Walking speed and incline impact on mediolateral-stability control.

BACKGROUND

Controlling and stabilizing the body are crucial for walking on an inclined path. Healthy individuals adjust their gait to improve stability by reducing stride length and increasing cadence. Incline influences anteroposterior stability; however, its effects on mediolateral stability are inconclusive.

RESEARCH QUESTION: What are the effects of walking inclination and speed on mediolateral stability using foot placement quantified by explained variance (EV)?

METHODS

Fifteen healthy young adults walked on a treadmill under four speed (moderate 0.83 m/s, fast 1.0 m/s) and grade (0 and +6° inclines) combinations. The participants wore markers and surface electromyography (EMG) electrodes. A motion-capture system captured the three-dimensional marker data. The relative EV was used to calculate the ratio between the predicted and actual foot-placement variances. The EV and EMG parameters were tested to identify statistically significant differences between conditions.

RESULTS

Two-way analysis of variance revealed no significant interaction between the condition and speed in EV and most EMG measurements, except for the vastus medialis (p = 0.03). Additionally, speed and incline significantly affected all EMG values (p = 0.001-0.04 and 0.0001-0.003, respectively); however, incline did not affect EV. The EMG was higher in incline than in the level condition.

SIGNIFICANCE: Foot placement was used to identify the effects of walking inclination and speed on mediolateral stability control. Walking speed and incline affect mediolateral stability and muscle activation differently, with higher speeds improving stability and incline increasing quadriceps activation. This highlights the need to incorporate varied speeds and targeted muscle strengthening in rehabilitation.