快、慢两种速度下最大等速离心运动训练对伸膝肌群的影响

Effect of maximum isokinetic centrifugal exercise training at fast and slow speeds on knee extensors

背景:日常生活中的下阶梯、下坡跑、深蹲训练等,此时人体下肢肌群处于离心收缩很容易引发伸膝肌群酸痛及造成肌肉细微损伤现象,但目前缺少以相同等速离心速度的屈肘肌方案应用于伸膝肌的所引发损伤报道。目的:对膝伸肌群分别采用快、慢2种速度进行一回合最大等速离心收缩运动,据此揭示该训练模式可能引发的肌肉损伤规律。方法:该研究方案经重庆应用技术职业学院的医学伦理委员会审核通过。以16名未接受过训练的健康大学男性为受试对象,所有受试者均在充分了解试验方案的前提下签署了"知情同意书"。在为期2周内,运用平衡次序法让每一位受试者的左、右腿分别使用快、慢2种速度,进行一回合120s最大等速离心收缩运动。慢速度为30 (°)/s的角速度下进行6组×5次;快速度为210 (°)/s的角速度下进行次6组×35次。并于运动前、后分别测试肌肉酸痛程度、大腿围、膝关节活动范围、最大自主等长肌力、血液肌酸激酶活性等指标。结果与结论:(1)不同速度进行最大等速离心收缩训练,皆在结束后两三天肌肉酸痛达到峰值,表现为快速下诱发的肌肉酸痛程度比慢速更严重,但两者皆可在运动结束后第5天恢复到训练前水平;(2)不同速度进行最大等速离心收缩训练皆能引发大腿围增加,但快速下大腿围增幅显著高于慢速且恢复速度更慢;(3)快速下进行最大等速离心收缩训练后膝关节活动范围、最大等长肌力皆显著小于慢速训练,且两者恢复速度也差异明显,表现为慢速训练结束后膝关节活动范围及最大等长肌力下降值较低,约在结束后第3天就基本恢复到训练后水平;而快速情况下,膝关节活动范围及最大等长肌力下降程度大,峰值出现更晚,恢复时间更长,在训练结束第5天依旧未能完全恢复;(4)快速训练诱发血液肌酸激酶的活性显著高于慢速,且慢速训练很快能获得恢复,但快速组在训练结束第5天血液肌酸激酶酶活性还在增加,这足见快速引发肌肉损伤比慢速要大得多;(5)结果说明,离心收缩所引发的肌肉酸痛程度、大腿围、膝关节活动范围、最大等长肌力、血液肌酸激酶、肌力峰值等值及恢复时间差异可能与离心"训练总量"有关;在控制快、慢2种速度肌肉激活时间前提下,快速下的最大等速离心训练所引起肌肉损伤程度显著高于慢速度,从而支持离心收缩速度与肌肉损伤有关的论断,亦证实了快速离心运动较容易引起肌肉损伤的观点。

BACKGROUND: In lower steps, downhill running, and squatting training, the lower limb muscles are in centrifugal contraction, and it is easy to cause soreness of extensor muscles and minor muscle damage. However, there are few reports on the injury caused by the application of elbow flexor with the same centrifugal speed to extensor muscles.OBJECTIVE: To reveal the law of muscle injury by given maximum isokinetic eccentric contraction exercise at fast and slow speeds to the knee extensor.METHODS: The study was approved by the Ethics Committee of Chongqing Vocational College of Applied Technology. Sixteen untrained healthy male college students were selected and signed the informed consents. During the period of 2 weeks, the left and right legs of each participant were given 120 seconds of maximum isokinetic eccentric contraction exercise at slow((30(°)/s, 6 groups x 5 times)) and fast(210(°)/s,6 groups x 35 times) speeds, respectively. The degree of muscle soreness, thigh circumference, knee joint range of motion, maximum autonomic isometric muscle strength, and blood creatine kinase activity were measured before and after exercise.RESULTS AND CONCLUSION:(1) Muscle soreness peaked at 2-3 days after the end of training at different speeds, which showed that muscle soreness induced by rapid training was more serious than slow training, but both of them could recover to the level before training on day 5 after the end of exercise.(2) Thigh circumference increased at different speeds, but thigh circumference increased significantly faster than slow training and recovered more slowly.(3) The range of motion and maximum isometric muscle strength of knee joint after rapid training were significantly lower than those after slow training. The recovery speed of both was significantly different, which showed that range of motion of knee joint and maximum isometric muscle strength decreased slowly after slow training, and basically returned to the level after training on day 3 after the end of slow training. In fast condition, range of motion of knee joint and maximum isometric muscle strength decreased significantly, peaked later, and recovery was more significant, and took longer time to recover completely on day 5 after the training.(4) The creatine kinase activity induced by fast training was significantly higher than that induced by slow training, and the slow training could recover quickly, but the creatine kinase activity of fast training group was still increasing on day 5 after the end of training, which showed that the muscle damage caused by fast training was much higher than that caused by slow training.(5) These results imply that the difference of muscle soreness, thigh circumference, range of motion of knee joint, maximum isometric muscle strength, blood creatine kinase, maximal muscle strength and recovery time caused by centrifugal contraction may be related to the total amount of centrifugal training. On the premise of controlling the activation time of fast and slow speed muscles, the degree of muscle injury caused by rapid isokinetic centrifugal training is much higher than that caused by slow speed, which supports the conclusion that centrifugal contraction speed is related to muscle injury. It also confirms that rapid centrifugal exercise is more likely to cause muscle injury.