Relationships between oxygen consumption, heart rate, perceived exertion, and walking speed during ecological walking tasks in stroke survivors and healthy controls: a secondary cross-sectional analysis.

BACKGROUND: Although direct measurement of task-specificoxygen consumption( ˙VO2) using portable metabolic gas analysis is the gold standard for exercise intensity assessment, it is impractical for home-based monitoring. Heart rate (HR), rating of perceived exertion (RPE), and walking speed (WS) are more accessible, but their associations with ˙VO2 during real-life walking tasks remain unclear. OBJECTIVE: To examine the relationship between ˙VO2 and HR, RPE, and WS during ecologically walking tasks in stroke survivors and healthy controls. METHOD: This secondary cross-sectional analysis included 30 stroke survivors and 30 healthy controls. Participants completed six walking tasks: overground walking, stair ascent and descent, irregular terrain walking, level-to-uphill and downhill-to-level walking. ˙VO2 was measured using a portable gas analyzer, HR with a Polar H10 monitor, RPE using the Borg 6-20 RPE scale, and WS from task distance and duration. Linear mixed-effects models were used to investigate the associations between ˙VO2 and each predictor (HR, RPE, and WS), adjusting for task and testing predictor-by-task interactions. RESULTS: In stroke survivors, RPE showed an inverse association with ˙VO2 during stair ascent, whereas no significant association was observed in healthy controls. HR showed a significant positive task-independent association with ˙VO2 in both groups (stroke: β = 0.031; healthy controls: β = 0.104 mL·kg-1·min-1 per bpm; both p < .001). The relationship between WS and ˙VO2 was task-dependent in both groups, with the strongest associations observed during stair ascent (stroke: β = 2.172 and healthy controls: β = 2.344 mL·kg-1·min-1 per 0.1 m·s-1 increase in WS; both p < .001) and level-to-uphill walking (stroke: β = 0.687 and healthy controls: β = 1.135 mL·kg-1·min-1 per 0.1 m·s-1 increase in WS; both p < .001). CONCLUSION: HR may be a practical supportive indicator for monitoring exercise intensity after stroke, whereas WS should be interpreted according to the walking task performed. TRIAL REGISTRY NAME: Oxygen Consumption in Post-stroke Patients During Various Walking Activities Compared to Healthy Controls (STROXCO). REGISTRATION NUMBER ON CLINICALTRIALS.GOV: NCT05477238.