Abstract

We determined how the in vivo mobility of the first tarsometatarsal (TMT) joint can be quantified during gait. Twenty-five healthy participants (12 females) with no history of foot disorders were included. Non-invasive ultrasound (US) with a three-dimensional motion analysis (MA) system was used to evaluate the kinematic characteristics of first TMT joint during stance phase of gait. US probe was positioned longitudinally above the first TMT joint and adjusted to its proximal dorsal prominence. Gait analysis was conducted by the MA system starting with the activation of B-mode US video at 80 frames per second and 60-mm depth for simultaneous capture. During stance phase, the first metatarsal was translated dorsally with respect to the medial cuneiform, returning to a neutral level at toe-off in all subjects. During middle stance phase, the medial cuneiform was stable in males but displaced in the plantar direction in females and was the primary contributor to the differences in sagittal mobility observed between groups. Quantitatively measuring sagittal mobility of the first TMT joint could be useful for the early detection of foot abnormalities. The dynamic characteristics of the medial cuneiform during gait in healthy females may be associated with a high prevalence of hallux valgus.

Objective: A previous study focused on tennis players highlighted greater muscle thickness on the non-dominant side related to trunk rotation in serves and strokes. However, the influence of experience duration on this side-to-side asymmetry in trunk muscles remains unexplored. This study aimed to compare trunk muscle thickness and cross-sectional area between dominant and non-dominant sides among tennis players, while also investigating correlations with playing experience.

Methods: Eighteen tennis players with at least one year of experience practicing twice weekly participated in this study. Ultrasound sonography was employed to measure the thickness and cross-sectional area of abdominal muscles (rectus abdominis, external oblique, internal oblique, and transversus abdominis) and dorsal muscles (erector spinae and multifidus) on both sides. The morphology between dominant and non-dominant sides was compared using a paired t-test, and the correlation between asymmetry (calculated as non-dominant / dominant side ratio) and sports experience was assessed using Pearson’s correlation.

Results: Tennis players exhibited significantly greater thickness in the non-dominant abdominal muscles. Notably, only the asymmetry in internal oblique thickness showed a positive correlation with playing experience.

Conclusion: This study demonstrated that among the trunk muscles assessed, only the internal oblique showed a significant positive correlation between asymmetry and playing experience. These findings indicate that playing experience is associated with asymmetric adaptation of the internal oblique, a muscle involved in trunk rotation and stabilization. However, since this was a cross-sectional study, causality cannot be determined. Further longitudinal studies are needed to clarify how long-term tennis play contributes to trunk muscle asymmetry.

Objective: Injuries in volleyball often occur during jump landing. Greater vertical ground reaction force (vGRF) during jump landing is one of the risk factors for ankle sprains and anterior cruciate ligament injuries. While experienced players typically achieve higher spike jump heights, no differences in vGRF have been observed between experience levels. Additionally, vGRF is positively correlated with landing sound. Quieter landing is associated with greater lower limb joint displacement. We compared the landing sound and mechanics during spike jump landing between inexperienced and experienced players.

Methods: Twenty male university students (inexperienced, n＝10; experienced, n＝10) participated in this study. After measuring maximum spike jump height, they performed spike jumps at that height and landed on both feet. Landing sound was measured using a smartphone application (Sonic Tools SVM, Rokki Systems). Knee and ankle joint angles during jump landing were analyzed using software (Tracker 6.2.0, Open Source Physics). Group differences in jump height, landing sound, and joint angles were compared using t-tests, and correlations between landing sound and joint angles were analyzed using Pearson correlation coefficients (p<0.05).

Results: In experienced players, landing sound was significantly negatively correlated with maximum ankle dorsiflexion. For maximum knee flexion and knee angular displacement, negative correlations were observed, although they are not statistical significance.

Conclusion: Our findings suggest that volleyball experience may enhance the ability to absorb impact during spike jump landing. Instructing players to increase ankle dorsiflexion during spike jump landing may help reduce landing sound.

Objective: Anterior cruciate ligament (ACL) injuries often occur when the knee is in a slightly flexed and valgus position. The larger vertical ground reaction force（vGRF） also increases the risk of ACL injuries. ACL injuries are common in basketball players, especially during landing. Rebound-jumps in games often involve body rotation in mid-air. A previous study reported during rebound-jump landings with body rotation toward the takeoff leg (TL), the non-takeoff leg (NTL) showed smaller knee flexion and greater valgus angles than the TL. However, direction of rotation was limited in previous study, but multidirectional body rotation may occur. Therefore, this study aimed to investigate differences in knee joint angles and vGRF during rebound-jump landings under different rotational conditions.

Methods: Eleven female basketball players participated in this study. Three-dimensional motion analysis was used to calculate knee joint angles. Participants performed the rebound-jump landing under 3 conditions: (1) front-facing, (2) body rotation at 90° toward the TL (TL-side), and (3) body rotation at 90° toward the NTL (NTL-side). Measurements were taken every 10 ms from initial contact (IC) up to 40 ms.

Results: In the TL-side condition, the NTL demonstrated significantly smaller knee flexion angles and larger vGRF than the TL. In the NTL-side condition, the TL exhibited significantly greater knee valgus angles and larger vGRF than the NTL.

Conclusion: Knee joint angles during rebound-jump landings vary with body rotation direction. These directional differences may be involved in injury risk.

Objective Youth soccer players are in a period of rapid physical growth, raising concerns that the synergistic effect of rapid physical growth and high training intensity may increase the risk of injury. It has been shown that navicular drop (ND) is associated with injuries in various athletes, but there are no studies that have examined the association between ND and a history of injury in youth soccer players. This study aimed to examine the association between a history of injury and ND in male youth soccer players. The study's results offer new injury prevention strategies for male youth soccer players. Methods This is a cross-sectional study. The study included 63 male youth soccer players (16 ± 1 years). Participants self-reported their injury history. ND was determined by measuring the navicular bone height with a caliper and calculating the difference between sitting and standing positions. Statistical analysis was conducted using binary logistic regression, with injury history (reference number) as the dependent variable and ND as the independent variable. Results The no-injury group included 34 participants (age: 16 ± 1 years), while the injury group included 29 participants (age: 16 ± 1 years). Comparison of measurement items showed that the ND was significantly lower in the no-injury group than in the injury group (p = 0.006, effect size (ES) = -0.74), with no significant differences in the other variables. The analysis revealed a significant association between injury history and ND (odds ratio (OR): 13.8 (1.8-103.6), p = 0.011). This finding was also observed in Model 2, which was adjusted for propensity scores (PS) (OR: 16.7 (1.8-158.4), p = 0.014). Conclusions It was found that a greater ND in male youth soccer players was associated with higher odds of injury history. To prevent injury, evaluating ND and implementing interventions to maintain and improve it was recommended.

OBJECTIVES: Dynamic knee valgus (DKV), characterized by knee abduction and external rotation, has been associated with anterior cruciate ligament (ACL) injury, but the predictive accuracy of DKV for ACL injury remains unclear. METHODS: This controlled laboratory study examined fatigue effects on lower limb biomechanics and electromyography (EMG) during jump landing in healthy men. Participants were categorized into induced (n=11) and non-induced (n=8) DKV groups based on changes in knee abduction moment after a fatigue task. RESULTS: Compared to the non-induced DKV group, the induced group exhibited a significantly reduced hip flexion angle (p=0.030), lower vertical ground reaction force (p=0.040), and decreased quadriceps peak EMG amplitude (p=0.008), along with a significant increase in hip internal rotation moment (p=0.001). Receiver operating characteristic analysis revealed that hip internal rotation moment had the highest discriminative power for classifying DKV occurrence, with an area under the curve (AUC) of 0.994 (95% CI: 0.960-1.000), followed by hip adduction moment (AUC = 0.896) and quadriceps peak amplitude (AUC = 0.883). CONCLUSIONS: Findings suggest that DKV occurrence after fatigue is associated with altered quadriceps activity and hip rotation mechanics. These insights may inform ACL injury prevention strategies.

Objective: The popularity of electronic sports (esports) is increasing worldwide, and it is estimated that the number of domestic and international tournament participants will correspondingly increase in the future. Compared to overseas esports athletes, there are currently a lack of surveys on injuries among domestic esports athletes. This study therefore aimed to confirm the current status of esports-related injuries, ways of dealing with them, and support systems among esports athletes in Japan. We formulated two hypotheses: First, esports-related injuries would occur in domestic esports athletes, and the most common locations of injury would be the wrist, neck, lumbar back, and fingers. Second, the ways of dealing with injuries would be original.

Methods: Eight professional esports athletes participated in this study. Semi-structured interviews were conducted online using videoconferencing software. First, participants were asked about competitive information such as playing time per day and playing frequency per week. Next, participants were queried about their history of esports-related injuries. Those who had experienced injuries were asked about their injury locations, number of days away from the competition, and how they dealt with the injuries. Finally, the participants were asked whether they had a support system. Participants who had a support system were asked about it.

Results: The average playing time per day was 7.3 hours and the average playing frequency per week was 6.6 days. Seven esports-related injuries occurred in five of the eight participants (62.5 %), with injuries located in the wrist, fingers, lumbar back, the cervical spine, and the shoulder girdle. Participants with the injuries experience did not have a support system. They each have their own ways of dealing with icing and stretching. Three participants without injury had physical, mental, and nutritional support systems in place.

Conclusion: This study revealed that esports-related injuries occur among esports athletes in Japan. Athletes who reported injuries had ways of dealing with injuries, but no support system in place. In contrast, athletes who had never experienced injuries had a support system in place, suggesting that the support system may have contributed to injury prevention.

Objectives

Japanese people are known to get the least amount of sleep in the world, and in particular, the increase in sleep deprived young women is a serious problem. Sleep deprivation is considered to be associated with depression, but the factors involved in this problem are unclear. This study aimed to examine the association between sociodemographic factors, lifestyle choices, sleep-related characteristics and depressive symptoms in young Japanese women.

Design

Web-based cross-sectional study.

Participants

We distributed an online survey aiming to recruit young Japanese women ages 18 to 29 from 8 November 2022 to 2 February 2023.

Primary and secondary outcome measures

Sociodemographic, lifestyle, health, and sleep characteristics were compared among participants according to the presence or absence of depressive symptoms, as assessed by the Patient Health Questionnaire 2 (Cut-off value: 3 points).

Results

Overall, 540 participants aged between 19 and 29 years were enrolled in the study. The overall prevalence of depressive symptoms was 15.6%. The group with depressive symptoms had a higher rate of current smoking status at 38.5% (unadjusted OR 3.716, 95% CI 1.624 to 8.502). Multiple logistic analyses revealed that depressive symptoms were associated with increased sleep onset latency (β=0.282; p=0.048; OR, 1.325; 95% CI, 1.003 to 1.752) and daytime dysfunction (β=0.550; p<0.001; OR, 1.733; 95% CI, 1.281 to 2.343) after adjusting for the effects of smoking habits.

Conclusions

Depressive symptoms were found to be associated with sleep disorders in young Japanese women, and paying attention to sleep onset latency and daytime dysfunction which are one of the strongest related factors to depressive symptoms could be a clue to improving sleep disorders and depressive symptoms.

OBJECTIVES: To investigate the relationship between sleep quality and perimenstrual symptoms among Japanese female students. DESIGN: Observational, cross-sectional, online survey SETTING: We used an online questionnaire to collate responses from Japanese female students on sleep quality and perimenstrual symptoms. PARTICIPANTS: A total of 298 female students aged 18-25 years in Japan were included in this study. PRIMARY AND SECONDARY OUTCOME MEASURES: The Menstrual Distress Questionnaire (MDQ) was used to assess the severity of perimenstrual symptoms for three periods-premenstrual, menstrual and postmenstrual-and the Japanese version of the Pittsburgh Sleep Quality Index was used to assess sleep quality. The MDQ scores were compared between two groups (normal-sleep quality and low-sleep quality) using Mann-Whitney U test. In addition, multiple logistic regression analysis was performed, and the MDQ subscales that showed significant differences between the groups were used as independent variables. The MDQ subscale that was strongly associated with sleep quality was calculated. RESULTS: Of the female students, 160 were classified into the normal-sleep quality group and 138 into the low-sleep quality group. The total MDQ scores were significantly higher in the low-sleep quality group at all phases of the menstrual cycle (respectively p<0.05). Among the MDQ subscales, 'pain' during menstruation and 'concentration' in the premenstrual and postmenstrual stages were associated with sleep quality (respectively p<0.05). CONCLUSIONS: Improving sleep quality was one possible strategy to reduce the severity of perimenstrual symptoms. These results may provide useful information for Japanese female students who suffer from perimenstrual symptoms.

[Purpose] The coronavirus disease of 2019 (COVID-19) pandemic and its associated restrictions have raised concerns regarding the lack of exercise among college students. Videos on digital platforms have addressed this issue, although their effects on student behavior are unclear. The present study investigated whether the simultaneous distribution of e-learning and exercise videos among college students during the lifting of behavioral restrictions during the COVID-19 pandemic was effective in promoting health. [Participants and Methods] We conducted a randomized controlled trial in which 100 college students were recruited. The data of 61 students (e-learning and exercise video group=21, exercise video group=20, and control group=20) who completed baseline surveys were analyzed. The preliminary outcomes were physical activity, health habits, eHealth literacy, health-related quality of life, subjective well-being, and psychological stress. A mixed-model repeated-measures analysis of variance was used to compare these variables before and after the intervention. [Results] Health practice and eHealth literacy scales exhibited significant interactions in the e-learning and exercise video groups compared to the other groups. [Conclusion] The combined distribution of e-learning and exercise videos did not significantly enhance physical activity among college students during the COVID-19 pandemic; however, health literacy and habits improved.

Wheelchair basketball players often develop shoulder pain due to repetitive wheelchair propulsion motion. Wheelchair propulsion involves two phases, push and recovery, with several different muscles simultaneously active in each phase. Although differences in the coordinated activity of multiple muscles may influence the mechanism of injury occurrence, there have been no studies investigating muscle synergy in wheelchair propulsion motion. Twelve healthy adult males with no previous wheelchair driving experience were included. The surface electromyography data of 10 muscles involved in shoulder joint movements were measured during a 20 m wheelchair propulsion motion. Muscle synergies were extracted using non-negative matrix factorization analysis of the electromyography data. Four muscle synergies were identified during wheelchair propulsion. Synergy 1 reflects propulsion through shoulder flexion and elbow flexion, while Synergy 2 involves shoulder flexion and elbow extension. Synergy 3 describes shoulder extension returning the upper limb, which has moved forward during the push, back to its original position, and Synergy 4 relates to stabilize the shoulder girdle during the recovery phase. This study is the first to explore muscle synergy during wheelchair propulsion, and the data from healthy participants without disabilities or pain will provide a baseline for future comparisons with data from wheelchair basketball players.

[Purpose] This study aimed to investigate the differences in the acute effects of virtual and actual throwing training on throwing performance. [Participants and Methods] Twenty healthy men and six women with no boccia experience were randomly divided into the virtual and non-virtual groups. The task involved throwing boccia balls at target sets of 2 (short), 5 (middle), and 9 m (long). Both the groups were trained in three rows for each condition. The distance from the ball to the target was calculated as throwing accuracy for both pre- and post-training. Confidence in throwing was measured using a visual analog scale pre-and immediately post-training. A two-way analysis of variance with a post-hoc Bonferroni test or t-test was conducted for throwing accuracy and confidence. [Results] For throwing accuracy, the post hoc test results showed that both groups improved after training, but only in the middle-distance throw. Throwing confidence improved after training in both groups. [Conclusion] Boccia-throwing training using virtual reality may have an acute training effect comparable to that of actual training.

This study aimed to investigate the effects of wearing virtual reality (VR) with a head-mounted display (HMD) on body sway in younger and older adults. A standing posture with eyes open without an HMD constituted the control condition. Wearing an HMD and viewing a 30°-tilt image and a 60°-tilt image in a resting standing position were the experimental conditions. Measurements were made using a force plate. All conditions were performed three times each and included the X-axis trajectory length (mm), Y-axis trajectory length (mm), total trajectory length (mm), trajectory length per unit time (mm/s), outer peripheral area (mm2), and rectangular area (mm2). The results showed a significant interaction between generation and condition in Y-axis trajectory length (mm) and total trajectory length (mm), with an increased body center-of-gravity sway during the viewing of tilted VR images in older adults than in younger adults in both sexes. The results of this study show that body sway can be induced by visual stimulation alone with VR without movement, suggesting the possibility of providing safe and simple balance training to older adults.

OBJECTIVE: This study examined the impact of sports participation on the health status of individuals with spinal cord injuries (SCI), with emphasis on the role of health-related social capital (HRSC). METHODS: This study included 65 individuals with SCI (42 who participated in sports and 23 who did not). The following information was obtained from the participants through an online questionnaire: their basic information, information regarding activities of daily life independence, physical activity, mental health, lifestyle, insomnia, and social capital. We compared the outcomes between participants with and without sports participation and examined their correlations. Multiple regression analysis with forced entry was performed to determine the association between HRSC and health outcomes. RESULTS: Physical activity, mental health, and HRSC were significantly higher in individuals with SCI who participated in sports (p <0.01 or p <0.05) than in individuals with SCI who did not participate in sports. The HRSC of individuals with SCI with sports participation showed a significant positive correlation with lifestyle and a significant negative correlation with insomnia score (p <0.05). Multiple regression analysis revealed that higher HRSC was associated with lifestyle in individuals with SCI who participated in sports (p <0.05) compared with individuals with SCI who did not participate in sports. CONCLUSION: The study findings underscore the potential benefits of sports participation in individuals with SCI, including increased physical activity and development of HRSC. However, it is essential to consider the implications of sports involvement on the psychological well-being of individuals with disabilities and provide appropriate support.

This report describes the initiation of injury survey and the Pre-participation Physical Exam (PPE) at a collegiate athletic setting. The subjects were 62 student athletes from Hiroshima University’s athletic teams. Prior to the PPE, the current and previous injury history from each subject were recorded. The PPE consisted of 9 items related to flexibility, muscle strength, explosive power, and balance ability. In the individual feedback session after PPE, we explained the results of the PPE and provided specific physical conditioning instructions. The medical interview, PPE, and feedback were conducted by a Japan Sport Association certified athletic trainer (JSPO-AT) or a physical therapist who was given the specific instructions by athletic trainers. At the time of the medical interview, 25 of the 62 players suffered from sports injuries that kept them out of practice for more than one day or interfered with their athletic performance. We advised 10 of these players (e.g., back pain with numbness) to seek medical attention. The results of the PPE showed that many of the athletes had flexibility issues, and the physical conditioning instruction in the feedback likewise emphasized flexibility improvement. This activity could be considered essential from the perspective of injury prevention, and will be expanded and continued in the future.

This cross-sectional study aimed to investigate the relationship between foot shape and intrinsic foot muscles (IFMs) in adolescent swimmers compared with other athletes. Foot morphology of swimmers was compared with other athletes of comparable age and a competition level (n = 32 [64 feet]; a total of 64 feet; 128 feet in two groups). Foot morphology and variables of IFMs were measured using a three-dimensional foot scanner and an ultrasound imaging system, respectively. Multiple linear regression analysis with forced entry was performed to clarify the association of the thickness and the cross-sectional area (CSA) of IMFs with the navicular height in both sitting and standing positions. Navicular height in a standing position, the thickness of the abductor hallucis (AbH) and the flexor digitorum brevis (FDB), as well as the CSA were significantly lower in swimmers compared with other athletes (p < 0.05). A larger CSA for the flexor hallucis brevis (FHB) was observed in swimmers than in other athletes (p < 0.01). The navicular height of swimmers in sitting and standing positions was positively correlated with the thickness and the CSA of the FHB and the FDB (p < 0.05). Multiple regression analysis showed that navicular height was associated with the CSA of the FDB in both sitting and standing positions (β = 0.395; p < 0.002, β = 0.201; p < 0.018). This study showed that the navicular height of elite adolescent swimmers was lower than that of other athletes. Furthermore, the swimmers' high navicular height was associated with the CSA of the FDB, suggesting that the FDB might be more involved in the formation of the medial longitudinal arch than the AbH.

BACKGROUND: Foot malalignment can augment the risk of lower-extremity injuries and lead to musculoskeletal disorders. This study aimed to clarify the contribution of rearfoot alignment to plantar pressure distribution and spatiotemporal parameters during gait in healthy adolescent athletes. METHODS: This retrospective study included 39 adolescent athletes who were divided into the rearfoot eversion and control groups according to a leg heel angle of 7°. A total of 78 legs were analyzed (45 and 33 legs in the rearfoot eversion [women, 53.3%] and control groups [women, 48.5%], respectively). Gait was assessed using an in-shoe plantar pressure measuring system and a wearable inertial sensor. RESULTS: The foot plantar pressure distribution in the hallux was higher in the rearfoot eversion group than that in the control group (p = 0.034). Spatiotemporal parameters showed that the foot pitch angle at heel strike was significantly larger in the rearfoot eversion group than that in the control group (24.5° vs. 21.7°; p = 0.015). Total sagittal range of motion of the ankle during the stance phase of gait was significantly larger in the rearfoot eversion group than that in the control group (102.5 ± 7.1° vs. 95.6 ± 15.8°; p = 0.020). Logistic regression analysis revealed that plantar pressure at the hallux and medial heel and foot pitch angle at heel strike were significantly associated with rearfoot eversion. CONCLUSIONS: Our findings suggest that rearfoot eversion affects the gait patterns of adolescent athletes. Notably, leg heel angle assessment, which is a simple and quick procedure, should be considered as an alternative screening tool for estimating plantar pressure and spatiotemporal gait parameters to prevent sports-related and overuse injuries in adolescent athletes.

BACKGROUND: The effects of a long-term static stretching program on physical performance parameters have not been elucidated completely, although the effects on muscle flexibility have a consensus. OBJECTIVE: This study aimed to investigate the effect of a long-term static stretching program on physical performance and muscle properties. METHODS: Participants performed a 2-min static stretching for the ankle joint 5 times per week for 4 weeks. Physical performance and muscle properties was measured before and after the static stretching program. RESULTS: Results showed that range of motion (ROM), dynamic postural stability, and muscle hardness were positively changed, whereas other variables i.e. maximal isometric plantar flexion moment, jump heights, muscle-tendon junction displacement and its angle, were not. CONCLUSIONS: Four-week of SS program may improve ROM, dynamic postural stability, and muscle hardness without decreasing physical performance.

Dysmenorrhea is a monthly menstrual pain that can limit a woman’s quality of life (QOL). The relationship between dysmenorrhea severity and QOL has been reported in several countries; however, the results cannot be generalized because lifestyle and cultural background affect menstrual pain. This study sought to uncover whether 1) different factors, such as emotions and ways of coping with symptoms, vary with the severity of dysmenorrhea and 2) the severity of dysmenorrhea ultimately affects QOL in Japan. A web-based cross-sectional survey was sent to 1000 Japanese females aged 16–30 years. The respondents were divided into two groups: those without dysmenorrhea (n = 24) and those with dysmenorrhea (n = 471). The severity of dysmenorrhea was classified using the Numerical Rating Scale as either mild (1–3), moderate (4–7), or severe (8–10). In total, 156 respondents reported mild dysmenorrhea, 249 reported moderate dysmenorrhea, and 66 reported severe dysmenorrhea. QOL was measured using the 26-item World Health Organization Quality of Life scale. One-way ANOVA and Kruskal-Wallis tests were used to compare QOL across different levels of dysmenorrhea severity, depending on normality. Ultimately, significant differences in QOL scores (p&lt;0.001) were observed based on dysmenorrhea severity, with respondents with severe dysmenorrhea reporting the lowest QOL scores. Meanwhile, significant differences were observed in the physical, psychological, and environmental subscales (p&lt;0.001, p&lt;0.001, p = 0.019) across respondents with different levels of dysmenorrhea severity; notably, respondents with severe dysmenorrhea demonstrated a negative spiral of chronic pain, which may significantly impact QOL, and, relatedly, a relatively low psychological QOL. This study is the first to show the relationship between dysmenorrhea severity and QOL in Japanese females, who are more likely to experience negative feelings during menstruation.

BACKGROUND: Intrinsic foot muscle exercises are used in clinical and sports practice to improve performance. Force generation during toe flexion is greater in the standing posture than in the sitting posture; nonetheless, the mechanism underlying the activation of intrinsic foot muscles during force generation and whether there exists a difference between these two postures still remain unclear. RESEARCH QUESTION: Are the activities of intrinsic foot muscles affected by standing and sitting postures during gradual force generation? METHODS: Seventeen men participated in the laboratory based cross-sectional study. Each participant performed a force ramp-up toe flexion task from 0% to 80% of the maximal toe flexor strength (MTFS) in sitting and standing postures. High-density surface electromyography signals obtained during the task were determined by calculating the root mean square (RMS). Additionally, modified entropy and coefficient of variation (CoV) were calculated at 20-80 % MTFS for each 10 % MTFS. RESULTS: The RMS between the two postures indicated an interaction effect (p < 0.01). Post-hoc analyses revealed that intrinsic foot muscle activity during the ramp-up task was significantly higher in the standing posture than in the sitting posture at 60 % MTFS (67.53 ± 15.91 vs 54.64 ± 19.28 % maximal voluntary contraction [MVC], p = 0.03), 70 % MTFS (78.11 ± 12.93 vs 63.28 ± 18.65 % MVC, p = 0.01), and 80 % MTFS (81.78 ± 14.07 vs 66.90 ± 20.32 % MVC, p = 0.02). In the standing posture, the modified entropy at 80 % MTFS was lower than that at 20 % MTFS (p = 0.03), and the CoV at 80 % MTFS was higher than that at 20 % MTFS (p = 0.03). SIGNIFICANCE: These results indicated that posture selection is important for high-intensity exercises of the intrinsic foot muscles, such as resistance training. Thus, improving performance related to toe flexor strength might be more effective when conducted under adequate weight-bearing situations, such as in the standing posture.

Knee orthoses can potentially reduce muscular activities of the quadriceps. The aim of this study was to investigate the effect of a custom flexion-resist and extension-assist knee orthosis on electromyographic activities of quadriceps during lateral stepping (step-up and step-down). Flexion resistance and extension assistance mechanisms were set by a pair of linear springs built into the orthotic knee joints. Electromyography (EMG) signals were collected from rectus femoris (RF), vastus medialis obliquus (VMO), and vastus lateralis (VL) during lateral step-up and lateral step-down activities in 7 healthy young adults. Peak normalized root mean square (RMS) EMG signals of each muscle, as well as VMO:VL ratio, were compared between orthotic and nonorthotic conditions using the Wilcoxon signed-rank test. The knee orthosis significantly reduced the normalized RMS EMG signals of the RF and VL during lateral stepping (p < 0.05). No significant difference was found in the VMO. The VMO:VL ratio significantly (p < 0.05) increased under orthotic condition. The experiments demonstrated that the knee orthosis reduces the peak normalized RMS EMG signals of RF and VL, and alter the VMO:VL ratio of quadriceps in healthy young adults. Therefore, this study suggests that the flexion-resist and extension-assist knee orthosis may be effective in reducing muscular activities of RF and VL, which may alleviate patellofemoral loading. Future studies should delve into the effects of the knee orthosis in individuals with patellofemoral pain.

BACKGROUND: Intrinsic foot muscle (IFM) dysfunction and poor foot arch are associated with various foot conditions. Toe flexor exercise (TFE) has been used to improve it; however, the immediate effects of TFE on each IFM and how it relates to changes in navicular bone height (NH) are unclear. OBJECTIVE: This study aimed to investigate acute muscle swelling in the IFM after TFE and the association between changes in NH and IFM size. METHODS: Fourteen adults participated in this study. NH and cross-sectional area (CSA) of the IFM were acquired pre and post- TFE. The CSA of the IFM, including the abductor hallucis (AbH), flexor hallucis brevis, flexor digitorum brevis, and quadratus plantae, was acquired with ultrasonography. In the TFE, each participant completed five sets of eight repetitions with maximum strength. RESULTS: The NH and CSA of all IFM significantly increased significantly post-TFE (p&lt; 0.01). Only the increase in AbH was moderately and positively correlated with the change in NH (r= 0.54, p&lt; 0.01). CONCLUSION: This study suggests that the acute swelling of AbH after TFE is associated with an immediate increase in NH, supporting the important role of AbH in the formation of foot arch.

Forward head posture (FHP) is a serious problem causing head and neck disability, but the characteristics of muscle activity during long-term postural maintenance are unclear. This study aimed to investigate a comparison of electromyography (EMG) activation properties and subjective fatigue between young adults with and without habitual FHP. In this study, we examined the changes in the spatial and temporal distribution patterns of muscle activity using high-density surface EMG (HD-SEMG) in addition to mean frequency, a conventional measure of muscle fatigue. Nineteen male participants were included in the study (FHP group (n = 9; age = 22.3 ± 1.5 years) and normal group (n = 10; age = 22.5 ± 1.4 years)). Participants held three head positions (e.g., forward, backward, and neutral positions) for a total of 30 min each, and the EMG activity of the trapezius pars descendens muscle during posture maintenance was measured by HD-SEMG. The root mean square (RMS), the modified entropy, and the correlation coefficient were calculated. Additionally, the visual analogue scale (VAS) was evaluated to assess subjective fatigue. The RMS, VAS, modified entropy, and correlation coefficients were significantly higher in the FHP group than in the normal group (p < 0.001). With increasing postural maintenance time, the modified entropy and correlation coefficient values significantly decreased, and the mean frequency and VAS values significantly increased (p < 0.001). Furthermore, the forward position had significantly higher RMS, correlation coefficient, modified entropy, and VAS values than in the neutral position (p < 0.001). The HD-SEMG potential distribution patterns in the FHP group showed less heterogeneity and greater muscle activity in the entire muscle and subjective fatigue than those in the normal group. Excess muscle activity even in the neutral/comfortable position in the FHP group could potentially be a mechanism of neuromuscular conditions in this population.

PURPOSE: Electrical muscle stimulation (EMS) is known to be effective at stimulating brain-derived neurotrophic factor (BDNF) levels, but the relationship between the volume of muscle stimulated and BDNF levels is not clear. The purpose of this study was to quantify BDNF as a function of muscle volume stimulated in young adults. METHODS: Twelve young adults (male, n = 9, age = 27.3 ± 5.5 years) were enrolled in this study. Participants completed three testing conditions in randomized order: 23 min of maximum tolerated bilateral stimulation of (1) the quadriceps muscle or (2) the musculature of the entire lower limbs and (3) control testing and retesting after 23 min without an intervention. Blood samples were collected before, immediately after, 20 min after, and 40 min after the intervention when EMS was applied to the thighs or the entire lower limb conditions. Serum obtained from blood collection was used for BDNF analysis. RESULTS: The delta value of BDNF for the test and retest in the control condition was - 42.1 ± 73.8 pg/mL, and there was no significant difference between the test and retest BDNF. Compared to stimulation of the quadriceps muscle, stimulation of the entire lower limbs produced significantly higher BDNF at 20 min post-treatment than those at pre-treatment or 40 min post-treatment, and BDNF was also significantly higher immediately post-treatment than those at pre-treatment. Only stimulation of the quadriceps muscle did not induce a significant change between pre- and post-treatment. CONCLUSION: Our findings suggest that the volume of muscle stimulation is important for increased BDNF.

The peroneal muscles undergo morphological changes and functional decline after an ankle sprain, contributing to recurrence. We reported that different morphological changes occur in the peroneus longus (PL) and peroneus brevis (PB) after an ankle sprain (Arima et al., 2022), and we believe that selective muscle strength train for the PL and PB is necessary. This study aimed to examine whether the morphology of PL and PB is selectively altered by different training methods. Two tasks were performed on separate days: the ball of the foot task in which a Thera-Band was placed on the ball of the foot and pushed out from the contact point, and the fifth metatarsal task in which the Thera-Band was pushed out from the base of the fifth metatarsal. Muscle cross-sectional area (CSA) and muscle echogenicity of the peroneus muscles at 25% and 75% proximal to the line connecting the fibular head and the lateral malleolus, and ankle joint strength were measured before and immediately after the task and at 10, 20, and 30 minutes later. A repeated measures analysis of variance was used to compare each item measured at each time point. In the ball of the foot task, the CSA at the proximal 25% was significantly higher immediately and 10 minutes after the task than before (p<0.05). In the fifth metatarsal task, the CSA increased significantly in the proximal 75% after the task (p<0.05). Transient muscle hypertrophy immediately after training is due to edema caused by muscle injury, indicating an immediate effect of training (Damas et al., 2016). The CSA of the proximal 25% showing PL in the ball of the foot task and the distal 75% showing PB in the fifth metatarsal task increased immediately after the task, suggesting the possibility of selectively training PL and PB in this task.

The aim of this study was to investigate the effect of changes in the living environment caused by the emergency declaration issued by the COVID-19 pandemic on the swimmers’ range of activities and mental health, and to examine the differences between swimmers with and without disabilities. The participants were 39 competitive swimmers, including 10 male para-swimmers, 10 female para-swimmers, 10 male swimmers, and 9 female swimmers. The online questionnaire was conducted twice: during the state of the emergency period, and after the period. The differences in the Life-Space Assessment (LSA) and Japanese Apathy Scale (JAS) between para-swimmers and able-bodied swimmers, by gender, were analyzed using a two-way repeated-measures ANOVA during and after the period. Concerning LSA, a significant main effect was shown only in the period related to the state of emergency (p<0.01). Among the female participants, there was a significant interaction effect of JAS (p<0.05). Female para-swimmers may be more susceptible to experiencing changes in mental health following their circumstances. Therefore, it is important to create opportunities for exercise in place of swimming by planning exercises that could be done on the spots, and to consider measures that consider mental health from the aspect of sex and disabilities.

INTRODUCTION: This study investigated how toe flexor muscles are related to postural stability in 11 ballet dancers and 12 non-dancers. METHODS: Toe flexor strength (TFS), cross-sectional areas (CSA) of the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, flexor hallucis longus (FHL), and flexor digitorum longus, and center of pressure (COP) displacement during single-leg demi-pointe were measured. Correlations between toe flexor strength and COP displacement and between CSA and COP displacement within each group were calculated using Pearson's correlation coefficient or Spearman's correlation coefficient. RESULTS: The dancers showed smaller COP displacement than the non-dancers (p < 0.05). Toe flexor strength in dancers was moderately negatively correlated with COP displacement in the anterior-posterior direction (r = -0.54, p < 0.01) and total COP displacement (r = -0.57, p < 0.01). Only the CSA of the FHL in dancers exhibited a significant negative correlation with COP displacement in the anterior-posterior direction (r = -0.42, p < 0.05) and total COP displacement (r = -0.52, p < 0.01). CONCLUSION: The present study found a relationship between the toe flexor strength and COP displacement and CSA of toe flexor muscles and COP displacement during one-legged demi-pointe standing. These results suggest that the development of the toe flexor muscles may be involved in the balance control of dancers.

BACKGROUND: Figure-8 straps are commonly used in ankle orthoses, which are provided to reduce the risks of primary and recurrent sprain by providing functional support. Functional treatment with ankle orthoses can provide better rehabilitation than immobilization for a mild ankle sprain. However, it is not known how much tension should be applied to the straps while donning the orthosis to optimize its effectiveness. RESEARCH QUESTION: The aim of this study was to investigate the effects of figure-8 strap tension of a soft ankle orthosis on ankle joint kinematics in the sagittal, coronal, and transverse planes during gait in healthy young adults. METHODS: Ten healthy adults (five males and five females) were enrolled in this study. The 3-dimensional motion analysis system was used to evaluate the ankle kinematics of the participants during gait under five conditions: no soft ankle orthosis, soft ankle orthosis with no figure-8 straps tension (lace-up only), 50 N, 80 N, and 110 N tension of the figure-8 straps, respectively. All participants walked in a straight path at a comfortable speed. RESULTS: Plantarflexion angles were significantly reduced with 110 N of tension in the figure-8 straps when compared to the lace-up only and a moderate correlation with r = 0.34 (p = 0.03) was observed between the tensions of figure-8 straps and maximum plantarflexion angles at pre-swing of a gait cycle. No significant effects on ankle joint angles were demonstrated in the coronal and transverse planes. SIGNIFICANCE: This study showed that increasing the tension of the figure-8 straps could restrict the ankle joint plantarflexion angle during pre-swing in gait. However, it might not affect inversion/eversion or internal/external rotation angles of the ankle joint in individuals without ankle pathologies.

OBJECTIVES: To identify the fall characteristics of athletes in wheelchair rugby and wheelchair basketball during the Tokyo 2020 Paralympic Games and descriptively compare these with those of the Rio 2016 Paralympic Games. DESIGN: Cross-sectional analysis. PRIMARY AND SECONDARY OUTCOME MEASURES: We obtained video footage from the International Paralympic Committee of the Tokyo 2020 Paralympic Games that included 8 teams from each of the 18 wheelchair rugby and 10 wheelchair basketball games (men and women). The data were analysed to evaluate the number of falls, class difference (low or high pointer), time of play during the fall, phase of play, contact with other athletes, fall direction, fall location and the body part that first contacted the floor during the fall. These data from the Rio 2016 and Tokyo 2020 games were compared. RESULTS: Overall, 430 falls (rugby, 104; men's basketball, 230 and women's basketball, 96) occurred (average per game ±SD: 5.8±3.1, 23.0±5.4 and 9.6±5.0, respectively). Significant differences in class, direction, fall location and body part point of contact between the three sports were observed. In wheelchair rugby, falls occurred mainly in high pointers and tended to be more lateral due to contact. In wheelchair basketball, falls occurred more in female high-pointers and in male low pointers, with more forward falls due to forward contact. Unlike in the Rio 2016 games, no difference between the events based on the presence or absence of contact was observed in the Tokyo 2020 games. CONCLUSIONS: The number of falls increased in Tokyo 2020 compared with Rio 2016, with no significant difference in the characteristics of falls between the Rio 2016 and Tokyo 2020 games. Only in men's wheelchair basketball, the number of falls in low pointers significantly increased in the Tokyo 2020 games when compared with that in the Rio 2016 games.

This systematic review aimed to evaluate custom-made 3D printed insoles for people with flatfeet. PubMed, Embase, ISI web of knowledge, ProQuest, Scopus, and Cochrane databases, were searched from inception until January 2022. The quality assessment of included studies was performed through the Downs and Black checklist. A narrative analysis was performed since a meta-analysis could not be conducted. Ten studies including 225 subjects with flexible flatfeet were chosen for final evaluation. Although the evidence from selected literature was generally weak, using insoles with 3D printing technology may positively affect pain (comfort score) and foot function, with no significant change in vertical loading rate during walking or running. There were discrepancies among studies for plantar pressures, center of pressure trajectories, 3D ankle joint kinematics and kinetics of gait while wearing these insoles. Dose-response effects of medial posting on 3D printed insoles suggested beneficial effects on lower limb gait biomechanics in people with flatfeet. There was insufficient evidence to conclude the comparison between 3D printed insoles and other types of insoles. In conclusion, using a 3D printed insole may improve comfort score and foot function in people with flatfeet.

OBJECTIVE: The purpose of this study was to detect specific motor unit (MU) abnormalities in people with amyotrophic lateral sclerosis (ALS) compared to controls using high-density surface electromyography (HD-SEMG). METHODS: Sixteen people with ALS and 16 control subjects. The participants performed ramp up and sustained contractions at 30% of their maximal voluntary contraction. HD-SEMG signals were recorded in the vastus lateralis muscle and decomposed into individual MU firing behavior using a convolution blind source separation method. RESULTS: In total, 339 MUs were detected (people with ALS; n = 93, control subjects; n = 246). People with ALS showed significantly higher mean firing rate, recruitment threshold, coefficient of variation of the MU firing rate, MU firing rate at recruitment, and motoneurons excitability than those of control subjects (p < 0.001). The number of MU, MU firing rate, recruitment threshold, and MU firing rate at recruitment were significantly correlated with disease severity (p < 0.001). Multivariable analysis revealed that an increased MU firing rate at recruitment was independently associated with ALS. CONCLUSIONS: These results suggest increased excitability at recruitment, which is consistent with neurodegeneration results in a compensatory increase in MU activity. SIGNIFICANCE: Abnormal MU firing behavior provides an important physiological index for understanding the pathophysiology of ALS.

Abstract

Background

Experiencing perimenstrual symptoms is a major health concern for young women. Women in the reproductive age experience menstruation about once a month, and many experience perimenstrual symptoms. Drug therapies such as painkillers (commonly used) and hormonal medications help to achieve symptomatic relief from perimenstrual symptoms. However, many women are concerned about tolerance and compliance of the drugs used to treat perimenstrual symptoms and lack awareness on how to cope with perimenstrual symptoms. If the association between exercise habits and the severity of symptoms is emphasized in young women, methods for coping with perimenstrual symptoms can be established, not relying only on pharmaceuticals. The objective of this study was to determine the differences in the severity of perimenstrual symptoms in young Japanese women with and without a regular exercise habit.

Methods

A cross-sectional study using an online survey was sent among 500 Japanese women aged 18–25 years. The severity of perimenstrual symptoms was assessed using the Menstrual Distress Questionnaire (MDQ). The differences in MDQ scores between those with and without exercise habits (exercise for more than 30 min for 2 days a week) were compared using the chi-square test and Mann–Whitney U test. The logistic regression analysis detected subscales of the premenstrual and menstrual symptoms affected by an exercise habit.

Results

282 (56.4%) young Japanese women were answered this survey. Respondents were divided into the exercise group (n = 157) and the non-exercise group (n = 125). The exercise group had significantly low premenstrual and menstrual MDQ scores. The results of the logistic regression analysis stated that the subscale related to negative emotion before menstruation was associated with an exercise habit. In the analysis performed during menstruation, a statistically significant association was detected between an exercise habit and a behavioral change such as avoiding interaction with others.

Conclusions

This study suggested that exercise habits may reduce the severity of perimenstrual symptoms and could help to develop a non-pharmacological coping strategy. In addition, this study provides useful information for young women who want to prevent perimenstrual symptoms but do not have an exercise habit. Further, it may encourage young women to start exercising.

Abstract

Background

Ankle orthotics decreases the maximal vertical jump height. It is essential to maximize jump height and minimize ground contact time during athletic performance. However, the effect of ankle orthotics on athletic performance has not been reported. We aimed to investigate the effect of ankle orthotics on squat jump (SJ), countermovement jump (CMJ), and repetitive rebound jump (RJ) performance.

Methods

Twenty healthy volunteers performed SJ, CMJ, repetitive RJ under no-orthosis and two orthotic conditions (orthosis 1 and orthosis 2). During SJ and CMJ, we measured the vertical ground reaction force and calculated the following parameters: jump height, peak vertical ground reaction force, rate of force development, net vertical impulse, and peak power. During repetitive RJ, the jump height, contact time, and RJ index were measured. A two-dimensional motion analysis was used to quantify the ankle range of motion in the sagittal plane during SJ, CMJ, and repetitive RJ.

Results

Multivariate analysis of variance and the post hoc test showed orthosis 2 significantly decreased in the vertical jump height (p = 0.003), peak power (p = 0.007), and maximum plantarflexion and dorsiflexion angles (p &lt; 0.001) during SJ Ankle orthoses 1 and 2 did not influence to the RJ performance compared to those using the no-orthosis condition. Additionally, orthosis 2 significantly decreased the jump height at the end of repetitive RJ (p = 0.046).

Conclusions

These results suggest that ankle orthosis do not affect average RJ performance but should be considered when performing repetitive jumps frequently.

Hallux valgus (HV) entails changes in the alignment of the rotating sesamoids and a shift of the abductor hallucis muscle (ABH) in the plantar direction, decreasing the abductor force. Load on the foot while walking may change the sesamoid rotation angle (SRA). Nevertheless, no study has investigated the relationship between the change in SRA during assumed walking and ABH muscle size. The aim of our study was to examine the changes in SRA at different foot postures assumed to generate skeletal alignments during walking and muscle size of the ABH in participants with HV and to discuss the association between the change in the SRA and cross-sectional area (CSA) of the ABH. Thirteen female participants were recruited and divided into the HV and non-HV groups according to the HV angle. The SRA and cross-sectional area of the ABH were measured using B-mode ultrasound. The SRA was measured under four conditions; sitting, standing, mid-stance, and pre-swing posture. The CSA was assessed in the supine position. In all postures, the SRA increased more in the HV group than in the non-HV group (p < 0.05). The change in the SRA at the pre-swing posture was greater in the HV group than in the non-HV group (p < 0.05). The change in the SRA at pre-swing posture negatively correlated with the CSA of the ABH in the HV group (r = -0.554, p < 0.05). In the HV group, increasing the load on the forefoot enhanced the sesamoid rotation. Abductor torque on the ABH decreased with ABH displacement as the sesamoids moved laterally in the pre-swing. Repeated walking increased sesamoid rotation and led to HV progression. Therefore, it may be beneficial to use an orthosis or arch pad that corrects pronation of the metatarsal with the rotation of the sesamoids.

The aim of this study was to quantify the laterality of motor unit (MU) activation properties in people with Parkinson's disease (PD) during force production (low- to high-intensity contraction) using high-density surface electromyography (HD-SEMG). Sixteen females with PD (age = 69.9 ± 7.6 years, disease duration = 4.9 ± 5.1 years) and 14 healthy female subjects (age = 68.6 ± 3.6 years) were enrolled in the study and performed submaximal ramp-up contractions during isometric knee extension. HD-SEMG signals were recorded from both vastus lateralis muscles. We calculated the level of heterogeneity in the spatial distribution patterns of the HD-SEMG signals and determined the modified entropy, coefficient of variation of the root mean square (RMS), and correlation coefficient to evaluate MU activation properties. Pearson's correlation coefficients were calculated to examine the relationships between disease severity and the RMS and EMG variables. The RMS value and heterogeneity were significantly higher and lower on the more-affected side in people with PD than on the other side in people with PD or either side in control subjects (p < 0.05). People with PD exhibited the temporal changes of spatial MUs activation properties showed significant laterality when compared to healthy control subjects not only in the low-intensity contractions but also in high-intensity contraction. Moderate-to-strong correlations were observed between disease severity and RMS and EMG variables in people with PD (r > 0.6, p < 0.001). We compared the laterality of MU activation properties between the people with PD and the control subjects. These findings suggest that people with PD have asymmetrical MU activation properties, regardless of the magnitude of force production.

BACKGROUND: The role of the serratus anterior is to maintain scapular stability. To strengthen this muscle, scapular protraction exercises are typically performed. Although the angle of arm rotation leads to changes in shoulder muscle activation, the arm rotation position is not normally determined. OBJECTIVE: To investigate if scapular muscle activations were changed by combining arm external rotation during scapular protraction exercises. METHODS: Thirty-four healthy men were enrolled in this study. Participants were instructed to perform scapular protraction exercises at 90∘ and 120∘ of shoulder flexion while in the standing and supine positions. Two different arm rotation angles were used: the thumb-up position (neutral position) and the maximum arm external rotation (ER) position. The percentages of maximum voluntary contractions (%MVCs) were measured, and %MVCs in the neutral and arm ER positions were compared. RESULTS: Muscle activities of the middle serratus anterior (MSA) and lower serratus anterior (LSA) in the arm ER position were significantly higher than those in the neutral position during all tasks. The highest MSA and LSA positions were observed with the arm ER position of 120∘ while standing. CONCLUSIONS: Scapular protraction exercises with arm ER resulted in a higher serratus anterior activity.

Background and Objectives: The effectiveness of multiple ultrasound evaluations of the peroneus muscles morphology, including muscle cross-sectional area (CSA) and connective tissue, after lateral ankle sprain (LAS) is unknown. This study aimed to measure the peroneus muscles after LAS at three points, adding distal 75% to the conventional measurement points, in order to obtain a detailed understanding of the post-injury morphology and to propose a new evaluation index of the peroneus muscles for multiple LAS. Materials and Methods: Participants with and without LAS (LAS and control groups, 16 each) were recruited. The muscle cross-sectional area (CSA) and muscle echogenicity were measured using a B-mode ultrasound system at 25%, 50%, and 75% proximal to the line connecting the fibular head to the lateral malleolus. The ankle evertor strength was measured using a handheld dynamometer. Simultaneously, the peroneus longus (PL) and peroneus brevis (PB) muscle activities were measured using surface electromyography. Measurements for the LAS side, non-LAS side, and control leg were performed separately. Results: The CSA was significantly higher at 75% on the LAS side than on the non-LAS side and in the control leg. Muscle echogenicity of the LAS side at 75% was significantly lower than that of the non-LAS side and the control leg. Muscle activity of the PL was significantly lower and the PB was higher on the LAS side than on the non-LAS side and in the control leg. Conclusions: The PL was less active than the PB, while the PB was found to be overactive, suggesting that PB hypertrophy occurs due to an increase in the percentage of muscle fibers and a decrease in the connective tissue. Therefore, it is necessary to evaluate the condition of the PL and PB separately after LAS.

Stroke causes balance dysfunction, leading to decreased physical activity and increased falls. Thus, effective balance exercises are needed to improve balance dysfunction. This single-blind, single-center randomized controlled trial evaluated the long-term and continuous effects of balance exercise using a real-time postural feedback system to improve balancing ability safely. Thirty participants were randomized into intervention (n = 15) and control (n = 15) groups; 11 in each group completed the final evaluation. The effect of the intervention was evaluated by muscle strength of knee extension, physical performance (short physical performance battery, the center of pressure trajectory length per second, and Timed Up and Go test [TUG]), and self-reported questionnaires (modified Gait Efficacy Scale [mGES] and the Fall Efficacy Scale) at pre (0 week), post (6-week), and at follow-up (10-week) visits. The TUG and mGES showed a significant interactive (group * time) effect (p = 0.007 and p = 0.038, respectively). The intervention group showed significant decreasing time to perform TUG from pre- to post-intervention (p = 0.015) and pre-intervention to follow-up (p = 0.016); mGES showed a significant change from pre-intervention to follow-up (p = 0.036). Thus, balance exercise using a real-time postural feedback system can confer a positive effect on the walking ability in patients with chronic stroke and increase their self-confidence in gait performance.

The Short Physical Performance Battery (SPPB) is a physical fall-risk screening tool and predictor of adverse health effects for the older. Its limited use in Japan is due to the relative ease for high-functioning older adults to achieve perfect scores. Japanese researchers thus created a community-based SPPB (SPPB-com). This study investigated whether the SPPB-com score can distinguish between older patients classified as “fallers” and “non-fallers.” Participants comprised 185 older outpatients aged 65 and above who self-reported their history of accidental falls and relevant physical activity. Fall risk was assessed using SPPB and SPPB-com. Handgrip strength, maximum isometric knee extensor strength, and maximum walking speed were measured as physical functions. Multivariate logistic regression and receiver-operating characteristic analyses determined criteria indicating faller status. Fallers were older and had lower physical function, physical activity, SPPB, and SPPB-com scores than non-fallers. Multivariate logistic regression analysis showed SPPB (OR 0.76, 95% CI 0.59–0.99, p = 0.045) and SPPB-com (OR 0.63, 95% CI 0.45–0.87, p = 0.005) scores were both independently associated with prior falls. The SPPB-com score may function as a fall-risk assessment tool for older outpatients, and its combined use with SPPB can increase the accuracy and precision of distinction between fallers and non-fallers.

BACKGROUND: Functional stability of the shoulder requires a balance of active forces, passive forces, and control subsystems of the joint complex. Although whole-body vibration enhances shoulder muscle function and proprioception, the impact of vibration on the sensorimotor control of the shoulder joint remains unclear. OBJECTIVE: To investigate the acute effect of vibratory stimuli on the sensorimotor control of the shoulder joint. METHODS: Fifteen male participants (age, 22.7 ± 2.3 years) were included and performed the exercise in a modified push-up position with partial weight-bearing on a vibration platform with and without vibratory stimuli. The vibration protocol included six sets lasting for 30 s each with a 30-s rest between sets. The main outcome measures included the upper limb static stability test, Upper Quarter Y Balance Test (UQYBT), and electromyography data of the upper limb. RESULTS: Vibratory stimuli resulted in an increased UQYBT score (all directions; P&lt; 0.01) and infraspinatus, serratus anterior, and lower trapezius muscle activity (P&lt; 0.05) between pre- and post-exercise versus the control condition. Stabilometric parameters showed no significant interaction between condition and time. CONCLUSIONS: Vibratory stimuli could maximize training benefits while limiting injury risk for athletes. Our findings could guide the development of rehabilitation programs for patients with shoulder instability.

The relationship between motor unit (MU) firing behavior and the severity of neurodegeneration in Parkinson’s disease (PD) is not clear. This study aimed to elucidate the association between degeneration with dopaminergic pathways and MU firing behavior in people with PD. Fourteen females with PD (age, 72.6 ± 7.2 years, disease duration, 3.5 ± 2.1 years) were enrolled in this study. All participants performed a submaximal, isometric knee extension ramp-up contraction from 0% to 80% of their maximal voluntary contraction strength. We used high-density surface electromyography with 64 electrodes to record the muscle activity of the vastus lateralis muscle and decomposed the signals with the convolution kernel compensation technique to extract the signals of individual MUs. We calculated the degree of degeneration of the central lesion-specific binding ratio by dopamine transporter single-photon emission computed tomography. The primary, novel results were as follows: (1) moderate-to-strong correlations were observed between the degree of degeneration of the central lesion and MU firing behavior; (2) a moderate correlation was observed between clinical measures of disease severity and MU firing behavior; and (3) the methods of predicting central nervous system degeneration from MU firing behavior abnormalities had a high detection accuracy with an area under the curve &gt;0.83. These findings suggest that abnormalities in MU activity can be used to predict central nervous system degeneration following PD.

Changes in the daily lives and mental health of people with disabilities due to the coronavirus disease (COVID-19) pandemic have not been reported. The Japanese government closed public facilities, including swimming pools, during the first wave of COVID-19, and many competitive swimmers lost their places of activities. This study aimed to investigate the impact of the COVID-19 pandemic on life space and apathy among swimmers and investigated differences in the impact on swimmers with and without disabilities. A total of 39 competitive swimmers participated in this study, including 11 male and nine female swimmers with disabilities (swimmers with disabilities = para-swimmers), and e11 male and eight female swimmers without disabilities. Baseline and follow-up web-based questionnaire surveys were conducted, and changes in life space and apathy scale (AS) were assessed. Female para-swimmers showed significantly lower apathy than female able-bodied subjects (para, during; 16.0 ± 1.9; after, 12.8 ± 3.2; non-disabled; during, 10.5 ± 4.4; after, 10.6 ± 4.8; p &lt; 0.05). Female swimmers with disabilities may be more likely to experience worsening mental health due to changes in their lifestyle.

Background: Shoulder microinstability is often overlooked, which can be problematic, especially in overhead athletes. The slipping phenomenon is defined as posterior or lateral sliding of the humeral head in an elevated arm. When the shoulder is close to the end range of stability, the infraspinatus is highly activated and keeps the shoulder in the glenoid cavity. This study aimed to examine the characteristic physical function and infraspinatus activity during the pitching motion in baseball pitchers with shoulder instability. Methods: Twenty-one male baseball pitchers participated and were divided into 2 groups based on radiograph findings at zero position: slipped (group S) and nonslipped (group N) groups. Physical function using Hara test and infraspinatus muscle activity during pitching were evaluated. Results: The infraspinatus muscle activity during the acceleration phase was significantly greater in group S (59.5 ± 33.0%MVC) than in group N (33.0 ± 16.9%MVC) (P < .05). Positive rate of the Hara test in group S was significantly high in the loose test and elbow push test. Conclusions: This study shows that baseball pitchers with slipping phenomenon have capsular laxity and scapular instability that indicate high infraspinatus muscle activity during the acceleration phase. Therefore, repetitive pitching with hyperactivity of the infraspinatus on the slipping shoulder may cause fatigue and dysfunction.

The plantar fascia and intrinsic foot muscles (IFM) modulate foot stiffness. However, it is unclear whether the corresponding ultrasonography findings reflect it. This study aimed to examine the effect of the plantar fascia and IFM morphologies on force attenuation during landing and reactivity when jumping in healthy adults (n = 21; age, 21-27 years). Thickness, cross-sectional area (CSA), and hardness of the plantar fascia, abductor hallucis (AbH), and flexor hallucis brevis (FHB) muscles were measured using ultrasonography. Single-leg drop landing and repetitive rebound jumping tests assessed the ground reaction force (GRF) and reactive jump index (RJI), respectively. The CSA of FHB was negatively correlated with maximum vertical GRF (r = -0.472, p = 0.031) in the single-leg drop landing test. The CSA of AbH was negatively correlated with contact time (r = -0.478, p = 0.028), and the plantar fascia thickness was positively correlated with jump height (r = 0.615, p = 0.003) and RJI (r = 0.645, p = 0.002) in the repetitive bound jump test. In multivariate regression analysis, only the plantar fascia thickness was associated with RJI (β = 0.152, 95% confidence interval: 7.219-38.743, p = 0.007). The CSA of FHB may contribute to force attenuation during landing. The thickness of the plantar fascia and CSA of AbH may facilitate jumping high with minimal contact time.

BACKGROUND: Individuals with a unilateral lower-limb amputation (LLA) rely heavily on their intact limb during daily physical activities. However, there is limited research on the resultant effects of this over-reliance on contractile properties of muscles in the intact limb. OBJECTIVE: To compare the muscle contractile properties of the intact limb among individuals with a unilateral LLA to those of age-matched able-bodied individuals, using tensiomyography. STUDY DESIGN: This is a cross-sectional, observational study. METHODS: Nine men with a unilateral LLA and 10 able-bodied men (control) were included. Tensiomyography measures were obtained for 5 muscles: gastrocnemius lateralis (GL) and medialis (GM), rectus femoris, vastus lateralis (VL), and vastus medialis. Contraction time (Tc), delay time (Td), maximal displacement (Dm), and velocity of deformation (Vd) for each muscle were compared between groups. RESULTS: Tc and Td for the GL and GM muscles were lower for the LLA than the control group (GL: P = .03, r = -0.51, P < .01, r = 0.67; GM: P = .02, r = 0.53, P = .07, r = 0.54, respectively). Dm and Vd of the VL were significantly smaller in the LLA than the control group (P < .01, r = 0.73, P < .01, r = 0.23, respectively). CONCLUSIONS: Men with a unilateral LLA seem to have slower deformation of the gastrocnemius muscles and higher stiffness of the VL than able-bodied controls. These findings may be indicative of an overuse of the intact limb as a compensation for the unilateral LLA. The confirmation of these findings in a larger sample size is required to translate these findings to practice.

The aim of this report was to examine the safety of physical therapy for hemiplegia in a patient with neuromyelitis optica in the acute phase. A 32-year-old female with neuromyelitis optica diagnosed by magnetic resonance imaging had a T2-weighted hyperintense lesion in the central cord from C2 to T2 and was positive for serum anti-aquaporin-4 antibodies. Upon admission to the hospital, her Expanded Disability Status Scale, Medical Research Council scale for muscle strength score, and sensory score (according to the American Spinal Injury Association sensory assessment) were 9.0, 37, and 158, respectively. The patient commenced physical therapy on day 4. A locomotion exercise using an orthosis was started as soon as possible. Her left-side limb muscle strength improved to approximately grade 4 by a manual muscle test with improvements in the Expanded Disability Status Scale score (from 9.0 to 6.0), Medical Research Council scale for muscle strength score (from 37 to 54), sensory score (from 152 to 203), and all functional independence measure dominants compared with the respective values on admission. This report shows that a carefully supervised physical therapy program did not cause deterioration of the patient’s symptoms.

Background: Despite the potential benefits, the effects of Hybrid Assistive Limb (HAL) gait training on changes in neuromuscular activation that accompany functional gains in individuals with spinal muscular atrophy (SMA) type III is not well known. In this article, we quantify the effects of HAL gait training on spatial muscle activity patterns in a patient with SMA type III using multi-channel surface electromyography (SEMG). Methods: A 21-years old male (168 cm, 47.8 kg) with spinal muscular atrophy type III, when diagnosed at 18-years old by genetic screening, participated in this case study. Although he presented with forearm distal muscle weakness, atrophy of the intrinsic muscles of the hand, and neuromuscular fatigue, his activities of daily living is independent. The patient underwent a separate, single 33-minute session of both HAL and treadmill gait training. To evaluate the coefficient of variation (CoV) of force and alterations in the SEMG spatial distribution patterns, modified entropy and CoV of root mean square (RMS) were calculated from the vastus lateralis (VL) muscle before and after the intervention of HAL and treadmill gait training. Each training session was separated by a period of one month to avoid cross-over effects. Results: There was a greater decrease in the ΔCoV of force and an increase in the magnitude of whole VL muscle activation from pre-intervention to post-intervention with the HAL gait training as compared to the treadmill gait training. In response to only HAL gait training, the CoV of RMS was higher, and the modified entropy was lower post-intervention than pre-intervention. Conclusions: Our results support the notion that HAL gait training has a positive benefit on motor output not only in the magnitude of SEMG generated but also the patterns of neural activation.

The aim of this study was to investigate the static balance ability by generation from teens to 80’s. Subjects were 541 subjects who participated in our physical fitness measurement project and measured one leg standing time with eye closed. The standing time was measured for up to 60 seconds, and the rate of under 30 seconds group was compared across generations. The maximum average of one leg standing time was 42.8 seconds in 20’s and 30’s. On the other hand, the average time of teens was 33.0 seconds. The average time of 60’s was significantly lower than that of teens (p<0.05). Static balance ability is important to prevent fall for elderly people. Static balance ability was lower in teens than 20’s and 30’s. This result indicated that it was necessary for this generation to prevent the reduction of static balance ability.

[Purpose] Locomotion training is recommended as a countermeasure against locomotive syndrome. Recently, whole-body vibration has been clinically applied in rehabilitation medicine. Therefore, we aimed to investigate the preliminary effectiveness of whole-body vibration on locomotion training. [Participants and Methods] Overall, 28 healthy adult females were randomly assigned to either a locomotion training group using a whole-body vibration device (whole-body vibration group, n=14) or training on the flat floor (non-whole-body vibration group: n=14). Participants conducted two sets of locomotion training twice a day and three times a week for 12 weeks. [Results] A significant difference was observed in the group factor for all outcome measures and in the before and after the training factor for Timed Up and Go test. After the training, knee muscle strength, dynamic balance, and mobility function in the whole-body vibration group were significantly improved compared with the non-whole-body vibration group. In the whole-body vibration group, the Timed Up and Go time after the training was significantly shorter compared with that before training. [Conclusion] The results suggest that locomotion training with whole-body vibration can improve the physical functions in healthy adult females and locomotion training using whole-body vibration might enhance the effectiveness of locomotion training.

[Purpose] Muscle quantity (e.g., cross-sectional area) and quality (e.g., muscle adipose tissue), which are muscle strength determinants, can be assessed using ultrasonography. The study aimed to investigate the changes in the quantity and quality of the peroneus longus and evaluate evertor strength in legs with chronic ankle instability (CAI). Furthermore, the associations among cross-sectional area, echogenicity, evertor strength, and frequency of ankle sprain were examined. [Participants and Methods] Nine males with CAI in unilateral legs were the voluntary participants in this study. The cross-sectional area of the peroneus longus, echogenicity, and evertor strength were measured for all the participants on the sides with CAI and that without. [Results] No significant difference in cross-sectional area was observed between the sides. Significant differences in echogenicity (higher on the CAI side) and evertor strength (lower on the CAI side) were observed between the sides. In addition, a moderate correlation was observed between echogenicity and increased sprain frequency on both sides. [Conclusion] Muscle adipose tissue increased, evertor strength decreased, and the cross-sectional area remained unchanged on the CAI side. The study results suggested that muscle adipose tissue increases with increasing frequency of ankle sprain.

[Purpose] Amputee soccer is a game for individuals with amputations. Players use lofstrand crutches to move around the field and kick the ball. Scoring quick goals during a match requires players to have maximum running skills. Notably, a few parameters affect the running speed in players; however, no study has reported the biomechanical analysis of running in amputee soccer. Thus study aimed to analyze the biomechanics of single-leg running using lofstrand crutches in 12 healthy adult males (6 with prior amputee soccer experience and 6 without such experience). [Participants and Methods] The kinematics of the lower limb and the pelvis, the ground reaction force, and skill in using the crutches were evaluated using 3 dimensional motion analysis combined with 8 force plates. Lower leg amputation was simulated in all participants by maintaining the non-dominant knee in a position of maximum flexion using an elastic band. [Results] Significant differences were observed between experienced and non-experienced participants with regard to the angle of the pelvis and the crutch stance phase. Specifically, higher running speed was associated with an increased forward tilt of the pelvis and a shorter crutch stance phase. [Conclusion] These findings will be useful to improve the running speed of amputee soccer players.

<sec sec-type="context"><title>Context:</title>Whole-body-vibration (WBV) stimulus equipment has been used as a new training method for health promotion. Its use in the clinic has expanded to the field of sports and rehabilitation for disabled patients. WBV training is rapidly gaining popularity in health and fitness centers as an alternative method for improving muscle performance. Acute positive effects of WBV have been shown on lower-extremity muscle power and vertical-jump ability; however, there have not been any studies focusing on the long-term effects of WBV for trunk muscle and dynamic balance.

</sec><sec sec-type="objective"><title>Objective:</title>To investigate the effects of an 8-wk program of WBV in combination with trunk-muscle training on muscle performance in healthy, untrained adults.

</sec><sec sec-type="design"><title>Design:</title>Laboratory-based, repeated-measures study.

</sec><sec sec-type="setting"><title>Setting:</title>University laboratory.

</sec><sec sec-type="participants"><title>Participants:</title>20 healthy university men.

</sec><sec sec-type="intervention"><title>Intervention:</title>Participants were randomly assigned to a WBV or non-WBV group. The WBV group performed a trunk-muscle-training program in combination with WBV; the non-WBV group performed the same muscle-training program without WBV for 8 wk.

</sec><sec sec-type="main outcome measures"><title>Main Outcome Measures:</title>In the pre- and posttraining period, the participants were evaluated using the Functional Movement Screen (FMS), Y Balance Test (Y-test) (anterior, posteromedial, and posterolateral reach), trunk-muscle isometric strength (flexor, extensor, and flexor:extensor ratio), squat jump, and countermovement jump.

</sec><sec sec-type="results"><title>Results:</title>The WBV group had greater improvement than the non-WBV group in both trunk-flexor muscle strength (<italic>P</italic> = .02) and the Y-test (anterior reach) (<italic>P</italic> = .004) between pre- and posttraining.

</sec><sec sec-type="conclusion"><title>Conclusion:</title>Adding WBV to a trunk-muscle-strengthening program may improve trunk-flexor isometric strength and anterior reach during the Y-test more than training without WBV. The WBV protocol used in this study had no significant impact on FMS scores, squat jumping, countermovement jumping, trunk-extensor isometric strength, or trunk flexor:extensor ratio.

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OBJECTIVE: To investigate the differences in energy consumption by patients with hip disarticulation between prosthetic walking and wheelchair locomotion. DESIGN: : The subjects consisted of seven amputees, all older than 60, with unilateral hip disarticulation. Energy consumption when walking with prosthesis and when propelling a wheelchair, each at the respective comfortable movement speed, was measured by means of a portable telemetric system. RESULTS: The average comfortable movement speed for prosthetic walking was 30.5 m/min, which was much slower than the 63.1 m/min average for wheelchair locomotion (P < 0.01). The average oxygen cost value for prosthetic walking was 0.639 ml/kg/m, and the average for wheelchair locomotion was 0.175 ml/kg/m, indicating that oxygen cost was significantly higher for prosthetic walking than for wheelchair locomotion (P < 0.01). CONCLUSIONS: The results of this research clearly showed that the efficiency of prosthetic walking for elderly hip disarticulation amputees was very low. When the subject is judged not to be a candidate for practical prosthetic walking after a careful multidisciplinary evaluation, wheelchair locomotion may be an alternative to prosthetic walking as a realistic goal.