Tomcik, K. A, Camera, D., Bone, J. L, Ross, M., Jeacocke, N. A, Tachtsis, B., Senden, J. M, Van Loon, L., Hawley, J. & Burke, L. (2018). Effects of creatine and carbohydrate loading on cycling time trial performance. Medicine and Science in Sports and Exercise,50(1), B. L. Gladden. 141-150. United States: Lippincott Williams and Wilkins. Retrieved from https://doi.org/10.1249/MSS.0000000000001401
Creatine (Cr) and carbohydrate loadings are dietary strategies used to enhance exercise capacity. This study examined the metabolic and performance effects of a combined CR and CHO loading regiment on time trial (TT) cycling bouts. Methods: Eighteen well-trained (~65 mLIkgj1Iminj1 V˙ O2peak) men completed three performance trials (PT) that comprised a 120-km cycling TT interspersed with alternating 1- and 4-km sprints (six sprints each) performed every 10 km followed by an inclined ride to fatigue (~90%V˙ O2peak). Subjects were pair matched into either CR-loaded (20 gIdj1 for 5 d + 3 gIdj1 for 9 d) or placebo (PLA) groups (n = 9) after the completion of PT1. All subjects undertook a crossover application of the carbohydrate interventions, consuming either moderate (6 gIkgj1 body mass (BM) per day; MOD) or CHO-loaded (12 gIkgj1 BMIdj1; LOAD) diets before PT2 and PT3. Muscle biopsies were taken before PT1, 18 h after PT1, and before both PT2 and PT3. Results: No significant differences in overall TT or inclined ride times were observed between intervention groups. PLA + LOAD improved power above baseline (P G 0.05) during the final 1-km sprint, whereas CR + MOD and CR + LOAD improved power (P G 0.05) during the final 4-km sprint. Greater power was achieved with MOD and LOAD compared with baseline with PLA (P G 0.05). CR increased pre-PT BM compared with PLA (+1.54% vs +0.99% from baseline). CR + LOAD facilitated greater [total CR] (P G 0.05 vs baseline) and muscle [glycogen] (P G 0.01 vs baseline and MOD) compared with PLA + LOAD. Mechanistic target of rapamycin decreased from baseline after glycogen depletion (~30%; P G 0.05). Conclusions: Power output in the closing sprints of exhaustive TT cycling increased with CR ingestion despite a CR-mediated increase in weight. CR cosupplemented with carbohydrates may therefore be beneficial strategy for late-stage breakaway moments in endurance events.
Mary MacKillop Institute for Health Research
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