(Key Laboratory of Exercise and Health Sciences of Ministry of Education,Shanghai University of Sport,Shanghai 200438,China) Abstract: The effects of 12-week gait retraining(GR) on Achilles tendon (AT) morphology, the plantarflexion moment and AT mechanical properties during maximal voluntary isometric contraction were explored in this study in order to increase the ability to transmit force and provide effective training methods decreasing and preventing the AT injuries. Participants were randomly divided into the GR group and control (CON) group. In total, 34 participants completed the intervention, with 20 in the GR group and 14 in the CON group. The GR group ran with forefoot strike pattern (FFS) with minimal shoes, while the CON group was trained with their own original running shoes and keep the original foot strike pattern and exercising intensities. The morphological properties of AT, namely, length and cross-sectional area (CSA) were obtained by ultrasound, and the Con-Trex dynamometer was used simultaneously to measure and calculate plantarflexion torque, rate of torque development, stress and strain of AT before and after training. Two-way repeated ANOVA was used to analyze data. Results are as follows: after 12-week gait retraining, the significant time effect of the plantarflexion torque was found (P < 0.01), specifically, the rate of increase of plantarflexion torque in the GR was 17.1% more than it in the CON group; 2) the significant group effect of the CSA was observed (P < 0.05), specifically, the CSA of the GR group was significantly larger than the CON group, the rate of increase of CSA in the GR was 5.3 % more than it in CON group; 3) the Achilles tendon force was found (P < 0.01), specifically, the rate of increase of plantarflexion torque in the GR was 17.1% more than it in CON group. Conclusion are as follows: the step-by-step 12-week gait retraining could be considered as an effective training method to enhance the muscle strength of the ankle, AT mechanical properties, and the loading ability. Key words: sports biomechanics;gait retraining;ultrasound;achilles tendon;plantarflexion torque;morphology;mechanical properties
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