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目的:观察在“拉长—缩短周期”运动中肌肉离心收缩和向心收缩后的疲劳、损伤状况和下肢髋、膝、踝关节的用力特征,为运动训练和预防损伤提供理论参考。方法:11名健康男性受试者通过确立的疲劳运动模型进行力竭性“拉长—缩短周期”运动,通过测试肌电图、关节用力分布特征和关节力量的变化评价SSC过程中肌肉离心、向心收缩阶段的疲劳损伤特征。结果:1)SSC运动后,肌肉向心收缩期的能力迅速降低,运动后10 min左右恢复,在运动后2 d4、d基本保持在同一水平;而离心阶段呈现出延迟性降低的特征。2)既定运动模型中,制动和爆发用力的蹲起阶段,膝关节承受的负荷最大。3)肌肉离心收缩后EMG和CK活性都呈现延迟性恢复的特征。结论:力竭性SSC运动中的离心收缩更容易造成肌肉的延迟性疼痛,且肌肉疲劳后恢复较慢。肌肉在向心收缩阶段,没有出现的明显的延迟性肌肉疼痛和/或损伤。力竭性SSC运动中膝关节是承受负荷的主要关节;髋关节和踝关节表现出对膝关节运动能力减弱的补偿性增长,共同构成下肢完成技术动作的协调机制。
OBJECTIVE: To observe the fatigue, injury conditions and the force characteristics of lower extremity hips, knees and ankles after eccentric contraction and centripetal contraction in the “stretch-shorten cycle” exercise and provide a theoretical reference for exercise training and prevention of injuries. METHODS: Eleven healthy male subjects underwent exhaustive “stretch-and-shorten cycle” exercise through a established fatigue exercise model. Muscles were assessed in the SSC by testing EMG, force distribution characteristics of joints, and changes in joint strength Centrifugal, concentric contraction phase of the fatigue damage characteristics. Results: 1) After SSC exercise, the ability of muscle to systole decreased rapidly and recovered at about 10 minutes after exercise, and kept the same level on day 2 and 2 after exercise. However, the characteristics of delayed decrease in centrifugation were observed. 2) In the established exercise model, the brachial joints bear the heaviest load during braking and bursting squatting. 3) The muscle activity of EMG and CK showed the characteristics of delayed recovery after centrifugation. CONCLUSIONS: Centrifugal contractions in exhaustive SSC exercise are more likely to cause delayed muscle pain and slower muscle recovery. Muscle contraction in the centripetal phase, there was no significant delayed muscle pain and / or damage. Knees in the exhaustive SSC exercise are the main joints that bear the load; the hip and ankle joints exhibit a compensatory increase that weakens the motor ability of the knee to form a coordination mechanism for the lower limb to complete the technical maneuver.