Department of Rehabilitation Medicine, Research Institute MOVE, VU University Medical Center, Amsterdam, The Netherlands.
Gait Posture. 2012 May;36(1):113-9. doi: 10.1016/j.gaitpost.2012.01.017. Epub 2012 Mar 3.
Humans have a remarkable capacity to perform complex movements requiring agility, timing, and strength. Disuse, aging, and disease can lead to a loss of muscle strength, which frequently limits the performance of motor tasks. It is unknown, however, how much weakness can be tolerated before normal daily activities become impaired. This study examines the extent to which lower limb muscles can be weakened before normal walking is affected. We developed muscle-driven simulations of normal walking and then progressively weakened all major muscle groups, one at the time and simultaneously, to evaluate how much weakness could be tolerated before execution of normal gait became impossible. We further examined the compensations that arose as a result of weakening muscles. Our simulations revealed that normal walking is remarkably robust to weakness of some muscles but sensitive to weakness of others. Gait appears most robust to weakness of hip and knee extensors, which can tolerate weakness well and without a substantial increase in muscle stress. In contrast, gait is most sensitive to weakness of plantarflexors, hip abductors, and hip flexors. Weakness of individual muscles results in increased activation of the weak muscle, and in compensatory activation of other muscles. These compensations are generally inefficient, and generate unbalanced joint moments that require compensatory activation in yet other muscles. As a result, total muscle activation increases with weakness as does the cost of walking. By clarifying which muscles are critical to maintaining normal gait, our results provide important insights for developing therapies to prevent or improve gait pathology.
人类具有执行复杂运动的非凡能力，这些运动需要敏捷性、时机把握和力量。不活动、衰老和疾病会导致肌肉力量下降，这经常会限制运动任务的表现。然而，目前还不清楚在正常日常活动受到影响之前，肌肉力量可以下降到什么程度。本研究考察了下肢肌肉可以减弱到何种程度，才会影响正常行走。我们开发了正常行走的肌肉驱动模拟，然后逐个同时逐渐削弱所有主要肌肉群，以评估在正常步态执行变得不可能之前，可以容忍多大程度的肌肉力量减弱。我们进一步研究了由于肌肉减弱而产生的代偿。我们的模拟表明，正常行走对某些肌肉的减弱具有很强的鲁棒性，但对其他肌肉的减弱则很敏感。步态对髋关节和膝关节伸肌的减弱最具鲁棒性，这些肌肉可以很好地耐受减弱而不会导致肌肉应力显著增加。相比之下，步态对跖屈肌、髋关节外展肌和髋关节屈肌的减弱最为敏感。个别肌肉的减弱会导致弱肌肉的激活增加，以及其他肌肉的代偿性激活。这些代偿通常效率低下，会产生不平衡的关节力矩，需要其他肌肉的代偿性激活。因此，随着肌肉力量的减弱，总肌肉激活增加，行走的成本也增加。通过阐明维持正常步态的关键肌肉，我们的结果为开发预防或改善步态病理的治疗方法提供了重要的见解。
