Pulmonary diffusing capacity as a predictor of performance in competitive swimming.

Pulmonary diffusing capacity has been noted by many investigators to be higher in championship swimmers than in average swimmers and in the non-swimming population. We measured pulmonary diffusing capacity (DLCO) and other parameters in 22 members of a collegiate swimming team and studied the relationship between pulmonary diffusing capacity and swimming performance. We also investigated change in lung function over a season of training and racing. Results suggested that while most good swimmers had above average diffusing capacities, there was no statistically significant difference in performance between those swimmers with high DLCO (greater than or equal to 110% predicted value) and those with a low DLCO (less than 100% predicted value). It was also determined that there was not a good correlation between performance (measured by either "best time" or "average time") and lung function (DLCO or VC).