Busque V; Department of Medicine, Stanford University, California, USA

Christle JW; Moneghetti KJ; Cauwenberghs N; Kouznetsova T;

Blumberg Y; Wheeler MT; Ashley E; Haddad F; Myers J

Clinical Obesity. 14(4):e12653, 2024 Aug.

The goal of this study is to quantify the assumptions associated with the

Wasserman-Hansen (WH) and Fitness Registry and the Importance of Exercise:

A National Database (FRIEND) predictive peak oxygen consumption (pVO2)

equations across body mass index (BMI). Assumptions in pVO2 for both

equations were first determined using a simulation and then evaluated

using exercise data from the Stanford Exercise Testing registry. We

calculated percent-predicted VO2 (ppVO2) values for both equations and

compared them using the Bland-Altman method. Assumptions associated with

pVO2 across BMI categories were quantified by comparing the slopes of

age-adjusted VO2 ratios (pVO2/pre-exercise VO2) and ppVO2 values for

different BMI categories. The simulation revealed lower predicted fitness

among adults with obesity using the FRIEND equation compared to the WH

equations. In the clinical cohort, we evaluated 2471 patients (56.9% male,

22% with BMI >30 kg/m2, pVO2 26.8 mlO2/kg/min). The Bland-Altman plot

revealed an average relative difference of -1.7% (95% CI: -2.1 to -1.2%)

between WH and FRIEND ppVO2 values with greater differences among those

with obesity. Analysis of the VO2 ratio to ppVO2 slopes across the BMI

spectrum confirmed the assumption of lower fitness in those with obesity,

and this trend was more pronounced using the FRIEND equation. Peak VO2

estimations between the WH and FRIEND equations differed significantly

among individuals with obesity. The FRIEND equation resulted in a greater

attributable reduction in pVO2 associated with obesity relative to the WH

equations.

The outlined relationships between BMI and predicted VO2 may

better inform the clinical interpretation of ppVO2 values during

cardiopulmonary exercise test evaluations