Forced and Voluntary Aerobic Cycling Interventions Improve Walking Capacity in Individuals With Chronic Stroke

Abstract

Objectives: To determine the efficacy of high-intensity cycling to improve walking capacity in individuals with chronic stroke, identify variables that predict improvement in walking capacity, and quantify the relationship between the 6-minute walk test (6MWT) and cardiopulmonary exercise (CPX) test variables.

Design: Secondary analysis of data from 2 randomized controlled trials.

Setting: Research laboratory.

Participants: Individuals with chronic stroke (N=43).

Interventions: Participants were randomized to 1 of the following time-matched interventions, occurring 3 times per week for 8 weeks: (1) forced aerobic exercise and upper extremity repetitive task practice (FE+RTP [n=16]), (2) voluntary aerobic exercise and upper extremity repetitive task practice (VE+RTP [n=14]), or (3) a non-aerobic control group (n=13).

Main outcome measure: Change in walking capacity as measured by the 6MWT from baseline to the end of treatment (EOT).

Results: Significant increases were observed in distance traveled during the 6MWT at the EOT compared with baseline in the FE+RTP (P<.001) and VE+RTP (P<.001) groups, but not in the control group (P=.21). Among aerobic exercise participants, a multivariate regression analysis revealed that cycling cadence, power output, and baseline 6MWT distance were significant predictors of change in walking capacity.

Conclusions: An 8-week aerobic cycling intervention prescribed at 60% to 80% of heart rate reserve and moderate to high cadence and resistance led to significant improvements in walking capacity in our cohort of individuals with chronic stroke. Individuals with low baseline walking capacity levels may benefit most from aerobic cycling to improve over ground locomotion. Although the 6MWT did not elicit a cardiorespiratory response comparable to the maximal exertion CPX test, the 6MWT can be considered a valid and clinically relevant submaximal test of cardiorespiratory function in individuals with chronic stroke.

Trial registration: ClinicalTrials.gov NCT02076776 NCT02494518.

Keywords: Exercise; Hemiplegia; Stroke rehabilitation; Walking and bicycling; Walking speed.

Figure 1:

Change in Six Minute Walk Test from baseline to end of treatment for each FE (left panel), VE (middle panel) and control group (right panel) participant is depicted in light gray with black bold lines representing group means. To provide context, the 6MWT normative distance range for individuals 50–70 years of age is presented in light blue while categorizations of home versus community ambulatory capacity as defined by Fulk and colleagues are presented along the right y-axis. The greatest improvement in 6MWT distance was made by FE group participants with the group mean at EOT approaching age norm values, though a significant improvement was also evident for the VE group. Among the 30 exercisers, 6 (20%) improved to a higher ambulatory capacity category. Cycling Improves Walking Capacity Poststroke

Figure 2:

Percent change in Six Minute Walk Test distance is depicted for each participant in the exercise (blue) and control (orange) groups. The solid vertical line demarcates those who improved by at least 10% versus those who did not. Higher exercise cadence and power were predictive of greatest improvements in walking capacity.

Figure 3:

The relationship between Six Minute Walk Test (6MWT) and cardiopulmonary exercise (CPX) testing variables was compared revealing moderate correlations between 6MWT distance and peak oxygen consumption (Fig 3a), 6MWT distance and maximal power achieved during the CPX test (Fig 3b), and maximum heart rate response during the 6MWT and the CPX test (Fig 3c). A poor correlation was observed between change in 6MWT distance and change in peak oxygen consumption from baseline to end of treatment (Fig 3d).