Determinants of cardiorespiratory fitness at 3, 6 and 12 months poststroke

Purpose: To better delineate intervention programs, knowledge of the factors that are associated with physical fitness in stroke survivors is crucial. This study aimed to predict cardiorespiratory fitness based on standardized measures along the several dimensions of the International Classification of Functioning, Disability and Health (ICF) model at several time intervals in the first year after stroke. Methods: Forty patients were assessed at 3, 6 and 12 months poststroke. A symptom-limited graded cycle ergometer test was used to assess cardiorespiratory fitness. Outcome variables were VO2 peak and the Oxygen Uptake Efficiency Slope (OUES). Impairments, activity limitations, participation restrictions, personal and environmental factors were assessed to determine predictive factors. Results: Explained variance at 3, 6 and 12 months poststroke was 39%, 55% and 91% for VO2 peak and 55%, 63% and 79% for OUES. A strong association between knee muscle strength and cardiorespiratory fitness was found at each measurement time, explaining up to 72 % of the variance in fitness. At 12 months poststroke, functional mobility, body mass index (BMI) and emotional status also contributed to explain variance. Conclusions: Knee muscle strength was found to be a very strong predictor of cardiorespiratory fitness during the first year after stroke and functional mobility became important at 12 months poststroke.