Effects of treadmill training on translational balance perturbation responses in chronic hemiparetic stroke patients

Abstract

Objectives: Individuals with chronic hemiparesis because of remote stroke are at greater risk for falls than healthy, age-matched controls. Despite this well documented risk, it is, nevertheless, generally assumed that limited or no improvements in dynamic balance responses are possible beyond a brief rehabilitative window after stroke. Consequently, little or no health care resources are available to treat balance disorders during the chronic phase of the disease. Design: We investigated the effects of 3 months of treadmill aerobic exercise training on dynamic responses to destabilizing horizontal balance perturbations in 11 chronic hemiparetic stroke patients. Measurements: Reaction time (RXT) was measured from perturbation onset to the initial loss of foot contact. Recovery time (RCT) was ascertained from perturbation onset to the recovery of stable foot contacts bilaterally. Movement time (MVT) was the calculated difference between RCT and RXT. Results: As a group, the RCTs did not improve with training. However, further analyses identified a subset of patients (n = 6) with markedly slower RCTs at baseline versus a subset (n = 5) with faster RCTs (1252.4 msec v 718.9 msec; P < .001). A secondary group × time analysis, using slow versus fast subgroups showed significant improvement in the slower group's RCTs post-training (↓ 300 msec, P < .05). Further analysis of RXTs and MVTs indicated that the global change in RCTs was attributable to improved MVTs in the slow group relative to the fast group. Conclusions: These findings suggest that progressive treadmill training may improve dynamic balance responses in selected patients, and that slow initial RCTs may predict positive responders. These results also suggest that treadmill training may help reduce the responders fall risk.