Background:The cardiopulmonary exercise test (CPET) has a large clinical applicability in the diagnosis and prognosis of exercise intolerance. The peak V’O2 is the primary variable
used to determine cardiopulmonary fitness (CPF), and it is estimated before the start of the test by the predictive equations, allowing the incremental workload of the ramp protocol can be calculated.
However, when it comes to obese individuals, such equations appear limited, overestimating CPF and resulting in premature interruption of the test. Therefore, the construction of a specific equation
can help to improve the estimate of peak V’O2 in obese.
Methods:346 obese subjects (BMI ≥ 30kg/m²) were selected from the EPIMOV (Epidemiological Study of Human Movement and Hypokinetic Diseases) study and the obesity ambulatory of
Angiocorpore Cardiovascular Medicine Institute. The subjects were randomized into two groups. The first group, containing 80% of subjects (n= 272) was used to create the peak V’O2 prediction equation
while the second group, with 20% of subjects (n= 74) was prospectively analyzed and cross validated to create the equation. Weight and height were measured and the body mass index (BMI) was
calculated. Cardiopulmonary fitness was obtained from the cardiopulmonary exercise testing in a treadmill with a ramp protocol, and the speed and inclination were incremented according to the peak
V’O2 estimated for each participant by equation Vivacqua & Spagna. The prediction equation was obtained using a multivariate linear regression model, adjusted by sex, age, height, physical inactivity,
diabetes, hypertension, hyperlipidemia, BMI and smoking. Finally, we compared the peak V’O2 measured values estimated from three previously published reference equations, through the Bland and Altman
Results:The main predictors for peak V’O2 (height, gender and age) were responsible for 73.1% of total variability. Mean difference between peak V’O2 estimated by the developed
equation and what was obtained was 7 mL/minute, with a 23.9% bias. The correlation between the mean value estimated and obtained on peak V’O2 and the mean difference of estimated and obtained on peak
V’O2 was r=0.05. The previously developed equations has significantly overestimated peak V’O2, with a 35.3% bias (Hansen et al.), 49.1% (Vivacqua & Spagna) and 46.2% (Almeida et al.)
Conclusions: The equation developed in this study presents a greater concordance and validity in evaluating peak V’O2 in asymptomatic obese adults when compared to other equations
available in scientific literature for non-obese subjects. This result have a relevant clinical applicability due to the fact that a better peak V’O2 estimate leads to a better design in the ramp
protocol, and consequently, a better evaluation of cardiopulmonary fitness in obese.