Mick Leahy’s MSc Thesis Defence

Title: Effects Of Inspired Air and Exercise in Diagnosing Exercise-Induced Bronchoconstriction in Swimmers

Thesis Supervisor: Dr. William Sheel (Kinesiology)
Committee members: Dr. Michael Koehle (Kinesiology/Medicine), Dr. Donald McKenzie (Kinesiology/Medicine), James Brotherhood

Chair: Dr Nicola Hodges

Abstract: Competitive swimmers have high rates of exercise induced bronchoconstriction (EIB), which may be associated with repeated exposure to chlorinated pool water. The eucapnic voluntary hyperpnea (EVH) test is often used in a laboratory setting to provoke a reduction in lung function associated with EIB. Swimmers however, experience EIB symptoms in warm, humid and chlorinated environments. The relationship between EVH testing conditions and the development of EIB from swim exercise is unclear. PURPOSE: To compare the provoking effects of inspired air and high-intensity exercise in inducing EIB in swimmers to the laboratory-based EVH method. METHODS: 15 collegiate swimmers (n=5 male, n=10 female; 21±2 years) completed three days of testing in random order. On day one, subjects performed an EVH test in a laboratory (EVHL). On a separate day, swimmers performed a modified EVH test, while breathing chlorinated pool air (EVHCl). On a third day subjects completed a swimming challenge (Swim), performing consecutive 200 and 400 m freestyle efforts at 85 % of their season’s best time (average achieved 200 and 400 m time; 2:18.52±7.79 and 4:55.22±20.38, respectively) and age-predicted heart rate maximum. Lung function was measured at baseline, as well as 3-, 5-, 10-, 15-, and 20-minutes following EVH testing and swim exercise. RESULTS: EVHL elicited a -9.7±6.4 % fall compared to the EVHCL test, -6.6±9.2 % (p>0.05) and Swim, -3.0±7.5 % (p>0.05). A significant correlation in FEV1 fall index between EVHL vs. EVHCl (r =0.78, p<0.05) with no significant relationship between EVHL vs. Swim (r =0.20, p>0.05) and EVHCL vs. Swim (r =0.50, p>0.05). A greater reduction in forced expired flow between 25 and 75 % lung volume (FEF25-75) was induced by the EVHL (-16.6±8.7 %) compared to the EVHCl (-8.2±14.9 %) (p>0.05) and Swim test (-1.3±15.6 %) (p<0.05). CONCLUSION: The EVHL elicits a greater bronchoconstrictive response, compared to EVHCl and Swim tests. There is little relationship in reduction of lung function between the EVHL test and Swim tests. The EVH test could potentially detect EIB in swimmers who do not experience the phenomenon in the aquatic setting. The argument can be made that condition specific lung dysfunction requires condition specific testing.