PURPOSE This study explored foot angle control’s influence on lower extremity joints’ kinematic variables during bodyweight squats in adult women. The study compared correlation variances among kinematic variables to evaluate foot angle control’s impact on knee stability and movement performance. METHODS Participants included 29 healthy adult women over 20 years old. Each participant completed three sets of five repetitions under two conditions: foot angles of 0° and foot external rotation angle of 30°. Data analysis used Cortex 8.0 software. A paired sample t-test compared lower limb joint angles and center of mass (COM) height of the pelvic region based on foot angle. The Pearson correlation coefficient was calculated to assess correlations between each dependent variable; to analyze differences, Fisher’s Z transformation was applied to significantly correlated pairs. Statistical significance was set at p < 0.05. RESULTS Findings indicated that, compared to 0° (p < 0.05), at a foot external rotation angle of 30°, hip joint abduction, knee joint flexion, and ankle external rotation angles significantly increased, whereas the knee valgus angle significantly decreased (p < 0.05). Moreover, at the foot external rotation angle of 30° (p < 0.01), pelvic COM’s vertical movement range increased, resulting in deeper squats. Correlation analysis among lower extremity joint kinematic variables under different foot angle conditions showed no significant differences. CONCLUSIONS At a foot external rotation angle of 30°, adult women performed bodyweight squats with reduced knee valgus angle and potentially decreased knee joint loading, indicating lower risk of injury and increased squat depth due to enhanced lower extremity joint freedom. Thus, adjusting the foot angle to 30° during adult women’s bodyweight squats can be recommended to enhance knee stability and movement performance.
PURPOSE This study analyzed the difference in lower extremity joint angle and shock absorption patterns at the point of maximum ground reaction force during single-leg drop landing with or without anterior cruciate ligament reconstruction (ACLR). METHODS Forty adult males were recruited for this study, with 19 in the ACLR group (age: 20.52±1.43years, height: 179.26±5.18cm, weight: 74.91±6.29kg) and 21 in the control group (age: 21.42±1.61years, height: 174.97±6.83cm, weight: 69.27±7.56kg). Participants performed single-leg landings on a 30cm tall box. An independent sample t-test was used to analyze the difference in kinetics variables at the point of maximum ground reaction force upon landing, with significance set at p=0.05. RESULTS The lower limb joint angle showed significant differences in hip flexion, hip abduction, knee flexion, and knee valgus (p<0.05) between groups. There was no significant difference between the groups in terms of the results of kinetics variables during single-leg landing (maximum ground reaction force, lower extremity stiffness, and shock absorption time). CONCLUSIONS The ACLR group showed a clear difference in kinematics compared to the control group, but no significant difference in kinetic results was found. The two groups compensated for the same impact with different movements, though movements in the ACLR group may increase the risk of ACL re-injury. Those with ACLR should strive to reduce the risk of re-injury by training to use correct movements.
PURPOSE The purpose of this study was to establish the criteria for measuring acute muscle fatigue using tensiomyography (TMG) by quantifying the trend of changes in TMG variables. METHODS Searches were conducted in the Web of Science and Pubmed databases using the keyword “Tensiomyography”. Sixteen studies which used TMG to measure acute muscle fatigue caused by acute exercises in rectus femoris or biceps femoris were included. All statistical data analyses were performed using Comprehensive Meta-Analysis software program. RESULTS The meta-analysis results indicated that the biceps femoris showed a significant (p<.05) decrease in all TMG variables of the elite athletes. Also, in the overall effects of maximum displacement and mean velocity until 90% Dm (Vc90) showed a significant (p<.05) decreasing trend. The rectus femoris showed a significant (p<.05) decreasing trend for maximum displacement (Dm) in the average person, while contraction time (Tc) showed a decreasing trend in elite athletes and overall. CONCLUSIONS These results suggest that TMG could be used as an indicator of muscle fatigue indicator, and will help to develop a more proper protocol to test the response of the body to muscle fatigue.
