Head impact differences in blind football between Rio 2016 and Tokyo 2020 Paralympic Games: video-based observational study.

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.

First tarsometatarsal joint mobility in hallux valgus during gait: A synchronized ultrasound and three-dimensional motion capture analysis.

PURPOSE: To quantify the vertical translation between the first metatarsal and medial cuneiform during the stance phase of gait in young individuals with and without hallux valgus. DESIGN: This cross-sectional observational study included 34 young adults (male, n = 4; female, n = 30) who were divided into three groups according to the hallux valgus angle: control (< 20°, n = 13), mild hallux valgus (≥ 20° to < 30°, n = 12), and moderate hallux valgus (≥ 30°, n = 9). The mobility of the first tarsometatarsal joint was evaluated during the stance phase using B-mode ultrasound synchronized with a motion analysis system. RESULTS: The medial cuneiform shifted more plantar during the early phase in mild hallux valgus and during the middle and terminal phases in moderate hallux valgus than in control. The severity of the hallux valgus was correlated with a trend toward plantar shift of the medial cuneiform. The first metatarsal was located more dorsal than the medial cuneiform; however, there was no significant variation. No significant differences in the peak ankle plantarflexion angle and moment were noted between the groups. CONCLUSION: The hypermobility of the first tarsometatarsal joint, especially plantar displacement of the medial cuneiform in the sagittal plane, was found in young individuals with hallux valgus during the stance phase of gait, and the mobility increased with the severity of hallux valgus. Our findings suggest the significance of preventing hallux valgus deformity early in life.

Relationship of Chronic Ankle Instability With Foot Alignment and Dynamic Postural Stability in Adolescent Competitive Athletes.

Background: Competitive adolescent athletes should be aware of the early signs of chronic ankle instability (CAI) and the connection between the condition and performance. Purpose: To investigate whether CAI is related to foot alignment and morphology as well as dynamic postural stability after a jump landing among adolescent competitive athletes with and without a history of a lateral ankle sprain and CAI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Between July 2020 and August 2021, adolescent competitive athletes (N = 85; n = 49 boys; n = 36 girls) were classified into 3 groups using Cumberland Ankle Instability Tool (CAIT) scores: healthy athletes (n = 55), coper athletes (n = 19), and athletes with CAI (n = 11). Results of foot alignment assessments involving the leg-heel angle (LHA) and navicular height, intrinsic foot muscle morphology, dynamic postural stability index (DPSI), and other parameters were compared among the 3 groups. The relationship between the CAIT score and the LHA and dynamic postural stability and instability were examined using multiple linear regression. Results: Compared with the healthy group, the CAI group had a significantly greater LHA (8.73°± 3.22° vs 6.09°± 3.26°; P < .05), higher DPSI (0.336 ± 0.046 vs 0.298 ± 0.035), and higher vertical stability index (0.303 ± 0.048 vs 0.264 ± 0.037; P < .05 for all). Multiple regression analysis showed that the LHA (ß = -0.228; P = .033) and DPSI (ß = -0.240; P = .025) were significantly associated with the CAIT score . Conclusion: Valgus rearfoot alignment and poorer dynamic postural control were associated with CAI among adolescent athletes.

Effect of postural differences on the activation of intrinsic foot muscles during ramp-up toe flexion in young men.

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.

Head Impact in Blind Football During the Tokyo Paralympics: Video-Based Observational Study.

ABSTRACT: Head impacts during blind football are common and have high injury rates; however, their characteristics and impact are still underreported. We compared head impact characteristics in blind football players with and without falls on all 18 official blind football match videos from the Tokyo 2020 Paralympic games. The rate of head impacts with falls was significantly higher in the preliminary phase, offense phase, and during dribbling. Significant differences in the region of the head impacted were also observed among the impact subjects/objects. The findings in this study would contribute to the development of injury prevention measures to minimize head injuries from head impact in blind football.

Association of the intrinsic foot muscles and plantar fascia with repetitive rebound jumping and jump landing in adolescent athletes: An ultrasound-based study.

BACKGROUND: The characteristics of foot structure in adolescents and adults are different, affecting sports performance and leading to the progression of foot and lower extremity disorders. RESEARCH QUESTION: This study aimed to investigate the relationship between the intrinsic foot muscles (IFM) and plantar fascia morphology and the repetitive rebound jumping and jump landing ability in adolescent athletes. METHODS: A total of 60 adolescent athletes (35 boys and 25 girls) participated in this study. B-mode ultrasonography was used to obtain images of the IFM and plantar fascia morphology [thickness and cross-sectional area (CSA) of the abductor hallucis (AbH), flexor hallucis brevis (FHB), flexor digitorum brevis (FDB), and thickness of the plantar fascia]. The repetitive rebound jump performance was evaluated using the Optojump™ system. Participants were instructed to jump five times continuously with one leg, jumping as high as possible with minimal ground contact time. The jump landing was assessed by measuring the dynamic posture stability index (DPSI) using forward one-legged jump landings. RESULTS: The thickness and CSA of the AbH and FDB were positively correlated with the jump height and reactive jump index. The DPSI score was significantly correlated with the thickness of the AbH, but not with other IFMs or plantar fascia. In the multiple regression analysis, only the thickness of the FDB was associated with the jump height and reactive jump index, indicating that FDB thickness might facilitate adolescent athletes to jump higher with minimal contact time in repetitive rebounding movements. SIGNIFICANCE: The IFM (especially FDB) should be focused on when examining sports performance in adolescent athletes.

Investigation of the Relationship Between the Morphology of the Toe Flexor Muscles in Ballet Dancers and the Postural Stability During Standing on Demi-Pointe: A Cross-Sectional Study.

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-pos- terior 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.

Quantitative evaluation of the vertical mobility of the first tarsometatarsal joint during stance phase of gait.

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.

The relationship between the severity of perimenstrual symptoms and a regular exercise habit in Japanese young women: a cross-sectional online survey.

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.