Cardiopulmonary Fitness in Children With Asthma Versus Healthy Children

This study aims to evaluate cardiopulmonary fitness using cardiopulmonary exercise testing (CPET) and maximum oxygen uptake (Vo_2max) in pediatric patients with asthma and compare these results to healthy controls.

Children 5 to 18 years old with asthma referred to Montpellier University Hospital and Saint-Pierre-Institute in France were compared with a control group evaluated for nonsevere functional symptoms linked to exercise like murmurs, palpitations, or dyspnea.

A cross-sectional controlled study of 446 children was performed from January 2015 to December 2019 at 2 tertiary pediatric care centers. Children included in the study were divided into those with and without asthma stratified based on Global Initiative for Asthma classifications. All children underwent complete CPET with a standardized pediatric cycle ergometer protocol for 8 to 12 mins. The maximum rate of oxygen consumption attainable during physical exertion, Vo_2max, was measured, and a value of <80% indicated impaired cardiopulmonary fitness. Ventilatory anaerobic thresholds (VAT) <55% of predicted Vo_2max values indicated physical deconditioning. CPET parameter comparisons using generalized linear models were adjusted for gender, age, and BMI.

All children were similar in the maximum load of exercise tolerable. However, the proportion of children with an impaired Vo_2max was 4 times higher in the asthma group than in the control group (24% vs 6%, P < .01, respectively). The proportion of children with a decreased VAT <55% was 3 times higher in the asthma group (31% vs 11%, P < .01) than in the controls. Adjustments of CPET parameters were made for age, gender, and BMI.

Lower Vo_2max was associated with female gender, high BMI, low forced expiratory volume 1, low VAT (deconditioning), and the degree of obstructive lung disease. There was no significant association between Vo_2max and level of asthma severity.

The use of CPET in childhood asthma can provide a comprehensive assessment of cardiopulmonary fitness. Children with asthma were prone to ventilatory inefficiency during exercise because of respiratory impairment and physical deconditioning. Decreased cardiopulmonary fitness was associated with female gender, high BMI, and lower forced expiratory volume 1. Thirty percent of asthmatic children had impairment because of deconditioning.

Children with asthma have difficulty exercising. Is it because of exercise-induced bronchospasm, poor asthma control, hyperinflation, or rapid breathing? Is it because of self or parental perception of impaired physical ability? Correlating exercise with difficulty breathing can lead to self-limiting behavior. The less exercise they do, the more deconditioned they become, creating a vicious cycle. The Vo_2max was lower in children with high BMI, as adipose tissue does not consume oxygen. Lower Vo_2max in girls reflects the established gender differences in muscle mass and adipose tissue. Regular physical activity for asthmatics is recommended by the Global Initiative for Asthma and the National Heart, Lung, and Blood Institute guidelines, with benefits for disease control, lung function, and mental health. Emphasizing compliance with medications and helping patients distinguish symptoms of exercise-induced bronchospasm from the normal dyspnea of deconditioning is essential for the long-term health of patients with asthma. Let’s get physical, physical.