Relationships between calf muscle density and muscle strength, mobility and bone status in the stroke survivors with subacute and chronic lower limb hemiparesis.

OBJECTIVE To determine the relationship between muscle density and neuromusculoskeletal status in stroke survivors with subacute and chronic hemiparesis. METHODS Community-dwelling adults were recruited into one of 3 groups (11 per group): subacute stroke group (SSG, <6 months post-stroke), chronic stroke group (CSG, >1 year post-stroke), or age- and gender-matched control group (CG). Muscle density, muscle mass and tibial bone status (cortical density, mass and polar stress-strain index (pSSI)) were measured bilaterally at the tibial 66% site using peripheral quantitative computed tomography. Muscle strength of ankle plantarflexors and knee extensors was assessed using isokinetic dynamometry. Mobility was assessed using the Berg Balance Scale. Univariate regression analyses by group tested whether side-to-side differences in muscle density and measures of neuromusculoskeletal status were related. RESULTS In the SSG and CG, relationships were observed for muscle density and ankle plantarflexor strength (R²= 0.365 and 0.503). Muscle density related to muscle mass in the CG only (R²= 0.889). Muscle density related to cortical bone density in the SSG (R²= 0.602) and pSSI in the CSG (R²= 0.434). CONCLUSIONS Muscle density may provide insight into the side-to-side changes in muscle and bone strength following hemiparetic stroke.