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Effects of creatine and carbohydrate loading on cycling time trial performance
Tomcik, Kristyen A. Camera, Donny Bone, Julia L. L. Ross, Meg Jeacocke, N. A. Tachtsis, Bill Senden, Joan M. Van Loon, Luc Hawley, John Burke, Louise
Tomcik, Kristyen A.
Camera, Donny
Bone, Julia L. L.
Ross, Meg
Jeacocke, N. A.
Tachtsis, Bill
Senden, Joan M.
Van Loon, Luc
Hawley, John
Burke, Louise
Abstract
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.
Keywords
Date
2018
Type
Journal article
Journal
Medicine and Science in Sports and Exercise
Book
Volume
50
Issue
1
Page Range
141-150
Article Number
ACU Department
Non-faculty
Centre for Exercise and Nutrition
Faculty of Health Sciences
School of Behavioural and Health Sciences
Mary MacKillop Institute for Health Research
Centre for Exercise and Nutrition
Faculty of Health Sciences
School of Behavioural and Health Sciences
Mary MacKillop Institute for Health Research
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Event URL
Open Access Status
License
File Access
Controlled