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

Purpose: To compare the dynamics of maximal oxygen uptake ((V) over dotO(2)), blood lactate ([La](b)), total energy expenditure (E-tot), and contributions of the aerobic (E-aer), alactic anaerobic (E-an,E-al), and lactic anaerobic (E-an,E-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 (V) over dotO(2) was measured 20 s postexercise. Results: The estimated energetic contributions for the 100-m trial are presented as mean (SD): E-aer, 51% (8%); E-an,E-al, 18% (2%); E-an,E-lac, 31% (9%). (V) over dotO(2) 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 = 4.1L.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)). E-tot (juniors, 138 [18] kJ; seniors, 168 [26] kJ), E-an,E-al (juniors, 27 [3] kJ; seniors, 30 [3] kJ), and E-an,E-lac (juniors, 38 [12] kJ; seniors, 62 [24] kJ) were 11-58% higher in seniors. Faster swimmers (n = 26) had higher (V) over dotO(2) (4.6 L.min(-1), 90% CI 4.4-4.8 L.min(-1) vs 3.9 L.min(-1), 90% CI 3.6-4.2 L.min(-1)), and E-aer power was associated with fast performances (P < .001). Conclusion: Faster swimmers were characterized by higher (V) over dotO(2) and less time to reach the highest (V) over dotO(2) at -50 m of the 100-m swim. Anaerobic qualities become more important with age.