Exhaled nitric oxide decreases during exercise in non‐asthmatic children

Introduction: Exhaled nitric oxide (FE_NO) measurements are recommended to be performed before spirometry and exercise challenge tests because forced breathing might influence FE_NO values. Information on the effect of exercise on FE_NO is lacking in non‐asthmatic children. Aim: To investigate the effect on FE_NO of a standardized exercise challenge test on a treadmill in non‐asthmatic children with and without allergic rhinoconjunctivitis (AR) symptoms. Methods: From the case‐control study ‘Asthma and allergy among school children in Nordland’, 330 non‐asthmatic pupils age 8–16 years were enrolled. FE_NO was measured at baseline and at 1 min and 30 min after exercise challenge test by the single breath technique with EcoMedics Exhalazer® (Eco Physics, Duernten, Switzerland). Results: Pair‐wise comparison of FE_NO from baseline demonstrated a highly significant reduction in FE_NO post‐exercise for all children at 1 min (27.4%) and at 30 min (16.1%) (P < 0.001). The AR group had a significantly higher decline in FE_NO value at 1 min post‐exercise compared to the non‐AR group, 4.2 parts per billion (ppb) vs 2.6 ppb (P < 0.001). Decline in FE_NO immediately post‐exercise was more significant if baseline FE_NO was ≥ 20 ppb; mean reduction 9.9 (95% CI: 8.7–11.4) ppb. Conclusion: FE_NO is reduced by 27.4% immediately after a standardized treadmill exercise test in non‐asthmatic children. Pupils reporting AR symptoms demonstrate a larger decline in FE_NO value at 1 min post‐exercise compared to pupils without AR symptoms. These findings confirm that children should refrain from physical activity before FE_NO measurement. Please cite this paper as: Evjenth B, Hansen TE and Holt J. Exhaled nitric oxide decreases during exercise in non‐asthmatic children. Clin Respir J 2013; 7: 121–127.