An abundant supply of balanced amino acids synergistically enhances
protein muscle anabolism after exercise.
Biolo, Gianni, Kevin Tipton, Samuel Klein, and Robert R. Wolfe.
Metabolism, Shriners Burns Institute and The University of Texas
Medical Branch, Galveston, Texas
APStracts 4:0065E, 1997.
Six normal untrained men were studied during the intravenous infusion
of a balanced amino acid mixture (0.15 g/kg x h for 3 h), at rest and
after a leg resistance exercise routine, in order to test the
influence of exercise on the regulation of muscle protein kinetics by
hyperaminoacidemia. Leg muscle protein kinetics and transport of
selected amino acids (alanine, phenylalanine, leucine and lysine)
were isotopically determined using a model based on arteriovenous
blood samples and muscle biopsy. The intravenous amino acid infusion
resulted in comparable increases in arterial amino acid
concentrations at rest and after exercise, whereas leg blood flow was
64+/-5% greater after exercise than at rest. During
hyperaminoacidemia, the increases in amino acid transport above basal
were 30% to 100% greater after exercise than at rest. Increases in
muscle protein synthesis were also greater after exercise than at
rest (291+/-42% versus 141+/-45%). Muscle protein breakdown was not
significantly affected by hyperaminoacidemia either at rest or after
exercise. We conclude that the stimulatory effect of exogenous amino
acids on muscle protein synthesis is enhanced by prior exercise,
perhaps in part due to enhanced blood flow. Our results imply that
protein intake immediately after exercise may be more anabolic than
when ingested at some later time.
Received 28 August 1996; accepted in final form 6 March 1997.
APS Manuscript Number E426-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 21 March 1997