Effects of limb loading on gait initiation in persons with moderate hemiparesis.

PURPOSE To examine the immediate effect of symmetrical weight bearing (SWB) on temporal events of gait initiation (GI) patterns and timing and amplitude of lower distal limb muscles activity during GI in persons with hemiparesis. METHOD The study was a within-subjects design. Twelve persons with hemiparesis were recruited from the Veterans Affairs Brain Rehabilitation Research Center at the Malcom Randall Veterans Affairs, Gainesville, Florida. GI trials were performed from 4 beginning limb-loading conditions presented in a randomized order: (1) GI with the paretic limb during natural (asymmetrical) weight bearing (NWB); (2) GI with the nonparetic limb during NWB; (3) GI with the paretic limb during SWB; and (4) GI with the nonparetic limb during SWB. Temporal events of ground reaction forces (GRFs) and timing and amplitude of distal muscles activity were measured during GI trials in a motion analysis laboratory. RESULTS There were no significant effects of SWB on the temporal events of GRFs and timing and amplitude of distal muscles activity when initiating gait with the paretic limb. Onset of tibilais anterior (TA) muscle was delayed significantly with less amplitude when initiating gait with the paretic limb in both NWB and SWB conditions. However, when initiating gait with the nonparetic limb, TA muscle on the paretic limb was activated normally with greater amplitude in both NWB and SWB conditions. CONCLUSION Initiating gait with the nonparetic limb as pregait activity may more effectively challenge the dynamic balance for a symmetrical gait pattern than the standard SWB in persons with hemiparesis.