A Multi-Center Comparison of O 2peak Trainability Between Interval Training and Moderate Intensity Continuous Training.
Level 3 - non-randomized controlled study
Pooled individual participant data analysis from multiple separate intervention cohorts
PubMed 30804794 · doi:10.3389/fphys.2019.00019
What was done
Individual participant data were pooled from 18 aerobic exercise training interventions across 8 universities in 5 countries to evaluate VO2peak trainability. The analysis included 677 participants (495 men; mixed healthy, elderly, and clinical populations) completing at least 3 weeks of high-volume HIIT (>15 min high-intensity effort/session, n = 299), low-volume HIIT/sprint interval training (SIT, <15 min high-intensity effort/session, n = 116), or moderate-intensity continuous training (MICT, n = 262). Trainability was assessed using adjusted absolute and relative VO2peak changes and a high-threshold responder analysis (technical error plus minimal clinically important difference).
What was found
All interventions improved mean VO2peak (P < 0.001). High-volume HIIT yielded significantly greater adjusted absolute VO2peak increases (0.29 L/min) compared with MICT (0.20 L/min) and low-volume HIIT/SIT (0.18 L/min) (P < 0.05). Adjusted relative VO2peak gains were significantly higher in high-volume HIIT (3.3 mL/kg/min) than MICT (2.4 mL/kg/min, P < 0.01), but not statistically different from low-volume HIIT/SIT (2.5 mL/kg/min, P = 0.09). High-volume HIIT had significantly more likely responders (31%) than low-volume HIIT/SIT (16%) and MICT (21%, P < 0.01). Measured covariates (age, sex, study site, population group, session frequency, duration, baseline/post average VO2peak) explained only 17.3% of the total variance in trainability.
Why it matters
High-volume interval training elicits larger VO2peak gains and a higher proportion of definitive cardiorespiratory fitness responders than either low-volume interval protocols or continuous moderate exercise. However, substantial unexplained inter-individual variability remains across all training modalities.
Limits
The dataset combines heterogeneous studies with varying durations (down to just 3 weeks), protocols, and populations (healthy, older, clinical). Men constituted 73% of the sample. Over 82% of the variance in VO2peak response remained unexplained by the measured covariates.
Cited by
- context Roughly 40 percent of people who engage in guideline-based moderate-intensity continuous exercise for six months do not show a measurable improvement in VO2 max.