Independent Influences of Increased Step Length and Step Frequency on Lower-Limb Joint Loading During Fast Walking

Excessive joint loading contributes to the progression of orthopedic diseases. Walking speed is a key factor affecting joint loading; thus, identifying walking patterns that minimize joint loading during fast walking is crucial to prevent the incidence of orthopedic diseases. This study aimed to determine the independent influences of factors that increase walking speed (i.e., increased step length and frequency) on hip-, knee-, and ankle-joint loading.

Twelve young healthy participants walked under one preferred walking condition (PW) and two fast-speed conditions (step-length-increased condition [SL] and step-frequency-increased condition [SF]). Marker trajectories and ground reaction forces were measured, and a scaled musculoskeletal model-estimated joint contact force peaks, impulses, and per-unit-distance (PUD) impulses in vertical, anteroposterior, and mediolateral directions.

Most peak forces increased with speed under both SL and SF, with greater increases in SL. Compared with PW, SL produced higher peaks in all hip-joint forces, most knee-joint forces (except for the late-stance vertical and anterior peaks), and all ankle-joint forces in the vertical and anteroposterior directions. In contrast, SF generally suppressed increases in joint loading. SF showed lower impulse and PUD impulse values than PW and/or SL, particularly for anteroposterior hip loading and mediolateral knee loading.

These findings suggest that increasing step length substantially elevates joint loading, whereas increasing step frequency helps attenuate such increases. Thus, step frequency modification may be an effective strategy for reducing joint loading during fast walking.