Investigator: Steven A. Kautz, PhD Project Staff: Richard R. Neptune, PhD and Carolynn Patten, PhD PT Project Category: Stroke - 2000 Post-stroke hemiparesis is a health care problem resulting in extensive human and economic burdens, including reduced locomotor function. Hemiparetic walking is profoundly asymmetric, but the extent to which that asymmetry may result from the neural influence of the non-paretic leg on the paretic leg is not known. This study investigated the influence of simultaneous performance of the non-paretic leg on paretic leg coordination. A unique servomotor system independently controlled each crank of a custom built bicycle ergometer while subjects produced force against instrumented pedals. Bilateral pedal forces, crank and pedal angles, surface EMG, and joint angles were collected from 23 persons with hemiparesis. Subjects generated an endpoint force with the paretic leg for a variety of unilateral and mechanically equivalent bilateral tasks: isometric force generation by paretic leg in four directions (extension, flexion, anterior, posterior) while non-paretic leg either relaxes or generates an isometric force (extension or flexion); discrete movement by paretic leg (extension or flexion while non-paretic leg relaxes or moves (extension or flexion); and pedaling by paretic leg (servomotor applies usual contribution of a non-paretic leg) while non-paretic leg relaxes or pedals (paretic leg is mechanically isolated from forces generated by non-paretic leg). The participation of the non-paretic leg significantly altered the coordination of the paretic leg from that used to unilaterally perform a mechanically equivalent task. During isometric force generation conditions, contra-lateral extension enhanced RF activity and contralateral flexion enhanced BF and SM activity. In addition, bilateral pedaling was often impaired relative to unilateral pedaling, with similar effects seen in RF, BF and SM. These results suggest that impaired interlimb neural coupling between the legs contributed to impaired paretic coordination. Publications: The following findings have been submitted, and it is anticipated that additional publications will be forthcoming. Kautz, S.A., Neptune, R.R. and Brown, D.A. (2000). Implications of inappropriate muscle timing for movement in hemiparetic persons: a forward dynamics simulation analysis. Journal of Biomechanics (submitted). Kautz, S.A, Patten, C., Neptune, R.R. and Harvey, J (2000). Interlimb coordination influences on the excitation of paretic leg muscles during lower limb tasks in persons with post-stroke hemiparesis. To be presented at the Annual Meeting of the Society for Neuroscience, New Orleans, LA; November, 2000. Funding Source: Whitaker Foundation |
