High-intensity exercise, known to be beneficial for athletes and healthy adults, is also helpful for people recovering from a stroke, new research led by McMaster shows.

The research, published in Stroke on Aug. 8, found that one-minute bursts of high-intensity interval training over 19 minutes was more effective than traditional moderate exercise for improving the body’s aerobic fitness after a stroke.

“With the right support and guidance, stroke survivors can safely and effectively engage in high-intensity interval training, significantly improving their overall health and recovery,” says lead author Kevin Moncion, an assistant clinical professor with the School of Rehabilitation Science.

“This is the first randomized trial to examine a time-efficient, high-intensity interval training program to incorporate a phased and progressive approach,” said senior author Ada Tang, professor and assistant dean with the School of Rehabilitation Science.

“We also used an adaptive recumbent stepper, which we believe allowed more people — even those who cannot walk on a treadmill — to participate in high-intensity interval training.”

The multi-site trial took place between September 2018 and March 2024 — with a two-year break during the pandemic — and included participants who had had a stroke in the previous six months to five year period.

Researchers randomly grouped participants to receive three days of high-intensity interval training for 12 weeks or three days of moderate exercise over the same period.

Fitness levels doubled in participants in the study’s high-intensity interval training group, compared to those in the moderate intensity group. The high-intensity interval group’s improved fitness levels are associated with improved survival and lower risk of stroke-related hospitalizations, researchers say.

The high-intensity interval training protocol involved 10 one-minute periods of high-intensity exercise, interspersed with nine one-minute low-intensity intervals, for 19 minutes total.

The moderate intensity continuous training involved 20 to 30 minutes of steady exercise at moderate intensity.

The study did have its limitations, researchers note: Physically, study participants were higher-functioning stroke survivors who were at lower risk for heart disease. And enrollment and exercise for the trial was halted for two years because of the pandemic, inflating the rate of participants who left the study.

Future research should examine stroke survivors with more severe impairment in physical function or heart disease risk, study authors say.

Each year, 795,000 people experience a new or recurrent stroke, the American Heart Association reports.

The study was funded by the Canadian Institutes of Health Research.