Breathing dry or humid air and exercise-induced asthma during swimming

Abstract

Recent studies have shown the relevance of air humidity to the provocation of bronchoconstriction by running. The present study was undertaken to ascertain whether the humid air breathed during swimming could explain the protective effect of swimming on the asthmatic. Nine asthmatic children 9--15 years old swam while inspiring dry (15--35% R.H.) or humid (80--90% R.H.) air administered in a random order, a week separating the two sessions. The exercise challenge was an 8-min tethered swim at a metabolic rate (VO2) of 29 ml.kg-1.min-1, minute ventilation (VE) of 34 L.min-1, and a heart rate (HR) of 161 beats.min-1. Ambient air and water temperature were 28 +/- 2 degrees C and 27 +/- 2 degrees C, respectively. Pulmonary functions were tested pre and post swimming. Exercise VE, VO2 and HR were similar under the two conditions. No reduction in any of the pulmonary functions (FVC,FEV1.0,MMEFR,MBC) was found after 5 and 10 minutes following the swimming exercise in either of the conditions. In contrast, a treadmill run of similar metabolic and ventilatory intensity induced bronchoconstriction when room air was dried to 25--30% R.H. It is suggested that, unlike running, swimming is of low asthmogenicity even when inspired air is dried to 25--30% at neutral temperatures.

Swimming and asthma: factors underlying respiratory symptoms in competitive swimmers

“…Warm and humid air may protect airways from cooling and drying effects such that the asthmatic symptoms might not be as severe as in land sports. (29, 34) The swimming environment may thus have a role in modulating the severity of symptoms. This suggests that the environmental factors in swimming are asthmatic symptom‐friendly rather than symptom‐inducing and may explain why athletes with allergies favor swimming when selecting a mode of sport (30).…”

Airway responsiveness and inflammation in adolescent elite swimmers

“…12 Swimming is one sport that has attracted attention; many children with childhood asthma were recommended to undertake swimming as their daily exercise because swimming was found to be less likely to lead to exercise-induced asthma. [13][14][15] A prevalence of AHR in adult swimmers of up to 79% is much higher than in healthy controls. [16][17][18] Further, differences in the cellular characteristics of induced sputum have been documented, with swimmers having significantly higher differential cell counts of both neutrophils and eosinophils than healthy controls.…”

Childhood Asthma and Environmental Exposures at Swimming Pools: State of the Science and Research Recommendations

“…They may do so because of the horizontal position of the body during swimming, which alters the breathing pathway compared with other forms of exercise, or the high humidity present in indoor pools (Bar-Yishay et al 1982; Bundgaard et al 1982; Fitch and Morton 1971; Inbar et al 1980; Matsumoto et al 1999; Reggiani et al 1988). However, increased ocular and respiratory symptoms and other adverse health end points have been reported in swimmers and attributed to exposure to disinfectants or their by-products.…”