title: Failure of glycine-arginine-α-ketoisocaproic acid to improve high-intensity exercise performance in trained cyclists.
abstract: Oral supplementation with glycine-arginine-α-ketoisocaproic acid (GAKIC) has previously been shown to improve exhaustive high-intensity exercise performance. There are no controlled studies involving GAKIC supplementation in well-trained subjects. The aim of the current study was to examine the effects of GAKIC supplementation on fatigue during high-intensity, repeated cycle sprints in trained cyclists. After at least 2 familiarization trials, 10 well-trained male cyclists completed 2 supramaximal sprint tests each involving 10 sprints of 10 s separated by 50-s rest intervals on an electrically braked cycle ergometer. Subjects ingested 11.2 g of GAKIC or placebo (Pl) during a period of 45 min before the 2 experimental trials, administered in a randomized and double-blind fashion. Peak power declined from the 1st sprint (M ± SD; Pl 1,332 ± 307 W, GAKIC 1,367 ± 342 W) to the 10th sprint (Pl 1,091 ± 229 W, GAKIC 1,061 ± 272 W) and did not differ between conditions (p = .88). Mean power declined from the 1st sprint (Pl 892 ± 151 W, GAKIC 892 ± 153 W) to the 10th sprint (Pl 766 ± 120 W, GAKIC 752 ± 138 W) and did not differ between conditions (p = .96). The fatigue index remained at ~38% throughout the series of sprints and did not differ between conditions (p = .99). Heart rate and ratings of perceived exertion increased from the 1st sprint to the 10th sprint and did not differ between conditions (p = .11 and p = .83, respectively). In contrast to previous studies in untrained individuals, these results suggest that GAKIC has no ergogenic effect on repeated bouts of high-intensity exercise in trained individuals.
authors.affiliation: College of Medicine, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Lukas
authors.initials: L
authors.lastname: Beis
authors.forename: Yaser
authors.initials: Y
authors.lastname: Mohammad
authors.forename: Chris
authors.initials: C
authors.lastname: Easton
authors.forename: Yannis P
authors.initials: YP
authors.lastname: Pitsiladis
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001642:Bicycling / Q000502:physiology*; D002208:Caproates / Q000008:administration & dosage / Q000494:pharmacology*; D019587:Dietary Supplements; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000187:drug effects; D005082:Physical Exertion / Q000187:drug effects*
chemical_list: D002208:Caproates; C423242:glycine-L-arginine-alpha-ketoisocaproic acid