Estimation of V̇O_2max from the ratio between HR_max and HR_rest – the Heart Rate Ratio Method

The effects of ṫ̇raining and/or ageing upon maximal oxygen uptake (V̇O_2max) and heart rate values at rest (HR_rest) and maximal exercise (HR_max), respectively, suggest a relationship between V̇O_2max and the HR_max-to-HR_rest ratio which may be of use for indirect testing of V̇O_2max. Fick principle calculations supplemented by literature data on maximum-to-rest ratios for stroke volume and the arterio-venous O₂ difference suggest that the conversion factor between mass-specific V̇O_2max (ml·min⁻¹·kg⁻¹) and HR_max·HR_rest ⁻¹ is ~15. In the study we experimentally examined this relationship and evaluated its potential for prediction of V̇O_2max. V̇O_2max was measured in 46 well-trained men (age 21–51 years) during a treadmill protocol. A subgroup (n=10) demonstrated that the proportionality factor between HR_max·HR_rest ⁻¹ and mass-specific V̇O_2max was 15.3 (0.7) ml·min⁻¹·kg⁻¹. Using this value, V̇O_2max in the remaining 36 individuals could be estimated with an SEE of 0.21 l·min⁻¹ or 2.7 ml·min⁻¹·kg⁻¹ (~4.5%). This compares favourably with other common indirect tests. When replacing measured HR_max with an age-predicted one, SEE was 0.37 l·min⁻¹ and 4.7 ml·min⁻¹·kg⁻¹ (~7.8%), which is still comparable with other indirect tests. We conclude that the HR_max-to-HR_rest ratio may provide a tool for estimation of V̇O_2max in well-trained men. The applicability of the test principle in relation to other groups will have to await direct validation. V̇O_2max can be estimated indirectly from the measured HR_max-to-HR_rest ratio with an accuracy that compares favourably with that of other common indirect tests. The results also suggest that the test may be of use for V̇O_2max estimation based on resting measurements alone.