Free 6-minute running test preceded and followed by spirometry done with and without a nose clip a day apart was conducted in 55 children with moderate persistent asthma and AR. Children were divided into two groups according to the severity of nasal symptoms.
There was a greater fall in forced expiratory volume in one second after exercise with a nose clip in children with less nasal symptoms than in children with more nasal symptoms (mean ± SD; −5.28 (7.91) vs. −0.08 (4.58), p = 0.0228) compared to testing without the nose clip (mean ± SD; LNS, −1.31 ± 3.89%, p = 0.2408; MNS, −1.47 ± 3.68%, p = 0.2883).
Our results show that regular mouth breathing due to nasal congestion may lessen the degree of EIB in patients with persistent AR and allergic asthma.