Allometric correction of peak VO2 in obese adults undergoing cardiopulmonary exercise testing

We hypothesised that the reduction in cardiorespiratory fitness (CRF) of individuals with less severe obesity is small or non-existent when the allometric rather than the ratio standard is used for the comparison. We aimed to evaluate the influence of obesity on CRF, and to compare peak VO2 using allometric corrections in asymptomatic adults with a wide range of body mass index. The results of 780 adults (age 41 +/- 13 years) who underwent cardiopulmonary exercise testing (CPET) were evaluated. Participants were stratified according to body mass index (BMI): normal weight (n=227), overweight (n=198), and obese class 1 (n=155), 2 (n=131), and 3 (n=69). After cardiovascular risk assessment, the participants underwent CPET on a treadmill ramp protocol. The allometric exponents calculated were 0.60 and 0.62 for obese and non-obese groups respectively, with no significant differences. After using BMI strata in a multivariate analysis of covariance, we found an allometric exponent of 0.65. Peak VO2 using ratio standards significantly declined among all stratified groups. After allometric correction, peak VO2 remained significantly reduced only in women with obesity class 3 and men with obesity classes 2 and 3. When ratio standards were used to compare peak VO2, the effect of obesity on CRF was overestimated. Allometric correction of peak VO2 is more reasonable, and should be adopted as a routine for CPET.