Abstract

Creatine (Cr) is transported into skeletal muscle fibers through a Na+ dependent Cr transport protein that operates against a 200:1 gradient. The Cr transporter is subject to saturation as it is limited by the Na+ gradient. PURPOSE: The aim of the investigation was to evaluate the efficacy of a novel Mg2+-Cr chelate that may function to permit enhanced intracellular Cr levels via entry through membrane-bound acetylcholine (Ach) receptors, which function as ligand-gated cation channels. Increased levels of Cr in muscle fibers may translate into enhanced muscle function. We tested the hypothesis that when compared with both placebo and Cr groups, the Mg2+-Cr chelate group would: A.) demonstrate greater improvements in the 1 RM for flat bench press; and B.) perform more work at 70% of the 1 RM for flat bench press. METHODS: Trained male weight lifters (n = 31) were randomly assigned in a double blind manner to either a placebo group (multidextran), a Cr group (2.5-g Cr daily), or a Mg2+-Cr group (2.5-g Cr daily). On day 0, baseline data was collected for the flat bench press 1 RM, and maximal work completed during a fatigue set at 70% of the 1 RM. During the subsequent 10-day supplement regimen, subjects were instructed to continue their normal resistance training programs. On day 11, follow up tests were completed. RESULTS: There was no difference between groups when the preto post-test 1 RM values were evaluated. When work was evaluated, however, compared with the placebo group, both the Cr and the Mg2+-Cr groups demonstrated an improved performance. CONCLUSION: Partial support for the hypothesis suggests that low doses of Cr may be effective at increasing muscle fiber Cr content levels, and consequently, performance. As there were no differences for either performance test between the Cr and Mg2+-Cr group, the proposed mechanism of Cr entry via Ach receptors may not play a significant role in enhancing Cr transport over the Cr transport protein. Supported by Albion Laboratories, Inc. (RAD, STD), and an OSU Seed Grant (STD).

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