The purpose of this study was to investigate the effect of different load carriage modes on coordinative patterns in the lower extremities during walking. Twenty-five university students walked on a treadmill at their preferred pace under three different load conditions: symmetric load (5% of body mass in messenger bags on each shoulder hanging vertically and against the hips), asymmetric load 1 (10% of body mass in a messenger bag on one shoulder hanging vertically against the ipsilateral hip), and asymmetric load 2 (10% of body mass in a messenger bag on one shoulder with the bag draped across the trunk to the contralateral hip). Altered thigh-shank and shank-foot couplings were found for the loaded side during the stance of gait when comparing the asymmetric 1 and 2 to the symmetric load. In addition, thigh-thigh coupling was changed during gait when comparing the asymmetric load 2 and symmetric load. However, we did not find any significant differences in intralimb and interlimb couplings between the two different asymmetric load conditions. The results suggest potential benefits when carrying symmetrical loads in order to decrease abnormal limb coordination in daily activities. Thus, it may be advisable to distribute load more symmetrically to avoid abnormal gait.

Background: Older adults are less stable and walk slower than younger adults, both of which are associated with higher fall risk. Older adults use ankle musculature less and rely more on hip contributions for forward propulsion than younger adults, which has been suggested to be a protective walking strategy to increase stability. However, whether distal-to-proximal redistribution of propulsion and dynamic margin of stability are related has not been determined. Objectives: To determine whether the distal-to-proximal redistribution of propulsion (redistribution ratio) is related to margin of stability during preferred walking conditions. Methods: 89 participants were classified as either young adults, high functioning older adults, or low functioning older adults. Participants completed walking trials at their preferred walking pace overground. From these trials, anterior-posterior margin of stability and mediolateral margin of stability at heelstrike, midstance, and toe-off, for each gait cycle were computed, alongside a redistribution ratio. Results: Lower functioning older adults exhibited an increased reliance on hip musculature for forward propulsion compared with younger and high-functioning older adults, in addition to greater mediolateral margins of stability. Accounting for group and walking speed, a proximal shift in individual joint contributions to propulsion was associated with increased mediolateral margin of stability at heelstrike, midstance, and toe-off; and not with any changes in anteroposterior margins of stability. Significance: Our results suggest prioritizing mediolateral stability is a potential explanation for, or consequence, of the age- and function-related shift toward proximal joint contributions to forward propulsion during walking.