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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.

Decreased muscle-to-fat mass ratio (MFR) is associated with pediatric nonalcoholic fatty liver disease (NAFLD) and may reduce muscular fitness. Regular exercise in sports clubs has not led to reductions in obesity in children and adolescents, they may have decreased MFR. Decreased MFR could cause reduced muscular fitness, which may put them at risk for NAFLD development. We investigated whether MFR is related to muscular fitness and serum alanine aminotransferase (ALT), to determine whether MFR could be used to screen for NAFLD in children and adolescent boys belonging to sports clubs. Altogether, 113 participants (aged 7–17 years) who underwent body composition, laboratory, and muscular fitness measurements during a medical checkup were divided into tertiles according to their MFR. Lower extremity muscular fitness values were significantly decreased in the lowest MFR tertile (p &lt, 0.001), conversely, serum ALT levels were significantly increased (p &lt, 0.01). Decreased MFR significantly increased the risk of elevated ALT, which requires screening for NAFLD, after adjusting for age, obesity, muscular fitness parameters, and metabolic risk factors (odds ratio = 8.53, 95% confidence interval = 1.60–45.6, p = 0.012). Physical fitness and body composition assessments, focusing on MFR, can be useful in improving performance and screening for NAFLD in children and adolescents exercising in sports clubs.

Objective. The physical condition of athletes can be assessed easily and quantitatively using objective indicators. Bioelectrical impedance measures the phase angle (PA), representing hydration and cell function, and is a potential clinical indicator of physical condition. This study aimed to investigate the association between PA and physical performance in adolescent athletes. Approach. Overall, 170 adolescent athletes underwent a sports medical check-up, including body composition measurements and physical performance tests. Whole-body and segmental PAs (arm and leg) were determined based on body composition values. Isometric grip power and knee isokinetic muscle strength were measured as parameters of muscle strength. Counter movement jump height and squat jump height were measured as jump parameters. Associations between PA and each muscle strength or jump parameters were analysed using Pearson product-moment correlation coefficient or Spearman’s rank correlation coefficient. Main results. Whole-body and upper limb PAs were highly correlated with grip power (r = 0.70–0.80). Whole-body and lower limb PAs were correlated with knee isokinetic muscle strength (r = 0.43–0.59). Whole and all segmental PAs were correlated with counter movement jump height (r = 0.46–0.57) and squat jump height (r = 0.42–0.52). Significance. PA can be used to monitor physical condition and sports performance in adolescent athletes. Segmental PAs can help assess the condition of the corresponding body part.

Design:Randomized controlled study.Setting:Laboratory.Participants:26 healthy swimmers randomly assigned to an exercise (n = 13; Ex) or control group (n = 13; Cont).Intervention:The Ex group performed respiratory-muscle exercises for 10 min thrice a week for 4 wk.Context:Respiratory-muscle exercises are used not only in the rehabilitation of patients with respiratory disease but also in endurance training for athletes. Respiration involves the back and abdominal muscles. These muscles are 1 of the elements responsible for posture control, which is integral to injury prevention and physical performance. However, the effects of respiratory-muscle exercise on posture remain unclear.Objective:To examine the potential of respiratory-muscle exercise for improving posture.Main Outcome Measures:Spinal curvature, pulmonary function, and trunk-muscle strength were measured for both the groups at baseline and after 4 wk. The data were compared between the Ex and Cont groups with Mann–Whitney U test and preintervention and postintervention within groups with a Wilcoxon signed rank-sum test.Results and Conclusion:The spinal curvature was significantly different in the Ex group, indicating a decrease in the thoracic (−13.1%, P < .01) and lumbar (−17.7%, P < .05) angles. The Ex group presented with lower thoracic (−8.6%) and lumbar (−20.9%) angles at postexercise than the Cont group (P < .05). With respect to trunk-muscle strength, only trunk-flexion strength significantly increased from pretest to posttest in the Ex group (P < .05). For pulmonary function, forced vital capacity and forced expiratory volume in 1.0 s were significantly increased after 4 wk in the Ex group (P < .05). The results suggest that respiratory-muscle exercise straightened the spine, leading to good posture control, possibly because of contraction of abdominal muscles.