Kojima, K., Wilhite, D. P., Ishimatsu, M., Wright, B. V., & Stager, J. M. (2012). Expiratory flow limitation during maximal exercise in young competitive swimmers following one-year of swim training. Presentation 2246 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

"Expiratory flow limitation during maximal exercise in prepubescent children has been principally explained by disproportionate growth of the lung-airway system and a conflict between ventilatory demand and capacity. Previous research comparing prepubescent swimmers and controls has shown that swim training improves the conductive properties of the airways independent of growth (Courteix et al., 1997)."

This study examined how an additional year of swim training influenced pulmonary function and metabolic demands of maximal exercise, and consequently the degree and prevalence of expiratory flow limitation in young children. Young competitive swimmers (M = 5; F = 5; age = ~10.3 years; an average of two years of competitive swimming experience) performed pulmonary function and VO2max tests before and after the 2010/2011 season. Pulmonary function values were collected during a set of maximal inspiratory and expiratory maneuvers for the determination of the maximal flow-volume loop. Metabolic variables and minute ventilation were collected each minute during an incremental exercise test to exhaustion on a cycle ergometer. The degree of expiratory flow limitation was determined by the percentage of the exercise tidal flow-volume loop that overlapped the expiratory portion of the maximal flow-volume loop. Data for both genders were combined since there were no gender-based differences.

After an additional year of swim training, absolute VO2max increased by 13.2%. Peak expiratory flow increased by 13.7%. There were no significant increases in any other resting pulmonary function variables. At maximal exercise, peak expiratory flow of tidal volume was increased by 10.6%, while expiratory and inspiratory reserve volumes did not change. The degree of expiratory flow limitation did not differ.

Implication. Despite an increase in demand during maximal exercise and an additional year of swim training, pulmonary function was similar in these children to others' measures. When compared to previous data and sedentary control values from the literature, young swimmers continue to show unique adaptations to swim training. The validity of testing swimming adaptations on a cycle ergometer was not reported.

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