Determining the minimum dose of exercise required to improve cardiorespiratory fitness in stroke survivors (ExDose).

It is unclear how much exercise people who have had a stroke should do to increase their cardiorespiratory fitness. We conducted a dose-escalation study to explore whether lower doses of exercise were more tolerable, yet also effective for people after stroke. Four groups of community dwelling, ambulant stroke survivors undertook telehealth supervised exercise sessions 3 days/week for 8 weeks at moderate-vigorous intensity. Session durations (doses) were 10 min (group 1) up to 25 min (group 4). Key Results: All doses were deemed tolerable, and while fitness increased by 17% (dose 1), 13% (dose 2), 19% (dose 3) and 6% (dose 4), increases in (VO2peak) >= 2mL/kg/min (pre-defined measure of success) were only seen in 2/5 participants (dose 1), 1/5 participants (dose 2), 3/5 participants (dose 3), and 2/5 participants (dose 4). Doses were deemed effective if >2/3 of a cohort exceeded this threshold, therefore, no doses were deemed effective. Conclusions: Low doses of home-based moderate-vigorous aerobic exercise were well-tolerated by a small sample of chronic stroke survivors and increased cardiorespiratory fitness and walking capacity overall. Limitations: This study was limited by the small sample size for each dose, and the length of the intervention period. We included only ambulant people with mild-moderate impairments who were, on average, many years post-stroke, and therefore the results may not be generalisable.