Quantifying Exercise Intensity to Predict Changes in Walking Capacity in Individuals with Chronic Stroke.

OBJECTIVE

To examine whether exercise intensity, quantified as heart rate or training speed, predicts walking outcomes in people with chronic stroke.

DESIGN

This is a secondary analysis from a larger randomized controlled trial ("Promoting Recovery Optimization of Walking Activity in Stroke"; NIH1R01HD086362).

SETTING

Four outpatient rehabilitation clinics.

PARTICIPANTS

Participants with chronic stroke with a walking speed of 0.3-1.0 m/s and step activity of <8000 steps per day. This analysis included participants (N=169; age, 63.1±12.5, 46% women) with complete baseline and postintervention data.

INTERVENTIONS: Participants were randomized into (1) fast-walking training or (2) fast-walking training and step-activity monitoring behavioral group. Of importance, participants received up to 36 sessions of 30-minute high-intensity treadmill walking training across 12 weeks.

MAIN OUTCOME MEASURES: The primary outcomes were a baseline-to-postintervention change in 6-minute walk test distance and fastest walking speed. Exercise intensity was quantified as either a percentage of heart rate reserve or self-selected walking speed.

RESULTS

Two separate multiple linear regressions with robust errors analyzed the relationship of exercise intensity metrics (% heart rate, training speed) on baseline-to-postintervention changes in 2 walking capacity outcomes (6-minute walk test, fastest walking speed) after accounting for covariates. Training speed was a significant predictor of both a change in 6-minute walk test distance (b=0.359; 95% CI, 0.108-0.610; P=.005) and fastest walking speed (b=0.001; 95% CI, 0.001-0.002; P=.003). Heart rate was not a significant predictor of either outcome (both P>.373).

CONCLUSIONS

Training speed significantly predicts changes in walking capacity outcomes in people with chronic stroke following a fast-walking treadmill intervention. This suggests rehabilitation clinicians may use training speed as the metric of exercise intensity when prescribing walking interventions to people with chronic stroke.