You can estimate VO2 max without an all-out test

You do not need an all-out lab test to get a useful estimate of your VO2 max (the most oxygen your body can use during hard exercise). A timed run, a brisk walk, a step test or a watch that estimates it from your workouts lands close for most people on average, typically within about 4 to 5 points. For any one person the miss can be bigger, up to about 10 points, so treat the number as a trend to track, not an exact score.

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., Szwed, P. 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.

  n=4424

• Dugas, M.-O., Paradis-Deschênes, P., Simard, L. 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); the best walking test was a 2-minute maximum-distance walk (R2 = 0.829), slightly behind all three stepping tests' upper range (the two 6-inch step tests reached R2 0.830 and 0.831). Stepping tests explained about 2.5% more variance than walking tests. The authors concluded the models give good group-mean prediction, with greater error expected at the individual level, and perform similarly across a broad adult age range.

  n=157

• 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.

  n=73

• Mayorga-Vega, D., Bocanegra-Parrilla, R., Ornelas, M. et al. (2016). Criterion-Related Validity of the Distance- and Time-Based Walk/Run Field Tests for Estimating Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis. PLOS ONE.

  Walk/run field tests correlated with measured VO2max at low to moderate levels (rp 0.42-0.79). The 1.5-mile test (rp 0.79) and the 12-minute test (rp 0.78) were the most valid distance- and time-based options, and validity did not appear to depend on sex, age or fitness level. The authors call these tests useful alternatives when a lab test is not feasible, while stressing they are estimates rather than direct measures.

• Molina-Garcia, P., Notbohm, H.L., Schumann, M. et al. (2022). Validity of Estimating the Maximal Oxygen Consumption by Consumer Wearables: A Systematic Review with Meta-analysis and Expert Statement of the INTERLIVE Network. Sports Medicine.

  Wearables using resting information overestimated VO2max (bias 2.17 mL/kg/min, limits of agreement -13.07 to 17.41). Devices using exercise-based information were far closer on average (bias -0.09 mL/kg/min) but still had wide individual error (limits of agreement -9.92 to 9.74). The authors judge exercise-based estimates suitable at the population level but too imprecise for individual sport or clinical decisions.

  n=403

Why we call confidence high

Meta-analyses of walk/run field tests (Mayorga-Vega 2016, 123 studies) and of exercise-based wearable estimates (Molina-Garcia 2022) agree that these methods track VO2 max well across groups but can miss for an individual by up to about 10 mL/kg/min. Validation studies of step and walk tests in general adults report typical errors of about 4 to 5 (Hong 2019, Rowley 2022), and the ACSM equation from a submaximal treadmill test ran about 3.4 to 3.8 high in 99 active adults (Dugas et al. 2023, filed under the kasiak row). In trained endurance athletes, published prediction equations performed poorly (Wiecha 2023), so this claim does not cover them.

Where it applies

Healthy adults in the general population.

Does not apply to: trained endurance athletes, for whom published prediction equations performed poorly; clinical or research decisions that need one person's exact VO2 max.