Determining maximal tolerable aerobic training intensity in the acute phase after stroke : A novel dose ranging trial protocol

Introduction
There is strong evidence that cardiorespiratory fitness (CRF) training improves fitness and mobility after stroke. Despite the large number of studies, the most efficacious dose is yet to be determined. Furthermore, the safety of early post-stroke training, while theoretically beneficial, remains uncertain. The aim of this study is to determine the maximum safe and tolerable intensity of CRF training early post-stroke.

Methods
This is a stratified (low to moderate exercise capacity), Phase I, 5+5 dose ranging trial protocol. Participants will be recruited within one month post-stroke and stratified by their exercise-capacity (i.e. low and moderate capacity). Cohorts of five participants will perform 12 interval-based training sessions for four-weeks at a pre-determined target-intensity. The intensity will increase in each consecutive cohort, in each stratum according to pre-defined rules until the maximum safe and tolerable intensity is reached, as determined by the occurrence of dose-limiting events and occurrence of adverse events. Dose-limiting events are defined as symptoms indicative of over-training including pain and inability to perform usual activities.

Study Outcome
Maximum safe and tolerable intensity of CRF training in stroke survivors with low and moderate exercise capacity.

Discussion
This study is a first step in the systematic development of a CRF training intervention. We believe similar dose ranging designs may be useful for development of other rehabilitation interventions in different study populations.