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Creatine supplementation reduces muscle inosine monophosphate during endurance exercise in humans

journal contribution
posted on 2005-12-01, 00:00 authored by G McConell, J Shinewell, T Stephens, C Stathis, B Canny, Rod SnowRod Snow
Introduction: Creatine (Cr) supplementation has been shown to attenuate increases in plasma ammonia and hypoxanthine during intense endurance exercise lasting 1 h, suggesting that Cr supplementation may improve muscle energy balance (matching of ATP resynthesis to ATP demand) during such exercise. We hypothesized that Cr supplementation would improve muscle energy balance (as assessed by muscle inosine monophosphate (IMP) accumulation) during intense endurance exercise.

Methods: Seven well-trained men completed two experimental trials involving approximately 1 h of intense endurance exercise (cycling 45 min at 78 ± 1% V̇O2peak followed by completion of 251 ± 6 kJ as quickly as possible (performance ride)). Subjects ingested approximately 42 g·d-1 dextrose for 5 d before the first experimental trial (CON), then approximately 21 g Cr monohydrate plus approximately 21 g·d-1 dextrose for 5 d before the second experimental trial (CREAT). Trials were ordered because of the long washout time for Cr. Subjects were blinded to the order of the trials.

Results: Creatine supplementation significantly (P < 0.05) increased muscle total Cr (resting values: CREAT: 138.1 ± 7.9; CON: 117.7 ± 6.5 mmol·kg-1 dm). No difference was seen between treatments in any measured muscle or blood metabolite after the first 45 min of exercise. Despite the performance ride completion time being similar in the two treatments (∼13.5 min, ∼86% V̇O2peak), IMP at the end of the performance ride was significantly (P < 0.05) lower in CREAT than in CON (CREAT: 1.2 ± 0.6; CON: 2.0 ± 0.7 mmol·kg-1 dm).

History

Journal

Medicine & science in sports & exercise

Volume

37

Issue

12

Pagination

2054 - 2061

Publisher

Lippincott Williams & Wilkins

Location

Baltimore, Md.

ISSN

0195-9131

eISSN

1530-0315

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2005, American College of Sports Medicine