The claimEvidence A · guideline-tier
You must walk 10,000 steps a day
The evidence
The number came from a 1960s Japanese pedometer ad; the benefit plateaus at about 7000-8000 steps (Lee 2019, Paluch 2022).
The mechanism, in brief
Sprint for a short stretch, slow down and catch your breath, and repeat for a few rounds: that is high-intensity interval training (HIIT). Its best-known selling point is saving time, but saving time is the result, not the principle. The principle is in those tens of seconds of hard effort.
Sources (3)
- Milanović, Z., Sporiš, G., & Weston, M. (2015). Effectiveness of high-intensity interval training (HIT) and continuous endurance training for VO2max improvements: A systematic review and meta-analysis of controlled trials. Sports Medicine, 45(10), 1469-1481. 28 controlled trials, 723 participants (mean age 25.1). Versus no-exercise controls, endurance training raised VO2max by 4.9 mL/kg/min (95% CL +/-1.4) and HIT by 5.5 (+/-1.2); HIT versus endurance training was 1.2 (+/-0.9), which the authors label a possibly small beneficial effect using magnitude-based inference rather than significance testing. The paper makes no comparison of training time.
- Gibala, M. J., Little, J. P., MacDonald, M. J., & Hawley, J. A. (2012). Physiological adaptations to low-volume, high-intensity interval training in health and disease. The Journal of Physiology, 590(5), 1077-1084. Mechanistic review of HIIT-induced mitochondrial and cardiovascular adaptations.
- Achten, J., & Jeukendrup, A. E. (2003). Maximal fat oxidation during exercise in trained men. International Journal of Sports Medicine, 24(8), 603-608. Max fat-oxidation occurs around 59-64% VO2max; above that the absolute fat-oxidation rate falls even as relative % rises — the empirical basis for debunking the 'fat-burning zone' marketing.