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Effects of Creatine and Carbohydrate Loading on Cycling Time Trial Performance

Tomcik Kristyen A.; Camera, Donny M.; Bone, Julia L.; Ross, Megan L.; Jeacocke, Nikki A.; Tachtsis, Bill; Senden, Joan; van Loon, Luc J.C.; Hawley, John A.; Burke, Louise M.
Medicine & Science in Sports & Exercise: Post Acceptance: August 11, 2017
doi: 10.1249/MSS.0000000000001401
Original Investigation: PDF Only

ABSTRACTIntroductionCreatine- and carbohydrate-loading are dietary strategies used to enhance exercise capacity. This study examined the metabolic and performance effects of a combined creatine and CHO-loading regiment on time-trial (TT) cycling bouts.MethodsEighteen well-trained (~65mL[BULLET OPERATOR]kg-1[BULLET OPERATOR]min-1 VO2peak) males completed three performance trials (PT) comprised of a 120-km cycling TT interspersed with alternating 1- and 4-km sprints (6 sprints each) performed every 10-km followed by an inclined ride to fatigue (~90% VO2peak). Subjects were pair-matched into either creatine-loaded (20g[BULLET OPERATOR]d-1 for 5d + 3 g[BULLET OPERATOR]d-1 for 9d; CR) or placebo (PLA) groups (n=9) following the completion of PT1. All subjects undertook a cross-over application of the carbohydrate interventions, consuming either moderate-(6g[BULLET OPERATOR]kg-1 body mass (BM)/d; MOD) or CHO-loaded (12g[BULLET OPERATOR]kg-1 BM/d; LOAD) diets before PT2 and PT3. Muscle biopsies were taken prior to PT1, 18h post-PT1, and prior to both PT2 and PT3.ResultsNo 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 to baseline with PLA (P<0.05). CR increased pre-PT BM compared to PLA (+1.54% vs +0.99% from baseline). CR+LOAD facilitated greater [total creatine] (P<0.05 vs. baseline) and muscle [glycogen] (P<0.01 vs. baseline and MOD) compared to PLA+LOAD. Mechanistic target of rapamycin (mTOR) decreased from baseline following glycogen depletion (~30%; P< 0.05).ConclusionPower output in the closing sprints of exhaustive time-trial cycling increased with creatine ingestion despite a creatine-mediated increase in weight. Creatine co-supplemented with carbohydrates may therefore be beneficial strategy for late-stage breakaway moments in endurance events.

Introduction

Creatine- and carbohydrate-loading are dietary strategies used to enhance exercise capacity. This study examined the metabolic and performance effects of a combined creatine and CHO-loading regiment on time-trial (TT) cycling bouts.

Methods

Eighteen well-trained (~65mL[BULLET OPERATOR]kg-1[BULLET OPERATOR]min-1 VO2peak) males completed three performance trials (PT) comprised of a 120-km cycling TT interspersed with alternating 1- and 4-km sprints (6 sprints each) performed every 10-km followed by an inclined ride to fatigue (~90% VO2peak). Subjects were pair-matched into either creatine-loaded (20g[BULLET OPERATOR]d-1 for 5d + 3 g[BULLET OPERATOR]d-1 for 9d; CR) or placebo (PLA) groups (n=9) following the completion of PT1. All subjects undertook a cross-over application of the carbohydrate interventions, consuming either moderate-(6g[BULLET OPERATOR]kg-1 body mass (BM)/d; MOD) or CHO-loaded (12g[BULLET OPERATOR]kg-1 BM/d; LOAD) diets before PT2 and PT3. Muscle biopsies were taken prior to PT1, 18h post-PT1, and prior to 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 to baseline with PLA (P<0.05). CR increased pre-PT BM compared to PLA (+1.54% vs +0.99% from baseline). CR+LOAD facilitated greater [total creatine] (P<0.05 vs. baseline) and muscle [glycogen] (P<0.01 vs. baseline and MOD) compared to PLA+LOAD. Mechanistic target of rapamycin (mTOR) decreased from baseline following glycogen depletion (~30%; P< 0.05).

Conclusion

Power output in the closing sprints of exhaustive time-trial cycling increased with creatine ingestion despite a creatine-mediated increase in weight. Creatine co-supplemented with carbohydrates may therefore be beneficial strategy for late-stage breakaway moments in endurance events.

Address for correspondence: Kristyen Tomcik, Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, VIC 3065, Australia. Email: kristyen.tomcik@acu.edu.au.

This study was funded by an ACURF Grant (2013000443) awarded to LMB. The authors declare no conflict of interest. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by ACSM.

Accepted for Publication: 1 August 2017

© 2017 American College of Sports Medicine