Effects of Creatine and Carbohydrate Loading on Cycling Time Trial Performance

Kristyen A. Tomcik*, Donny M. Camera, Julia L. Bone, Megan L. Ross, Nikki A. Jeacocke, Bill Tachtsis, Joan Senden, Luc J. C. Van Loon, John A. Hawley, Louise M. Burke

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Introduction 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 (similar to 65 mLkg(-1)min(-1) VO2peak) 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 (similar to 90% VO2peak). Subjects were pair matched into either CR-loaded (20 gd(-1) for 5 d + 3 gd(-1) 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 gkg(-1) body mass (BM) per day; MOD) or CHO-loaded (12 gkg(-1) BMd-1; 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 < 0.05) during the final 1-km sprint, whereas CR + MOD and CR + LOAD improved power (P < 0.05) during the final 4-km sprint. Greater power was achieved with MOD and LOAD compared with baseline with PLA (P < 0.05). CR increased pre-PT BM compared with PLA (+1.54% vs +0.99% from baseline). CR + LOAD facilitated greater [total CR] (P < 0.05 vs baseline) and muscle [glycogen] (P < 0.01 vs baseline and MOD) compared with PLA + LOAD. Mechanistic target of rapamycin decreased from baseline after glycogen depletion (similar to 30%; P < 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.
Original languageEnglish
Pages (from-to)141-150
Number of pages10
JournalMedicine and Science in Sports and Exercise
Volume50
Issue number1
DOIs
Publication statusPublished - 1 Jan 2018

Keywords

  • ENDURANCE EXERCISE
  • GLYCOGEN
  • CELL SIGNALING
  • ERGOGENIC AIDS
  • POWER OUTPUT
  • MUSCLE METABOLISM
  • HUMAN SKELETAL-MUSCLE
  • ACTIVATED PROTEIN-KINASE
  • MONOHYDRATE SUPPLEMENTATION
  • GLYCOGEN SUPERCOMPENSATION
  • RESISTANCE EXERCISE
  • BODY-COMPOSITION
  • ENDURANCE
  • HUMANS
  • SPRINT
  • TRANSPORTER

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