Efficacy of reduced exertion high intensity interval training to modify cardiovascular disease-related risk factors-a narrative review.

Fewer than 20 studies were reviewed, most with small samples (often under 30 participants) and training durations of 8 weeks or less. Only four studies included a non-exercise control group; the rest compared post-training values to pre-training, so effects could reflect maturation, testing familiarity, or attention rather than the exercise itself. The specific REHIT dose varied across studies (sprint duration 10–20 s, 2–3 sprints, 6–12 weeks, 2–5 days/week), making it impossible to identify a minimum effective dose. No study followed participants after they stopped training, so it is unknown whether the fitness and metabolic gains are maintained. No study measured actual cardiovascular events or CVD incidence; all outcomes are surrogate markers. Most studies were conducted in supervised laboratory settings; only two tested workplace adherence, so real-world feasibility in home or community settings remains untested. The literature search was not conducted as a systematic review (no PRISMA protocol, no independent screening, no quality appraisal of included studies), and the search window was under three weeks.

Funded by the National Institute on Aging (NIH) under Award Number R15AG093525. No industry sponsorship, no conflicts of interest declared by the authors.

Do not read this review as evidence that REHIT prevents heart disease or stroke. No study it covers measured cardiovascular events; every benefit reported is a surrogate marker (VO2 max, blood pressure, glucose, lipids) from small, mostly uncontrolled trials. The authors themselves state that true efficacy for CVD prevention remains unproven and that large-scale, longer-term randomised trials are still needed.