Cardiorespiratory fitness of asthmatic children and validation of predicted aerobic capacity

Abstract

Introduction: Predicted aerobic capacity (PAC) was estimated by submaximal exercise test and compared with monitored aerobic capacity (MAC) measured by laboratory conditions [maximal oxygen uptake (VO2peak)] in 18 children and adolescents, 10 asthmatics and 8 matched controls. Objectives: To compare aerobic capacity between asthmatic children and controls, to estimate the agreement between PAC and MAC and observe for trend of PAC. Materials and Methods: The design was prospective, 4 years (PAC) and cross-sectional (MAC and VO2peak). Non-parametric Wilcoxon rank sums were applied for statistical evaluation; the method of Bland and Altman estimated the agreement between PAC and MAC; P < 0.05. Results: PAC at baseline and follow-up, and MAC at follow-up, showed significant differences between groups (P < 0.05), and the mean difference between PAC and MAC at follow-up was -1.0 mLO 2/min/kg [non-significant (ns)], indicating that PAC had a bias towards underestimation as compared with MAC. Limits of agreement, mean difference [±2 standard deviations (SD)], ranged from -8.5 to 6.5 mLO2/min/kg, indicating good agreement between the two measurements. No trend of PAC was observed (ns). Physical activity level and subjective health showed no differences between groups, or level and categories, respectively. Conclusion: The asthmatic participants presented with lower aerobic capacity than controls in both PAC and MAC; therefore, results confirmed the validity of the PAC method. Data warrant exploration by large-scale paediatric asthma epidemiology. © 2008 Blackwell Publishing Ltd.