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

Abstract

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.