Efficacy of reduced exertion high intensity interval training to modify cardiovascular disease-related risk factors-a narrative review.
Todd A Astorino, Riley Givens, Hayden Kunz and 1 others
A review of fewer than 20 small studies suggests 6–12 weeks of brief all-out sprints (REHIT) can significantly raise aerobic fitness and modestly improve blood pressure, but the evidence is too thin to recommend it over standard exercise for preventing heart disease.
Key findings
1Across the reviewed studies, 6–12 weeks of REHIT produced significant increases in VO2 max compared to baseline, with healthy inactive adults gaining 9%–21% over 12 weeks, while adults with type 2 diabetes showed smaller gains.
2Only four of the reviewed studies included a non-exercise control group, and the majority used training durations of 8 weeks or less, so most reported effects cannot be confidently attributed to REHIT rather than to time or attention.
3No study in the review measured actual cardiovascular events or CVD incidence; all cardiometabolic benefits are indirect markers (VO2 max, blood pressure, glucose, lipids), and the authors state that true efficacy for CVD prevention remains unproven.
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What it does not show
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.
Declared interests
Funded by the National Institute on Aging (NIH) under Award Number R15AG093525. No industry sponsorship, no conflicts of interest declared by the authors.
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