Impairment from key lower limb antagonists vs. ambulation speed in chronic hemiparesis

Objective In hemiparesis, three main motor mechanisms in lower limb produce ambulation impairment: paresis in agonists and contracture and overactivity in antagonists. The present study explores correlations between ambulation speed and indices of contracture, spasticity, and cocontraction in key ankle, knee and hip muscles in chronic hemiparesis. Material/patients and methods This retrospective study has included 132 subjects with chronic hemiparesis (mean ± SD, 50 ± 15 years, time since stroke, 8 ± 10 years). Inclusion criteria were: time since stroke > 6 months; completion, at the same visit, of the 10-meter ambulation test (AT10), barefoot without assistance at comfortable speed (CS) and fast speed (FS) and of the Five-Step Assessment (FSA), in three key muscles: triceps surae (TS), quadriceps (QD) and gluteus maximus (GM); no botulinum toxin injections in the 3 months prior to the visit. FSA was carried out on ankle dorsiflexion knee extended (against TS resistance), knee flexion hip extended (against QD resistance) and hip flexion knee flexed (against GM resistance) and measured passive range of motion at slow stretch (XV1), angle of catch at fast stretch (XV3) and active range of motion (XA). A multivariable regression analysis was performed with XV1, XV3, XA against each muscle as predictors and ambulation speeds (CS, FS) as dependent variables. Results Mean ambulation speeds were CS = 0.63 ± 0.28 m/s and FS = 0.84 ± 0.39 m/s. Both speeds were positively correlated with XA against TS (vs. CS, r  = 0.50, P  = 0.005; FS, r  = 0.50, P  = 0.006), QD (vs. CS, r  = 0.62, P  = 0.0001; FS, r  = 0.56, P  = 0.001) and GM (vs. CS, r  = 0.68, P  = 0.002; FS, r  = 0.64, P  = 0.013). XV1 and XV3 were not correlated with ambulation speeds. Discussion – conclusion After stroke, ambulation speed is correlated with active range of motion against triceps surae, quadriceps and gluteus maximus rather than corresponding passive ranges of motion or spasticity levels. These results may encourage therapists to primarily aim for improvement of individual active ranges of motion against key lower limb antagonists to enhance ambulation in chronic hemiparesis.