TRAINING STUDIES WITHOUT CONTROL GROUPS DO NOT TELL MUCH
Godard, M. P., Godard, K. M., & Jessen, D. (2012). Ultrasound measured left ventricular strain in competitive youth swimmers: Acute and chronic effects of training. Presentation 1121 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.
This study examined the effects of a season of competitive youth swim training on cardiac and pulmonary function. Attempts were made to identify alterations in rest and stress tissue Doppler, left-ventricular wall dimensions and function, along with pulmonary function (PFT) that takes place over the course of a competitive swim season. Male youth swimmers (N = 12) were measured pre- and post-season. Pulmonary function was measured at rest using spirometry. Cardiovascular dimensions (LVIDd, LVIDs, IVSd, PWd) and functions (fractional shortening (FS%), mitral inflow, myocardial performance index) were measured by echocardiography (relevant parameters were adjusted for BSA via the Haycock formula) before and after a graded exercise test on a pediatric cycle ergometer.
There were no significant changes in any of the demographic factors pre- to post-season. There was a significant increase in time-to-exhaustion on the bike ergometer and peak watts. The only pulmonary function measure found to be significant was FIF50. A multivariate test for all left-ventricular wall dimension interactions was significant. A significant increase in fractional shortening, Mitral Valve E/A ratio, and Myocardial Performance Index at rest was found from pre- to post-season. Peak strain measurement of the basal inferior displacement significantly increased pre- to post-season.
Implication. The increases in time to exhaustion, peak watts and fractional shortening are consistent with previous studies. [Because of the design of this study (no control group), it is not possible to determine if the changes were due to growth, training, or both factors. The authors hint that the significant increases were due to training but there is no logical basis for such a belief. Readers should always be aware of "research" that is inadequately formulated.]
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