UC Irvine

Background: Obesity is associated with increased asthma risk in children. However this relationship is inconsistent between genders. While both obesity and asthma are associated with decreased fitness, it is unclear whether fitness plays a role in the relationship between obesity and asthma.

Overall objective: The objective of this study was to evaluate cardiorespiratory fitness on the relationship between obesity and asthma prevalence and morbidity in adolescents.

Methods: This is a cross-sectional analysis of participants aged 12-19 years of age in the National Health and Nutrition Examination Survey (NHANES) from 1999-2006 that completed cardiorespiratory fitness testing, body composition measurements and respiratory questionnaires.

Results: A total of 4963 participants were included. Overweight/obese females had a significant increased odds of asthma diagnoses, with OR of 1.60 (95% CI 1.14, 2.23) compared to normal weight females. Overweight/obese females had an increased odds of asthma-related ED visits, with adjusted odds ratio of 2.97 (95% CI 1.72, 5.15) compared to normal weight females. Among males, those in the highest fitness tertile had a decreased odds of wheezing visits (OR 0.36, 95% CI 0.14, 0.97) and wheezing-related missed days (OR 0.36, 95% CI 0.14, 0.97) compared to those in the lowest fitness tertile.

Conclusion: The relationship between obesity and asthma diagnoses and morbidity differs by gender. Fitness may play a role in the relationship between obesity and asthma in males but not in females. Gender and fitness should be considered when examining the association between obesity and asthma in adolescents.