Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of controlled trials
PubMed 26243014 · doi:10.1007/s40279-015-0365-0
What was done
A systematic review and meta-analysis of 28 controlled trials (searched across MEDLINE, PubMed, SPORTDiscus, Web of Science, CINAHL, and Google Scholar) evaluated the effects of high-intensity interval training (HIT) and continuous endurance training on VO2max. The analysis included 723 healthy adults aged 18–45 years (mean age 25.1 ± 5 years; baseline VO2max 40.8 ± 7.9 mL·kg⁻¹·min⁻¹) with intervention durations of ≥2 weeks. Probabilistic magnitude-based inferences were calculated from standardized baseline standard deviations.
What was found
Compared to no-exercise controls, endurance training improved VO2max by 4.9 mL·kg⁻¹·min⁻¹ (95% CL ±1.4), and HIT improved VO2max by 5.5 mL·kg⁻¹·min⁻¹ (95% CL ±1.2). When directly compared to endurance training, HIT provided a possibly small additional improvement of 1.2 mL·kg⁻¹·min⁻¹ (95% CL ±0.9). Greater relative gains for HIT over endurance training were observed with longer repetitions (+2.2 mL·kg⁻¹·min⁻¹; ±2.1), older subjects (+1.8 mL·kg⁻¹·min⁻¹; ±1.7), longer interventions (+1.7 mL·kg⁻¹·min⁻¹; ±1.7), and higher work/rest ratios (+1.6 mL·kg⁻¹·min⁻¹; ±1.5).
Why it matters
Both endurance training and HIT effectively improve VO2max in healthy young to middle-aged adults, with HIT offering a small additional boost in cardiorespiratory fitness compared to continuous endurance training.
Limits
The review included controlled trials broadly rather than exclusively randomized trials. Findings are restricted to healthy adults aged 18–45 and may not generalize to older, clinical, or elite athletic populations. Safety, adherence, and long-term clinical endpoints were not reported.
Cited by
- supports Interval durations in the 2 to 4-minute range appear particularly effective for improving VO2 max.