Significant advancements in aerobic fitness were observed after 12 weeks of high-intensity interval training sessions when compared to traditional moderate exercise sessions, according to a recent study.
Research published in Stroke, a journal from the American Stroke Association, indicates that engaging in short, one-minute high-intensity intervals for a total of 19 minutes might yield better fitness results for individuals who are at least six months post-stroke than conventional 20-30 minute sessions of moderate-intensity exercise.
“Our findings reveal that stroke survivors can also gain benefits from high-intensity interval training,” stated Kevin Moncion, Ph.D., a physiotherapist and the principal investigator of this study conducted as part of his doctoral research at McMaster University in Hamilton, Ontario, Canada. “With adequate support and direction, stroke survivors can safely partake in high-intensity interval training, leading to significant enhancements in their health and recovery.”
This multi-center study was conducted from September 2018 to March 2024 and included participants who had experienced a stroke from six months to five years prior. Participants were randomly assigned to either a regimen of three weekly sessions of high-intensity interval training for 12 weeks or three weekly sessions of traditional moderate exercise for the same duration. The high-intensity training consisted of ten one-minute intervals of high-intensity exercise, followed by nine one-minute low-intensity intervals, totaling 19 minutes. The moderate-intensity group performed steady exercise for 20 to 30 minutes at a moderate pace.
Researchers measured various factors, including fitness levels, cardiovascular health indicators such as blood pressure and vascular stiffness, as well as walking speeds and distances between the two groups. A follow-up assessment was conducted eight weeks after the exercises concluded to determine if the improvements were maintained.
The findings revealed:
- The high-intensity interval training participants saw their cardiorespiratory fitness (the volume of oxygen consumed at maximum effort) improve twice as much as the moderate exercise participants – 3.5 mL/kg/min compared to 1.7 mL/kg/min.
- The enhancements in the high-intensity group remained significantly above clinically important levels at the 8-week follow-up (1.71 mL/kg/min), unlike the moderate exercise group (0.67 mL/kg/min).
- Both groups improved their walking endurance, as shown by the distance covered in six minutes. Initially, both groups could walk about 355 meters (the equivalent of three American football fields) in six minutes. After 12 weeks, each group increased their walking distance by 8 meters, and at the 8-week follow-up, the distance improved by an additional 18 meters.
“This is the first randomized trial to evaluate a quick, high-intensity interval training regimen that employs a phased and progressive approach,” noted senior author Ada Tang, Ph.D., a physiotherapist, professor, and assistant dean of Rehabilitation Science at McMaster University. “We utilized an adaptive recumbent stepper, which we believe enabled more individuals to participate in high-intensity interval training, particularly those unable to walk fast or long distances on a treadmill.”
The study does have limitations: participants were higher-functioning stroke survivors, presenting a lower risk for heart disease. To qualify, individuals were required to walk 10 meters unaided, although they could use a cane or walker. Additionally, the follow-up assessments were not blinded, possibly affecting the results. Enrollment and exercise sessions were paused for two years due to COVID-19 restrictions, leading to a higher dropout rate and possibly reducing the statistical strength of the findings.
According to the American Heart Association’s Heart Disease and Stroke Statistics 2024 Update, there were 7.44 million stroke-related deaths globally in 2021.
Future studies should focus on stroke survivors who exhibit more severe physical impairments or higher heart disease risks, as per the authors of the study.
“The evidence now exists for stroke rehabilitation experts to integrate brief, high-intensity interval training protocols into their practice. Our findings demonstrate that this method is safe and effective in enhancing fitness and walking distance among stroke survivors, which are vital recovery outcomes,” Tang stated.
Study details and background:
- The research, conducted at McGill University in Montreal and McMaster University in Hamilton, Canada, involved 82 mainly white adults (50 men, 32 women) aged 40 to 80, all experiencing mild or minimal disability from a stroke approximately 1.8 years prior.
- Participants utilized adaptive recumbent steppers designed to accommodate stroke survivors with varying levels of ability while exercising at high intensities.
- Three assessments were carried out: prior to beginning the exercise training (baseline, 0 weeks), immediately following the exercise (post, 12 weeks), and an 8-week follow-up after the intervention concluded (i.e., 20 weeks from baseline).
- During each assessment, researchers evaluated cardiovascular fitness by measuring resting blood pressure, arterial stiffness, waist-hip ratio (calculated from waist circumference at the navel and hip circumference at the hip bone), and mobility (walking speed and distance).
- No participants experienced any adverse effects, such as fatigue, breathlessness, muscle soreness, cramps, or dizziness during exercise.
