Effect of Creatine Loading on Oxygen Uptake during a 1-km Cycling Time Trial.

• Autores: Kleiner Marcio de Andrade Nemezio, Adriano Eduardo Lima Silva, Rômulo C. de M. Bertuzzi, Carlos Rafaell Correia Oliveira, Bruno Gualano, David J. Bishop
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 47, Nº. 12, 2015, págs. 2660-2668
• Idioma: inglés
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• Resumen

  • AB Purpose: For the first time, we investigated the effects of altering cellular metabolic capacitance, via a 5-d creatine (Cr) loading protocol (20 g[middle dot]d-1), on oxygen uptake (V[spacing dot above]O2), accumulated oxygen deficit, muscle recruitment, and performance during a 1-km cycling time trial. Methods: In a double-blind, randomized, placebo-controlled design, 19 amateur cyclists were allocated to a Cr (n = 10, V[spacing dot above]O2peak = 56.0 +/- 7.8 mL[middle dot]kg-1[middle dot]min-1) or placebo (n = 9, V[spacing dot above]O2peak = 56.0 +/- 8.4 mL[middle dot]kg-1[middle dot]min-1) group, and performed a 1-km cycling time trial before and after the supplementation period. Results: Body mass was significantly increased in the Cr group (P < 0.05), but not in the placebo group. Participants adopted an "all-out" pacing strategy in both groups. However, Cr loading reduced V[spacing dot above]O2 immediately after the beginning (12th to 23th seconds), and this was accompanied by a reduced aerobic and increased anaerobic contribution. The V[spacing dot above]O2 mean response time was slower (pre: 17.2 +/- 5.6 s vs post: 19.9 +/- 4.6 s), the total O2 uptake was reduced (pre: 4.64 +/- 0.59 L vs post: 4.47 +/- 0.53 L), and the oxygen deficit was increased (pre: 0.82 +/- 0.27 L vs post: 0.98 +/- 0.25 L) after Cr loading. No differences were observed in the placebo group for these variables. Plasma lactate and integrated electromyography were not altered in either group, nor was the time to complete the trial (Cr group: pre: 89.1 +/- 6.7 s vs post 89.1 +/- 6.2 s and placebo group: pre 85.9 +/- 4.9 s vs post 87.0 +/- 5.4 s). Conclusion: Cr loading slows the V[spacing dot above]O2 response and increases the anaerobic contribution during a 1-km cycling time trial.