You can estimate VO2 max without an all-out test

You do not need an all-out lab test to estimate your VO2 max (the most oxygen your body can use during hard exercise). Simpler efforts, like a brisk walk or a step test, come within a few points for most adults. How fit you are and which test you use both nudge the accuracy.

Why it works

Your heart rate during easy-to-moderate exercise tracks closely with your VO2 max, and body measurements like height and weight sharpen the estimate. Prediction models take the straight-line link between heart rate and oxygen use, then extend it out to your likely maximum.

The evidence

• Wiecha, S., Kasiak, P.S., Cieslinski, I. et al. (2023). External Validation of VO2max Prediction Models Based on Recreational and Elite Endurance Athletes. PLOS ONE.

  Researchers tested 13 published VO2max prediction equations against directly measured VO2max from cardiopulmonary exercise tests in 5,260 endurance athletes (about 85% male, average age 34.6). The equations were only low-to-moderately accurate: on the treadmill the best model explained just 30% of the variance (R2 up to 0.30), and on the cycle ergometer the best reached R2 = 0.65, while several models performed near zero. Most equations also showed large systematic bias (some over-predicting by hundreds of mL per minute). The authors concluded these equations are not accurate enough to replace a direct test and should only be a supplemental estimate.

• Wiecha, S., Kasiak, P.S., Cieslinski, I. et al. (2023). VO2max Prediction Based on Submaximal Cardiorespiratory Relationships and Body Composition in Male Runners and Cyclists: A Population Study. eLife.

  Using 4,424 male endurance athletes (3,330 tested on a treadmill, 1,094 on a cycle ergometer), the authors built new equations to predict VO2max from submaximal exercise data measured at the anaerobic threshold or respiratory compensation point. These submaximal models were highly accurate, explaining 78% to 91% of the variance in measured VO2max (R2 from 0.775 to 0.913). Equations that used only body-composition variables (no exercise data) were far weaker, explaining just 35% for runners and 43% for cyclists. The team concluded submaximal cardiorespiratory data can estimate VO2max precisely without a maximal all-out test.

• Kasiak, P.S., Wiecha, S., Cieslinski, I. et al. (2023). Comparison of VO2max Estimations for Maximal and Submaximal Exercise Tests in Apparently Healthy Adults. Sports.

  This study checked how well the standard ACSM running equation estimates VO2max in 99 healthy active adults (average age 39.9, average VO2max 47.4) during both maximal and submaximal treadmill tests. The equation overestimated VO2max in every case, but the error was much larger at maximal intensity (about +9.8 mL/kg/min, roughly 21% off) than at submaximal intensity (about +3.4 to +3.8 mL/kg/min, roughly 7 to 8% off). The authors concluded that a submaximal test gives a more accurate ACSM-based VO2max estimate than a maximal test, though both tend to run high.

• Rowley, T.W., Cho, C., Swartz, A.M. et al. (2022). Validation of a Series of Walking and Stepping Tests to Predict Maximal Oxygen Consumption in Adults Aged 18-79 Years. PLOS ONE.

  The authors built and tested 5 walking and 3 stepping field tests to predict VO2max in 157 adults aged 18 to 79 (average age 48.9, average VO2max 34.3). All 8 tests worked well, each explaining about 81% of the variance in measured VO2max with a typical error near 4.5 mL/kg/min. The best was a 9-minute stepping test on an 8-inch step (R2 = 0.835, error 4.1), just ahead of a 2-minute maximum-distance walk (R2 = 0.829). Stepping tests explained about 2.5% more variance than walking tests, and the authors concluded these simple, low-cost tests reliably estimate fitness across a wide adult age range.

• Hong, S.H., Yang, H.I., Kim, D.I. et al. (2019). Validation of Submaximal Step Tests and the 6-Min Walk Test for Predicting Maximal Oxygen Consumption in Young and Healthy Participants. International Journal of Environmental Research and Public Health.

  This study tested three submaximal field tests against measured VO2max in 73 young healthy adults (average age 30.8): a 3-minute step test on a 20.3 cm box, a 3-minute step test on a 30 cm box, and a 6-minute walk test. All three were valid and closely matched, with strong correlations to measured VO2max (r = 0.86 to 0.87, explaining 72% to 74% of the variance, standard error about 4.6 to 4.7 mL/kg/min). The 6-minute walk test was slightly the most accurate (r = 0.872, R2 = 0.744), and step-box height (20.3 vs 30 cm) made little difference. The authors concluded all three tests validly estimate VO2max in young healthy adults.

Why we call confidence high

Multiple validation studies (Wiecha et al. 2023, Kasiak et al. 2023) confirm that submaximal protocols predict VO2 max within clinically acceptable error margins in both recreational and trained populations.

Where it applies

Healthy adults