Exercise Induces Peripheral Muscle But Not Cardiac Adaptations After Stroke: A Randomized Controlled Pilot Trial

Sarah A Moore,Djordje G Jakovljevic,Gary A Ford,Lynn Rochester,Michael I Trenell

doi:10.1016/j.apmr.2015.12.018

Sarah A Moore, Djordje G Jakovljevic + Show 3 more

Open Access

https://doi.org/10.1016/j.apmr.2015.12.018

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Abstract

ObjectiveTo explore the physiological factors affecting exercise-induced changes in peak oxygen consumption and function poststroke. DesignSingle-center, single-blind, randomized controlled pilot trial. SettingCommunity stroke services. ParticipantsAdults (N=40; age>50y; independent with/without stick) with stroke (diagnosed >6mo previously) were recruited from 117 eligible participants. Twenty participants were randomized to the intervention group and 20 to the control group. No dropouts or adverse events were reported. InterventionsIntervention group: 19-week (3times/wk) progressive mixed (aerobic/strength/balance/flexibility) community group exercise program. Control group: Matched duration home stretching program. Main Outcome Measures(1) Pre- and postintervention: maximal cardiopulmonary exercise testing with noninvasive (bioreactance) cardiac output measurements; and (2) functional outcome measures: 6-minute walk test; timed Up and Go test, and Berg Balance Scale. ResultsExercise improved peak oxygen consumption (18±5 to 21±5mL/(kg⋅min); P<.01) and peak arterial-venous oxygen difference (9.2±2.7 to 11.4±2.9mL of O2/100mL of blood; P<.01), but did not alter cardiac output (17.2±4 to 17.7±4.2L/min; P=.44) or cardiac power output (4.8±1.3 to 5.0±1.35W; P=.45). A significant relation existed between change in peak oxygen consumption and change in peak arterial-venous oxygen difference (r=.507; P<.05), but not with cardiac output. Change in peak oxygen consumption did not strongly correlate with change in function. ConclusionsExercise induced peripheral muscle, but not cardiac output, adaptations after stroke. Implications for stroke clinical care should be explored further in a broader cohort.

Highlights

It is the first study to explore physiological mechanisms associated with exercise-induced changes in peak oxygen consumption and function poststroke
The exercise-induced improvements in peripheral muscle observed during this study indicate that it may be possible to use exercise to mediate peripheral complications resulting from stroke
Previous data have demonstrated that peak oxygen consumption levels are associated with functional outcome measures in various conditions,[30,31] our results demonstrated only a moderate significant correlation between exercise-induced change in peak oxygen consumption and 2 of the functional outcome measures: walking speed and timed Up and Go (TUG) test

Summary

Methods

Study designThe study design was a single-center, single-blind, randomized controlled pilot trial. The study was performed in accordance with the ethical standards laid down in the 1975 Declaration of Helsinki and as revised in 2013. Primary outcomes for this study have been reported previously.[8] This article presents a subanalysis of the primary findings. Data were inspected for outliers using standard Z-distribution cutoffs and Mahalanobis distance tests. Pre- and postintervention within-group analyses were performed using a paired t test if data conformed to the assumptions of normality; if not, the Wilcoxon signed rank test was used. Between-group differences were assessed using change scores that were compared using independent sample t tests. All data are presented as means Æ SD or as otherwise indicated. The sample size calculation for the main trial was presented in our previous publication of the main trial findings.[8]

Results

Discussion

Conclusion