Supplement 1. Individual participant time normalised data for ankle, knee and hip joint angles and moments during all experimental conditions from Modulation of leg joint function to produce emulated acceleration during walking and running in humans

Understanding how humans adapt gait mechanics for a wide variety of locomotor tasks is important for inspiring the design of robotic, prosthetic and wearable assistive devices. We aimed to elicit the mechanical adjustments made to leg joint functions that are required to generate accelerative walking and running, using metrics with direct relevance to device design. Twelve healthy male participants completed constant speed (CS) walking and running and emulated acceleration (ACC) trials on an instrumented treadmill. External force and motion capture data were combined in an inverse dynamics analysis. Ankle, knee and hip joint mechanics were described and compared using angles, moments, powers and normalized functional indexes that described each joint as relatively more: spring, motor, damper or strut-like. To accelerate using a walking gait, the ankle joint was switched from predominantly spring-like to motor-like, while the hip joint was maintained as a motor, with an increase in hip motor-like function. Accelerating while running involved no change in the primary function of any leg joint, but involved high levels of spring and motor-like function at the hip and ankle joints. Mechanical adjustments for ACC walking were achieved primarily via altered limb positioning, but ACC running needed greater joint moments.

探明人类针对各类运动任务调整步态力学机制的规律，对于启发机器人、假肢及可穿戴辅助装置的设计具有重要意义。本研究采用与装置设计直接相关的量化指标，旨在解析人类在完成加速行走与加速跑步动作时，腿部关节功能所产生的力学调整。12名健康男性受试者在测力跑台（instrumented treadmill）上完成了恒速（constant speed, CS）行走、恒速跑步，以及模拟加速（emulated acceleration, ACC）试验。研究将外力采集数据与动作捕捉数据相结合，开展逆向动力学分析（inverse dynamics analysis）。研究通过关节角度、关节力矩、关节功率以及标准化功能指数——该指数将各关节归类为类弹簧、类动力、类阻尼或类支柱型——对踝关节、膝关节与髋关节的力学特征进行描述与对比。当以行走步态进行加速时，踝关节主要从类弹簧模式切换为类动力模式，而髋关节则维持类动力功能，且其动力化程度有所提升。跑步状态下进行加速时，腿部各关节的核心功能未发生改变，但髋关节与踝关节呈现出较高水平的类弹簧与类动力功能特性。加速行走的力学调整主要通过改变肢体位置实现，而加速跑步则需要施加更大的关节力矩。