The causes of age-related differences in lower-extremity joint moments and powers are unknown. The purpose of this study was to determine the effects of highly physically active older adults walking with (1) a step length similar to young adults and (2) an upright trunk posture, on hip and ankle joint kinetics. The authors hypothesized that, compared with their self-selected walking mechanics, older adults would exhibit decreased hip kinetics and increased ankle kinetics when prescribed a young adult step length, and would exhibit decreased hip extension moments when maintaining an upright trunk posture during walking. A total of 12 active older adults (67 [5] y) and 13 active young adults (21 [3] y) walked at 1.3 m/s. The older adults also walked at 1.3 m/s with step lengths prescribed from height-matched young adults and, in a separate condition, walked with an upright trunk. The older adults did not display larger ankle kinetics or smaller hip kinetics in either condition compared to walking with a self-selected step length. These findings indicate that step length and trunk position do not primarily contribute to age-related differences in kinetics in highly active older adults and should serve as a starting point for investigating alternative explanations.

下肢关节力矩和力量与年龄相关的差异的原因尚不清楚。本研究的目的是确定高度体力活动的老年人行走（1）与年轻人相似的步长和（2）直立躯干姿势对髋关节和踝关节动力学的影响。作者假设，与他们自己选择的步行力学相比，老年人在指定年轻人步长时会表现出髋部动力学降低和踝关节动力学增加，并且在行走过程中保持躯干直立姿势时会表现出髋部伸展力矩减少。共有 12 名活跃的老年人（67 [5] 岁）和 13 名活跃的年轻人（21 [3] 岁）以 1.3 m/s 的速度行走。老年人也按照身高匹配的年轻人规定的步长以 1.3 m/s 的速度行走，并且在单独的条件下，以直立的躯干行走。与以自我选择的步长行走相比，老年人在这两种情况下都没有表现出更大的踝关节动力学或更小的髋关节动力学。这些发现表明，步长和躯干位置并不是导致高度活跃的老年人中与年龄相关的动力学差异的主要因素，并且应该作为研究替代解释的起点。