ月間の体幹深部筋に注目した運動療法を実施した.介入前と介入3ヵ月後を比較した結果,腰痛評価のVASは有意に減少した.体幹筋の筋厚については,腹横筋,第3腰椎高位および第4腰椎高位の多裂筋において有意な増加を認めた.(著者抄録)

【目的】<BR>老化に伴う退行性変化として骨格筋の萎縮が起きることは周知の事実であり，リハビリテーションの分野では高齢者における筋の機能の維持および向上が重要な課題のひとつとなっている．この筋萎縮の評価法のひとつとして，近年，超音波画像診断装置による筋厚測定がよく用いられている．超音波画像診断装置は，MRIやCTと比較して，安価で簡便であり，信頼性と妥当性も高いことから，超音波画像診断装置を使用した研究が多くなされている．しかしながら，超音波法を用いて筋厚の加齢変化を調べた先行研究の多くは四肢の筋を対象としており，体幹筋，特に腹筋群について言及した研究は少ない．また，筋萎縮に関する横断研究の場合は，加齢による影響だけでなく，身長や体重，BMIといった体格の差異による影響も考慮する必要がある．しかしながら，腹筋群の筋厚にはどのような体格要因が関連するのかについては明らかではない。そこで本研究では，超音波画像診断装置を使用して腹筋群の筋厚を測定し，年齢や体格との関連について明らかにすることを目的とした．<BR>【方法】<BR>被験者は，健常成人120名（男性60名，女性60名）とした．男性被験者の年齢は33.1±18.1歳（20～84歳）であり，身長は170.5±6.8cm，体重は67.2±11.8kg，BMIは23.0±3.1であった．女性被験者の年齢は57.2±19.2歳（20～83歳）であり，身長は154.2±7.1m，体重は52.0±9.0kg，BMIは21.9±3.4であった．いずれも独歩または歩行補助具を使用し自立歩行が可能な者とした．筋厚の測定には超音波診断装置を使用した．対象筋は，腹直筋，外腹斜筋，内腹斜筋，腹横筋とした．測定肢位は安静背臥位で，いずれも安静呼気時に測定した．測定部位は腹直筋が臍から外側4cmの部位，外腹斜筋，内腹斜筋，腹横筋は臍高位の腋窩線から内側2.5cmの部位とし，いずれも右側を測定した．腹筋群の筋厚と年齢，身長，体重，BMIとの関係について，各筋厚を目的変数とし，年齢，身長，体重, BMIを説明変数として，男女別にそれぞれ重回帰分析を用いて検討した．いずれも有意水準は5％未満とした．<BR>【説明と同意】<BR>本研究の目的と方法について，すべての被験者に対し口頭および文書にして十分に説明し，同意を得た．<BR>【結果】<BR>腹直筋の筋厚の平均値は男性12.8±3.3mm，女性8.3±2.4mmであった．重回帰分析の結果，男女ともに年齢のみ筋厚に影響を与える有意な因子として抽出され（標準偏回帰係数：男性-0.58，女性-0.71），自由度調整済決定係数は男性0.59，女性0.59であった．外腹斜筋の筋厚の平均値は男性8.6±2.9mm，女性5.4±1.9mmであった．重回帰分析の結果，男女ともに年齢のみ有意な因子として抽出され（標準偏回帰係数：男性-0.56，女性-0.61），自由度調整済決定係数は男性0.48，女性0.43であった．内腹斜筋の筋厚の平均値は男性12.2±3.9mm，女性8.1±2.5mmであった．重回帰分析の結果，男女ともに年齢のみ有意な因子として抽出され（標準偏回帰係数：男性-0.66，女性-0.43），自由度調整済決定係数は男性0.44，女性0.23であった．腹横筋の筋厚は男性4.4±1.2mm，女性3.3±0.9mmであった．重回帰分析の結果，男女ともにいずれの説明変数も筋厚に影響を与える因子として抽出されなかった． <BR>【考察】<BR>本研究では，腹筋群における筋厚と年齢，身長，体重，BMIとの関連を明確にするため，若年者から高齢者までの男女の筋厚を測定し，重回帰分析を用いて検討した．その結果，腹直筋，外腹斜筋，内腹斜筋の筋厚については，年齢が影響を及ぼす因子として抽出されたが，腹横筋の筋厚では年齢は抽出されなかった。このことから，腹筋群のなかでも腹横筋の筋厚は加齢変化が少ないことが示唆された．また，身長，体重， BMIといった体格はすべての腹筋群の筋厚において影響を及ぼす因子として抽出されなかった．骨格筋の筋萎縮の程度を横断的に比較検討する際，四肢筋の筋厚については体格の差異を考慮し，体格要因で補正した筋厚が用いられることがある．本研究の結果，腹筋群の筋厚については体格による違いを考慮する必要性は少ないと考えられた．<BR>【理学療法学研究としての意義】<BR>本研究により，腹直筋，外腹斜筋，内腹斜筋の筋厚は，加齢に伴って減少するが，腹横筋の筋厚は加齢変化が少ないことが示された．また，腹筋群の筋厚は体格要因による影響は少ないことが示唆された．本研究の結果は腹筋群の筋萎縮の程度を評価する上で考慮すべき重要な知見であると考える．<BR>

【目的】近年，腰痛治療やパフォーマンス向上において体幹深部筋（腹横筋，多裂筋など）機能が重要であることが明らかにされている．その体幹深部筋は四肢を運動させる際，主動筋に先行して活動し，体幹安定性を制御していることが報告されている（Hodges et al., 1997）．四肢を激しく運動させるスポーツ動作においても，体幹安定性が確保された上での運動が要求されると推察できるが，体幹深部筋活動は表面電極では導出が困難であるため，スポーツ動作時の体幹深部筋活動を測定した研究は少ない．そこで本研究では，ワイヤ筋電図を用いて垂直跳び時の腹部筋反応時間を明らかにすることを目的とした．<BR><BR>【方法】本実験に参加した健常成人男性16名中，測定不備がなかった11名を対象とした（年齢：24.2±1.9歳，身長：171.7±7.2cm，体重：67.3±8.1kg，値はmean±SD）．上肢を胸の前で組ませ，安静立位から最大努力性の垂直跳びを行った際の筋電図および画像データを収集した．被験筋は左側の腹直筋，外腹斜筋，腹横筋，脊柱起立筋，多裂筋であり，腹横筋，多裂筋には滅菌したワイヤ電極を超音波画像ガイド下にて整形外科医が刺入し，刺入後電気刺激装置を用いて収縮を確認した．試技中の筋電波形から筋活動が開始した時点を視覚的に求め，画像で確認した離地時を基準（0秒）として筋反応時間を算出した．一元配置分散分析にて腹筋群（腹直筋，外腹斜筋，腹横筋）の筋反応時間を比較し，有意差が認められた場合はTukey-KramerのHSD検定により多重比較を行った．なお，有意水準は5%とした．<BR><BR>【説明と同意】本研究はヘルシンキ宣言に基づいた倫理的配慮の下行った。被験者には口頭及び文書にて，実験の概要，方法，研究による危険性とその対処法，自由意志による同意であること，同意を示された方でもいかなる場合においても理由を問われることなく実験への同意を撤回することができること，個人の人権を擁護することを説明し，同意書に署名後，実験を行った．なお，本研究は筑波大学人間総合科学研究科研究倫理委員会の承認を得ている（承認番号：590）．<BR><BR>【結果】各筋の筋反応時間は早い順に，多裂筋：－0.90±0.20sec，脊柱起立筋：－0.90±0.20sec，腹横筋：－0.41±0.18sec，外腹斜筋：－0.32±0.10sec，腹直筋：－0.22±0.12secであった．また，腹筋群の筋反応時間を統計処理した結果，腹横筋は腹直筋よりも有意に早く活動を開始していた（p＝0.0061）．<BR><BR>【考察】本結果より，垂直跳び動作時にはまず背筋群が活動した後，腹筋群が活動することが示された．垂直跳び動作は体幹の前傾から動作が開始されるため，まず背筋群から活動を開始し，その後腹筋群が活動したと考えられる．また，腹筋群の中では腹横筋が腹直筋よりも有意に早く活動を開始した．ドロップジャンプ動作では着地前に腹横筋が活動を開始し，その活動は腹直筋よりも有意に早かったことが報告されている（河端ら，2008）．ドロップジャンプは跳躍の前に着地動作が行われるため，着地に対する腹部筋反応が現れるが，垂直跳び動作においても同様の結果が得られた．腹横筋は腹腔内圧を高め腰椎の分節的安定性を制御しているのに対し，腹直筋や外腹斜筋などの体幹表層筋はトルクを産生し体幹の運動方向を制御している．従って，腹横筋の活動により体幹安定性を高めた後，表層筋を活動させることでジャンプ動作の推進力を産生していることが示唆された．さらに，腰痛患者では腹横筋の先行的活動が遅延すると報告されている（Hodges et al., 1996）ため，今後は腰痛患者が行うスポーツ動作において腹横筋反応時間が遅延しているか否かを検討することで，アスリートの腰痛治療や予防につながる可能性がある．<BR><BR>【理学療法学研究としての意義】本研究により，健常者が行う垂直跳び動作では，体幹深部筋から表層筋へと順に活動することが明らかとなった．本結果は，ジャンプ動作の体幹筋活動に関する基礎的データであり，リハビリテーションやトレーニング現場においてジャンプ動作を指導する際に有用な知見になると考える．

本研究では，急制動時における乗員の姿勢変化に対して身体各部位に働く筋応答の影響を分析するために志願者を用いた低衝撃実験を実施した．実験では志願者に対して筋緊張と非緊張の2種類の条件で実施し，衝撃時における姿勢変化の違いや，身体に作用する物理量について表面筋電位から得られた筋活動の状況より考察した．

In competitive diving, divers jump up from 1 or 3 m springboards or 5-10 m platforms and dive into the water. At the time of water entry, the force of impact is very large, which places tremendous physical stress on the diver. However, there are few investigations about injury occurrence in divers, especially during the junior period. Thus, this study aimed to describe the prevalence of injuries among elite junior divers over a 7-year period. One hundred and sixteen (60 male, 56 female) Japanese elite junior divers were included in this study. Parts of pain and injury incidence scene that the divers experienced were assessed by questionnaires during national training camps. Low back pain(LBP)was assessed by interviews, and physical examinations. The major findings were as follows: (1) Among all types of injuries, there was high prevalence of LBP (38.4%) in elite junior divers in Japan. (2) Most injuries occurred at the time of water entry.

慢性腰痛者21名(男性2名、女性19名)を対象に、1回60分の水中運動プログラムを週2回、3ヵ月間実施した。運動前後で、身体計測、体幹・下肢の筋力・柔軟性測定、MRIによる筋横断面積計測、バランス能力評価、VAS、JOABPEQ、アンケート調査を行い、運動前後で比較した。その結果、体脂肪率は有意に減少し、腹直筋と大腰筋の横断面積は有意に増加し、下肢筋力・バランス能力・下肢柔軟性は有意に向上し、腰痛程度は有意差を認めないものの改善した。これらの結果より、水中運動は慢性腰痛者に有効な運動療法であることが示唆された。(著者抄録)

In competitive diving, divers jump up from 1 or 3 m springboards or 5-10 m platforms and dive into the water. At the time of water entry, the force of impact is very large, which places tremendous physical stress on the diver. However, there are few investigations about injury occurrence in divers, especially during the junior period. Thus, this study aimed to describe the prevalence of injuries among elite junior divers over a 7-year period. One hundred and sixteen (60 male, 56 female) Japanese elite junior divers were included in this study. Parts of pain and injury incidence scene that the divers experienced were assessed by questionnaires during national training camps. Low back pain(LBP)was assessed by interviews, and physical examinations. The major findings were as follows: (1) Among all types of injuries, there was high prevalence of LBP (38.4%) in elite junior divers in Japan. (2) Most injuries occurred at the time of water entry.

Surface electromyography (EMG) has been used to estimate deep trunk muscle activity. However, it remains unknown whether surface EMG provides an accurate estimation of this activity. The purposes of this study were to compare surface and intramuscular EMG activity measurements and investigate the efficacy of surface EMG measurement for the transversus abdominis (TrA) and the multifidus (MF) muscles. Eight healthy men participated in the study. TrA and MF activities were simultaneously measured by both intramuscular and surface EMG during isometric trunk exercises. Spearman correlation coefficients for the relationship between the two activity measurements for the right TrA, left TrA, right MF, and left MF were 0.55, 0.36, 0.67, and 0.79, respectively. For the TrA, Bland-Altman plots revealed that mean differences between measurements obtained by intramuscular EMG and surface EMG were not close to zero, with a systematic bias toward higher surface EMG values. In conclusion, surface and intramuscular EMG activity measurements were strongly correlated for MF muscles, but poorly correlated for TrA muscles.

STUDY DESIGN Experimental laboratory study
OBJECTIVES To measure trunk muscle activity using wire electrodes during lumbar stabilization exercises and to examine if more effective exercises to activate the deep trunk muscles (local muscles) exist
OBJECTIVES To measure trunk muscle activity using wire electrodes during lumbar stabilization exercises and to examine if more effective exercises to activate the deep trunk muscles (local muscles) exist
METHODS Nine healthy men with no history of lumbar spine disorders participated in the study Fine wire electrodes were inserted into the transversus abdominis (TrA) and lumbar multifidus bilaterally In addition surface electrodes were attached to the rectus abdominis external obliques and erector spinae bilaterally Electromyographic signal amplitude was measured during the following exercises elbow toe hand knee back bridge side bridge and curl up Two way analyses of variance were used to compare muscle activity level among exercises and between sides for each muscle
RESULTS The exercise showing the greatest activity level for the TrA was elbow toe exercise with contralateral arm and leg lift In addition for the TrA a significant side to side difference in activation level was demonstrated for 7 of the 11 exercises that were performed The activity level of the multifidus was greatest during the back bridge exercises The curl up exercise generated the highest activity level for the rectus abdominis and the back bridge with single leg lift exercises generating the highest erector spinae activity
CONCLUSIONS The exercises investigated in this study resulted in a wide range of effort level for all 5 muscles monitored Many of the exercises also resulted in an asymmetrical (right versus left side) activation level for a muscle including the TrA J Orthop Sports Phys Ther 2010 40(11) 743 750 doi 10.2519/jospt.2010.3192

本研究では慢性腰痛患者を対象とし、体幹の深部筋に注目した運動療法を指導し、自主トレーニングを行わせ、それによる腰痛およびQOLの変化について明確にすることを目的とした。さらに、慢性腰痛患者を年代によって群分けし、運動療法の効果に差があるか、検討した。対象者は16名(男性3名、女性13名)で、運動療法の介入期間は1ヵ月とした。介入前と介入1ヵ月後を比較した結果、VASは有意に減少した。JOABPEQについては、腰椎機能障害・歩行機能障害・社会生活障害・心理的障害の項目において有意な変化があった。疼痛関連障害の項目においては有意な変化は認められなかったが、改善の傾向がみられた。また慢性腰痛患者を壮年群および中高年群に群分けし、運動療法の効果の有無について検討した結果、有意差はみられなかった。慢性腰痛患者において、体幹の深部筋に注目した運動療法の有効性が示唆された。(著者抄録)

STUDY DESIGN: Controlled laboratory study.
OBJECTIVES: To clarify whether differences in surface stability influence trunk muscle activity.
BACKGROUND: Lumbar stabilization exercises on unstable surfaces are performed widely. One perceived advantage in performing stabilization exercises on unstable surfaces is the potential for increased muscular demand. However, there is little evidence in the literature to help establish whether this assumption is correct.
METHODS: Nine healthy male subjects performed lumbar stabilization exercises. Pairs of intramuscular fine-wire or surface electrodes were used to record the electromyographic signal amplitude of the rectus abdominis, the external obliques, the transversus abdominis, the erector spinae, and lumbar multifidus. Five exercises were performed on the floor and on an unstable surface: elbow-toe, hand-knee, curl-up, side bridge, and back bridge. The EMG data were normalized as the percentage of the maximum voluntary contraction, and data between doing each exercise on the stable versus unstable surface were compared using a Wilcoxon signed-rank test.
RESULTS: With the elbow-toe exercise, the activity level for all muscles was enhanced when performed on the unstable surface. When performing the hand-knee and side bridge exercises, activity level of the more global muscles was enhanced when performed on an unstable surface. Performing the curl-up exercise on an unstable surface, increased the activity of the external obliques but reduced transversus abdominis activation.
CONCLUSION: This study indicates that lumbar stabilization exercises on an unstable surface enhanced the activities of trunk muscles, except for the back bridge exercise. J Orthop Sports Phys Ther 2010;40(6):369-375. doi:10.2519/jospt.2010.3211

STUDY DESIGN: Controlled laboratory study.
OBJECTIVES: To clarify whether differences in surface stability influence trunk muscle activity.
BACKGROUND: Lumbar stabilization exercises on unstable surfaces are performed widely. One perceived advantage in performing stabilization exercises on unstable surfaces is the potential for increased muscular demand. However, there is little evidence in the literature to help establish whether this assumption is correct.
METHODS: Nine healthy male subjects performed lumbar stabilization exercises. Pairs of intramuscular fine-wire or surface electrodes were used to record the electromyographic signal amplitude of the rectus abdominis, the external obliques, the transversus abdominis, the erector spinae, and lumbar multifidus. Five exercises were performed on the floor and on an unstable surface: elbow-toe, hand-knee, curl-up, side bridge, and back bridge. The EMG data were normalized as the percentage of the maximum voluntary contraction, and data between doing each exercise on the stable versus unstable surface were compared using a Wilcoxon signed-rank test.
RESULTS: With the elbow-toe exercise, the activity level for all muscles was enhanced when performed on the unstable surface. When performing the hand-knee and side bridge exercises, activity level of the more global muscles was enhanced when performed on an unstable surface. Performing the curl-up exercise on an unstable surface, increased the activity of the external obliques but reduced transversus abdominis activation.
CONCLUSION: This study indicates that lumbar stabilization exercises on an unstable surface enhanced the activities of trunk muscles, except for the back bridge exercise. J Orthop Sports Phys Ther 2010;40(6):369-375. doi:10.2519/jospt.2010.3211

Background: Low back pain is a significant problem not only for the adult, but also during youth. However, the relationship between low back pain during youth and the duration or types of competitive sports has not been clarified.
Hypothesis: Low back pain during youth is associated with the duration and types of competitive sports.
Study Design: Cross-sectional study; Level of evidence, 4.
Methods: Study participants were 4667 new university students who, from 2004 to 2006, answered a questionnaire concerning low back pain and their participation in competitive sports. The participants were divided into a "no&apos;&apos; group (NO), a middle group (MID), and a high group (HI) based on the duration of participation in competitive sports. The answers to the questionnaire were analyzed using the Cochran-Mantel-Haenszel test. Furthermore, we selected students who had participated in the same sport for 5 or more years and categorized the students according to the type of sport. Differences in low back pain among the groups were analyzed using logistic regression with the NO group as the reference group.
Results: There were statistically significant linear associations in the NO, MID, and HI groups, with 50.0%, 61.8%, and 71.7%, respectively, of the students experiencing low back pain. Among the NO, MID, and HI groups, 4.4%, 5.7%, 9.6%, respectively, had experienced school absence due to low back pain; and 4.0%, 8.5%, and 14.6%, respectively had low back pain with associated lower extremity pain and numbness. All 8 sports groups that were analyzed had experienced low back pain significantly higher than the NO group, and the odds ratios differed by sport with the highest (3.8) for the volleyball group.
Conclusion: Excessive exposure to competitive sports activities during youth was associated with low back pain and symptoms in the lower extremities, with the severity varying with the sport. To reduce low back pain in youth, factors that may be causing low back pain, such as sport-specific postures and motions, need to be investigated.

Background: Low back pain is a significant problem not only for the adult, but also during youth. However, the relationship between low back pain during youth and the duration or types of competitive sports has not been clarified.
Hypothesis: Low back pain during youth is associated with the duration and types of competitive sports.
Study Design: Cross-sectional study; Level of evidence, 4.
Methods: Study participants were 4667 new university students who, from 2004 to 2006, answered a questionnaire concerning low back pain and their participation in competitive sports. The participants were divided into a "no&apos;&apos; group (NO), a middle group (MID), and a high group (HI) based on the duration of participation in competitive sports. The answers to the questionnaire were analyzed using the Cochran-Mantel-Haenszel test. Furthermore, we selected students who had participated in the same sport for 5 or more years and categorized the students according to the type of sport. Differences in low back pain among the groups were analyzed using logistic regression with the NO group as the reference group.
Results: There were statistically significant linear associations in the NO, MID, and HI groups, with 50.0%, 61.8%, and 71.7%, respectively, of the students experiencing low back pain. Among the NO, MID, and HI groups, 4.4%, 5.7%, 9.6%, respectively, had experienced school absence due to low back pain; and 4.0%, 8.5%, and 14.6%, respectively had low back pain with associated lower extremity pain and numbness. All 8 sports groups that were analyzed had experienced low back pain significantly higher than the NO group, and the odds ratios differed by sport with the highest (3.8) for the volleyball group.
Conclusion: Excessive exposure to competitive sports activities during youth was associated with low back pain and symptoms in the lower extremities, with the severity varying with the sport. To reduce low back pain in youth, factors that may be causing low back pain, such as sport-specific postures and motions, need to be investigated.

The purpose of this study was to have verified a muscle that began to contract fastest in the punch of boxing. The Fifteen university-age males with no history of chronic low back pain participated in the study. Participants were ranked as BOX (n=8) or CON (n=7). Subjects performed a straight punch with the rear arm (dominant arm). Electromyographic activity of deltoid muscle, rectus femoris muscle, rectus abdominis muscle, external oblique muscle, internal oblique muscle-transversus abdominis muscle; IO-TrA, multifidus muscle were measured. As a result, the IO-TrA was invariably the first contractive muscle in BOX and CON, supporting the hypothesized role of this muscle in spinal stiffness generation.

【目的】<BR> 飛込競技は高さ10mの固定台、3m・1mの飛板から跳び上がり、入水までの空間で宙返りや捻り技を行う競技である。入水時の衝撃はおおよそ400kgfと大きく、身体に様々な痛みを抱えながら競技を行っている選手は多い。今まで我々が行ってきた調査により、特に腰痛有訴者が多い事が分かってきた。飛込選手の腰痛には、入水時に身体へかかる大きな負荷が関わっていると考えられ、身体的要因および技術特性の関連が推察される。しかし、飛込選手の腰痛と関連する要因を、身体的要因、技術特性を含めて調査した研究はない。<BR>本研究の目的は、飛込競技女子全日本ジュニア選手の腰痛と関連する要因を身体的要因、技術特性も含め検討することとする。<BR><BR>【方法】<BR> 2003～2008年に全日本ジュニア合宿に参加した女子飛込選手26名を対象に、自覚的慢性腰痛の有無を問診にて調査した。<BR>腰痛に関連する因子として形態、体力・身体特性、技術特性の3つの項目を測定した（複数年参加している選手は、初年度の測定値）。形態項目には身長、体重、BMI、体力・身体特性項目には長座体前屈、上体そらし、立幅跳、垂直跳、30秒上体起こし、肩回旋幅（両手で棒を持ち体の前から後に回した時の両手の最少距離）、背筋力が含まれた。技術特性項目は競技歴（年）、倒立技術（保持時間、姿勢）、踏切技術（陸上での前、後、前逆、後踏切前宙返りの優劣を各10点満点で評価）、入水技術（1群：前跳、2群：後跳、3群：前逆跳、4群：後踏切前跳時の優劣を各30点満点で評価）を含んだ。技術の評価は日本水泳連盟公認審判3人が行い、得点の平均値を点数とした。<BR>腰痛に関連する要因の抽出には、ロジスティック回帰分析変数増加法（尤度比）を用いた。また、腰痛の有無により腰痛群、非腰痛群に分け、形態、体力・身体特性、技術特性の各項目に対する群間比較をMann-Whitney検定にて行った。いずれも有意水準は5％とした。<BR><BR>【説明と同意】<BR> 口頭及び文章にて、研究の概要、方法、被験者の自由意志による同意であること、同意を示された場合でも理由を問われることなく実験への同意を撤回することができること、個人の人権を擁護することを被験者及びコーチに説明を行った。その後、研究の主旨に同意を得られた選手に対し、測定を行った。<BR><BR>【結果】<BR> 対象26名中、自覚的慢性腰痛を訴えている選手は11名（42.3％）であった。ロジスティック回帰分析より、腰痛は入水技術4群：後前跳び（P＝0.044、オッズ比：3.632）との間に有意な関連を認め、年齢（P＝0.053、オッズ比：5.970）、身長（P＝0.087、オッズ比：1.607）との間にその傾向を認めた。また、腰痛群［身長（cm）：157.3±4.2、体重（kg）：50.7±4.2、BMI：20.5±1.1、競技歴（年）：7.1±2.6］、非腰痛群［身長（cm）：153.0±6.0、体重（kg）：43.8±6.8、BMI：18.6±2.2、競技歴（年）：6.0±2.3］の比較では以下の項目に有意差を認めた。年齢（歳）：腰痛群：16.0±1.0、非腰痛群：14.0±1.7（以下同順）、体重（kg）：50.7±4.2、43.8±6.9。他の項目に有意差は認められなかった。<BR><BR>【考察】<BR> 今回のロジスティック回帰分析の結果では、入水技術4群（後に跳び前方回転）のみ腰痛に関連していることが示唆された。この事から、飛込競技では身体的要因よりも技術特性が腰痛に関わっている可能性が考えられる。入水技術4群とは、台や飛板から後に跳び、前方に回転し最後は手から入水する種目で、入水時には腰椎は屈曲位になっている事が多い。腰椎屈曲肢位では椎間板の髄核が後方に移動し、椎間板由来の前屈型腰痛が生じやすいと報告されている。よって今後は、空中動作における体幹筋群の活動や動作解析とともに椎間板変性などの腰椎器質的変化を調査する必要があると考える。<BR>また、腰痛群、非腰痛群の比較では、年齢及び体重に有意差が認められた。腰痛群の年齢の平均が16.0±1.0歳、非腰痛群は14.0±1.7歳であり、ロジスティック解析でも腰痛との関連性に傾向が認められた事から、年齢が高くなるほど腰痛を有している可能性が高いと考える。<BR>また、腰痛群は非腰痛群と比較し体重が重かった。運動エネルギーの法則から考えると、体重が重い群は、軽い群と比較し入水時の衝撃が大きく、腰部への負荷は強いと思われる。この事が、腰痛に関連していると推測する。<BR><BR><BR>【理学療法学研究としての意義】<BR> 今回の結果では、飛込選手の腰痛には、4群という入水技術が影響している事が示唆された。この事から、スポーツ選手に理学療法を展開する場合、身体的要因の評価のみならず、選手の行っている技術特性にも着目する必要性が確認された。

【目的】腰部固有受容感覚は体幹運動をコントロールするために重要な機能である．その腰部固有受容感覚は慢性腰痛により低下すると報告されている一方，腰痛患者と健常者で差がないと報告している研究もあり，見解が分かれている．また，大学生アスリートの腰部固有受容感覚機能を調査した報告は少ない．そこで本研究では，大学サッカー選手の腰部固有受容感覚機能を測定し，腰痛経験との関係を検討することを目的とした．<BR><BR>【方法】対象はT大学に所属する男子大学サッカー選手で，腰痛経験のない健常群14名（年齢：20.6±1.1歳，身長：175.0±4.0cm，体重：65.6±4.2kg，競技歴：12.6±2.5年）と今までに腰痛経験を有する腰痛群14名（年齢：20.7±1.1歳，身長：172.3±4.7cm，体重：65.3±4.9kg，競技歴：12.9±2.1年）とした．腰部固有受容感覚は，磁気式三次元位置センサーを用いたrepositioning testにより評価した．センサーを第12胸椎（T），第3腰椎（L），第1仙椎（S）棘突起高位の体表に貼付し，試技中にセンサーが動かないよう固定した．試技は，閉眼座位にて課題角度まで体幹を傾斜させ，10秒間静止してその課題角度（D）を記憶させた．その後，最大前後屈動作を5回行わせ，記憶した課題角度に戻した際の角度（D'）を測定し，D'とDの差をrepositioning error（RE）とした．課題角度はTのセンサーが前屈40゜，後屈15゜，右側屈20゜，左側屈20゜となった角度とし，それぞれ3回ずつ，順番をランダムに施行した． 各課題角度において，T，L，SそれぞれのREの3回の平均値を算出し，健常群と腰痛群のREをWilcoxonの符号付順位検定により比較した．尚，有意水準は5%とした．<BR><BR>【説明と同意】口頭及び文書にて，実験の概要，方法，研究による危険性とその対処法，被験者の自由意志による同意であること，同意を示された方でもいかなる場合においても理由を問われることなく実験への同意を撤回することができること，個人の人権を擁護することを説明し，同意書に署名後，実験を行った．<BR><BR>【結果】年齢，身長，体重，競技歴に両群で有意差は認められなかった．T，L，Sの順に，健常群の屈曲REは5.8±4.0゜，4.7±2.5゜，3.7±1.2゜，腰痛群の屈曲REは3.9±2.5゜，3.5±1.4゜，2.5±1.4゜で，SのREが腰痛群で有意に低い値を示した．健常群の伸展REは5.6±2.3゜，3.8±1.9゜，3.4±2.6゜，腰痛群の伸展REは3.7±2.0゜，3.6±2.0゜，4.4±2.5゜で，TのREが腰痛群で有意に低い値を示した．健常群の右側屈REは2.3±1.1゜，2.0±0.8゜，1.7±0.7゜，腰痛群の右側屈REは2.1±1.4゜，1.9±1.0゜，1.6±0.7゜で，全ての高位に群間で有意差はみられなかった．健常群の左側屈REは3.1±1.9゜，3.2±2.0゜，2.5±1.3゜，腰痛群の左側屈REは2.2±0.7゜，2.3±1.2゜，2.7±1.3゜で，全ての高位に群間で有意差はみられなかった（値は全てmean±SD）．<BR><BR>【考察】本研究での健常群の屈曲REは3.7゜～5.8゜，伸展REは3.4゜～5.6゜，側屈REは1.7゜～3.2であり，一般健常人を測定した先行研究と類似の値を示した．しかし，今回は非アスリートの測定を行っていないため，今後は同年代の非アスリートのREを測定し，大学サッカー選手の腰部固有受容感覚機能の特性を明らかにする必要があると考える．また，本研究の結果から，腰痛群におけるSの屈曲REやTの伸展REが健常群に比べ有意に低い値を示した．Newcomerらは腰痛経験者のREは健常者よりも有意に低いという本研究と同様の結果を報告している．痛み刺激は椎間関節に存在するメカノレセプターの数や感度を増加させると報告されており，本研究でも同様の機序が作用し，腰痛群の腰部固有受容感覚機能を向上させた可能性が考えられる．腰部固有受容感覚の低下をもたらすのは腰椎の分節的不安定性を有する腰痛患者に限定されるとの報告もあるため，今後は腰痛を病態別に分類した上で腰部固有受容感覚機能を検証する必要があると考える．<BR><BR>【理学療法学研究としての意義】本研究により，大学サッカー選手の腰部固有受容感覚機能が明らかになり，腰痛群の固有受容感覚機能は健常群よりも鋭敏であることが示唆された．本結果は，アスリートの腰痛経験が腰部固有受容感覚に影響を及ぼしている一知見となると考える．

【目的】<BR>腰痛患者に対する運動療法の有効性について、多くの報告がされている。しかし、その効果の検討は運動機能にとどまっており、生活の質(Quality of Life:以下QOL)ついての報告は少ない。そこで本研究では、腰痛患者に運動療法を施行し、それによる疼痛の程度およびQOLの変化について明確にすることを目的とした。<BR>【方法】<BR>対象者は、公立昭和病院整形外科外来を受診し、運動療法の適応があると医師によって判断された腰痛患者16名(男性3名、女性13名、年齢50.6±14.7歳、身長158.9±8.7cm、体重58.0±10.6kg)で、いずれも日常では杖または独歩で生活している者とした。病態は椎間板性腰痛3名、椎間関節性腰痛3名、筋・筋膜性腰痛1名、既記のいずれの病態にも分類されない非特異性腰痛9名であった。除外基準は、明らかな腰椎由来の下肢の麻痺症状がある者、脊椎炎、脊髄腫瘍、その他内臓器の疾患が原因とされる腰痛患者、腰部以外の部位に重篤な障害を有する者とした。<BR>運動療法は、臍の引き込み運動および四つ這い位での四肢の挙上運動とした。いずれも被験者に合わせて段階的に難易度を上げた。初回に運動療法を指導し、自宅にて毎日継続するよう指導した。介入期間は1ヶ月間とした。<BR>腰部および下肢の疼痛の程度の評価には、視覚的アナログ尺度(Visual Analogue Scale:以下VAS)を用いた。VASは、評価日以前の1週間以内で最も強かった疼痛を想起させ、回答させた。<BR>QOLの評価には、日本整形外科学会が作成した腰痛評価質問票(JOA Back Pain Evaluation Questionnaire:以下JOABPEQ)を用いた。JOABPEQは、疼痛関連障害、腰痛機能障害、歩行機能障害、社会生活障害、心理的障害の5項目で構成されている。25問の質問について評価日以前の1週間以内の状態を回答させ、定められた計算式に基づいて5項目の重症度スコアを算出する。各項目は100ポイント満点で、値が大きいほど良好であることを示し、介入前より介入後の方が20ポイント以上増加した場合、または介入前に90ポイント未満で介入後に90ポイント以上だった場合のみ改善があったと判定するよう規定されている。<BR>介入前および介入1ヶ月後に同様の評価を実施した。介入前後におけるVASおよびJOABPEQの変化については、Wilcoxon符号付順位和検定を用いて解析した。いずれも有意水準は5％とした。<BR>【説明と同意】<BR>対象者には、本研究の趣旨について口頭および文書にて十分な説明をし、文書にて同意を得た。<BR>【結果】<BR>介入前のJOABPEQの中央値(最小値-最大値)は、疼痛関連障害の項目が71.0ポイント(0-100)、腰痛機能障害の項目が58.0ポイント(17-100)、歩行機能障害の項目が86.0ポイント(0-100)、社会生活障害の項目が62.0ポイント(3-100)、心理的障害の項目が52.5ポイント(39-89)であった。VASの中央値(最小値-最大値)は5.4cm(1-10)であった。<BR>介入後のJOABPEQの中央値(最小値-最大値)は、疼痛関連障害の項目が93.0ポイント(43-100)、腰痛機能障害の項目が100ポイント(58-100)、歩行機能障害の項目が100ポイント(29-100)、社会生活障害の項目が82.0ポイント(38-100)、心理的障害の項目が66.0ポイント(42-89)であった。VASの中央値(最小値-最大値)は3.9cm(0-10)であった。<BR>介入前後の比較では、VASについては有意差がみられた(p<0.05)。JOABPEQについては、いずれの項目においても改善の傾向がみられ、腰痛機能障害・歩行機能障害・社会生活障害・心理的障害の項目においては有意に改善していた(p<0.05)。<BR>【考察】<BR>本研究では、腰痛患者に対して1ヶ月間の運動療法を施行し、それによる疼痛およびQOLの変化を検討した。その結果、VAS、JOABPEQの腰痛機能障害・歩行機能障害・社会生活障害・心理的障害の項目においては有意に改善していた。疼痛関連障害の項目においては有意な改善はなかったが、いずれの項目においても改善の傾向がみられた。以上のことから、腰痛患者に対する運動療法の効果として、疼痛の改善だけでなく、QOLの向上にも関与することが示された。<BR>【理学療法学研究としての意義】<BR>本研究では、腰痛患者に対して理学療法士が評価および指導し、1ヶ月間の運動療法を実施した結果、疼痛の改善だけでなく、QOLの向上がみられた。腰痛患者に対する運動療法の有効性を示す結果となったといえる。<BR> 尚、本研究は（財）日本スポーツ治療医学研究会の平成20年度研究助成金を受けた。<BR>

【目的】<BR>外乱刺激により体幹が不意に不安定になる場合、多裂筋や脊柱起立筋は同時に活動させるが、予測される場合では、多裂筋と脊柱起立筋は異なった活動をするといわれている。しかし、物体挙上動作時に質量予測の有無が体幹筋全体に対してどのような影響を与えているかの報告は見当たらない。本研究では予測よりも重い重量物を挙上したときの体幹筋の筋活動にどのような影響を与えるのかを分析し比較検討した。<BR><BR>【方法】<BR>被検者は特記する既往および腰痛の訴えがなく、本研究への同意を示した成人男性11名を被検者とした。動作課題は、テーブル上に提示された物体を、光刺激を合図に右上肢で挙上するよう指示した。挙上動作は物体を10回挙上させ重さを認識させた場合の1.0kg（予測1.0kg）、4.0kg（予測4.0kg）、重さ1.0kgと認識させたあとに、分からないようにすり替え4.0kgを挙上させた場合（予測外4.0kg）の計3種類でおこなった。被検筋はワイヤ電極にて腹横筋、多裂筋、表面電極にて腹直筋、外腹斜筋、脊柱起立筋の左右5筋、計10筋とした。物体が床から離れた時点を0msecと定め、‐200から+200msecを解析区間とし，区間内を100msecごとに4相に分けた。記録されたデータはモーションアーチファクトを除去し整流化後にRoot Mean Squareにより平滑化し、各相の筋活動量の平均値を算出した。次に、その値を予測4.0kgにおける解析区間内の最大活動量の値で除すことで正規化し％筋活動量とした。％筋活動量を用い各相および各条件間での比較検討をおこなった。統計処理は一元配置の分散分析をおこない、有意差があったものに対してTukeyによる多重比較検定をおこなった。<BR><BR>【説明と同意】<BR>被検者には研究内容を理解してもらった上で同意を得、整形外科医立会いのもと実施した。なお、本研究は早稲田大学スポーツ科学学術院、人を対象とする研究等倫理委員会の承認を得て実施した。<BR><BR>【結果】<BR>・条件ごとの各相による筋比較<BR>予測1.0kgでは左右多裂筋が1相（-200～-100msec）より2相（-100～0msec）で有意に高くなっていた（p＜0.01）。3相（0～100msec）、4相（100～200msec）では2相に対し有意に低くなっていた（p＜0.01）。その他の筋には有意差が認められなかった。予測外4.0kgでは右多裂筋が1相より2相で有意に高くなっていた（p＜0.05）。また、左多裂筋が1相や3相に対し4相で有意に高くなっていた（p＜0.05）。その他の筋には有意差が認められなかった。予測4.0kgでは右脊柱起立筋、右多裂筋が1相より2相、3相、4相で有意に高くなっていた（p＜0.01）。また、左脊柱起立筋、左多裂筋が1相より2相、3相で有意に高くなっていた(p＜0.05）。その他の筋には有意差が認められなかった。<BR>・相ごとの条件による筋比較<BR>1相および2相ではすべての筋において有意差が認められなかった。3相では左右脊柱起立筋が予測1kg、予測外4kgに対し予測4kgで有意に高くなっていた（p＜0.05）。また、左右多裂筋も同様に予測4kgで有意に高くなっていた（p＜0.01）。その他の筋には有意差が認められなかった。4相では左右多裂筋が予測1kgに対し予測外4kgで有意に高くなっていた（p＜0.05）。その他の筋には有意差が認められなかった。<BR><BR>【考察】<BR>予測1kgの挙上動作において、左右多裂筋は挙上直前から筋活動を高めていた。挙上直後（0～100msec）には筋活動が低下し挙上前と有意差は認められなくなった。予測4kgでは左右脊柱起立筋は左右多裂筋と同時に挙上直前（-100～0msec）から筋活動を高め、挙上後（100～200msec）も高めた筋活動を維持していた。予測外4kgでは、右多裂筋が挙上直前から筋活動を高めていた。左多裂筋は挙上後に遅れて筋活動を高めていた。予測1kg、予測外4kgと予測4kgを比較すると、予測4kgでは脊柱起立筋と多裂筋が挙上直後に筋活動を有意に高めていた。挙上後では予測外4kgが予測1kgに対し、左右多裂筋の筋活動を有意に高めていた。今回の結果より、1kgの質量と誤認して4kgの質量を挙上する場合には、挙上（-200～100msec）まで1kgと同様の体幹筋の筋活動をおこない、挙上後（100～200msec）に両側多裂筋の筋活動が高くなっていた。つまり、予測よりも重い物体を挙上した場合には、挙上直前や直後に負荷に適応した体幹筋の筋活動がおこなえていないため、腰部・体幹の安定性に何らかの影響を与えている可能性が示唆された。<BR><BR>【理学療法学研究としての意義】<BR>物体を挙上する際、質量を誤認して発症する急性腰痛の一要因を解明し、不意の動作においても腰椎の安定性を高めておくことができる、腰痛予防のためのリハビリテーションへと応用していく。

【目的】骨盤傾斜角度は脊柱アライメントに影響を与え、骨盤前傾位では腰椎前彎角は増加し、骨盤後傾位では逆に減少する。腰椎の過剰な前彎は腰痛の原因の一つと考えられ、腰痛のリハビリテーションとして腰椎前彎角を減ずることを目的に下肢のストレッチや骨盤後傾運動が行われている。骨盤前後傾運動においては，体幹の表層に位置するグローバル筋だけでなく，深層に位置するローカル筋の関与が最近の研究によって明らかにされてきているが，まだ詳細については不明な点が多い。また臨床において骨盤前後傾運動を実施する際，その運動範囲や運動様式には個人差が見られ，その評価は評価者の技術・経験などに影響される主観的なものであるため、より客観的に評価するための指標が望まれる。その指標の一つとして，骨盤前後傾可動域は比較的簡便かつ定量化が可能であり，有用だと考える。しかし，これまでに骨盤前後傾運動時の筋活動と可動域との関係を報告した研究は見当たらない。そこで本研究の目的は骨盤自動前後傾運動時の骨盤周囲筋の筋活動を明らかにし，さらに矢状面での骨盤前後傾可動域と筋活動との関係性を明らかにすることとした。<BR>【方法】健常成人男性12名（22.6±1.4歳，169.9±5.7cm，69.6±7.6kg）を対象とし，動作課題は立位骨盤中間位から最大前傾位までの骨盤前傾運動，次いで最大後傾位までの骨盤後傾運動を指示し，各運動中の筋電図を計測した。筋電図測定には，両側の腹直筋（RA）、外腹斜筋（EO）、脊柱起立筋（ES）および片側（右側）の広背筋（LD）、大殿筋（GMA）、半腱様筋（ST）、大腿直筋（RF）に表面電極（Vitrode F-150S; 日本光電）を貼布し，両側の腹横筋（TrA）、多裂筋（MF）にはワイヤ電極（UNIQUE MEDICAL社）を超音波ガイド下に23G注射針をガイドとして整形外科医によって挿入した。その後，電極が適切に刺入されていることを確認するために，電気刺激を加えて目的筋の収縮を超音波で描出した。ワイヤ電極刺入に関しては筑波大学倫理委員会の承認を得て実施した。サンプリング周波数は2000Hz，バンドパスフィルターは20-500Hzとした。等尺性最大随意収縮（MVC）時の筋活動で標準化した%MVCを算出し，さらに立位姿勢を保持するために要する筋活動の影響を取り除くため，骨盤前後傾運動時と安静立位保持時の%MVCの差で各筋を比較した。また骨盤前後傾可動域測定には，被験者の上前腸骨棘（ASIS）と上後腸骨棘（PSIS）にマーカーを貼付し，デジタルカメラを用いて矢状面における骨盤前傾位・中間位・後傾位の静止画を撮影した。その後，画像解析ソフトimage-J（NIH）を用いてASISとPSISを結んだ線が水平となす角度（骨盤傾斜角度）から骨盤前後傾可動域を算出した。さらに骨盤前後傾運動でそれぞれ大きい活動を示した筋を抽出し，筋活動と骨盤前後傾可動域との関係性について検討した。分析には骨盤前後傾運動時の各筋の筋活動の比較にTukey HSD法による多重比較検定を用い，骨盤前後傾可動域と筋活動との関係にはPearsonの積率相関係数を算出した。有意水準は5%未満とした。<BR>【説明と同意】被験者には事前に研究について書面と口頭による説明の後，同意を得て研究を実施した。<BR>【結果】骨盤前傾運動時には骨盤中間位に比較して，両側のMFが23.9%，右ESは19.0%，左ESは13.6%と有意に増加した。また骨盤後傾運動時は左TrAのみ14.7%と有意に増加した。また，特に大きい活動を示した両側MF（前傾）、左TrA（後傾）と骨盤前後傾可動域との相関係数はそれぞれ，0.68（右MF），0.62（左MF），0.53（TrA）であり，骨盤前傾可動域と両側MFでは有意に高い関係を示した。<BR>【考察】骨盤前傾運動では骨盤の上後方に付着するMFやESによって，骨盤の後方が引き上げられ，骨盤の前傾運動が生じると考えられる。一方の骨盤後傾運動では，これまで恥骨に付着するRAが主に作用すると考えられていたが，今回の結果ではRAよりもTrAの筋活動が大きかった。TrAは骨盤前方の腸骨稜や鼠径靭帯にも付着するため，収縮により骨盤の前方が引き上げられ，骨盤後傾運動が生じると考えられる。また，骨盤前傾可動域とMFの間には有意に高い関係が認められたことから，より大きく骨盤を前傾させるには，MFの大きい筋活動が必要とされることが考えられた。骨盤後傾運動では左TrAと後傾可動域に正の相関は認めたものの，ばらつきが大きく個人差や左右差が大きいことも推察された。<BR>【理学療法学研究としての意義】本研究により，骨盤自動前後傾運動時の筋活動が明らかとなり，骨盤の運動を客観的に評価する指標として，骨盤前後傾可動域の有用性が示唆された。

被追突事故において頚椎椎体間の過度な動きにより椎間関節包や椎間板などの軟組織に局所的なひずみが生じ，頚部の痛みを惹起するとの仮説から頚部傷害指標を提案する．椎体間の動きをひずみで定義し，このひずみと相関のあるダミーで計測可能な物理量を頚部傷害の評価指標として選定し頚部傷害発生のリスクカーブを導いた．

[目的]ボクシングによる全身の外傷・障害およびノックアウト(KO)された経験を調査することを目的とした。[方法]大学生以上のアマチュアボクシング選手(シニア)114名と高校生のアマチュアボクシング選手(ジュニア)56名の計170名にアンケート調査を行った。[結果]外傷・障害はコンタクト部位である手部(シニア:42.1%、ジュニア:30.4%、以下同順)、眼部(19.3%、26.8%)、鼻部(36.8%、21.4%)等に多かった。非コンタクト部位では腰部(17.5%、28.6%)に多くみられた。KOされた経験のある選手はシニア、ジュニア間で差はなかった。KO後にシニアは30%、ジュニアは50%に脳振盪に関連する症状がみられていた。[考察]シニア・ジュニアともに腰痛と脳振盪への対策が必要である。(著者抄録)

Objective : The aim of this study was to analyze the three-dimentional Kinematics of the trunk between skilled and novice boxers in the boxing defense (Swaying thechnique). Methods : Eight university boxers (BOX) and seven university students without the boxing experience (CON) were subjects. The angle of thoracolumbar vertebrae was measured by the three-dimensional magnetic position sensor. The trunk angle, the hip joint angle, and the knee joint angle were measured with three-dimensional motion analysis system. Results : As a result of the three-dimensional magnetic position sensor, there was not the difference to thoracolumbar vertebrae extension angle, and the thoracolumbar vertebrae extension angle was about 23 degrees. From three-dimensional motion analysis, CON suited the tendency for the knee joint angle of non dominant leg to be larger than BOX (p＝0.06). Discussion : The possibility that a lumbar extension contributed to the low back pain onset of the boxer was suggested.

Background: Several studies have reported that physical loading related to competitive sports activities is associated with lumbar intervertebral disk degeneration. However, the association between types of sports activities and disk degeneration has not been clarified.
Hypothesis: The frequencies of disk degeneration may vary with the competitive sport because of the different postures and actions specific to each sport.
Study Design: Cross-sectional study (prevalence); Level of evidence, 3.
Methods: Study participants were 308 well-trained university athletes (baseball players, basketball players, kendo competitors, runners, soccer players, swimmers) and 71 nonathlete university students (reference group). Disk degeneration was evaluated using T2-weighted magnetic resonance imaging. A self-reported questionnaire concerning low back pain was also conducted.
Results: The proportions of the participants who had disk degeneration among the baseball players (odds ratio, 3.23) and the swimmers (odds ratio, 2.95) were significantly higher than among the nonathletes using logistic regression analysis. When all patients were grouped together, the association between lifetime experience of low back pain and participants with disk degeneration was significant, and a linear association between the degree of severest low back pain experienced and participants with disk degeneration, analyzed by a Cochran-Mantel-Haenszel test, was also significant.
Conclusion: Continuous competitive baseball and swimming activities during youth may be associated with disk degeneration. Furthermore, the study indicates that the experience of severe low back pain might be a predictor of disk degeneration in youth. The authors hope that preventive measures and management to protect against disk degeneration and low back pain in athletes will be established by further studies based on these results.

【目的】これまで単純X線画像による腰椎の運動学的研究は行われてきたが，連続的に腰椎挙動を評価した研究は少ない．本研究の目的は，X線シネ撮影装置により立位体幹前後屈時の矢状面腰椎挙動を撮影し，各椎間の可動域及び挙動開始の位相差を比較することである．<BR>【方法】側面X線画像にて腰椎に明らかなすべりのない健常男性9名（平均年齢23.2歳，平均身長171.0cm，平均体重65.2kg）を対象とした．立位にて骨盤を固定した状態の下，体幹前後屈を行わせた腰椎挙動をX線シネ撮影装置にて撮影した．前屈及び後屈動作は腰椎の撮影が行える範囲までとし， 撮影速度は15frames/secとした．得られたX線シネ画像をデジタイズ処理によって各椎間（L1/2，L2/3，L3/4，L4/5）及び腰椎全体（L1/5）の矢状面角度を計側し，前屈及び後屈動作においてL1/5可動域に対する各椎間可動域の百分率を椎間別に比較した．さらに，各椎間の動作が開始した時点を求め，各椎間挙動の位相差を検討した．統計処理は一元配置分散分析を用い，有意水準を5%とした．<BR>【結果】全対象者のL1/5可動域は前屈35±10゜（Mean±SD），後屈10±8゜であった．前屈動作における各椎間可動域の百分率はL1/2：23±8％，L2/3：30±9％，L3/4：28±5％，L4/5：19±11％であり，L2/3の可動域がL4/5に比べ大きい傾向を示した（p＝0.06）．一方，後屈動作ではL1/2：27±31％，L2/3：39±46％，L3/4：20±23％，L4/5：17±59％と，被験者毎にばらつきが大きく一定の傾向を示さなかった．各椎間挙動の開始時点の比較では，前屈動作においてL4/5の挙動が他の椎間（L1/2，L2/3，L3/4）に比べ有意に遅かったが，後屈動作では椎間別に有意な位相差を認めなかった．<BR>【考察】本研究の結果より，前屈動作ではL2/3の可動域が大きく，L4/5の挙動が他の上位椎間に比べて遅れることが示された．腰椎の前屈可動域はL4/5において最大と言われているが，Miyasakaらは腰椎全体の前屈可動域が40゜未満の場合，L2/3が最大可動域を示すことを報告しており，本研究でも同様の傾向を認めた．また，椎間挙動の位相差に関して，Kanayamaらは腰椎の前屈動作においてL3/4，L4/5，L5/S1の順に挙動が開始することを報告しており，本研究においても類似の結果が得られた．<BR>【まとめ】立位体幹前後屈時の矢状面腰椎挙動を連続的に計側した結果，可動域が中程度の前屈動作においてL2/3の可動域が大きく，L4/5の挙動が上位椎間に比べ遅れることが示唆された．一方，後屈動作では可動域，位相差ともに椎間別で特異的な傾向を認めなかった．

BACKGROUND CONTEXT: Lumbar intervertebral disc degeneration (DD) precedes degenerative diseases of the lumbar spine. Various factors in addition to normal aging are reported to be associated with DD, and recently atherosclerosis and risk factors for cardiovascular diseases (cardiovascular risk factors) have received much attention; however, the links between these risk factors and DD are unclear.
PURPOSE: By correlating magnetic resonance images (MRI) with suspected degenerative disc risk factors such as obesity, cardiovascular risk factors, and atherosclerosis, we hope to clarify the factors associated with DD.
STUDY DESIGN/SETTING: An observational study.
PATIENT SAMPLE: Two hundred seventy adults (51-86 years old) who participated in a health promotion program.
OUTCOME MEASURES: DD evaluated based on the signal intensity of MR T2-weighted midsagittal images of the lumbar spine.
METHODS: Age, gender, body mass index (BMI), low-density lipoprotein cholesterol (LDLc), triglyceride (TG), glycosylated hemoglobin (HbA(1c)), brachial-ankle pulse wave velocity (baPWV) as an index of atherosclerosis, osteo-sono-assessment index (OSI) calculated from quantitative ultrasound assessment of the calcaneus as an index of bone mineral density (BMD), history of low back pain (LBP), smoking and drinking habits, and physical loading related to occupations and sports were assessed. The univariate relationships between DD and the variables were evaluated, and finally, odds ratios (OR) and 95% confidence intervals (0) for the associations of each factor with DD were calculated using logistic regression at each disc level.
RESULTS: Aging correlated significantly with DD of L1/2 (OR, 2.14), L2/3 (OR, 3.56), L3/4 (OR, 2.84), and L4/5 (OR, 3.05); high BMI, with 1-2/3 (OR, 2.98), L3/4 (OR, 3.58), L4/5 (OR, 2.32), and L5/S1 (OR, 3.34); high LDLc, with L4/5 (OR, 2.65); occupational lifting, with L1/2 (OR, 4.25); and sports activities, with L5/S1 (OR, 3.36).
CONCLUSIONS: Aging, high BMI, high LDLc, occupational lifting, and sports activities are associated with DD. The results of this study raise our index of suspicion that cardiovascular risk factors and particular physical loading may contribute to DD; however additional studies are required to further investigate associations between DD and these factors. (C) 2008 Elsevier Inc. All rights reserved.

経絡テストによる大学ボクシング選手のコンディション評価について検討した。対象は大学ボクシング部に所属する選手20名(平均年齢20.3歳)で、7日間の夏季合宿期間に経絡テストと自覚的コンディション項目(練習状況4項目、身体状況5項目)を評価した。その結果、1)経絡テスト陽性動作数平均値は初日練習開始前1.6であったが、合宿の進行とともに陽性動作数は上昇し、4日目の午前練習後にピーク(24.3)となり、その後は減少し7日目の午前練習後17.4となった。2)自覚的コンディション項目では、練習状況は練習の強度、きつさは練習内容により有意な変化が認められたが、練習への意欲と技術的調子に大きな変化はなかった。3)身体状況は朝の目覚め、体調、食事に有意な変化はなく、起床時の疲労回復は3日目に低下し、けがや痛みの状態は3日目に有意に減少した。4)経絡テストは練習のきつさ、食事と有意な正の相関、起床時の疲労回復度、体調と有意な負の相関を認めた。

Background: The majority of orthopaedic problems experienced by competitive swimmers are related to pain in the shoulder, low back, and knee. Three of 39 national swim team members were hampered in their performance due to lumbar disk herniation at an international competition in 2001. There has been no previous research into lumbar disk degeneration in elite competitive swimmers.
Hypothesis: Excessive competitive swimming activities accelerate lumbar disk degeneration.
Study Design: Case control study; Level of evidence, 3.
Methods: Fifty-six elite swimmers (high-load group, 35 men and 21 women; mean age, 19.6 years) and a control group of 38 university recreational level swimmers (low-load group, 24 men and 14 women; mean age, 21.1 years) were evaluated for lumbar disk degeneration using magnetic resonance imaging. We compared the prevalence of disk degeneration and the disk level between the 2 groups and further investigated the relationship among their symptoms, swimming styles, and disk degeneration.
Results: Thirty-eight (68%) elite swimmers and 11 (29%) controls had degenerated disks at various disk levels, and the prevalence was significantly greater in the elite swimmers (P =.0002). Comparison between the 2 groups of the prevalence of disk degeneration at each level revealed that the disk level of L5-S1 was significantly more frequently degenerated in the high-load group (P =.026). There was no significant relationship observed among the variables of low back pain symptoms, swimming strokes, and disk degeneration.
Conclusion: Excessive competitive swimming activities might exaggerate lumbar intervertebral disk degeneration, especially in the L5-S1 intervertebral segment.

Study Design. Digitized measurements of the intervertebral motions using cervical cineradiographs of 10 volunteers during direct impacts applied to their faces.
Objectives. To clarify the cervical spine motion during direct face impact and postulate some mechanisms of neck injuries.
Summary of Background Data. Neck injury occurs mostly in traffic or falling accidents. Hyperextension of the neck is considered the most common mechanism of the injury because most victims have lacerations or contusions on their faces.
Methods. A low-level backward impact load was applied to 10 healthy male volunteers' faces at the forehead and maxilla via a strap using a free-falling small mass. Cervical vertebral motion was recorded by radiograph cineradiography during the impact.
Results. The upper cervical spine showed a flexion motion for both conditions. Consequently, the cervical spine had an S-shaped curvature similar to that in cervical retraction. Intervertebral motions of the cervical spine were evaluated using an radiograph frame taken at the maximum cervical retraction. For the forehead load, intervertebral motion at C1-C2 was flexion, and motions of the lower cervical spine were extension. For the maxilla load, intervertebral motions from occiput-C1 through C4-C5 were flexion. The inflection point of the curvature was influenced by the impact location.
Conclusion. We detected a flexion motion of the upper or middle cervical spine during direct face impact. In an actual accident, if the cervical spine is forced into similar motion, we speculate that neck injury would occur in this retraction-like curvature of the cervical spine.

Study Design. A case report and review of previous literature are presented.
Objective. The objective of this manuscript was to report a case of cervical myelopathy due to anomalous laminae of the axis in a patient with spina bifida.
Summary of Background Data. In previous studies, few cases of invaginated anomalous laminae of the axis have been reported. Treatment was surgical removal of the invaginated laminae.
Methods. The patient's history, clinical examination, imaging findings, and treatment were reported.
Results. Characteristic findings were revealed from imaging studies, a multiplane reconstruction of the CT images, and a stereolithographic model of the cervical spine. The patient was treated with a posterior decompressive operation. The outcome was satisfactory, with an improvement in the patient's neurology.
Conclusions. This is a report of a rare characteristic anomaly of the laminae of the axis. A multiplane reconstruction of the CT images and a stereolithographic model were useful for treatment of this case. Possible causes of this anomaly may be the failure of ossification or fusion of the embryological term.

STUDY DESIGN: A case report and review of previous literature are presented. OBJECTIVE: The objective of this manuscript was to report a case of cervical myelopathy due to anomalous laminae of the axis in a patient with spina bifida. SUMMARY OF BACKGROUND DATA: In previous studies, few cases of invaginated anomalous laminae of the axis have been reported. Treatment was surgical removal of the invaginated laminae. METHODS: The patient's history, clinical examination, imaging findings, and treatment were reported. RESULTS: Characteristic findings were revealed from imaging studies, a multiplane reconstruction of the CT images, and a stereolithographic model of the cervical spine. The patient was treated with a posterior decompressive operation. The outcome was satisfactory, with an improvement in the patient's neurology. CONCLUSIONS: This is a report of a rare characteristic anomaly of the laminae of the axis. A multiplane reconstruction of the CT images and a stereolithographic model were useful for treatment of this case. Possible causes of this anomaly may be the failure of ossification or fusion of the embryological term.

Background. The mechanism of whiplash injury has not been revealed yet. We analyzed in vivo cervical spine motion during simulated rear-end car collisions to clarify the whiplash injury mechanism. Method. The subjects were ten male volunteers. The ethics committee approved the protocol of this study. The subjects sat on a sled that glided backward on inclined rails and crashed into a damper at 8 km/hr. Cineradiography recorded the cervical spine motion during impact and the motion analysis of each vertebra was performed. Findings. During simulated rear-end impacts, torso motion forced the cervical spine to extend from the lowest vertebrae. This early extension motion of lowest cervical vertebrae caused the cervical spine to flex in the early phase. After this initial flexion motion, extension motion started from the lowest motion segment and gradually moved to the upper segments. Approximately 110 ms after impact, while the upper segments were still in the flexion mode, the lower segments have already been extended, creating an S-shaped curvature of the cervical spine. Interpretation. We observed abnormal cervical spine motions during simulated rear-end impacts and consider that this motion may be related to the whiplash injury mechanism. © 2002 by The Haworth Press, Inc. All rights reserved.

To analyze the effect of the seat characteristics on dummy motions and human volunteer motions, sled tests simulating low-speed rear impacts were conducted with some seats which had different characteristics. Volunteer's cervical vertebral motions were photographed with an X-ray cineradiographic system at a speed of 90 frames/s as well as the visible motions of dummy's and volunteer's were recorded. Although the tests were conducted under limited conditions, the results indicated the relationship between the occupant's visible motions, which are assumed to be closely related to the whiplash injury mechanism, and seat characteristics. It should be noted that the volunteer sled tests were discussed and approved by the Tsukuba University Ethics Committee and the volunteer submitted his informed consent in writing in line with the Helsinki Declaration. (C) 2000 Elsevier Science Ltd. All rights reserved.

The non-physiological motions of human cervical vertebrae were analyzed in volunteer tests for rear-end impacts and were considered to be an important parameter for neck injuries. The objectives of this study are to improve the Marko de Jager neck model using volunteer test data and to analyze the influence of horizontal and vertical accelerations on cervical vertebral motion. In the beginning of this study, a neck model was positioned based on X-ray cineradiography of a volunteer. Motions of each vertebra were compared with those of volunteer test data for low speed rear-end impacts (4, 6, 8km/h). In these comparisons, the differences of vertebrae motions between the neck model and the volunteer tests were found. To improve the validity of the neck model, the connection properties and the bending properties of the upper and lower vertebrae of the model were modified to increase rigidity. Using the modified neck model, simulation analysis was performed by changing horizontal and vertical accelerations to analyze the influence of seat property on vertebrae motion. The forces caused by contact with each adjacent facet of the vertebrae, vertebra angles and vertebra rotation center relative to adjacent vertebra were calculated to evaluate the severity for the vertebrae and to analyze the motions of the vertebrae just before facet contact. It was found that the facet force and the height of rotation center were influenced not only by horizontal acceleration but also by vertical acceleration. Copyright © 2000 Society of Automotive Engineers, Inc.

Few detailed studies of synovial folds of cervical facet joints exist at the moment. This study was performed to provide anatomical data for each synovial fold in the cervical facet joints, using 20 cervical spines from C2 to C7 for dissection. Anatomic evaluation of the synovial folds included the gross morphology, in three dimensions, and the histology. Also, degenerative changes of the lower facet surface on which synovial folds occurred were evaluated. On the basis of gross morphology and histological composition, three types of synovial folds were identified. Type-1 synovial folds, shaped like a crescent, consisted principally of adipose tissue. Type-2 synovial folds had an apical region made up of dense fibrous tissue, with the base and middle region consisting of adipose tissue. In type-2 folds, the size and shape varied, including some elliptic-shaped synovial folds projecting well into the joint cavity. Type-3 synovial folds were thin with ragged free borders, and were formed exclusively of fibrous tissue. This study shows the variable appearance of synovial folds. Speculation was raised that the articular facet impingement of a large synovial fold and the subluxation of a smaller structure may play a possible role in the pathology of some disorders of the neck.

Study Design. The motion of each cervical vertebra during simulated rear-end car collisions was analyzed.
Objectives. To clarify the mechanism of zygapophysial joint injury during whiplash loading,
Summary of Background Data. The zygapophysial joint is the suspected origin of neck pain after rear-end car collision. However, no studies have been conducted on the mechanisms of zygapophysial joint injuries.
Methods. Ten healthy male volunteers participated in this study. Subjects sat on a sled that glided backward on inclined rails and crashed into a damper at 4 km/hr. The motion of the cervical spine was recorded using cineradiography. Each vertebra's rotational angle and the instantaneous axes of rotation of the C5-C6 motion segments were quantified. These measurements implemented the template method.
Results. There were three distinct patterns of cervical spine motion after impact, In the flexion-extension group, C6 rotated backward before the upper vertebrae in the early phase; thus, the cervical spine showed a flexion position (initial flexion), After C6 reached its maximum rotational angle, C5 was induced to extend. As upper motion segments went into flexion, and the lower segments into extension, the cervical spine took an S-shaped position. In this position, the C5-C6 motion segments showed an open-book motion with an upward-shifted instantaneous axis of rotation.
Conclusions. The cervical spine is forced to move from the lower vertebrae during rear-end collisions. This motion completely differs from normal extension motion and is probably related to the injury mechanism.

The present study was performed to evaluate the effects of physical exercise at altitudes on serum vascular endothelial growth factor (VEGF) levels. Eight subjects underwent intensive swimming training for 21 days at 1886 m. After altitude training commenced, red blood cell (RBC) counts and erythropoietin levels increased, but both haemoglobin and haematocrit levels did not change significantly. The serum level of VEGF, measured by means of a highly sensitive chemiluminescence (ELISA), showed a transient decrease 10 days after start of the altitude training, thereafter increasing significantly to reach a peak level 19 days later, rising from 23.0 +/- 5.3 to 46.0 +/- 14.6 pg mL(-1) (P &lt; 0.05 vs. before). On return to low altitude in japan,the level of VEGF decreased, and 1 month later had returned to initial levels. Endurance training at altitudes increases serum VEGF levels, this could be an adaptive reaction to hypoxic conditions. This result suggests that VEGF may provide a new physiological parameter for hypoxic stress imposed by high altitude training.

Twelve volunteers participated in the experiment under the supervision of Tsukuba University Ethics Committee. The subjects sat on a seat mounted on a newly developed sled that simulated actual car impact acceleration. We selected impact speeds (4, 6 and 8 km/h), seat stiffness, neck muscle tension, and alignment of the cervical spine for the parameter study of the head-neck-torso kinematics and cervical spine responses. The effects of those parameters were studies without headrest. The muscle activity was measured with surface electromyography. The cervical vertebrae motion was recorded by cineradiography (90 frames/s X-ray) and analyzed to quantify the rotation and translation of cervical vertebrae at impact. Furthermore, the motion patterns of cervical vertebrae in the crash motion and in the normal motion were compared. Subject's muscles in the relaxed state did not affect the head-neck-torso kinematics upon rear-end impact. The ramping-up motion of the subject's torso was observed due to the inclination of seatback. An axial compression force occurred when this motion was applied to the cervical spine, which in turn developed the initial flexion, with the lower cervical vertebral segments extended and rotated prior to the motions of the upper segments. Those motions were beyond the normal physiological cervical motion, which should be attributed to the facet joint injury mechanism. Furthermore, the more rigid the seat cushion, the greater was the axial compression force applied to the cervical spine. On the other hand, the torso rebounding caused by the softer seat cushion tended to intensify the shearing force applied to the upper vertebrae. It was also deduced that the difference in alignment of the cervical spine affected the impact responses of head and neck markedly. Also the kyphosis of the cervical spine caused the upper travel of rotation center of the lower cervical vertebral segments and its rotational motion resulting in a higher neck injury incidence. Based on the differences in the alignment of the cervical spine between male and female occupants, it is also pointed out that the female neck injury incidence tends to become higher than that of male, as the female cervical spines lake the kyphosis position more often than the male cervical spines. © Copyright 1997 Society of Automotive Engineers, Inc.