The anabolic potential of dietary protein intake on skeletal muscle is prolonged by prior light-load exercise

• Published in: Clinical nutrition (Edinburgh, Scotland) Scotland), 2013-04, Vol.32 (2), p.236-244
• Main Authors: Bechshoeft, Rasmus, Dideriksen, Kasper J, Reitelseder, Søren, Scheike, Thomas, Kjaer, Michael, Holm, Lars
• Format: Article
• Language: English
• Subjects: Administration, Oral; Adult; Amino Acids, Essential - administration & dosage; Amino Acids, Essential - blood; Anabolic Agents - administration & dosage; Biological and medical sciences; biosynthesis; Blood Glucose - analysis; Caseinate; dietary protein; Dietary Proteins - administration & dosage; Dietary Supplements; essential amino acids; Exercise - physiology; Feeding. Feeding behavior; fractional synthesis rate; Fundamental and applied biological sciences. Psychology; Gastroenterology and Hepatology; Humans; Insulin - blood; leucine; Leucine - administration & dosage; Leucine - blood; Male; males; muscle protein; Muscle protein synthesis rate; Muscle, Skeletal - drug effects; Muscle, Skeletal - metabolism; muscles; Myofibrils - drug effects; Myofibrils - metabolism; Protein feeding; protein intake; Rest - physiology; skeletal muscle; strength training; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Young Adult
• ISSN: 0261-5614; 1532-1983
• DOI: 10.1016/j.clnu.2012.06.015

Summary Background & aims Hyperaminoacidemia stimulates myofibrillar fractional synthesis rate (myoFSR) transiently in resting skeletal muscle. We investigated whether light-load resistance exercise can extent this responsiveness. Methods Ten healthy males exercised one leg with a light-load resistance-like exercise at 16% of 1 repetition maximum and received oral protein boluses every hour for a 10-h period. Their myoFSR was determined by [1-13 C]-leucine incorporation. Muscle biopsies were obtained from the resting (REST) and exercised (EXC) muscles every 2.5-h in the protein-fed period. Results Protein feeding significantly elevated plasma leucine and essential amino acids by an average of 39 ± 9% (mean ± SEM) and 20 ± 4%, respectively, compared to the basal concentrations: 197 ± 12 μmol L−1 and 854 ± 35 μmol L−1 , respectively. The myoFSR was similar in EXC and REST muscles in the first 8 h (all time intervals p  > 0.05). After 8 h the myoFSR dropped in the REST muscle to 0.041 ± 0.005%·h−1 , which was 65 ± 5% of the rate in EXC leg at the same time point (0.062 ± 0.004%·h−1 ) and 80 ± 14% of the level in REST leg from 0.5 to 8 h (0.056 ± 0.005%·h−1 ) (interaction p