Effects of glycine-arginine-α-ketoisocaproic acid supplementation in college-age trained females during multi-bouts of resistance exercise

J Diet Suppl. 2013 Mar;10(1):6-16. doi: 10.3109/19390211.2012.758216. Epub 2013 Jan 29.


Glycine-arginine-α-ketoisocaproic acid (GAKIC) has been proposed to increase anaerobic high-intensity exercise performance in male subjects. However, the effects of GAKIC ingestion in female subjects have not been studied. Therefore, the purpose of this study was to investigate the effects of GAKIC supplementation on total load volume (i.e., mass lifted) and metabolic parameters during repeated bouts of submaximal leg extensions in college-age females. Nine resistance-trained females participated in a randomized, counterbalanced, double blind study. Subjects were randomly assigned to placebo or GAKIC (10.2 g) and performed six sets of 50% of one repetition maximum leg extensions (two legs simultaneously) to failure. One week later, subjects ingested the other supplement and performed the same exercise protocol. Furthermore, blood lactic acid, blood glucose, and heart rate were also measured preexercise and 5 s after the completion of the exercise protocol (postexercise). GAKIC supplementation significantly increased leg extension total load volume (GAKIC = 1721.7 ± 479.9 kg; placebo = 1479.1 ± 396.8 kg, p < .01). Heart rate and blood lactic acid were significantly increased (p < .01 for both measures) postexercise compared to preexercise, but were not significantly different between GAKIC and placebo (p = .40 for heart rate; p = .88 for lactic acid). Blood glucose was significantly decreased (p = .03) postexercise compared to preexercise, but was not significantly different (p = .78) between GAKIC and placebo. Collectively, these findings suggest that GAKIC increased lower body resistance performance in trained college-age females; however, these findings are not necessarily generalizable.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Arginine / pharmacology*
  • Blood Glucose / metabolism
  • Dietary Supplements*
  • Double-Blind Method
  • Exercise / physiology*
  • Female
  • Glycine / pharmacology*
  • Heart Rate / drug effects
  • Humans
  • Keto Acids / pharmacology*
  • Lactic Acid / blood
  • Leg
  • Physical Exertion / drug effects*
  • Physical Exertion / physiology
  • Resistance Training
  • Weight Lifting / physiology*
  • Young Adult


  • Blood Glucose
  • Keto Acids
  • Lactic Acid
  • alpha-ketoisocaproic acid
  • Arginine
  • Glycine