Neuromuscular Adaptations in Elderly Adults are Task-Specific During Stepping and Obstacle Clearance Tasks

Elderly adults have a diminished movement capacity due to physiological and neurological declines associated with advancing age. Previous research suggests that elderly adults use altered neuromuscular patterns to conduct activities of daily living (ADLs). Limited research has addressed these altered activation strategies in obstacle clearance, stair ascent and stair descent. The purpose of this study was to compare neuromuscular activation patterns in young and elderly adults during these tasks. Eleven young and 10 healthy elderly adults performed five downward stepping, upward stepping and obstacle clearance trials. Surface EMG was measured from the quadriceps, hamstrings, gastrocnemius and tibialis anterior muscles. A 2×3 (group × condition) repeated measures analysis of variance was used to determine significant differences in muscle activation intensity. An apriori alpha level was set at p<0.05. The results showed that elderly adults exhibited greater activation intensity than the young adults in all movement conditions. The significant differences in muscle activation intensity in the elderly adults were limited to the musculature driving the tested movement. The findings of the current study support previous research that elderly adults perform ADLs at a greater relative intensity than young adults. Furthermore, the current study shows that the disproportionate increase in muscle activation intensity is limited to the muscles that functionally drive the required task.