The purpose of this dissertation was to investigate how asymmetric load carriage affects joint kinetics and postural control during walking and stair negotiation.

In the first two studies, frontal plane joint moments were analyzed when carrying unilateral versus bilateral loads during stair negotiation. Peak L5/S1 contralateral bending moments were significantly higher when carrying a 20% body weight (BW) unilateral load for both stair ascent and descent. In addition, peak external knee varus and hip abduction moments were significantly higher in unloaded limb stance as compared to loaded limb stance. Based on our findings, we suggest that the low back and lower extremity play different roles in adjusting to asymmetric loads and recommend splitting loads bilaterally in order to decrease the frontal plane joint moments.

In the last dissertation study, we assessed postural control when carrying unilateral versus bilateral loads during walking on even and uneven surfaces. Carrying 20% BW bilateral or unilateral loads resulted in a significantly higher double stance ratio than unloaded walking. Carrying a 20% BW unilateral load or walking on an uneven surface resulted in a significantly increased coefficient of variation (CV) of double stance ratio. Unloaded limb stance had a significantly higher double stance ratio and mean medial-lateral (ML) center of pressure (COP) velocity, although the loaded limb had a significantly higher CV of ML COP velocity. We suggest that load carriage and unloaded limb stance require more conservative postural control, while asymmetric loads and uneven surfaces require more step-by-step postural adjustments.