Grosset Jean François, Mora Isabelle, Lambertz Daniel, Pérot Chantal
Département de Génie Biologique, UMR CNRS - 6600, Université de Technologie, F-60205, Compiègne cedex, France.
J Electromyogr Kinesiol. 2008 Jun;18(3):455-65. doi: 10.1016/j.jelekin.2006.11.002. Epub 2006 Dec 29.
The activation capacities and neuromuscular efficiency (NME) of the triceps surae (TS) of prepubescent children (7-11 years) and adults were evaluated during submaximal and maximal (MVC) isometric plantarflexion to determine whether they varied with age. TS-EMG were obtained by summing-up the rectified electromyograms of the soleus and gastrocnemii muscles; these data were quantified using a sliding average method and normalized with reference to the TS maximal compound action potential (TS-M-wave). The maximal EMG increased significantly with age in the children, but less than MVC, what led to a significant increase in NME(Max) (MVC/TS-EMG(max) ratio). The EMG-torque relationship indicated an age-related overactivation of TS at low torque, what led to a lower NME(Sub-max) (inverse of the slope of the EMG-torque relationship) for the youngest children. The overactivation of TS was accompanied by contraction of the TA, which decreased with age. The youngest children were also less able to maintain a target torque and muscle activation. Finally, the twitch interpolated method revealed an age-dependant activation deficit. We conclude that central mechanisms are the main cause of the lower torques developed by children and they appear to vary with age in prepubertal children.
在次最大和最大（MVC）等长跖屈过程中，评估了青春期前儿童（7至11岁）和成年人小腿三头肌（TS）的激活能力和神经肌肉效率（NME），以确定它们是否随年龄变化。通过将比目鱼肌和腓肠肌的整流肌电图相加获得TS-EMG；这些数据使用滑动平均法进行量化，并参照TS最大复合动作电位（TS-M波）进行归一化。儿童的最大肌电图随年龄显著增加，但低于MVC，这导致NME（Max）（MVC/TS-EMG（max）比值）显著增加。肌电图-扭矩关系表明，在低扭矩时TS存在与年龄相关的过度激活，这导致最年幼的儿童NME（次最大）较低（肌电图-扭矩关系斜率的倒数）。TS的过度激活伴随着胫骨前肌的收缩，而胫骨前肌的收缩随年龄下降。最年幼的儿童也较难维持目标扭矩和肌肉激活。最后，抽搐插值法显示存在年龄依赖性激活不足。我们得出结论，中枢机制是儿童产生较低扭矩的主要原因，并且它们在青春期前儿童中似乎随年龄而变化。
