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Abstract The level of dynamic mechanical instability between the bony parts of the ankle joint provides important information on biomechanical function. However, the dynamics of the distance between the talus and lateral malleolus during gait remain unclear. This study aimed to compare the distance between the talus and lateral malleolus and the ankle joint angles during the stance phase of gait between individuals with chronic ankle instability (CAI) and healthy adults. The comparison was conducted using a synchronized ultrasound (US) imaging with a three-dimensional motion analysis (MA) system. This cross-sectional study included 12 participants (5 males, 7 females; age, 20.5 ± 1.8 years; height, 166.6 ± 9.4 cm; body weight, 60.2 ± 5.3 kg; body mass index, 21.7 ± 2.0 kg/m2; 16 feet) with CAI and 10 healthy controls (4 males, 6 females; age, 21.2 ± 1.6 years; height, 164.6 ± 10.5 cm; body weight, 56.8 ± 11.3 kg; body mass index, 20.8 ± 2.6 kg/m2; 20 feet). The distance between the talus and lateral malleolus during gait was significantly increased in the CAI group compared with that in the control group throughout the stance phase. The ankle dorsiflexion angle was smaller in the CAI group during the middle and terminal stance phases. Additionally, the ankle inversion angle was greater in the CAI group than in the control group. Our findings show the application of the synchronized US and MA system in the assessment of mechanical instability in CAI group, which may be used to determine treatment efficacy.

Abstract This study aimed to translate a web-based hamstring outcome score (HaOS) questionnaire to the Japanese context. First, the validity and reliability of the translated questionnaires were examined among Japanese athletes. Second, the association between the previous history of hamstring strain and HaOS was examined. The translation was performed according to internationally recognized methodologies. A total of 233 athletes were asked to complete the HaOS questionnaire, and four questions were added to examine the content validity of the questionnaire. Intraclass correlation coefficient (ICC) was calculated to evaluate the test–retest reliability. Internal consistency was determined by calculating Cronbach’s alpha values. The translated questionnaires had high acceptance and compliance rates, with a response rate of 84.4%. The ICC for each scale ranged from 0.80 to 0.93, and Cronbach's α from 0.72 to 0.96, confirming good reliability and high internal consistency. HaOS of the previous injury group (93.4 [78.9, 100]) was significantly lower than that of the healthy group (86.2 [68.1, 100]) (p

Abstract The forced turnout has a perceived risk of development of hallux valgus (HV) in ballet dancers. We determined how the forced turnout affects the sagittal mobility of the first tarsometatarsal (TMT) joint, which is one of the pathogenic factors of HV development. Seventeen female ballet dancers (body mass index: 18.2 ± 1.8 kg/m2) were included and performed demi-plié in control, functional turnout, and forced turnout conditions. Ultrasound imaging synchronized with a three-dimensional motion analysis system was used for measuring the vertical locations of the first metatarsal and medial cuneiform (MC) to evaluate the first TMT joint mobility. Plantar displacement of MC and the first TMT joint mobility in the forced turnout were the greatest among the 3 conditions. Multiple regression analysis indicated that the greater extent of the forcing angle might increase the displacement of MC and the first TMT joint mobility. Evaluating the sagittal mobility of the first TMT joint in the forced turnout can assist in understanding the association between inappropriate techniques including the forced turnout and HV development in ballet dancers. Since the excessive mobility of the first TMT joint is a factor in HV development, the acquirement of adequate active turnout may have the potential to prevent HV development in ballet dancers.

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.

Objective In Tokyo 2020 Paralympic Games, there were the rule and goal size changes at the blind football competition. This study aimed to compare the scoring and head impact characteristics during blind football competition between the Rio 2016 and Tokyo 2020 Paralympic Games using the official videos.Design Video-based observational study.Participants In total, 36 blind football (men’s football 5-a-side) game videos were obtained from the official International Paralympic Committee.Primary and secondary outcome measures Head impact was defined as the sudden contact of any object with the head. Videos were analysed to assess the number of scores and head impacts along with their corresponding details (ie, round, playing phase, scoring situation, impact situation, occurrence area, impact object, head impact site, fall and foul).Results The total number of goals scored at the Tokyo 2020 Paralympic Games was nearly double that at the Rio 2016 Paralympic Games. Regarding head impacts, a total of 2036 cases (Rio 2016, n=1105; Tokyo 2020, n=931) were evaluated. Significant differences were observed in head impact characteristics between the Rio 2016 and Tokyo 2020 Paralympic Games among seven outcomes (round, scoring situation, impact situation, occurrence area, impact object, site of head impact and fall).Conclusions Compared with the Rio 2016 Paralympic Games, the Tokyo 2020 Paralympic Games showed an increase in the number of points scored and different head impact characteristics.

Pelvic floor muscle (PFM) exercises have been shown to strengthen PFM function and improve urinary incontinence (UI) symptoms. Several studies have focused on voluntary PFM activity changes among various supine postures. However, few studies have investigated standing postures that promote PFM contraction. Since patients often complain of UI symptoms in the standing position, knowing which posture during voluntary PFM contraction in the standing position promotes contraction would be useful from the viewpoint of issuing exercise instructions and improving prevention. This study aimed to investigate adequate standing postures for PFM contraction and included nine healthy women. All participants performed maximum voluntary contraction (MVC) of PFM in six standing postures: neutral, abduction, adduction, neutral-external rotation, abduction-external rotation, and adduction-external rotation. The MVC of PFM, adductor magnus muscle, and internal oblique muscles were measured in each posture, and muscle activities were recorded using surface electromyography. We compared muscle activity, with and without hip joint external rotation, in the neutral, abduction, and adduction positions, and looked for increased muscle activity of PFM in standing postures with hip joint external rotation compared to standing positions without hip joint external rotation (p < 0.01). Since PFM contracts in conjunction with hip adductors and external rotators, the activity of PFM may have been higher in the standing posture with hip external rotation. Selecting the effective posture is important to increase PFM activity.

BackgroundIn response to the serious lack of physical activity among young adults, recent attempts have been made to encourage young people to exercise through exercise video distribution. However, merely distributing videos does not lead to improved physical activity levels. Metaverse space, which enables web-based interaction through avatars, allows users to watch exercise videos in the same space as other avatars. ObjectiveThis study explored whether exercise video distribution using metaverse space is effective in improving physical activity levels, along with mental health and locomotive function, among young people. MethodsIn this parallel-group randomized controlled trial participants were recruited using printed poster displays. A total of 48 young adults aged between 18 and 30 years were assigned to 3 groups of 16 each: the metaverse, YouTube, and control group. To encourage exercise, the metaverse group was given an exercise video each week with a load of around 4-8 metabolic equivalents of tasks (METs) for 8 videos delivered in the metaverse space. The YouTube group was sent a URL on YouTube every week to view exercise videos with the same content as the metaverse group. The control group was given no special instructions. The intervention period was 8 weeks. Pre- and postintervention physical activity, well-being, locomotive syndrome risk tests, and social capital were measured. Although this study was not blinded to the participants, the measurers did not know to which group the participants belonged. Mixed model repeated-measures analyses and a post hoc Wilcoxon signed rank sum test were performed to detect the effects of the intervention in all groups. ResultsThe results of the mixed model repeated-measures analyses showed a significant interaction between groups and before and after the intervention for total physical activity (metaverse group: pre 737.1, SD 609.5 METs/week, post 1575.4, SD 1071.8 METs/week; YouTube group: pre 661.7, SD 710.7 METs/week, post 911.9, SD 1103.3 METs/week; and control group: pre 930.6, SD 665.1 METs/week, post 844.7, SD 701.8 METs/week; P=.04) but none for the indicators of well-being (P=.40), locomotive function scale (P=.17), and social capital (P=.23). A post hoc test showed a significant increase in physical activity in the metaverse group before and after the intervention (P=.006). ConclusionsThis study is the first to show that delivering exercise videos through metaverse space can increase physical activity in young adults by providing a gathering space for individuals similarly motivated for exercise practice. This way, the sense of isolation during exercise is reduced compared with merely distributing videos on YouTube. The use of metaverse space in health promotion is likely to spread, and this study provides a useful reference for its exploration. Trial RegistrationClinicalTrials.gov NCT06019156; https://ichgcp.net/clinical-trials-registry/NCT06019156

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.

Category: Other Introduction/Purpose: The peroneal muscles undergo morphological changes and functional decline after a lateral ankle sprain, contributing to recurrence. We reported that different morphological changes occur in the peroneus longus (PL) and peroneus brevis (PB) after the lateral ankle sprain (Arima et al., 2022), and we believe that separate strength training for the PL and PB is necessary. However, the effect of selective training has not been studied. This study examined the acute effects of two different strength training interventions on PL and PB muscle morphology, one emphasizing loading on the ball of foot in PL training and the other emphasizing ankle eversion in PB training. The aim was then to determine the validity of selective strength training interventions for the peroneal muscles. Methods: Twenty healthy adults participated. Two training interventions were performed using a Thera-Band (strength: level +3 (black), Sakai Medical) in the right leg on separate days: the PL intervention in which the Thera-Band was placed on the ball of foot and pushed out from the contact point, and the PB intervention in which the Thera-Band was pushed out from the base of the fifth metatarsal. Muscle cross-sectional area (CSA) and thickness of the peroneus muscles at the proximal 25% (showing PL) and 75% (showing PB) from the line connecting the fibular head and lateral malleolus were measured with an ultrasound device. Measurements were taken before (Pre), immediately after (Post), and 10, 20, and 30 minutes after the intervention (time effect). A repeated measures two-way ANOVA was conducted to identify differences in the training effects of PL and PB interventions on PL and PB CSA, thickness. The significance level was 5%. Results: Significant main effects of time and intervention and a significant interaction between time and intervention were found in the proximal 25% and distal 75% CSA and thickness (p < 0.05). For the proximal 25% CSA, only PL intervention significantly increased the CSA compared to Pre at Post, 10 and 20 minutes (p < 0.05). With regard to the proximal 75% CSA, only PB intervention significantly increased the CSA compared to Pre at Post, 10 and 20 minutes (p < 0.05). For the proximal 25% thickness, only PL intervention showed a significant increase in Post compared to Pre (p < 0.05). Regarding proximal 75% thickness, only PB intervention significantly increased the thickness compared to Pre at Post, 10, and 20 minutes (p < 0.05). Conclusion: Previous studies have reported that PL muscle activity is increased by the ball of foot loading (Ishida et al., 2011), and the PB contributes to ankle eversion compared to the PL (Otis et al., 2007). Transient muscle hypertrophy immediately after training is due to edema caused by muscle damage, indicating an acute effect of training (Damas et al., 2016). The CSA and thickness of the proximal 25% showing PL in the PL intervention and the distal 75% showing PB in the PB intervention increased immediately after those interventions in this study, suggesting the possibility of selectively training PL and PB.

Category: Sports; Ankle Introduction/Purpose: In general, Static Stretching (SS) is widely used during warm-ups and cool-downs at competitive practices and events. Previous studies have shown that SS have improved muscle stiffness. On the other hand, previous studies have not shown range of motion, or vertical jump. Recently, acute effects of Cyclic Stretching (CS) have suggested to improve muscle stiffness and dynamic balance. CS is moved at a constant speed and angle using continuous passive and dynamometer-equipped exercise equipment. However, long-term CS and SS programs have been shown to improve muscle stiffness, hardness, and It is not known if muscle strength or physical performance is altered. This study aimed to examine the effects of a 4-week CS and SS program on muscle stiffness and hardness, muscle strength, and jump performance. Methods: The subjects participated 18 healthy men and were randomly assigned to a CS or SS group. Each stretching program was stretched in each condition for 2 minutes in a standing position in 5 days a week for 4 weeks. To assess muscle stiffness, muscle- tendon junction (MTJ) displacement and MTJ angle of gastrocnemius medialis (MG) were measured using ultrasonography and 20° before (pre-training) and after (post-training) conducting CS and SS program. MG hardness was measured using ultrasound real- time tissue elastography (RTE). ROM max and normalized peak torque (NPT) of ankle plantar flexor, squat jump (SJ) performance were measured in the pre- and post-training. The effects of the intervention on all outcome measures were determined using 2- way repeated-measures ANOVA with two group as a between participants factor and time (pre-training, post-training) When interaction effects were detected, post hoc comparisons were performed to test the differences in physical variables between pre- and post-training. Results: ROM max was significantly affected by time between CS and SS program (P < .001, F = 26.0). MTJ displacement from 0°to 20°were significantly affected by time (P < .05, F = 5.49; P < .01, F = 10.26; P < .01, F = 9.74). RTE from 0°to 20°were significantly affected by time (P < .01, F = 13.27; P < .01, F = 8.33; P < .01, F = 53.52). There was significantly interaction for NPT between CS and SS program (P < .01, F = 4.80). SJ were significantly affected by time (P < .05, F = 5.70). Conclusion: This study examined the long-term effect of CS and SS on ROM max, muscle stiffness, NPT, and SJ. The results indicate that CS training had greater improvement than SS training in muscle strength between pre- and post-training. A significant decrease in muscle stiffness and hardness after SS was observed compared with CS. However, CS not only improves muscle stiffness and hardness as shown the effect of SS but also suggests the possibility of being a new extension method to improve muscle strength.

Category: Ankle; Trauma Introduction/Purpose: It has been reported that there are no significant sex differences in muscle hypertrophy response after strength training for the quadriceps muscles (Roth et al., 2002). After an ankle sprain, the peroneus longus (PL) and peroneus brevis (PB) muscles develop morphological changes and dysfunction, which requires training for the PL and PB (Arima et al., 2022). However, to our knowledge, sex differences in muscle hypertrophic response to the PL and PB training have not been studied. This study aimed to compare the changes in muscle cross-sectional area (CSA) after the PL and PB training between men and women, and to examine the possible influence of sex on the muscle hypertrophy response to training for the PL and PB. Methods: Eighteen healthy adults (9 men and 9 women) were participated. All participants performed two types of ankle eversion training on the right leg with Thera-Band on separate days. PL training in which the Thera-Band was placed on the ball of foot and pushed out from the contact point, and PB training in which the Thera-Band was pushed out from the base of the fifth metatarsal. An ultrasound imaging device was used to measure the CSA of the peroneal muscles at the proximal 25% and distal 75% of the line connecting the fibular head and the lateral malleolus. The measurements were taken before (pre), immediately after (post), 10, 20, and 30 minutes after each training, and the amount of change over time relative to pre was calculated. Unpaired t-tests were used to compare the change in CSA between men and women at each time. Statistical significance was set at 5%. Results: After the PL training, the amount of change in CSA of the PL was significantly greater by 29.7 mm² in women than in men only at post (p < 0.05), but there were no significant differences at other times (10 minutes: p = 0.06, 20 minutes: p = 0.19, 30 minutes: p = 0.11). After the PB training, the amount of change in CSA of the PB was significantly greater by 16.0 mm² at post (p < 0.05) and 3.1 mm² at 30 minutes (p < 0.01) in women than in men. However, there were no significant differences at 10 and 20 minutes (10 minutes: p = 0.27, 20 minutes: p = 0.55). Conclusion: The results indicate that sex differences may influence the immediate muscle hypertrophic response to training for the PL and PB. The immediate muscle hypertrophy response after training is due to edema resulting from muscle damage, reflecting an immediate effect of training (Damas et al., 2016), which suggests that women are more likely to achieve effects of the PL and PB training than men in similar loads. Furthermore, the results also show that the effect of the PB training may be maintained longer in women, thus it is necessary to investigate the long-term effects of the training in the future.

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.

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 Sedentary behavior, particularly prevalent during the 2019 coronavirus disease (COVID-19), has been shown to lead to depression. In medical students, this could negatively affect the provision of healthcare. Thus, this study aimed to investigate the association between sedentary behavior and depression in Japanese medical students during the COVID-19 pandemic. Methods An online cross-sectional survey was conducted from July 30 to August 30, 2021, using anonymous questionnaire system to assess respondents’ sociodemographic characteristics, physical activity, sedentary behavior among 1000 Japanese university students. Depression was assessed using the Patient Health Questionnaire-2 (PHQ-2). The data of 484 respondents (48.4%) were included in a stepwise analysis, where we set the difference between medical and non-medical students as Model 1 and that between medical students with and without depression as Model 2. For group comparisons of both models, the chi-square test was used for sociodemographic characteristics, and the Mann–Whitney U-test was used for physical activity and sedentary behavior. In Model 2, factors associated with depression among medical students were analyzed by logistic regression analysis. Results In Model 1, medical students were less physically active (p

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

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

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.

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

Background: Because the worldwide spread of coronavirus disease 2019 has forced a moratorium on student sports activity in Japan, reports on its impact on sports injuries are limited given its novelty. This study aimed to determine the characteristics and gender differences of injuries in adolescent athletes after returning to sport following restriction of club activities due to the coronavirus pandemic. Methods: An online retrospective questionnaire was distributed to 500 adolescent athletes who belong to school sports clubs in Japan from March 1–19, 2021. An anonymous questionnaire was created before and after the restriction of sports activities following the declaration of the first state of emergency of the COVID-19 pandemic in Japan. Subsequently, 258 valid responses were obtained, and injury-related characteristics were compared between injured and non-injured athletes after returning to sports and between genders for injured athletes. There were no differences in the body areas of sports injuries between males and females. Result: We found that injury experience before club activity restriction was significantly associated with injury after returning to sports (p < 0.001). Moreover, practice time increased before and after the restriction in the injury group (p = 0.038). The injury rate was higher in females (p < 0.024), and the trauma rate was higher among males (p = 0.016). There were no differences in the body areas of sports injuries between males and females. Conclusions: Our results provide gender-differentiated ideas and suggestions as they relate to injury prevention once in adolescent athletes returning to sports after the coronavirus disease 2019 induced restriction of club activities. We show the need for injury rehabilitation and practice time control in adolescent athletes in the coronavirus disease 2019 setting.

ObjectivesTo present the fall characteristics of athletes playing wheelchair rugby (WR) and wheelchair basketball (WB) using official videos from the Rio 2016 Paralympic Games and compare the key fall characteristics among the team wheelchair sports event.MethodsEighteen WR and 10 WB game videos for men (MWB) and women (WWB), including 8 teams per sport, were obtained from the official International Paralympic Committee of the Rio 2016 Paralympic Games. The videos were analysed to assess the number of falls, playing time of fall, playing phase, contact with other athletes, the direction of the fall and the body part first in contact with the floor during the fall.ResultsIn total, 359 falls (96 for WR, 172 for MWB and 91 for WWB) occurred with a mean of 5.3, 17.2 and 9.1 falls per match, respectively (p

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.

Background and Objectives: Double poling is an important fundamental skill required for cross-country skiing in able-bodied athletes and in those with physical disabilities. Meanwhile, the performance improvement and injury prevention related to double poling requires a thorough assessment, whereas the scapular and shoulder kinematics in different postural conditions remain to be clarified. The main purpose of this study was to evaluate the biomechanics during cross-country ski double poling in the standing and sitting positions. Materials and Methods: Eleven participants underwent kinematic assessments of the shoulder girdle during double poling on a ski ergometer with an electromagnetic tracking device. The cycle rate, stroke length, stroke speed, thorax motion relative to pelvis, scapular motions relative to thorax, humeral motions relative to thorax, and humeral motions relative to scapula were calculated for five double-poling cycles. Results: In the sitting position, the angles of humerothoracic elevation were 18 degrees larger and glenohumeral elevation 13 degrees larger than in the standing position at the upward point and range of motion. Conclusions: The study revealed that double poling in the sitting condition increased the humerothoracic and glenohumeral elevation angle to secure the poling margin. If these are excessive, there is a risk of shoulder injuries such as subacromial impingement.

Virtual reality (VR)-based rehabilitation has been used in lower limb amputees; however, the extent to which VR is effective in reacquiring symmetrical gait in lower limb amputees is unclear. The purpose of this study was to confirm whether a VR intervention is effective in obtaining a simulated prosthetic gait. The participants were 24 healthy males who had never worn a simulated prosthesis. They were divided into three groups: VR, tablet, and control groups. The intervention consisted of 5 min of in situ stepping on parallel bars and watching a video of a simulated prosthetic leg walker on a head-mounted display or a tablet. Measurements included Gait Up parameters during a 10-m walk and immersion scores. After the intervention, there was a significant interaction between walking speed and leg swing speed in the VR group. The rate of improvement in walking speed and immersion scores was significantly higher in the VR group than in the other two groups, and there was a significant positive correlation between the rate of improvement and immersion scores. Compared to the tablet and control groups, the VR group showed the highest rate of immersion and improvement in walking speed.

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.

This study aimed to evaluate motor unit recruitment during submaximal voluntary ramp contraction in the medial head of the gastrocnemius muscle (MG) by high-density spatial electromyography (SEMG) before and after static stretching (SS) in healthy young adults. SS for gastrocnemius was performed in 15 healthy participants for 2 min. Normalized peak torque by bodyweight of the plantar flexor, muscle activity at peak torque, and muscle activation patterns during ramp-up task were evaluated before and after SS. Motor unit recruitment during the submaximal voluntary contraction of the MG was measured using SEMG when performing submaximal ramp contractions during isometric ankle plantar flexion from 30 to 80% of the maximum voluntary contraction (MVC). To evaluate the changes in the potential distribution of SEMG, the root mean square (RMS), modified entropy, and coefficient of variation (CV) were calculated from the dense surface EMG data when 10% of the MVC force was applied. Muscle activation patterns during the 30 to 80% of MVC submaximal voluntary contraction tasks were significantly changed from 50 to 70% of MVC after SS when compared to before. The variations in motor unit recruitment after SS indicate diverse motor unit recruitments and inhomogeneous muscle activities, which may adversely affect the performance of sports activities.

Background and objectives: The long head of the biceps (LHB) and rotator cuff tendinopathy is the major cause of shoulder pain in competitive swimmers. The risk of tendinopathy increases with aging; however, the structural changes of LHB and rotator cuff in populations of masters swimmers have not been well examined. The purpose of this study was to investigate the prevalence of ultrasonographic abnormalities of the shoulders in masters swimmers, and the association of pain, age, and swim training with structural changes in this population. Materials and Methods: A total of 60 subjects participated in this study, with 20 masters swimmers with shoulder pain, 20 asymptomatic masters swimmers, and 20 sex- and age-matched controls. All swimmers completed a self-reported questionnaire for shoulder pain, their history of competition, and training volume. Each subject underwent ultrasonographic examination of both shoulders for pathologic findings in the LHB tendon, rotator cuff (supraspinatus (SSP) and subscapularis (SSC)) tendons, and subacromial bursa (SAB) of both shoulders and had thickness measured. Results: The prevalence of tendinosis (LHB, 48.8%; SSP, 17.5%; SSC, 15.9%), partial tear (SSP, 35.0%), and calcification (SSC, 10.0%) were higher in swimmers than in controls. LHB and SSP tendinosis were associated with shoulder pain. Older age and later start of competition were associated with an increased risk of LHB tendinosis and SSC calcification. Earlier initiation of swimming and longer history of competition were associated with an increased risk of SSP and SSC tendinosis. The thicker SSP tendon significantly increased the risk of tendinosis and partial tear. Conclusions: A high prevalence of structural changes in the rotator cuff and biceps tendons in masters swimmers reflects the effect of shoulder symptoms, aging, and swim training.

Functional predictors of home discharge after hip fractures have been widely reported; however, no study has considered the geographical features surrounding patients’ homes. This study aimed to identify home discharge predictors and determine the cutoff points required for home discharge of patients living in sloped neighborhoods or islands. A total of 437 postoperative hip fracture patients were included and classified into the flat, slope, and island groups according to their residential area before the fracture. Multivariate logistic regression analysis was used to identify significant home discharge predictors, and receiver-operating characteristic analysis to calculate cutoff values. In all the groups, the functional independence measure-motor score was a significant home discharge predictor, with cutoff values of 69 for the flat group and 65 points for the slope and island group. In the slope group, the 6-minute walking distance (odds ratio, 1.02; 95% confidence interval, 1.01–1.04) and revised Hasegawa dementia scale score (odds ratio, 1.06; 95% confidence interval, 1.01–1.12) were also identified as predictors, with cutoff values of 150 m and 18 points, respectively. The outcomes required for home discharge after hip fracture differ depending on the neighborhood terrain, especially for patients living in areas with many slopes and stairs.

Recently, many people are using insoles. They are used for structural and positional imbalance such as foot deformities. However, evidence of their effect remains unclear. The aim of this review is to investigate the scientific evidence on the effect of various insoles. A comprehensive review of the English-language scientific literature was carried out covering the period from April 1980 to January 2013 of MEDLINE, CINAHL and EMBASE databases, to search for articles relating to insoles for the prevention and treatment of lower extremity injuries. When data were available for stratification, we extracted information concerning patients with knee osteoarthritis (15 studies), Diabetes mellitus (3 studies) and other diseases (12 studies), comparisons of different insoles (10 studies), and sports injuries (6 studies). An improvement effect on alignment was found in femorotibial alignment; and it was suggested that such alignment is effective for knee osteoarthritis (OA). The insole has an effect on preventing the progression of the transformation of the foot part of patients with diabetes; and, as a result, it is thought of as an effective therapy for patients with diabetes. This review provides evidence for the beneficial effect of insoles in the treatment of some musculoskeletal disorders. However, some trials were compromised by poor methodology. Likewise, it is necessary to determine the effect of shoes, in addition to insoles, and to investigate their effect in the future.

This study aimed to investigate the 8-week selective training effect of the peroneus longus (PL) and the peroneus brevis (PB) on muscle morphology, echogenicity, and ankle strength and to examine post-intervention detraining effects. Twenty healthy participants without orthopedic disease in the lower extremities were assigned to either the PL intervention group (training consisted of pushing the Thera-Band® out from the ball of the foot to emphasize ankle eversion) or the PB intervention group (training consisted of pulling the Thera-Band® from the base of the fifth metatarsal to enhance ankle valgus and external rotation). Each intervention was performed three times per week for 8 weeks. The cross-sectional area (CSA), thickness, echogenicity, and ankle strength of the PL and the PB were measured before week 1 and after each training session. Detraining effects were evaluated after the 8-week intervention. The results revealed a significant interaction between within-group (week) and between-group (type of intervention) variables on CSA and ankle strength of both the PL and the PB. Over the 8-week training period, the CSA and ankle strength of the PL significantly increased in the PL intervention group, as did the CSA and ankle strength of the PB in the PB intervention group (p < 0.05). The residual effect of muscle hypertrophy was observed during the detraining period. In conclusion, 8- week selective PL and PB training interventions can increase the CSA and ankle strength of these muscles over time. Long-term selective intervention is required to improve peroneus muscle morphology and function, with separate assessments of the CSA and ankle strength of the PL and the PB. [ABSTRACT FROM AUTHOR]

Introduction: Groin pain is one of the prevalent injuries in soccer players.1 Since groin pain takes time to heal and affects the performance of the players, it is necessary to monitor the groin condition regularly to prevent its onset and reccurence. The Groin Injury Screening Questionnaire (GISQ) was developed in Norway to evaluate the groin condition for soccer players.2 GISQ has already been translated in several language, but not into Japanese. Objectives: To develop the Japanese version of the GISQ (GISQ-J), and to examine its validity and reliability. Moreover, to investigate the relationship between a history of groin pain and GISQ-J scores. Study design: Cross-sectional study Methods: The GISQ-J, translated with permission from the original author, was distributed twice to 114 Japanese high school and university soccer players by Google Forms. The second response was given within 72 hours of the first 79 80 response, recalling the condition of the groin at the time of the first response. The GISQ-J is a 100-point scale, with a higher score indicating better groin conditions. Cronbach's α was calculated to assess the validity of each GISQ-J scale, and the intraclass correlation coefficient (ICC) was calculated to evaluate the reliability. In addition, an unpaired t-test was used to compare GISQ-J scores by the presence or absence of a history of groin pain. Results: A total of 60 soccer players (52.6%) responded. Cronbach's α for each scale ranged from 0.71 to 0.97, and the ICC from 0.72 to 0.86. Those with a history of groin pain (n=14) had significantly lower GISQ-J scores than those without (n=46)(p<0.05). Conclusions: The GISQ-J showed good validity and reliability on each scale. The GISQ-J scores were poor with a history of groin pain, suggesting that the GISQ-J may be useful in the evaluation of groin conditions in Japanese soccer players. [ABSTRACT FROM AUTHOR]

Introduction: Blind football is a para-sport played by athletes with severe visual impairments, and ranked second highest of the five levels for concussion risk rate in para-sports competition.1 In Tokyo 2020 Paralympic Games, there were game time and goal size changes at the blind football competition. It is possible that this may have also changed the head impact characteristics in Tokyo 2020, but this has not been examined. Objectives: To compare the head impact characteristics during blind football competition between Rio 2016 and Tokyo 2020 Paralympic Games using the official videos. Study design: Cross-sectional study Methods: All 36 official game videos from the national blind football teams participating in the Rio 2016 and Tokyo 2020 summer Paralympic Games were obtained from the International Paralympic Committee's official website channel YouTube (https://www.youtube.com/c/paralympics). The duration of the match was 50 minutes for Rio 2016 and 40 minutes for Tokyo 2020. Eight teams participated in each Paralympic Game, which consisted of 12 preliminary games and six ranking and final games. The videos were analyzed to assess the number of scores, number of head impacts, and their details (round, playing phase, scoring situation, impact situation, occurrence area, impact object, site of head impact, fall, and foul). Results: The total number of goals scored at the Rio 2016 and Tokyo 2020 were 23 and 45, respectively. The number of head impacts was 1,105 and 931 for Rio 2016 and Tokyo 2020, respectively. Significant differences were observed in head impact characteristics between the Rio 2016 and Tokyo 2020 among seven outcomes (round, scoring situation, impact situation, occurrence area, impact object, site of head impact, and fall). Conclusions: Compared with the Rio 2016 Paralympic Games, the Tokyo 2020 Paralympic Games showed an increase in the number of points scored and different head impact characteristics. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]