Enhanced phasic calf muscle activation with swing resistance enhances propulsion of the paretic leg in people post-stroke.

Abstract

Reduced propulsion of the paretic leg contributes to impaired walking in people post-stroke. The goal of this study was to determine whether phasic electrical stimulation to the paretic gastrocnemius muscle combined with resistance applied to the non-paretic leg during swing phase while walking would enhance muscle activation of the paretic gastrocnemius and propulsive force of the paretic leg. Fifteen individuals who had a stroke visited the lab once to complete two experimental sessions (i.e., cross-over design; session order randomized). Each session consisted of 1) treadmill walking with either "motor stimulation and swing resistance" or "swing resistance only" (10-min walking: 1-min baseline, 7-min adaptation to intervention, & 2-min post-adaptation) and 2) instrumented treadmill walking before and after treadmill walking. Results: Participants showed enhanced muscle activation of the paretic gastrocnemius (P=0.03) and improved anteroposterior ground reaction force of the paretic leg (P=0.01) immediately after the treadmill walking with "motor stimulation and swing resistance", whereas no improvements after the walking with "swing resistance only". Those enhanced gastrocnemius muscle activation (P=0.02) and improved ground reaction force (P=0.03) were retained until the late post-adaptation period and 10 min after treadmill walking, respectively. Conclusion: Walking with "motor stimulation and swing resistance" may enhance forced use of the paretic leg and improve propulsive force of the paretic leg. Applying phasic electrical stimulation to the paretic gastrocnemius muscle and swing resistance to the non-paretic leg during walking can be used as a novel intervention strategy to improve motor control of the paretic leg and walking in people post-stroke.