Association of Activity Limitations and Lower-Limb Explosive Extensor Power in Ambulatory People With Stroke

Saunders DH, Greig CA, Young A, Mead GE. Association of activity limitations and lower-limb explosive extensor power in ambulatory people with stroke.ObjectiveTo determine whether the explosive lower-limb extensor power of the affected and unaffected sides, and any asymmetry, are associated with activity limitations after stroke.DesignCross-sectional observational study of baseline data from a randomized controlled trial.SettingMeasurements made in a hospital clinical research facility.ParticipantsCommunity-dwelling (N=66) subjects with stroke who were independently ambulatory. Subjects’ mean age was 72±10 years.InterventionsNot applicable.Main Outcome MeasuresThe lower-limb extensor power of each lower limb (in W/kg), performance of specific functional activities (comfortable walking velocity, Functional Reach Test, chair-rise time, Timed Up & Go test), and global indices of activity limitation (FIM instrument, Rivermead Mobility Index, Nottingham Extended Activities of Daily Living).ResultsLow lower-limb extensor power in either lower limb was the principal factor from among the confounders we recorded that significantly (R2 range, .21–.46) predicted the limitation of specific functional activities, and low lower-limb extensor power in either lower limb was the principal predictive factor for global indices of activity limitation (R2 range, .13–.38). The degree of asymmetry of lower-limb extensor power between legs was low and had little or no predictive value.ConclusionsIn ambulatory persons with stroke, activity limitations are associated with deficits in lower-limb extensor power of both lower limbs, and not the severity of any residual asymmetry. These findings suggest that interventions to increase lower-limb extensor power in both lower limbs might reduce activity limitations after stroke.