Heart Rate Ratio: A Valid Method for Maximal Oxygen Uptake Assessment in Professional Football Players

Paulo Roberto Santos-Silva, Júlia Maria Andrea Greve, Eneas Martins de Oliveira Lima, Júlio Cesar Carvalho Nardelli, Adriano Marques Almeida, Arnaldo José Hernandez, André Pedrinelli, Celso Ferreira, Guilherme Veiga Guimarães.

Abstract

Background: Direct measurement of V? O2 max (the gold standard) requires expensive equipment and exhaustive exercise testing. In football, the search for non-invasive, practical, and low-cost methods is essential for frequent athlete monitoring. The Heart Rate Ratio (HRratio) method emerges as a viable alternative, based on the linear relationship between oxygen uptake and heart rate.

Objective: The aim of the study was to estimate maximal oxygen uptake (V? O2 max) from the Heart Rate Ratio (HRmax/HRrest) method, providing a practical and non-invasive alternative to maximal testing.

Methods: A proportionality factor (PF) of 15.8 mL.kg-1.min-1 was calculated from an experimental group of 24 football players and subsequently validated in a confirmatory group of 70 players. The criterion V? O2 max was measured using a cardiopulmonary treadmill (Heck protocol) exercise test (gold standard). The estimated V? O2 max was compared with the measured V? O2 max and with V? O2 max predicted using the Tanaka equation for HRmax. 

Results: No significant difference was found between the measured V? O2 max and the V? O2 max predicted by the validated PF of 15.8 (PF) and HRmax/HRrest (58.3 vs. 59 mL.kg-1.min-1; p=0.108; d=0.27, small) or the Tanaka equation (58.3 vs. 58.9 mL.kg-1.min-1; p=0.158; d=0.22, small). Significant correlations were observed for both the PF method (r = 0.455, p<0.001) and the Tanaka method (r=0.509, p<0.001). Regression analyses revealed a low Standard Error of Estimation (SEE) for the V? O2 max measured from HRmax (4%) and HRmax predicted from Tanaka (4.5%). Bland-Altman analysis demonstrated good agreement between the two methods.

Conclusion: The Heart Rate Ratio Method is a valid tool for estimating V? O2 max in this population. V? O2 max can be estimated indirectly by the following equation, using a factor specific to football players: V? O2 max = (PF times HRmax/HRrest), where PF is 15.8 mL.kg-1.min-1.