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Effects of Creatine and Carbohydrate Loading on Cycling Time Trial Performance

TOMCIK, KRISTYEN, A.1; CAMERA, DONNY, M.1; BONE, JULIA, L.1,2; ROSS, MEGAN, L.1,2; JEACOCKE, NIKKI, A.2; TACHTSIS, BILL1; SENDEN, JOAN3; VAN LOON, LUC J., C.1,3; HAWLEY, JOHN, A.1,4; BURKE, LOUISE, M.1,2

Medicine & Science in Sports & Exercise: January 2018 - Volume 50 - Issue 1 - p 141–150
doi: 10.1249/MSS.0000000000001401
APPLIED SCIENCES

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 (~65 mL·kg−1·min−1 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 g·d−1 for 5 d + 3 g·d−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 g·kg−1 body mass (BM) per day; MOD) or CHO-loaded (12 g·kg−1 BM·d−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 (~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.

1Centre for Exercise and Nutrition, Mary MacKillop Institute for Health Research, Australian Catholic University, Melbourne, Victoria, AUSTRALIA; 2Sports Nutrition, Australian Institute of Sport, Belconnen, Australian Capital Territory, AUSTRALIA; 3NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastricht, THE NETHERLANDS; and 4Research Institute for Sports and Exercise Sciences, Liverpool John Moores University, Liverpool, UNITED KINGDOM

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

Submitted for publication October 2016.

Accepted for publication August 2017.

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© 2018 American College of Sports Medicine