Cross-validation of a non-exercise measure for cardiorespiratory fitness in Singaporean adults.

INTRODUCTION Cardiorespiratory fitness (CRF) is an independent predictor of voluminous health outcomes and can be measured using non-exercise fitness assessment (NEFA) equations. However, the accuracy of such equations in Asian populations is unknown. The objective of this study was to cross-validate the NEFA equation, developed by Jurca et al in 2005, in the adult Singaporean population. METHODS A total of 100 participants (57 men, 43 women; aged 18-65 years) were recruited, and their maximal oxygen consumption (VO2 max) was measured in the laboratory by indirect calorimetry. The participants also completed the NEFA questionnaire, which helps to predict VO2 max with the NEFA equation. The relationship between NEFA-predicted and laboratory-measured VO2 max values was analysed. RESULTS Overall, our study demonstrated a high correlation between the NEFA-predicted and laboratory-measured VO2 max values (r = 0.83). The Pearson's correlation coefficient values for the men and women in the study were 0.61 and 0.77, respectively. To improve the accuracy of the predictive equation, we transformed the original equation developed by Jurca et al into new equations that would allow estimation of VO2 max with and without resting heart rate as a variable. CONCLUSION The modified NEFA equations accurately estimated CRF and may be applied to the majority of adult Singaporeans. With this, health practitioners and researchers are now able to assess CRF levels at both the individual and population levels in either the primary care, fitness or research setting.