Chinese Journal of Tissue Engineering Research ›› 2023, Vol. 27 ›› Issue (35): 5603-5609.doi: 10.12307/2023.890

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Mechanism by which high-intensity intermittent exercise improves skeletal muscle injury and enhances exercise capacity in rats

Zhang Liumei1, Liu Jingjing1, Lin Xiaoye2, Liu Lin1, Lu Jiao1, 3   

  1. 1School of Sports and Health, Nanjing Sport Institute, Nanjing 210014, Jiangsu Province, China; 2School of Sports and Health, Shanghai University of Sport, Shanghai 200000, China; 3Jiangsu Collaborative Innovation Center for Sport and Health, Nanjing 210014, Jiangsu Province, China
  • Received:2022-10-13 Accepted:2022-12-14 Online:2023-12-18 Published:2023-06-01
  • Contact: Lu Jiao, PhD, Lecturer, School of Sports and Health, Nanjing Sport Institute, Nanjing 210014, Jiangsu Province, China; Jiangsu Collaborative Innovation Center for Sport and Health, Nanjing 210014, Jiangsu Province, China
  • About author:Zhang Liumei, Master candidate, School of Sports and Health, Nanjing Sport Institute, Nanjing 210014, Jiangsu Province, China
  • Supported by:
    National Natural Science Foundation of China, No. 32000829 (to LL); Natural Science Research of Jiangsu Higher Education Institutions of China, No. 19KJB180019 (to LJ); Jiangsu Collaborative Innovation Center for Sport and Health, No. JSCIC-YP21003 (to LJ); National Key R&D Program of China, No. 2020YFC2007002 (to LJ)

Abstract: BACKGROUND: The potential mechanism of high-intensity intermittent exercise to enhance body adaptability and improve exercise capacity may be related to the phosphorylation level of AMP-activated protein kinase (AMPK) in skeletal muscle.
OBJECTIVE: To clarify the role of high-intensity intermittent exercise in reducing skeletal muscle damage induced by exhaustion and improving exercise capacity and to elucidate the mechanism of AMPK-mediated changes in glucose transporter protein 4 during this process.
METHODS: Forty-five Sprague-Dawley rats were randomly divided into control group, exhaustive exercise group (EE group) and high-intensity intermittent exercise group (HIIT+EE group), with 15 rats in each group. No intervention was given in the control group. The EE group was exhausted on the treadmill at the speed of 25-28 m/min. The HIIT+EE group underwent high-intensity intermittent exercise: running on the treadmill, 4 times a day at the speed of 28 m/min, once for 10 minutes, with an interval of 10 minutes, for 3 consecutive days, and then experienced exhaustive exercise at 24 hours after the completion of high-intensity intermittent exercise to reproduce animal models of exhaustive exercise. The exercise distance of the rats was recorded. After exhaustive exercise, plasma creatine kinase and superoxide dismutase levels were measured in each group. Apoptosis of cells in gastrocnemius muscle was detected by TUNEL staining and western blot. AMPK phosphorylation in gastrocnemius muscle was detected by western blot. Glucose transporter protein 4 expression and translocation in gastrocnemius muscle was detected by immunofluorescence staining and western blot. 
RESULTS AND CONCLUSION: The exercise distance of rats in the HIIT+EE group was greater than that in the EE group (P < 0.05). The levels of creatine kinase and superoxide dismutase were increased in the EE group compared with the control group (P < 0.05). The levels of creatine kinase and superoxide dismutase were decreased in the HIIT+EE group compared with the EE group (P < 0.05). TUNEL staining and western blot results showed that the apoptotic rate of gastrocnemius cells in the EE group was higher than that in the control group (P < 0.05), while the apoptotic rate of gastrocnemius cells in the HIIT+EE group was less than that in the EE group (P < 0.05). There was no significant difference in the expression of apoptosis-related proteins Bax and Bcl-2 between the three groups (P > 0.05). Western blot results showed that the expression of AMPK and p-AMPK protein was increased in the EE group compared with the control group (P < 0.05), while the expression of AMPK protein was decreased and the expression of p-AMPK protein was increased in the HIIT+EE group compared with the EE group (P < 0.05). Results from immunofluorescence staining and western blot assay indicated that the expression of cytosolic glucose transporter protein 4 was increased in skeletal muscle fibers in the EE and HIIT+EE groups compared with the control group. To conclude, high-intensity intermittent exercise attenuates muscle fiber damage induced by exhaustive exercise, promotes the expression and translocation of glucose transporter protein 4 in skeletal muscle by increasing the level and efficiency of AMPK phosphorylation during exercise, and thereby improves the exercise capacity of rats.

Key words: high-intensity intermittent exercise, sports injury, exhaustive exercise, apoptosis, AMP-activated protein kinase (AMPK), glucose transporter protein 4 (GLUT4)

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