A generalized equation for predicting peak oxygen consumption during treadmill exercise testing: mitigating the bias from total body mass scaling

Everton J Santana; Nicholas Cauwenberghs; Bettia E Celestin; Tatiana Kuznetsova; Christopher Gardner; Ross Arena; Leonard A Kaminsky; Matthew P Harber; Euan Ashley; Jeffrey W Christle; Jonathan Myers; Francois Haddad

doi:10.3389/fcvm.2024.1393363

A generalized equation for predicting peak oxygen consumption during treadmill exercise testing: mitigating the bias from total body mass scaling

Front Cardiovasc Med. 2024 Dec 10:11:1393363. doi: 10.3389/fcvm.2024.1393363. eCollection 2024.

Authors

Everton J Santana^{1

2

3}, Nicholas Cauwenberghs³, Bettia E Celestin^{2

4}, Tatiana Kuznetsova³, Christopher Gardner⁵, Ross Arena⁶, Leonard A Kaminsky⁷, Matthew P Harber⁸, Euan Ashley¹, Jeffrey W Christle¹, Jonathan Myers^{1

9}, Francois Haddad^{1

2}

Affiliations

¹ Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, United States.
² Stanford Cardiovascular Institute, Stanford University, Stanford, CA, United States.
³ Research Unit Hypertension and Cardiovascular Epidemiology, Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
⁴ Division of Pathology, Stanford University School of Medicine, Stanford, CA, United States.
⁵ Department of Medicine, Stanford Prevention Research Center, Stanford University, Stanford, CA, United States.
⁶ Department of Physical Therapy, College of Applied Sciences, University of Illinois at Chicago, Chicago, IL, United States.
⁷ Fisher Institute for Health and Well-Being, Ball State University, Muncie, IN, United States.
⁸ Clinical Exercise Physiology, Ball State University, Muncie, IN, United States.
⁹ Cardiology Division, Veterans Affairs Palo Alto Healthcare System, Palo Alto, CA, United States.

Abstract

Background: Indexing peak oxygen uptake (VO₂peak) to total body mass can underestimate cardiorespiratory fitness (CRF) in women, older adults, and individuals with obesity. The primary objective of this multicenter study was to derive and validate a body size-independent scaling metric for VO₂peak. This metric was termed exercise body mass (EBM).

Method: In a cohort of apparently healthy individuals from the Fitness Registry and the Importance of Exercise National Database, we derived EBM using multivariable log-normal regression analysis. Subsequently, we developed a novel workload (WL) equation based on speed (Sp), fractional grade (fGr), and heart rate reserve (HRR). The generalized equation for VO₂peak can be expressed as VO₂peak = Cst × EBM × WL, where Cst is a constant representing the VO₂peak equivalent of one metabolic equivalent of task. This generalized equation was externally validated using the Stanford exercise testing (SET) dataset.

Results: A total of 5,618 apparently healthy individuals with a respiratory exchange ratio >1.0 (57% men, mean age 44 ± 13 years) were included. The EBM was expressed as Mass (kg)^0.63 × Height (m)^0.53 × 1.16 (if a man) × exp (-0.39 × 10^-4 × age²), which was also approximated using simple sex-specific additive equations. Unlike total body mass, EBM provided body size-independent scaling across both sexes and WL categories. The generalized VO₂peak equation was expressed as 11 × EBM × [2 + Sp (in mph) × (1.06 + 5.22 × fGr) + 0.019 × HRR] and had an R ² of 0.83, p < 0.001. This generalized equation mitigated bias in VO₂peak estimations across age, sex, and body mass index subgroups and was validated in the SET registry, achieving an R ² of 0.84 (p < 0.001).

Conclusions: We derived a generalized equation for measuring VO₂peak during treadmill exercise testing using a novel body size-independent scaling metric. This approach significantly reduced biases in CRF estimates across age, sex, and body composition.

Keywords: bias; body composition; cardiopulmonary exercise testing; exercise physiology; generalized equation; oxygen uptake; scaling; sex differences.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study was funded by the Stanford Cardiovascular Institute and the Wu Tsai Human Performance Alliance at Stanford University.