VO2max prediction based on submaximal cardiorespiratory relationships and body composition in male runners and cyclists: a population study

Abstract

Background: Oxygen uptake (VO₂) is one of the most important measures of fitness and critical vital sign. Cardiopulmonary exercise testing (CPET) is a valuable method of assessing fitness in sport and clinical settings. There is a lack of large studies on athletic populations to predict VO_2max using somatic or submaximal CPET variables. Thus, this study aimed to: (1) derive prediction models for maximal VO₂ (VO_2max) based on submaximal exercise variables at anaerobic threshold (AT) or respiratory compensation point (RCP) or only somatic and (2) internally validate provided equations.

Methods: Four thousand four hundred twenty-four male endurance athletes (EA) underwent maximal symptom-limited CPET on a treadmill (n=3330) or cycle ergometer (n=1094). The cohort was randomly divided between: variables selection (n_runners = 1998; n_cyclist = 656), model building (n_runners = 666; n_cyclist = 219), and validation (n_runners = 666; n_cyclist = 219). Random forest was used to select the most significant variables. Models were derived and internally validated with multiple linear regression.

Results: Runners were 36.24±8.45 years; BMI = 23.94 ± 2.43 kg·m^-2; VO_2max=53.81±6.67 mL·min^-1·kg^-1. Cyclists were 37.33±9.13 years; BMI = 24.34 ± 2.63 kg·m^-2; VO_2max=51.74±7.99 mL·min^-1·kg^-1. VO₂ at AT and RCP were the most contributing variables to exercise equations. Body mass and body fat had the highest impact on the somatic equation. Model performance for VO_2max based on variables at AT was R²=0.81, at RCP was R²=0.91, at AT and RCP was R²=0.91 and for somatic-only was R²=0.43.

Conclusions: Derived prediction models were highly accurate and fairly replicable. Formulae allow for precise estimation of VO_2max based on submaximal exercise performance or somatic variables. Presented models are applicable for sport and clinical settling. They are a valuable supplementary method for fitness practitioners to adjust individualised training recommendations.

Funding: No external funding was received for this work.

Keywords: VO2max; athletes; body composition; cardiopulmonary; human; medicine; prediction; threshold.

Figure 1.. Flowchart of the preliminary inclusion and exclusion process.

Abbreviations: EA, endurance athlete; CPET, cardiopulmonary exercise testing; SD, standard deviation; TE, treadmill; RER, respiratory exchange ratio; VO₂, oxygen uptake (mL·min⁻¹·kg⁻¹); [La⁻]_b, lactate concentration (mmol·L⁻¹); fR, breathing frequency (breaths·min⁻¹); RCP, respiratory compensation point; HR_peak, peak heart rate (beats·min⁻¹); HR_max, maximal heart rate (bpm). At both stages of the selection, some participants met several (>1) exclusion criteria.

Figure 2.. Performance of prediction equations for VO_2max.

Abbreviations: VO_2max; maximal oxygen uptake; AT, anaerobic threshold; RCP, respiratory compensation point; Max, maximal; Som, somatic. All values are presented in mL·min^–1·kg^–1. Upper panel shows performance for running equations, while the lower panel shows performance for cycling equations. Panel A shows performance of the prediction model for AT; panel B for RCP; panel C for AT and RCP; panel D for somatic-only equation.

Figure 3.. Bland-Altman plots comparing observed with predicted VO_2max in runners derivation and validation cohorts.

Abbreviations: VO_2max; maximal oxygen uptake; AT, anaerobic threshold; RCP, respiratory compensation point; Max, maximal; Som, somatic. All values are presented in mL·min^–1·kg^–1. Upper panel shows performance for running equations, while the lower panel shows performance for cycling equations. Panel A shows performance of the prediction model for AT; panel B for RCP; panel C for AT and RCP; panel D for the somatic-only equation.