Swimming Exercise Transiently Decrease Lung Diffusing Capacity In Elite Swimmers

BACKGROUND: Swimmers have larger lungs and a higher diffusion capacity than other athletes, but it remains unknown whether swimming exercise changes lung diffusing properties. This study aimed to evaluate modifications in pulmonary alveolar-capillary diffusion after swimming exercise.METHODS: The participants were 21 elite level swimmers, including 7 females and 14 males, with a training volume of 45-70 kilometers of swimming per week. The single-breath method was used to measure the lung diffusing capacity for carbon monoxide (DLCO and the transfer coefficient of the lungs for carbon monoxide (K-CO) before and after 10 training sessions over 4 weeks along 207 pre- to postevaluations.RESULTS: Swimming training consistently decreased lung diffusion capacity during the follow-up period, both DLCO (44.4 +/- 8.1 to 43.3 +/- 8.9 mL.min-1.mmHg-1, P=0.047,eta(2)(p)=0.55) and K-CO (5.92 +/- 0.79 to 5.70 +/- 0.81 mL.min-1.mmHg-1.L-1, P=0.003,eta(2)(p)=0.75).CONCLUSIONS: Elite swimmers experience a subclinical impairment in lung diffusing capacity after swimming exercise, but the stress caused by swimming on the lungs and the acute reduction in DLCO does not lead to physiological dysfunction.