title: Contribution of creatine to protein homeostasis in athletes after endurance and sprint running.
abstract: OBJECTIVE
  Few studies have focused on the metabolic changes induced by creatine supplementation. This study investigated the effects of creatine supplementation on plasma and urinary metabolite changes of athletes after endurance and sprint running.
  
  
  METHODS
  Twelve male athletes (20.3 ± 1.4 y) performed two identical (65-70 % maximum heart rate reserved) 60 min running exercises (endurance trial) before and after creatine supplementation (12 g creatine monohydrate/day for 15 days), followed by a 5-day washout period. Subsequently, they performed two identical 100 m sprint running exercises (power trial) before and after 15 days of creatine supplementation in accordance with the supplementary protocol of the endurance trial. Body composition measurements were performed during the entire study. Plasma samples were examined for the concentrations of glucose, lactate, branched-chain amino acids (BCAAs), free-tryptophan (f-TRP), glutamine, alanine, hypoxanthine, and uric acid. Urinary samples were examined for the concentrations of hydroxyproline, 3-methylhistidine, urea nitrogen, and creatinine.
  
  
  RESULTS
  Creatine supplementation significantly increased body weights of the athletes of endurance trial. Plasma lactate concentration and ratio of f-TRP/BCAAs after recovery from endurance running were significantly decreased with creatine supplementation. Plasma purine metabolites (the sum of hypoxanthine and uric acid), glutamine, urinary 3-methylhistidine, and urea nitrogen concentrations tended to decrease before running in trials with creatine supplements. After running, urinary hydroxyproline concentration significantly increased in the power trial with creatine supplements.
  
  
  CONCLUSIONS
  The findings suggest that creatine supplementation tended to decrease muscle glycogen and protein degradation, especially after endurance exercise. However, creatine supplementation might induce collagen proteolysis in athletes after sprint running.
authors: Graduate Institute of Nutritional Sciences and Education, #162, Hoping E. Rd. 1st Sec, Taipei, 10600, Taiwan, ROC, t10013@ntnu.edu.tw.
authors: Fu-Chun
authors: FC
authors: Tang
authors: Chun-Chen
authors: CC
authors: Chan
authors: Po-Ling
authors: PL
authors: Kuo
mesh_terms: D000293:Adolescent; D000597:Amino Acids, Branched-Chain / Q000097:blood; D056352:Athletes; D001786:Blood Glucose / Q000378:metabolism; D001827:Body Height; D001835:Body Weight; D003401:Creatine / Q000008:administration & dosage*; D003404:Creatinine / Q000652:urine; D019587:Dietary Supplements; D006706:Homeostasis; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008297:Male; D008762:Methylhistidines / Q000652:urine; D009584:Nitrogen / Q000652:urine; D010807:Physical Endurance / Q000187:drug effects* / Q000502:physiology; D012420:Running / Q000502:physiology*; D064133:Sports Nutritional Physiological Phenomena; D055815:Young Adult
chemical_list: D000597:Amino Acids, Branched-Chain; D001786:Blood Glucose; D008762:Methylhistidines; D019344:Lactic Acid; D003404:Creatinine; C028118:3-methylhistidine; D003401:Creatine; D009584:Nitrogen
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