Does increased muscular tension along the torso disturb postural equilibrium more when it is asymmetrical?

- Unilateral and bilateral increase of muscular tension was induced along the torso.
- Body balance was assessed by means of a posturographic examination.
- Center of pressure displacements were higher in unilateral increase of muscular tension.
- Increased muscular tension disturbs postural equilibrium more when it is asymmetrical.

The aim of this study was to determine whether increased muscular tension disturbs postural equilibrium more when it is asymmetrical. Ten healthy male subjects underwent a posturographic examination associated with an original uni and bilateral compressive load paradigm designed to set the active muscular tension at different controlled levels along each side of the torso. Respiratory kinematics were recorded by means of two sensing belts. Two electromyographic pre-tests were used to map out the main motor muscles of the task and to quantify the level of asymmetry induced by unilateral loads. The posturographic examination revealed that the mean deviation of the CP along the medial-lateral axis was significantly greater in unilateral than in bilateral compressive loads. It was suggested that increased muscular tension along the torso induces a more disturbing effect on posture when it is asymmetrical.