CHARACTERIZATION OF CONTRALATERAL TORQUES DURING STATIC HIP EFFORTS IN HEALTHY-SUBJECTS AND SUBJECTS WITH HEMIPARESIS

Contralateral torques exerted at the hip were measured in healthy subjects and subjects with hemiparesis performing unilateral static hip efforts in abduction, adduction, flexion and extension, in a sitting position, at two torque levels. In general, the ipsilateral hip efforts were accompanied by mirrored contralateral torques in both groups of subjects. The directionality of these contralateral torques indicates that their action at the pelvis is mechanically opposite to the ipsilateral efforts, suggesting that they ensure the stabilization of the pelvis. In healthy subjects, analyses of variance showed no difference in the magnitude of the contralateral torques with regard to which limb was used to perform the task. However, a significant increase in magnitude was demonstrated in the contralateral torques concurrent with the increasing level of effort requested ipsilaterally. In hemiparetic subjects, when performing the tasks with their paretic limb, the magnitude of the contralateral torques was significantly increased in the non-paretic limb when compared with those measured in the paretic limb during non-paretic limb efforts. Based on the present results, a model of postural control is presented to explain the relationship between the ipsilateral and contralateral torques. Using this model, it is hypothesized that the increased contralateral torques observed in hemiparetic subjects when performing the tasks with their paretic limb is related to the weakness of the paretic muscles. The clinical importance of exercises used for the re-education of the paretic lower limb in this population. which consist of resisting the non-paretic hip movements in order to strengthen the paretic hip muscles, is discussed in light of these results.