Joshua Bovard’s MSc Thesis Defence

Title: “Does competitive swimming during puberty affect lung development in pubertal females?”

Thesis Supervisor: Dr. Bill Sheel (Kinesiology)
Committee members: Dr. Kristin Houghton (Division of Pediatrics, Medicine), Dr. Don McKenzie (Kinesiology, Medicine), Dr. Jim Potts (Division of Pediatrics, Medicine)
Chair: Dr. Ian Franks

Introduction: Whether the large lungs of competitive swimmers result from intensive swim training or genetic endowment has been widely debated. Given that peak growth velocities for the lungs occur during puberty, this longitudinal study aimed to determine if competitive swimming during puberty affected lung development.

Methods: Female swimmers and healthy controls aged 11-14 years old were assessed before and after one competitive swimming season. Pulmonary function testing included lung volumes, spirometry, diffusion capacity (DL,CO), and maximal inspiratory (PIMAX) and expiratory (PEMAX) mouth pressures. Ventilatory constraints, including end-expiratory lung volume (EELV), expiratory flow limitation (EFL), and utilization of ventilatory capacity (V̇E/V̇ECAP), were assessed during an incremental cycling test.

Results: Despite being of similar age, maturational development, and size as controls, swimmers had a larger total lung capacity, forced vital capacity, and peak expiratory flow. Although DL,CO was greater in swimmers, there was no difference when expressed relative to alveolar volume. Both PIMAX and PEMAX were greater in swimmers. Swimmers and controls achieved a similar relative maximal oxygen consumption and experienced similar ventilatory constraints as characterized by EELV, severity and prevalence of EFL, and V̇E/V̇ECAP. Changes over time were similar between groups.

Conclusion: Pubertal female swimmers already had larger lung capacities, higher flows, and greater indices of respiratory muscle strength compared to controls, but had similar ventilatory constraints while cycling. One competitive swimming season did not further accentuate this enhanced function or alter exercise ventilatory mechanics, suggesting that competitive swimming during puberty did not affect lung development.