Regueme Sophie C, Nicol Caroline, Barthèlemy Joëlle, Grélot Laurent
UPRES EA 3285, Department of Biology of Physical Activity, University of the Mediterranean, 163, Avenue de Luminy CP 910, 13288 , Marseilles cedex 9, France.
Eur J Appl Physiol. 2005 Jan;93(4):398-410. doi: 10.1007/s00421-004-1221-3. Epub 2004 Oct 5.
Stretch-shortening cycle (SSC)-type fatigue is associated with acute and delayed functional defects, and appears to be a useful model to reveal the flexibility of both central and reflex adjustments to the contractile failure. SSC fatigue was induced in an experimental (EXP) group (n=6) on a sledge ergometer with an exhaustive rebound exercise with submaximal effort. The acute (POST) and 2-day delayed (2D) neuromuscular changes with fatigue were examined in a short submaximal rebound task (REBOUND) and in a maximal isometric plantarflexion test (ISOM). The EXP group results were compared to those of a control group (n=6) who did not perform the exhaustive SSC exercise and did not present any change in the tests. In the EXP group, the ISOM test revealed mostly a large decrease in maximal plantarflexion force at 2D that was correlated with the reduced mean soleus muscle (SOL) activation. Indicating "task-dependent" fatigue effects on the neural changes, the REBOUND test revealed both acute and delayed increases in SOL activation. Supporting central neural changes, SOL preactivation increased in POST and 2D. The neural flexibility along time and across muscles was demonstrated by the shifted increase in SOL activation from the braking phase in POST to the push-off phase in 2D, and associated increased gastrocnemius medialis preactivation in 2D. In contrast, activation during the stretch-reflex period was constant in POST, and decreased in 2D. These results would support the influence of musculotendinous afferents on the flexible neural adjustments to the SSC-induced contractile failure.
伸缩周期（SSC）型疲劳与急性和延迟性功能缺陷相关，似乎是揭示中枢和反射对收缩功能衰竭调整灵活性的有用模型。在雪橇测力计上，对实验组（n = 6）进行次最大努力的力竭性反弹运动，诱导产生SSC疲劳。在短时间次最大反弹任务（REBOUND）和最大等长跖屈试验（ISOM）中，检查了疲劳引起的急性（POST）和2天延迟（2D）神经肌肉变化。将实验组的结果与未进行力竭性SSC运动且测试中未出现任何变化的对照组（n = 6）的结果进行比较。在实验组中，ISOM测试显示，在2D时最大跖屈力大多大幅下降，这与比目鱼肌（SOL）平均激活减少相关。REBOUND测试显示SOL激活的急性和延迟增加，表明对神经变化有“任务依赖性”疲劳效应。支持中枢神经变化，SOL预激活在POST和2D时增加。SOL激活从POST的制动阶段到2D的蹬离阶段的转移增加，以及2D时内侧腓肠肌预激活增加，证明了神经随时间和跨肌肉的灵活性。相比之下，牵张反射期的激活在POST时保持不变，在2D时减少。这些结果将支持肌腱传入对SSC诱导的收缩功能衰竭的灵活神经调节的影响。
