VO2max trainability and high intensity interval training in humans: a meta-analysis.
Level 1 - systematic review of randomized trials
Meta-analysis of exercise intervention studies
PubMed 24066036 · doi:10.1371/journal.pone.0073182
What was done
Meta-analysis of interval training (IT) and combined IT/continuous training (CT) studies published from 1965 to 2012. Inclusion criteria were: 1) ≥3 healthy sedentary/recreationally active humans <45 years old; 2) 6–13 weeks duration; 3) ≥3 days/week; 4) ≥10 minutes of high-intensity work; 5) ≥1:1 work/rest ratio; and 6) reported mean ± SD/SE, change ranges, or individual data. Change in VO2max was synthesized using a random-effects model.
What was found
Across 37 studies (40 distinct training groups, 334 subjects, 120 women), VO2max increased by 0.51 L·min(-1) (95% CI: 0.43 to 0.60 L·min(-1); I2 = 70). A subset of 9 studies (72 subjects) featuring longer intervals showed larger increases of ~0.8–0.9 L·min(-1) with marked response in all subjects.
Why it matters
Demonstrates that interval training reliably increases VO2max, with longer intervals producing substantially larger improvements and challenging concepts of non-trainability.
Limits
High heterogeneity (I2 = 70) among included studies. The population was limited to healthy individuals under 45 years old, individual study sample sizes were small (some with as few as 3 participants), and long-term adherence or outcomes beyond 13 weeks were not assessed.
Cited by
- supports Interval repeats lasting three to five minutes performed at the highest sustainable intensity are the most effective interval protocol for maximizing VO2 max gains.