Diagnosis of Exercise-induced Bronchoconstriction in Swimmers: Context Matters

Swimmers have a high prevalence of exercise-induced bronchoconstriction (EIB), which may be associated with repeated exposure to chlorinated pool water. The eucapnic voluntary hyperpnea (EVH) test is used to diagnose EIB; however, it fails to replicate the environmental conditions experienced by swimmers. The relationship between the composition of the EVH inspired gas and the development of EIB from swim exercise remains unclear. Purpose This study aimed to compare the bronchoconstrictive effect of a chlorinated inspirate EVH test and swim test to a laboratory-based EVH test in swimmers. Methods Fifteen collegiate swimmers (n= 5 male,n= 10 female; 21 +/- 2 yr) completed 3 d of testing in pseudorandom order; a standard EVH test (EVHL), a pool air EVH test (EVHCl), and a swimming test (Swim). Spirometry was measured at baseline, and 3, 5, 10, 15, and 20 min after each test. Results EVH(L)elicited a forced expired volume in 1 s (FEV1) fall index of -9.7% +/- 6.4% compared with -6.6% +/- 9.2% and -3.0% +/- 7.5% after EVH(Cl)and Swim, respectively (P< 0.05). Using Bland-Altman analysis, we found good agreement between EVH(L)and EVHCl(bias = -2.8,r= 0.79;P< 0.05) with poor agreement between EVH(L)and Swim (bias = -6.7,r= 0.20) and between EVH(Cl)and Swim (bias = -3.9,r= 0.50; bothP< 0.05). Forced expired flow between 25% and 75% lung volume and peak expired flow were significantly reduced by the EVH(L)compared with the EVH(Cl)and Swim tests (P< 0.05). Conclusions EVH(L)elicits a greater forced expired volume in 1-s fall index compared with EVH(Cl)and Swim. The unique aquatic environment of swimmers potentially protects against bronchoconstriction and should be considered in the determination of EIB.