Purpose:
This study investigated the EMG characteristics of muscles crossing the knee and the kinetics of the lower extremity during side-slope walking and other activities of daily living. We studied the difference in EMG data of the medial gastrocnemius and vastus lateralis muscles bilaterally and the relative rotation of the thigh to leg.

Methods:
Eleven outdoor workers (47.3 ± 13.9 years old) were recruited for this study. Participants walked on a 0° flat surface, 5° and 10° side-sloped surfaces, 10° inclined treadmill and ascended stairs. The EMG activity and rotation about a vertical axis during stance phase were analyzed.

Results:
Except for minor variations, ANOVA showed no significant difference in EMG activity between the walking surfaces, furthermore, the relative rotation of thigh-to-leg showed little or no differences between the variables. Multivariate ANOVA showed p-values between 0.1602 and 0.9943 when comparing the EMG data of all side-sloped surfaces. The relative rotation of the thigh to the leg showed p-values of 0.7837 and 0.9813 when comparing the left 0° to 10° and right 0° to 10°, respectively.

Conclusions:
The results of this study indirectly indicate that when considering rotation about a vertical axis and EMG activity, there is little difference in knee joint loading.