The effects of a training season on pulmonary and cardiovascular function in competitive youth swimmers

Swim training can produce improvement in cardiac function, aerobic capacity, pulmonary function, and body composition. This study examined the effects of a full season of competitive youth swim training on body composition, aerobic capacity, cardiac function, and pulmonary function. This study is the first to examine the effects of a full season of competitive youth swim training on left ventricular wall size and function using echocardiography. Purpose. This study's purpose was to identify alterations in body composition, pulmonary function (FEV1/FVC%), maximal oxygen consumption (VO2max), and left ventricular wall dimensions and function that take place over the course of a competitive swim season. Method. This study included 25 competitive youth swimmers (6--18 yrs.). All measures were taken immediately before and after the season. Body composition was measured using air plethysomgraphy. Pulmonary function was measured at rest using spirometry. Aerobic capacity was measured by collecting expired gases following a 50--200 yd maximal swim. Cardiovascular dimensions (LVIDd, LVIDs, IVSd, PWd) and functions (SV, CI, shortening fraction, E/E') were measured by echocardiography. Results. Significant increases in height (P=.002) and lean body mass (P=.005) occurred. There was no change in FEV1/FVC% (P=.827). An increase in VO 2max also occurred (P=.007). Multivariate test for all LV wall dimension interactions was significant Wilks Lambda = .012, p<.001, partial eta squared .988. A significant increase in shortening fraction was the only change in cardiac function at rest (P<.001). Conclusion. Alterations in body composition is attributed to maturation and training. The lack of change in pulmonary function is consistent with previous studies and maybe attributed to the height increase. The increase in aerobic capacity is consistent with previous studies that have found aerobic training programs typically result in increases in VO2max. The increases in LV dimensions are consistent with previous findings that endurance training results in LV hypertrophy. The change in shortening fraction was unexpected with the findings a first of its kind. Future studies should focus on alterations in shortening fraction as a result of competitive endurance training in youth swimmers and incorporate a stress echocardiograph to assess the chronic exercise effects to LV function.