Mercer T H, Gleeson N P, Claridge S, Clement S
Division of Sport, Health and Exercise, School of Health, Staffordshire University, Stoke-on-Trent, UK.
Eur J Appl Physiol Occup Physiol. 1998 May;77(6):560-2. doi: 10.1007/s004210050377.
This study investigated the effect of prolonged intermittent high intensity exercise upon the isokinetic leg strength and electromechanical delay of the knee flexors. Seven male collegiate soccer players were exposed to: (i) a prolonged intermittent high intensity exercise task (PIHIET) which required subjects to complete a single-leg pedalling task, with the preferred limb, (75 rpm for all constant-load portions of the task) consisting of 48 x 1.8 minute cycles of exercise, and (ii) a control task consisting of no exercise. Pre-, mid- and post-PIHIET gravity corrected indices of knee flexion angle-specific torque (0.44 rad knee flexion (AST); 0 rad=full knee extension; [1.05 rad x s(-1)]) were made for both intervention and control limbs. Electromechanical delay (EMD) of the m. biceps femoris during supine knee flexion movements was evaluated in the preferred leg on both intervention and control days. Repeated measures ANOVAs revealed significant condition (intervention; control) by time (pre; mid; post) interactions for both knee flexor AST (F[2,12]=4.8; p < 0.03) and EMD (F[2,12]=4.1; p < 0.05). AST was observed to decrease by 16% and EMD increase by 30% pre to post intervention. These observations suggest an impairment of neuromuscular control and the ability to maintain force generation in the knee flexors, near the extremes of the range of motion during prolonged intermittent high-intensity exercise activities. Changes of this magnitude may pose a threat to the integrity of the knee joint.
本研究调查了长时间间歇性高强度运动对膝关节屈肌等速肌力和肌电延迟的影响。七名男性大学足球运动员接受了以下两项测试：（i）一项长时间间歇性高强度运动任务（PIHIET），要求受试者用优势腿完成单腿蹬踏任务（任务中所有恒定负荷部分的转速为75转/分钟），该任务由48个1.8分钟的运动周期组成；（ii）一项无运动的对照任务。在PIHIET前、中、后，分别对干预组和对照组肢体的膝关节屈曲角度特异性扭矩（0.44弧度膝关节屈曲（AST）；0弧度=膝关节完全伸展；[1.05弧度×秒⁻¹]）进行重力校正指数测量。在干预日和对照日，对优势腿仰卧位膝关节屈曲运动过程中股二头肌的肌电延迟（EMD）进行评估。重复测量方差分析显示，膝关节屈肌AST（F[2,12]=4.8；p<0.03）和EMD（F[2,12]=4.1；p<0.05）在条件（干预；对照）和时间（前；中；后）之间存在显著交互作用。干预前后，AST下降了16%，EMD增加了30%。这些观察结果表明，在长时间间歇性高强度运动活动中，接近运动范围极限时，膝关节屈肌的神经肌肉控制和维持力量产生的能力受损。这种程度的变化可能会对膝关节的完整性构成威胁。
