Grosset Jean-Francois, Mora Isabelle, Lambertz Daniel, Pérot Chantal
Université de Technologie, Département Génie Biologique CNRS UMR-6600, F-60205 Compiègne cedex, France.
J Appl Physiol (1985). 2007 Jun;102(6):2352-60. doi: 10.1152/japplphysiol.01045.2006. Epub 2007 Mar 8.
Musculo-articular stiffness of the triceps surae (TS) increases with age in prepubescent children, under both passive and active conditions. This study investigates whether these changes in muscle stiffness influence the amplitude of the reflex response to muscle stretch. TS stiffness and reflex activities were measured in 46 children (7-11 yr old) and in 9 adults. The TS Hoffmann reflex (H reflex) and T reflex (tendon jerk) in response to taping the Achilles tendon were evaluated at rest and normalized to the maximal motor response (Mmax). Sinusoidal perturbations of passive or activated muscles were used to evoke stretch reflexes and to measure passive and active musculoarticular stiffness. The children's Hmax-to-Mmax ratio did not change with age and did not differ from adult values. The T-to-Mmax ratio increased with age but remained significantly lower than in adults. Passive stiffness also increased with age and was correlated with the T-to-Mmax ratio. Similarly, the children's stretch reflex and active musculoarticular stiffness were significantly correlated and increased with age. We conclude that prepubescent children have smaller T reflexes and stretch reflexes than adults, and the lower musculoarticular stiffness is mainly responsible for these smaller reflexes, as indicated by the parallel increases in reflex and stiffness.
在青春期前儿童中，无论在被动还是主动条件下，小腿三头肌（TS）的肌肉关节僵硬程度都会随着年龄增长而增加。本研究调查了肌肉僵硬程度的这些变化是否会影响对肌肉拉伸的反射反应幅度。对46名儿童（7 - 11岁）和9名成年人测量了TS僵硬程度和反射活动。在静息状态下评估了TS对跟腱叩击的霍夫曼反射（H反射）和T反射（腱反射），并将其标准化为最大运动反应（Mmax）。使用被动或激活肌肉的正弦扰动来诱发牵张反射，并测量被动和主动肌肉关节僵硬程度。儿童的Hmax与Mmax之比不随年龄变化，且与成人值无差异。T与Mmax之比随年龄增加，但仍显著低于成年人。被动僵硬程度也随年龄增加，且与T与Mmax之比相关。同样，儿童的牵张反射和主动肌肉关节僵硬程度显著相关且随年龄增加。我们得出结论，青春期前儿童的T反射和牵张反射比成年人小，较低的肌肉关节僵硬程度主要是导致这些较小反射的原因，反射和僵硬程度的平行增加表明了这一点。
