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