Estimate your maximal oxygen uptake using two independent methods. No signup required.
Run as far as you can in exactly 12 minutes on flat ground.
Uth-Sørensen-Overgaard-Pedersen formula: VO₂max = 15.3 × (HRmax / HRrest)
VO2max (maximal oxygen uptake) is the maximum rate at which your body can consume oxygen during intense exercise, measured in mL·kg⁻¹·min⁻¹. It's the single best predictor of endurance performance at the physiological level — but it's not destiny.
The Cooper test: This 12-minute maximal run test was developed by Dr. Kenneth Cooper in 1968 for the US Air Force. The formula (VO2max = (distance in meters − 504.9) / 44.73) correlates strongly (r ≈ 0.90) with lab-measured VO2max in healthy adults. You must run as far as you can in exactly 12 minutes — not 11, not 13 — on a flat track or road. If you paced yourself, the estimate will be low.
The Uth-Sørensen-Overgaard-Pedersen method: Uses resting HR and estimated max HR (220 − age). VO2max = 15.3 × (HRmax / HRrest). This is a rough estimate (±15%) — it assumes normal stroke volume and arteriovenous O₂ difference, which vary significantly between individuals. A person with a resting HR of 40 is not automatically twice as fit as someone with a resting HR of 80; genetics, medication (beta blockers), hydration, and recent training all influence resting HR.
When it's wrong: Cooper test if you didn't truly go all-out. Resting HR method if you measured HR right after coffee, alcohol, a hard workout, or while sick. Neither method works for cyclists or swimmers (different muscle-mass utilisation). Both methods are biased against older athletes (the age-based HRmax formula is population-average, not individual).
What matters more: Running economy (how efficiently you use oxygen at a given pace) and lactate threshold (the percentage of VO2max you can sustain) are better predictors of race performance than VO2max alone. Two runners with the same VO2max can have vastly different 5K times if one has better economy. Baseline tracks your efficiency trends over time — same pace at a lower heart rate means you're getting fitter, regardless of what your VO2max number says.