Influence of age on neuromuscular control during a dynamic weight-bearing task.

Neuromuscular control strategies might change with age and predispose the elderly to knee-joint injury. The purposes of this study were to determine whether long latency responses (LLRs), muscle-activation patterns, and movement accuracy differ between the young and elderly during a novel single-limb-squat (SLS) task. Ten young and 10 elderly participants performed a series of resistive SLSs (approximately 0-30 degrees) while matching a computer-generated sinusoidal target. The SLS device provided a 16% body-weight resistance to knee movement. Both young and elderly showed significant overshoot error when the knee was perturbed (p < .05). Accuracy ofthe tracking taskwas similar between the young and elderly (p = .34), but the elderly required more muscle activity than the younger participants (p < .05). The elderly group had larger LLRs than the younger group (p < .05). These results support the hypothesis that neuromuscular control of the knee changes with age and might contribute to injury.