Effects of Creatine Monohydrate and Polyethylene Glycosylated Creatine Supplementation on Muscular Strength, Endurance, and Power Output

• Published in: Journal of strength and conditioning research 2009-05, Vol.23 (3), p.818-826
• Main Authors: Herda, Trent J, Beck, Travis W, Ryan, Eric D, Smith, Abbie E, Walter, Ashley A, Hartman, Michael J, Stout, Jeffrey R, Cramer, Joel T
• Format: Article
• Language: English
• Subjects: Anaerobic Threshold; Analysis of Variance; Body Mass Index; Creatine - administration & dosage; Cross-Sectional Studies; Dietary Supplements; Double-Blind Method; Exercise Test; Humans; Male; Muscle Strength - drug effects; Muscular system; Nutrition research; Physical Endurance - drug effects; Physical fitness; Placebos; Polyethylene Glycols - administration & dosage; Weight Lifting - physiology; Young Adult
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1519/JSC.0b013e3181a2ed11

Herda, TJ, Beck, TW, Ryan, ED, Smith, AE, Walter, AA, Hartman, MJ, Stout, JR, and Cramer, JT. Effects of creatine monohydrate and polyethylene glycosylated creatine supplementation on muscular strength, endurance, and power output. J Strength Cond Res 23(3)818-826, 2009-The purpose of this study was to examine the effects of a moderate dose of creatine monohydrate (CM) and two smaller doses of polyethylene glycosylated (PEG) creatine on muscular strength, endurance, and power output. Fifty-eight healthy men (mean ± SDage, 21 ± 2 years; height, 176 ± 6 cm; body mass [BM], 75 ± 14 kg) volunteered and were randomly assigned to 1 of 4 groups(a) placebo (PL; 3.6 g of microcrystalline cellulose; n = 15), (b) CM (5 g of creatine; n = 13), (c) small-dose PEG creatine (1.25 g of creatinePEG1.25; n = 14), or (d) moderate-dose PEG creatine (2.50 g of creatinePEG2.50; n = 16). Testing was conducted before (pre-) and after (post-) a 30-day supplementation period. Measurements included body mass, countermovement vertical jump (CVJ) height, power output during the Wingate test (peak power [PP] and mean power [MP]), 1 repetition maximum bench press (1RMBP), 1RM leg press (1RMLP) strength, and repetitions to failure at 80% of the 1RM for bench press (REPBP) and leg press (REPLP). BM and MP (W) increased (p ≤ 0.05) from pre- to postsupplementation for the CM group only, whereas 1RMBP and 1RMLP increased (p ≤ 0.05) for the CM, PEG1.25, and PEG2.50 groups. CVJ height (cm and cm·kg), MP (W·kg), PP (W and W·kg), REPBP, and REPLP increased (p ≤ 0.05) for all groups. These findings indicated that the recommended safe dose of 5 g·d of CM increased BM and improved muscle strength (1RMBP and 1RMLP). Smaller doses of PEG creatine (1.25 and 2.50 g·d) improved muscle strength (1RMBP and 1RMLP) to the same extent as 5 g·d of CM, but did not alter BM, power output, or endurance. When compared to the PL group, neither CM nor PEG creatine supplementation improved peak power output (CVJ or PP), MP, or muscle endurance (REPBP or REPLP). Thus, PEG creatine may have ergogenic effects that are comparable to those of CM, but with a smaller dose of creatine.