Ochala Julien, Lambertz Daniel, Pousson Michel, Goubel Francis, Hoecke Jacques Van
Equipe INSERM/ERIT- M 0207 Motricité-Plasticité, Faculté des Sciences du Sport, Université de Bourgogne, BP 27877, 21078 Dijon cedex, France.
Exp Gerontol. 2004 Mar;39(3):349-58. doi: 10.1016/j.exger.2003.11.004.
Changes in contractile and elastic properties of human plantar flexor muscles in ageing, were investigated in 12 young (19-24 years, YG) and 11 old (61-74 year, OG) men. Maximal isometric and concentric voluntary torques, at several angular velocities, were measured to construct torque-angular velocity relationship. This led to the calculation of an index of maximal shorting velocity (VImax) at low torque. Two methods were then used to calculate musculotendinous (MT, quick-release movements) and musculoarticular (MA, sinusoidal perturbations) stiffness. In both cases, stiffness was linearly related to torque, leading to the calculation of a stiffness index (SI) as the slope of the stiffness-torque relationship: SI(MT) and SI(MA), respectively. MA stiffness under passive conditions (Kp) was also determined. Surface electromyograms were useful to control agonist and antagonist myoelectrical activities. As expected, maximal isometric (P<0.005) and concentric torques (P<0.05) as well as VImax(p<0.05) were lower in OG compared to YG. SI(MT) values were higher for OG compared to YG (P<0.05) leading to a mean difference of 55%, whereas SI(MA) and Kp were not significantly different between the two groups. Thus, older men were weaker and exhibited higher SI(MT) values. These impairments seem to be principally due to muscular atrophy and modifications in both muscle fibre-type distribution and fibre composition, in ageing. Invariance of SI(MA) and Kp would suggest an adaptive mechanism in articular structures to avoid the continuous integration of the ankle joint stiffness by the central nervous system, what may simplify most daily motor tasks.
对12名年轻男性（19 - 24岁，YG组）和11名老年男性（61 - 74岁，OG组）的人体跖屈肌收缩和弹性特性变化进行了研究。测量了多个角速度下的最大等长和向心自愿扭矩，以构建扭矩 - 角速度关系。由此计算出低扭矩下的最大缩短速度指数（VImax）。然后使用两种方法计算肌肉 - 肌腱（MT，快速释放运动）和肌肉 - 关节（MA，正弦扰动）刚度。在这两种情况下，刚度均与扭矩呈线性相关，从而计算出刚度指数（SI）作为刚度 - 扭矩关系的斜率：分别为SI(MT)和SI(MA)。还测定了被动条件下的MA刚度（Kp）。表面肌电图有助于控制主动肌和拮抗肌的肌电活动。正如预期的那样，与YG组相比，OG组的最大等长扭矩（P < 0.005）、向心扭矩（P < 0.05）以及VImax（P < 0.05）较低。与YG组相比，OG组的SI(MT)值更高（P < 0.05），平均差异为55%，而两组之间的SI(MA)和Kp没有显著差异。因此，老年男性力量较弱且SI(MT)值较高。这些损伤似乎主要是由于衰老过程中的肌肉萎缩以及肌纤维类型分布和纤维组成的改变。SI(MA)和Kp的不变性表明关节结构中存在一种适应性机制，以避免中枢神经系统持续整合踝关节刚度，这可能简化了大多数日常运动任务。
