Kwon Yujin, Kim Hoon, Franz Jason R
Department of Rehabilitation Medicine, Seoul National University Hospital, Seoul, South Korea.
Department of Sports Medicine, Soonchunhyang University, Asan, South Korea.
Eur J Appl Physiol. 2025 Jun 25. doi: 10.1007/s00421-025-05867-2.
The ways in which age affects neuromuscular control in response to walking-related fatigue are poorly understood. Better understanding of the consequences of walking-related fatigue can inform the development of strategies to improve independent mobility for older adults. In this study, we measured leg muscle excitations and net joint moments in younger and older adults during a 30-min walking trial. Twelve leg muscles were monitored, and wavelet transformation and principal component analyses quantified the effects of age and time on muscle excitation patterns. Perceived exertion increased in both age groups, with higher terminal values in older adults. Over the course of prolonged walking, mean EMG frequency and amplitude decreased while EMG intensities in the slower frequency ranges increased for soleus, lateral gastrocnemius, tibialis anterior, peroneus longus, and gluteus maximus muscles. For soleus muscle, a time-dependent decrease in mean frequency was observed only for older adults. We observed a distal-to-proximal redistribution of net joint moments during prolonged walking independent of age; however, older adults walked with greater peak hip joint moments than younger adults. Our results suggest that shank muscles may exhibit higher fatigability during prolonged walking, precipitating an increased demand on proximal leg muscles to power walking. Walking in older adults is often characterized by an increased reliance on proximal leg muscles, which has in turn been implicated in their higher metabolic cost of transport. Accordingly, our collective findings point to neuromuscular changes during prolonged walking that may cause older adults to be more susceptible to walking-related fatigue than younger adults.
年龄如何影响对与步行相关疲劳的神经肌肉控制，目前还知之甚少。更好地理解与步行相关疲劳的后果，可以为制定改善老年人独立移动能力的策略提供依据。在这项研究中，我们在30分钟的步行试验中测量了年轻人和老年人的腿部肌肉兴奋度和净关节力矩。监测了12条腿部肌肉，并通过小波变换和主成分分析量化了年龄和时间对肌肉兴奋模式的影响。两个年龄组的主观用力程度均增加，老年人的终末值更高。在长时间步行过程中，比目鱼肌、外侧腓肠肌、胫骨前肌、腓骨长肌和臀大肌的平均肌电图频率和幅度下降，而低频范围内的肌电图强度增加。仅在老年人中观察到比目鱼肌平均频率随时间下降。我们观察到在长时间步行过程中，净关节力矩从远端到近端重新分布，与年龄无关；然而，老年人行走时髋关节力矩峰值高于年轻人。我们的结果表明，在长时间步行过程中，小腿肌肉可能表现出更高的易疲劳性，导致对近端腿部肌肉的需求增加以维持步行。老年人行走的特点通常是对近端腿部肌肉的依赖增加，这反过来又与其较高的运输代谢成本有关。因此，我们的综合研究结果指出，长时间步行过程中的神经肌肉变化可能使老年人比年轻人更容易受到与步行相关的疲劳影响。
