Jakovljevic, D. G., & McConnell, A. K. (2009). Influence of different breathing frequencies on the severity of inspiratory muscle fatigue induced by high-intensity front crawl swimming. Journal of Strength and Conditioning Research, 23, 1169-1174.

This study assessed the influence of two different breathing frequencies on the magnitude of inspiratory muscle fatigue after high-intensity front crawl swimming. The influences of different breathing frequencies on post-exercise blood lactate and heart rate were also examined. Collegiate swimmers (N = 10) performed 2 x 200-m front crawl swims at 90% of race pace with the following breathing frequencies: 1) every second stroke, and 2) every fourth stroke. Maximal inspiratory pressure was measured in a standing position at the mouth from residual volume before swimming (baseline) and after swimming. Heart rates and blood lactates were assessed at rest and immediately after swimming.

Maximal inspiratory pressure decreased by 21% after breathing every fourth stroke and by 11% after breathing every second stroke compared with baseline. Lactate was lower by 15% after breathing every fourth stroke than after breathing every second stroke. Heart rate did not differ between the two breathing cadences.

Implication. High-intensity swimming induces significant global inspiratory muscle fatigue. Inspiratory muscle fatigue is greater when breathing frequency is reduced during high-intensity front crawl swimming. Respiratory muscle training should be used to improve respiratory muscle strength and endurance in swimmers.

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