Feasibility of Measuring Ventilatory Threshold in Adults with Stroke-Induced Hemiparesis: Implications for Exercise Prescription

Objectives To assess the feasibility of measuring ventilatory threshold (VT) in adults with walking impairments due to stroke. Secondary objectives are to assess reliability of VT over trials; assess whether participants could sustain treadmill walking at VT; and compare mean heart rate during sustained treadmill walking to estimated heart rate reserve (HRR). Design Cross-sectional, single-group design. Setting University research laboratory. Participants Volunteer sample of adults (N=8) with impaired walking resulting from chronic stroke. Interventions Three submaximal treadmill walking tests on 3 separate days; a 30-minute treadmill walking session on a fourth day. Main Outcome Measures Gas exchange variables were measured, and 2 independent observers identified VT. Mean heart rate response to treadmill walking at VT was measured and compared with estimated 40% of HRR. Results VT was measured successfully in 88% of all trials. There was no difference in VT among trials (P=.17). After multiple imputations to account for 3 missing data points, the intraclass correlation coefficient was.87 (95% confidence interval,.80-.95). All participants were able to walk for 20 minutes at VT. Mean ± SD heart rate during the session was 66.0%±8.0% of estimated maximal heart rate. There was no significant difference between mean heart rate and estimated HRR values (P=.70). Conclusions In adults with impaired walking resulting from stroke, VT can be safely measured during submaximal treadmill walking. Participants were able to sustain walking at VT, and this value may provide an appropriate stimulus for aerobic exercise prescription in this population.