Development of a reference equation for maximal exercise capacity in normal Indian subjects using cardiopulmonary exercise testing

ABSTRACT

Objectives: Cardiopulmonary exercise testing (CPET) is an integrative assessment of multiple interdependent variables contributing to exercise response. CPET parameters such as maximum or peak oxygen uptake (VO2max/peak) are used to estimate this response. VO2max/peak varies with physiological predictors such as age, sex, body mass index (BMI), and activity level. The existing normative values for Indian subjects have, thus, far been adapted from Western populations who have a different body habitus in terms of these physiological predictors. We aimed to determine the relation and a prediction equation of these variables with VO2peak. Materials and Method: One hundred and twenty-one healthy subjects underwent CPET on a treadmill (Cortex Metalyzer) in a tertiary care hospital and VO2peak was calculated through Metasoft software. Statistical analysis: Student’s t-test and one-way analysis of variance (ANOVA) were used for calculating the between-group difference. Logistic regression with univariate and multivariate ANOVA was used for computing the reference equation. Results: Mean VO2peak (ml/min/kg) was 29.9 ± 7.7. It was higher for males (32.81 ± 7.9 vs. 26.79 ± 6.1 [P < 0.001]) and active individuals (32.8 ± 7 vs. 26.1 ± 6.9 [P < 0.001]). Higher values were observed in younger and non-obese population (P < 0.001). Regression coefficient (r2) was 0.44 and 0.36 for male and female, respectively. Reference equation was then calculated for males and females using the r2 value. Conclusion: VO2peak was higher in males and active individuals, it declined with increasing age and BMI. The values obtained were much lower than the Western population, therefore stressing the need for the development of our own set of reference equations.