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Cardio
Meta-analysis of trials
HIIT or steady cardio: which improves fitness more?
Reviewed by Joseph Korban, Certified Personal Trainer & Rehabilitation Specialist · Last reviewed 27 September 2026
Both raise VO2max (aerobic fitness). In a meta-analysis of women, moderate-to-vigorous continuous training and HIIT improved VO2max by almost the same amount (about 3.2 ml/kg/min each; difference between them -0.42, 95% CI -1.43 to 0.60). HIIT's main advantage is time: similar gains in shorter sessions.
What to know
- Pick the style you will actually keep doing; both work.
- Short interval sessions suit busy people; steady cardio suits beginners and easy recovery days.
- Build up gradually and get medical clearance if you have heart or health conditions.
Evidence
- Milanović Z, Sporiš G, Weston M. Effectiveness of high-intensity interval training (HIT) and continuous endurance training for VO2max improvements: a systematic review and meta-analysis of controlled trials. Sports Med. 2015;45(10):1469-1481. 28 studies, 723 healthy adults.
- Lindner R, et al. Moderate to vigorous-intensity continuous training versus high-intensity interval training for improving VO2max in women: a systematic review and meta-analysis. Int J Sports Med. 2023.