ABSTRACT
PURPOSE: To compare the dynamics of maximal oxygen uptake ([Formula: see text]), 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 4 consecutive 25-m laps (L0-25, L25-50, etc) of a 100-m maximal freestyle swim. METHODS: Elite swimmers comprising 26 juniors (age = 16 [1] y) and 23 seniors (age = 24 [5] y) performed 100 m at maximal speed and then 3 trials (25, 50, and 75 m) at the same pace as that of the 100 m. [La]b was collected, and [Formula: see text] was measured 20 s postexercise. RESULTS: The estimated energetic contributions for the 100-m trial are presented as mean (SD): Eaer, 51% (8%); Ean,al, 18% (2%); Ean,lac, 31% (9%). [Formula: see text] increased from L0-25 to L25-50 (mean = 3.5 L·min-1; 90% confidence interval [CI], 3.4-3.7 L·min-1 to mean = 4.2 L·min-1; 90% CI, 4.0-4.3 L·min-1) and then stabilized in the 2nd 50 m (mean = 4.1 L·min-1; 90% CI, 3.9-4.3 L·min-1 to mean = 4.2 L·min-1; 90% CI, 4.0-4.4 L·min-1). Etot (juniors, 138 [18] kJ; seniors, 168 [26] kJ), Ean,al (juniors, 27 [3] kJ; seniors, 30 [3] kJ), and Ean,lac (juniors, 38 [12] kJ; seniors, 62 [24] kJ) were 11-58% higher in seniors. Faster swimmers (n = 26) had higher [Formula: see text], 90% CI 4.4-4.8 L·min-1 [Formula: see text] L·min-1, 90% CI 3.6-4.2 L·min-1), and Eaer power was associated with fast performances (P < .001). CONCLUSION: Faster swimmers were characterized by higher [Formula: see text] and less time to reach the highest [Formula: see text] at â¼50 m of the 100-m swim. Anaerobic qualities become more important with age.
