What Is the Dose-Response Relationship Between Exercise and Cardiorespiratory Fitness After Stroke? A Systematic Review.

BACKGROUND: Undertaking exercise after stroke improves cardiorespiratory fitness and walking capacity after stroke, but the effect of altering exercise dose (via frequency, intensity, time, and type) on fitness or walking capacity is unclear.

PURPOSE: The purpose of this study was to synthesize the current evidence for the effects of different doses of exercise on cardiorespiratory fitness and walking capacity in people after stroke.

DATA SOURCES: Seven relevant electronic databases were searched using keywords relating to stroke and cardiorespiratory fitness.

STUDY SELECTION: Trials that compared more than 1 dose of exercise for people (≥ 18 years old) after stroke and measured peak oxygen consumption or 6-minute walk test distance as an outcome were included. Two reviewers independently appraised all trials.

DATA EXTRACTION: Two reviewers independently extracted data from included articles. Intervention variables were extracted in accordance with the Template for Intervention Description and Replication checklist.

DATA SYNTHESIS: Data were synthesized narratively. Nine trials involving 279 participants were included. Three of 5 trials comparing exercise intensity showed that higher-intensity training was associated with greater improvements in cardiorespiratory fitness. The effects of other exercise dose components (frequency, time, and type) on fitness were not determined. Overall, walking capacity improved as program length increased.

LIMITATIONS: All trials had a high risk of bias, and most had a high rate of attrition. Most trials included people more than 6 months after stroke and who walked independently, limiting the generalizability of the findings.

CONCLUSIONS: Exercising at an intensity greater than 72% of heart rate reserve may be more effective in increasing cardiorespiratory fitness after stroke than exercising at lower intensities. More trials that compare exercise doses by manipulating only 1 parameter of dose at a time for people after stroke are needed.