The Role of Physical Activity in Mitigating Age-Related Changes in the Neuromuscular Control of Gait

Exercise is known to induce several neural and muscular adaptations, such as increased muscle mass and functional capacity in older adults. In this study, we investigated its impact on the neuromuscular control of gait among young and older adults, divided into two groups: more active (young: n=15; 5185 ± 1471 MET-min/week; old: n=14; 6481 ± 4846 MET-min/week) and less active participants (young: n=14; 1265 ± 965 MET-min/week; old: n=14; 1473 ± 859 MET-min/week). Maximal isometric tests of ankle and knee extension revealed a reduction in force among older adults, with differences associated with the level of physical activity at the ankle level. Gait mechanics revealed no significant differences between young adults and the more active older adults. In contrast, less active older adults exhibited shorter steps, higher mechanical cost, and greater collision at heel strike. These changes cannot be attributed solely to reductions in muscle strength. Instead, they are likely the result of modifications in neuromuscular control and mechanical properties of muscles in less active older adults. Specifically, wider activation (and greater coactivation) of lumbar and sacral motor pools as well as a different timing of activation were observed. Also, their muscle-tendon stiffness was reduced. In conclusion, our findings highlight that the age-related decline in gait efficiency is exacerbated by a sedentary lifestyle. Even modest increases in physical activity appear to preserve neuromuscular control and improve walking performance. This suggests that interventions aiming to enhance physical activity levels could mitigate age-related declines in gait mechanics.