Effect of aging on the coordination between equilibrium and movement: what changes?

This investigation studies the effect of aging on the coordination between equilibrium and trunk movement. Eight young adults and seven adults at the end of middle age bent their trunk forward and stabilized their position. The center of mass shift was studied as an indicator of equilibrium control as was the electromyographic pattern of the main muscles involved in the movement. The kinematic strategy responsible for both the movement and equilibrium control was quantified by performing a principal components analysis on the hip, knee, ankle angle changes occurring during the movement. We observed that the effect of aging can be detected early. It is not expressed as a deterioration of equilibrium control but rather as "over control". The kinematic strategy is modified, the central command adapted. These results could express the onset of a lesser ability to simplify the coordination between equilibrium and movement as young adults leading to its deterioration in the elderly.