BACKGROUND: This study investigated the impact of different breathing patterns and stroke variations on inspiratory and expiratory muscle fatigue (IMF and EMF) in front crawl swimming. METHODS: Twelve club-level swimmers (3 females) performed four maximal effort 200-m front crawl swims in a random order: breathing every two strokes (B2), every four strokes (B4), ad libitum via a snorkel (S), and legs only with a kickboard (K). RESULTS: Postswim maximal inspiratory mouth pressure decreased in B2 (34±26%), B4 (41±23%), S (26±16%), and K (13±15%). The only significant difference in IMF was between B4 and K. Significant EMF was observed only in S (12±11%) and K (13±15%). IMF was greater than EMF in B2 and B4. Swim time was slower in K (217 (199-231) s) compared to B2 (139 (136-156) s), B4 (142 (138-155) s), and S (142 (138-155) s), but similar among B2, B4, and S. Postswim, pH and HCO<
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CONCLUSIONS: These findings suggest that the mechanisms of IMF and EMF differ during front crawl swimming.