Dynamics of the Metabolic Response During a Competitive 100-M Freestyle in Elite Male Swimmers

International audiencePurpose: To compare the dynamics of V̇O2, blood lactate ([La]b), total energy expenditure (Etot), and contributions of the aerobic (Eaer), alactic anaerobic (Ean,al) and lactic anaerobic (Ean,lac) metabolic energy pathways over four consecutive 25-m laps (L0-25, L25-50, L50-75, L75-100) of a 100-m maximal freestyle swim.Methods: Elite swimmers comprising 26 juniors (16 ± 1 y) and 23 seniors (24 ± 5 y) performed 100 m at maximal speed, and then three trials (25, 50 and 75 m) at the same pace as that of the 100 m. [La]b was collected and V̇O2 was measured 20 s post-exercise using a Cosmed K4 b2 analyser.Results: The estimated energetic contributions (%Etot) for the 100-m trial were Eaer: 51 ± 8%, Ean,al: 18 ± 2% and Ean,lac: 31 ± 9% (mean ± SD). V̇O2 increased from L0-25 to L25-50: 3.5 (3.4-3.7) to 4.2 (4.0-4.3) l·min-1 [mean (90% CI)] and then stabilized: 4.1 (3.9-4.3), 4.2 (4.0-4.4) in the 2nd 50-m. Etot (138 ±18, 168 ± 26 kJ; juniors, seniors), Ean,al (27 ± 3, 30 ± 3 kJ), and Ean,lac (38 ± 12, 62 ± 24 kJ) were 11-58% higher in seniors. Faster swimmers (n=26) had higher V̇O2: 4.6 (4.4-4.8) vs. 3.9 (3.6-4.2 l·min-1) and Eaer power was associated with fast performances (p