Exercise-induced bronchoconstriction (EIB) is not associated with exhaled nitric oxide (FeNO) in adolescent athletes

Abstract

Background: The mechanisms of EIB have been suggested to differ between adult athletes and the general population. In line with this, FeNO has been associated with EIB in the general population, but not in adult athletes. Respiratory resistance measured by forced oscillation technique is suggested to be a more sensitive measurement of airway obstruction than FEV1.

Aim: To study the association between baseline FeNO and post-exercise changes in FEV1 and respiratory resistance in adolescents either attending a sports high school or from the general population.

Methods: Study group A consisted of 148 adolescents, aged 13-15 years, from the general population. Study group B consisted of 98 adolescents, aged 15-17 years, attending sports high school. The subjects performed FeNO before and FEV1 and respiratory resistance measurements at 5 Hz (R5) before and after a standardised exercise test.

Results: A positive EIB test (fall in FEV1 ≥10%) was found in 48 subjects in group A and in 24 subjects in group B. FeNO related to post-exercise fall in FEV1 as well as increase in R5 in group A (rho=-0.17, p=0.04 and rho=0.34, p<0.001, respectively). No such relation was found in group B (p>0.05). Elevated FeNO (>25 ppb) was associated with EIB in group A: odds ratio (OR) 2.6 (CI 95% 1.1, 6.2), but not in group B (OR 1.0, CI 95% 0.3, 3.2). The findings in group A were consistent after adjusting for age, gender and height (aOR 2.6 CI 95% 1.1, 6.6).

Conclusion: EIB in adolescent athletes is not associated with FeNO in contrast to adolescents from the general population. This indicates that the mechanisms leading to EIB in adolescent athletes may differ from the general population.