Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 22124524 · doi:10.1007/s00421-011-2254-z
What was done
Twenty-nine healthy but sedentary young men and women were randomly assigned to a reduced-exertion high-intensity interval training (REHIT) intervention (7 men, 8 women) or a sedentary control group (6 men, 8 women). The REHIT group completed 3 sessions per week for 6 weeks. Each 10-minute session consisted of 60 W cycling with one (session 1) or two (all other sessions) all-out sprints lasting 10 seconds in week 1, 15 seconds in weeks 2-3, and 20 seconds in weeks 4-6. Aerobic capacity (VO2max) and glucose/insulin responses to a 75-g oral glucose tolerance test (OGTT) were measured before and 3 days after the 6-week intervention.
What was found
Participants reported relatively low perceived exertion (RPE 13 ± 1). Aerobic capacity increased in the male training (+15%) and female training (+12%) groups (P < 0.01). Insulin sensitivity increased significantly by 28% in the male training group (P < 0.05). The abstract does not report numerical data or significant changes in insulin sensitivity for the female training group, nor does it provide control group numerical values.
Why it matters
This study demonstrates that an abbreviated exercise protocol with minimal sprint time can improve cardiorespiratory fitness and male insulin sensitivity with low perceived exertion, offering a time-efficient training alternative.
Limits
The sample size is small (6-8 participants per subgroup). Insulin sensitivity improvements were only observed in men. The study was conducted in young, healthy sedentary participants, limiting generalizability to older or clinical populations with type 2 diabetes. The abstract does not report numerical values for the control group or female metabolic outcomes.
Cited by
- supports The reduced-exertion high-intensity interval training (REHIT) protocol on the CAROL bike improves VO2 max by 12% to 15% after 8 weeks with 15 minutes of total exercise per week.