Cattagni T, Scaglioni G, Laroche D, Gremeaux V, Martin A
Faculté des sciences du sport - UFR STAPS, Université de Bourgogne, France; INSERM unité 1093, Cognition, action et plasticité sensorimotrice, France.
Faculté des sciences du sport - UFR STAPS, Université de Bourgogne, France; INSERM unité 1093, Cognition, action et plasticité sensorimotrice, France.
Exp Gerontol. 2016 May;77:38-45. doi: 10.1016/j.exger.2016.02.010. Epub 2016 Feb 16.
The purpose of this study was to determine whether the mechanical contribution of ankle muscles in the upright stance differed among young adults (YA) (n=10, age: ~24.3), elderly non-fallers (ENF) (n=12, age: ~77.3) and elderly fallers (EF) (n=20, age: ~80.7). Torque and electromyographic (EMG) activity were recorded on the triceps surae and tibialis anterior during maximum and submaximum contractions in the seated position. EMG activity was also recorded in subjects standing still. Plantar flexor (PF) and dorsal flexor (DF) torques generated in the upright posture were estimated from the torque-EMG relationship obtained during submaximum contractions in the seated position. Center of pressure (CoP) displacement was measured to quantify postural stability. Results showed that, in upright standing, EF generated greater ankle muscle relative torque (i.e. PF+DF torque in the upright stance/PF+DF during maximum isometric torque) than non-fallers (i.e. ENF, YA). The greater involvement of ankle muscles in EF was associated with higher CoP displacement. PF+DF torque in the upright stance was no different among the groups, but PF+DF torque during maximum effort was impaired in older groups compared with YA and was lower in EF than ENF. These results suggest that the postural stability impairment observed with aging is highly related to ankle muscle weakness.
本研究的目的是确定在直立姿势下，年轻成年人（YA）（n = 10，年龄：约24.3岁）、非跌倒老年人群（ENF）（n = 12，年龄：约77.3岁）和跌倒老年人群（EF）（n = 20，年龄：约80.7岁）的踝关节肌肉的力学贡献是否存在差异。在坐位最大收缩和次最大收缩期间，记录了腓肠肌和胫骨前肌的扭矩和肌电图（EMG）活动。还记录了受试者静止站立时的EMG活动。根据坐位次最大收缩期间获得的扭矩-EMG关系，估计直立姿势下产生的跖屈肌（PF）和背屈肌（DF）扭矩。测量压力中心（CoP）位移以量化姿势稳定性。结果表明，在直立站立时，EF产生的踝关节肌肉相对扭矩（即直立姿势下的PF + DF扭矩/最大等长扭矩期间的PF + DF扭矩）比非跌倒人群（即ENF、YA）更大。EF中踝关节肌肉的更大参与与更高的CoP位移相关。直立姿势下的PF + DF扭矩在各组之间没有差异，但与YA相比，老年组在最大用力时的PF + DF扭矩受损，并且EF中的该扭矩低于ENF。这些结果表明，观察到的与衰老相关的姿势稳定性损害与踝关节肌肉无力高度相关。
