Walking velocity and lower limb coordination in hemiparesis

Background/objective: Gait training at fast speed has been suggested as an efficient rehabilitation method in hemiparesis. We investigated whether maximal speed walking might positively impact intersegmental coordination in hemiparetic subjects. Methods: We measured thigh-shank and shank-foot coordination in the sagittal plane during gait at preferred (P) and maximal (M) speed using the continuous relative phase (CRP), in 20 healthy and 27 hemiparetic subjects. We calculated the root-mean square (CRPRMS) and its variability (CRPSD) over each phase of the gait cycle. A small CRPRMS indicates in-phasing, i.e. high level of synchronization between two segments along the gait cycle. A small CRPSD indicates high stability of the inter-segmental coordination across gait cycles. Results: Increase from preferred to maximal speed was 57% in healthy and 49% in hemiparetic subjects (difference NS). In healthy subjects, the main change was shank-foot in-phasing at stance (CRPShank-Foot/RMS, P. 98 +/- 10; M, 67 +/- 12, p < 0.001). In hemiparetic subjects, we also found shank-foot in-phasing at late stance bilaterally (non-paretic CRPShank-Foot/RMS, P, 37 +/- 9; M, 29 +/- 8, p < 0.001; paretic CRPShank-Foot/RMS, P, 38 +/- 13; M, 32 +/- 12, p < 0.001), and thigh-shank in-phasing at mid-stance in the non-paretic limb (CRPThigh-shank/RMS, P. 57 +/- 9; M, 49 +/- 9, p < 0.001). CRPThigh-Shank variability diminished in the paretic limb (CRPThigh-Shank/SD. P. 18.3 +/- 6.3; M, 16.1 +/- 5.2, p < 0.001). Conclusion: During gait velocity increase in hemiparesis, there is improvement of thigh-shank coordination stability in the paretic limb and of shank-foot synchronization at late stance bilaterally, which optimizes the propulsive phase similarly to healthy subjects. These findings may add incentive for rehabilitation clinicians to explore maximal velocity gait training in hemiparesis. (C) 2012 Elsevier B.V. All rights reserved.