The link between age-related changes in muscle strength and gait is unclear. We tested if knee extensor functional demand differs by age and physical activity status and if functional demand increases with walking speed or after exercise. Gait and knee extensor muscle torque were collected from young adults and highly and less active older adults before and after treadmill walking. Functional demand was the ratio of knee moments during gait to knee extensor muscle torques estimated from participant-specific torque–velocity curves. Functional demand at the peak knee flexion moment was greater in less active older adults than young adults (29.3% [14.3%] vs 24.6% [12.1%]) and increased with walking speed (32.0% [13.9%] vs 22.8% [10.4%]). Functional demand at both knee extension moments increased ∼2% to 3% after exercise. The low functional demand found in this study suggests that healthy adults maintain a reserve of knee extensor strength.

与年龄相关的肌肉力量变化和步态之间的联系尚不清楚。我们测试了膝关节伸肌功能需求是否因年龄和身体活动状态而异，以及功能需求是否随着步行速度或运动后而增加。在跑步机行走之前和之后，收集了年轻人以及活跃程度高和不太活跃的老年人的步态和膝伸肌扭矩。功能需求是步态期间膝关节力矩与根据参与者特定扭矩-速度曲线估计的膝伸肌扭矩之比。活动较少的老年人在膝关节弯曲峰值时刻的功能需求高于年轻人（29.3% [14.3%] vs 24.6% [12.1%]），并且随着步行速度的增加而增加（32.0% [13.9%] vs 22.8% [10.4] %]）。运动后两个膝关节伸展时刻的功能需求均增加~2% 至 3%。本研究中发现的低功能需求表明健康成年人保持膝关节伸肌力量的储备。