Sargeant A J, Dolan P
Department of Exercise Physiology and Health Sciences, Faculty of Human Movement Sciences, Free University, Amsterdam, The Netherlands.
Eur J Appl Physiol Occup Physiol. 1987;56(6):704-11. doi: 10.1007/BF00424814.
4 subjects performed repeated eccentric contractions with leg extensors during prolonged downhill walking (-25% gradient) at 6.44 km.h-1 until collapse due to muscle weakness (range of exercise duration 29 to 40 min). During the exercise oxygen uptake rose progressively from approximately 45% of the previously determined VO2max at 10 min to approximately 65% at the end of the exercise. Following the exercise there was an immediate, significant, and sustained reduction in maximal voluntary isometric contraction, and short term (anaerobic) power output measured concentrically on an isokinetic ergometer. These reductions in muscle function persisted for 96 hours post exercise, and were reflected by significant reductions in the tension generated at low frequency (20 Hz) relative to higher frequency (50 Hz) percutaneous stimulation of the quadriceps. All four subjects showed an increase in plasma levels of creatine kinase post eccentric exercise. Performing concentric contractions by walking uphill for one hour at a significantly greater metabolic cost failed to induce comparable reductions in muscle function. These results provide evidence for the consequences of prolonged eccentric work upon dynamic function which complements earlier reports of structural, enzymatic, and static function changes.
4名受试者在以6.44公里/小时的速度进行长时间下坡行走（-25%坡度）时，对腿部伸肌进行重复离心收缩，直至因肌肉无力而崩溃（运动持续时间为29至40分钟）。在运动过程中，摄氧量从10分钟时约为先前测定的最大摄氧量（VO2max）的45%逐渐上升至运动结束时的约65%。运动后，最大随意等长收缩以及在等动测力计上以向心方式测量的短期（无氧）功率输出立即出现显著且持续的下降。这些肌肉功能的下降在运动后持续了96小时，并且通过相对于较高频率（50赫兹）经皮刺激股四头肌时低频（20赫兹）产生的张力显著降低得以体现。所有四名受试者在离心运动后血浆肌酸激酶水平均升高。以显著更高的代谢成本进行一小时上坡行走的向心收缩未能引发类似的肌肉功能下降。这些结果为长时间离心运动对动态功能的影响提供了证据，补充了早期关于结构、酶和静态功能变化的报道。
