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Breaking Research For 10-6-99 |
Study shows
protein intake after exercise is more anabolic than protein intake at
other times.
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An abundant supply of amino acids enhances
the metabolic effect of exercise on muscle protein.
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- Biolo G; Tipton KD; Klein S; Wolfe RR
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- Department of Metabolism, Shriners Burns
Institute, Galveston, Texas, USA.
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- Am J Physiol, 273(1 Pt 1):E122-9 1997
Jul
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- Abstract:
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- Six normal untrained men were studied
during the intravenous infusion of a balanced amino acid mixture
(approximately 0.15 g.kg-1.h-1 for 3 h) at rest and after a leg
resistance exercise routine 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.
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- 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 30-100% greater
after exercise than at rest. Increases in muscle protein synthesis
were also greater after exercise than at rest (291 +/- 42% vs. 141 +/-
45%). Muscle protein breakdown was not significantly affected by
hyperminoacidemia either at rest or after exercise.
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- We conclude that the stimulatory effect
of exogenous amino acids on muscle protein synthesis is enhanced by
prior exercise, perhaps in part because of enhanced blood flow. Our
results imply that protein intake immediately after exercise may be
more anabolic than when ingested at some later time.
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