Cardiovascular fitness after stroke: Role of muscle mass and gait deficit severity

Functional disability after hemiparetic stroke may be compounded by physical deconditioning and muscular wasting, factors related to disuse and advancing age. However, the role of body composition, severity, and chronicity of gait deficits as determinants of exercise fitness after stroke is unknown. The purpose of this study was to determine whether oxygen consumption during peak exercise (VO₂ peak) is associated with body composition, the severity, or duration of gait deficits in chronic (> 6 months) hemiparetic stroke patients. Twenty-six patients (22 men, 4 women), aged 66 ± 9 years (mean ± standard deviation [SD]), completed a progressive graded treadmill test until fatigue to measure VO₂ peak (1.3 ± 0.4 L/minute). Timed 30-foot walks were used to determine self-selected floor walking velocity (0.63 ± 0.31 m/s), an index of gait deficit severity. Percent body fat (30.4% ± 10.6%), total lean mass (52.0 ± 9.3 kg), lean mass of the paretic and nonaffected legs (17.2 ± 3.7 kg), and lean mass of the paretic and nonaffected thighs (13.2 ± 2.7 kg) were determined by dual- energy x-ray absorptiometry. Total lean mass (r = 0.60), lean mass of both legs (r = 0.58), paretic leg lean mass (r = 0.55), lean mass of both thighs (r = 0.64), and self-selected floor walking velocity (r = 0.53, all P < .01) correlated with VO₂ peak. In contrast, percent body fat and latency since index stroke were unrelated to VO₂ peak. In a stepwise regression analysis, lean mass of both thighs (r = 0.64, P < .001) and self-selected walking velocity (cumulative r = 0.78, P < .001) were independent predictors of VO₂ peak and explained 61% of the variance. These results suggest that hemiparetic stroke patients are profoundly deconditioned, regardless of the latency since stroke, and that lower lean thigh mass and greater gait deficit severity predict even poorer peak exercise capacity.