Independent and Combined Effects of Liquid carbohydrate/essential Amino Acid Ingestion on Hormonal and Muscular Adaptations Following Resistance Training in Untrained Men

Eur J Appl Physiol. 2006 May;97(2):225-38. doi: 10.1007/s00421-005-0127-z. Epub 2006 Mar 24.

Abstract

This investigation examined chronic alteration of the acute hormonal response associated with liquid carbohydrate (CHO) and/or essential amino acid (EAA) ingestion on hormonal and muscular adaptations following resistance training. Thirty-two untrained young men performed 12 weeks of resistance training twice a week, consuming ~675 ml of either, a 6% CHO solution, 6 g EAA mixture, combined CHO + EAA supplement or placebo (PLA). Blood samples were obtained pre- and post-exercise (week 0, 4, 8, and 12), for determination of glucose, insulin, and cortisol. 3-Methylhistidine excretion and muscle fibre cross-sectional area (fCSA) were determined pre- and post-training. Post-exercise cortisol increased (P<0.05) during each training phase for PLA. No change was displayed by EAA; CHO and CHO + EAA demonstrated post-exercise decreases (P<0.05). All groups displayed reduced pre-exercise cortisol at week 12 compared to week 0 (P<0.05). Post-exercise insulin concentrations showed no change for PLA; increases were observed for the treatment groups (P<0.05), which remained greater for CHO and CHO + EAA (P<0.001) than PLA. EAA and CHO ingestion attenuated 3-methylhistidine excretion 48 h following the exercise bout. CHO + EAA resulted in a 26% decrease (P<0.01), while PLA displayed a 52% increase (P<0.01). fCSA increased across groups for type I, IIa, and IIb fibres (P<0.05), with CHO + EAA displaying the greatest gains in fCSA relative to PLA (P<0.05). These data indicate that CHO + EAA ingestion enhances muscle anabolism following resistance training to a greater extent than either CHO or EAA consumed independently. The synergistic effect of CHO + EAA ingestion maximises the anabolic response presumably by attenuating the post-exercise rise in protein degradation.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / drug effects
  • Adult
  • Amino Acids, Essential / administration & dosage
  • Amino Acids, Essential / pharmacology*
  • Blood Glucose / metabolism
  • Body Composition / physiology
  • Dietary Carbohydrates / administration & dosage
  • Dietary Carbohydrates / pharmacology*
  • Double-Blind Method
  • Exercise / physiology*
  • Hormones / blood*
  • Humans
  • Hydrocortisone / blood
  • Insulin / blood
  • Male
  • Methylhistidines / urine
  • Muscle Fibers, Fast-Twitch / cytology
  • Muscle Fibers, Fast-Twitch / drug effects
  • Muscle Fibers, Fast-Twitch / physiology
  • Muscle Fibers, Slow-Twitch / cytology
  • Muscle Fibers, Slow-Twitch / drug effects
  • Muscle Fibers, Slow-Twitch / physiology
  • Muscle, Skeletal / cytology
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / physiology*
  • Time Factors

Substances

  • Amino Acids, Essential
  • Blood Glucose
  • Dietary Carbohydrates
  • Hormones
  • Insulin
  • Methylhistidines
  • Hydrocortisone