title: Six-Week Oral Guanidinoacetic Acid Administration Improves Muscular Performance in Healthy Volunteers.
abstract: BACKGROUND
  Guanidinoacetic acid (GAA), a natural precursor of creatine, is a new promising dietary supplement, yet its performance-enhancing effect, if any, has yet to be established. The purpose of this pilot study was to evaluate the effects of supplemental GAA on muscle strength, anaerobic performance, and aerobic performance in healthy men and women.
  
  
  METHODS
  The study enrolled 48 young participants (age, 22.3 ± 1.5 years; height, 176.4 ± 10.0 cm; weight, 71.9 ± 14.3 kg), who received oral doses of GAA (1.2, 2.4, or 4.8 g/d) for 6 weeks in a randomized, double-blind, placebo-controlled trials.
  
  
  RESULTS
  Significant differences were observed between treatment groups for handgrip strength among participants receiving 1.2 g of GAA per day and 2.4 g of GAA per day, as compared with placebo (P < 0.05). In addition, muscle endurance expressed as the change from baseline in repetitions performed in the bench press exercise was significantly greater in the 1.2 g/d dose of GAA (P = 0.01) and the 4.8 g/d dose (P = 0.01) compared with placebo. No dose-response differences were found between trials.
  
  
  CONCLUSIONS
  Results from this preliminary study indicate that supplemental GAA ingested in young individuals can improve exercise performance, even at low doses (1.2 g/d).
authors.affiliation: From the *Center for Health, Exercise, and Sport Sciences, Stari DIF, Belgrade; †Faculty of Sport and Physical Education, University of Novi Sad, Novi Sad, Serbia; and ‡Sport and Exercise Science, University of Central Florida, Orlando, FL.
authors.forename: Sergej M
authors.initials: SM
authors.lastname: Ostojic
authors.forename: Marko D
authors.initials: MD
authors.lastname: Stojanovic
authors.forename: Jay R
authors.initials: JR
authors.lastname: Hoffman
mesh_terms: D000284:Administration, Oral; D000328:Adult; D019587:Dietary Supplements; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D005998:Glycine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000187:drug effects* / Q000502:physiology; D055815:Young Adult
chemical_list: C004946:glycocyamine; D005998:Glycine