Normalized Muscle Strength, Aerobic Capacity, and Walking Performance in Chronic Stroke: A Population-Based Study on the Potential for Endurance and Resistance Training

Severinsen K, Jakobsen JK, Overgaard K, Andersen H. Normalized muscle strength, aerobic capacity, and walking performance in chronic stroke: a population-based study on the potential for endurance and resistance training. Arch Phys Med Rehabil 2011;92:1663-8. Objectives: To assess muscle strength, aerobic capacity, and walking performance compared with normative values in chronic hemiparetic stroke patients and, thereby, to investigate the potential for endurance and resistance training. Second, to study the relations between muscle strength, aerobic capacity, and walking performance using normalized test values. Design: Population-based, cross-sectional study. Setting: University hospital, outpatient clinic. Participants: Patients (N=48) aged 50 to 80 years with reduced muscle strength and walking capacity due to an ischemic stroke 6 to 36 months prior to recruitment. Interventions: None. Main Outcome Measures: Peak oxygen consumption (Vo(2)peak) and isometric knee extensor muscle strength at the paretic knee were expressed as absolute and normalized values using normative data. The six-minute walk test (6MWT) and the habitual ten-meter walk test (10MWT) were secondary parameters. Results: Peak Vo(2) was 77% (95% confidence interval [CI], 71-84) of the expected value, and the strength of the paretic knee was 71% (95% CI, 64-78), whereas walking speed (10MWT) was 59% (95% CI, 52-66) and walking distance (6MWT) was 59% (95% CI, 52-67). The normalized Vo(2)peak correlated to the normalized 6MWT (r=.58; P<.001) and normalized 10MWT (r=.53; P<.001). Normalized strength of the paretic knee correlated to normalized 6MWT (r=.40; P<.01) and normalized 10MWT (r=.31; P<.05). Conclusions: Lower extremity muscle strength and aerobic capacity are related to walking performance, which suggests a potential for endurance and resistance training in rehabilitation of walking performance in chronic hemiparesis after stroke. Correction for the influence of age, weight, and height providing normalized values improves the interpretation of severity of impairments and enables comparisons between patients.