Hide/Show Apps

Generalization of mediolateral and anteroposterior postural control responses for different stance positions in quiet stance

Sümbül Ghasemlou, Ezgi
Human balance in quiet stance is the result of continuous center of pressure (COP) adjustments in anteroposterior (AP) and mediolateral (ML) directions and controlled by ankle and hip mechanisms. These mechanisms joins the balance control in different combinations, depending on the stance position. The purpose of this study is to determine the participation of these mechanisms on different stance positions. 22 healthy subjects (20-28 years) were required to maintain their balances on a dual force plate for 60 seconds in 9 different positions (feet side-by-side, intermediate stance: 30°, 45° and 60° right/left foot forward, tandem left, tandem right). Three postural parameters, COPnet, net COP change, COPc, ankle activity and COPv, hip activity and dependency or independency of COPc and COPnet or COPv and COPnet were calculated in addition to the amplitude of contributions. In ML direction, tandem stance is maintained mainly by ankle mechanism (p<0.001). For all conditions except tandem stance, ML balance is controlled by hip mechanism (p<0.001). In AP direction, tandem stance is controlled primarily by the hip mechanism (p<0.001), but all the other conditions are controlled dominantly by the ankle mechanism (p<0.001). Yet, secondary mechanisms also joins to this control. An effect of stance position was identified (p<0.001). Moreover, for intermediate stance conditions, this effect was evident only for the secondary mechanisms. Dominant mechanisms are not affected from the adopted position as much as secondary mechanisms. Secondary mechanisms on the other hand, are adjusted to adapt to new conditions.