title: Enriching a protein drink with leucine augments muscle protein synthesis after resistance exercise in young and older men.
abstract: Maximizing anabolic responses to feeding and exercise is crucial for muscle maintenance and adaptation to exercise training. We hypothesized that enriching a protein drink with leucine would improve anabolic responses to resistance exercise (RE: 6 × 8 knee-extension repetitions at 75% of 1-RM) in both young and older adults. Groups (n = 9) of young (24 ± 6 y, BMI 23 ± 2 kg m-2) and older men (70 ± 5 y, BMI 25 ± 2 kg m-2) were randomized to either: (i) RE followed by Slim-Fast Optima (SFO 10 g PRO; 24 g CHO) with 4.2 g of leucine (LEU) or, (ii) RE + SFO with 4.2 g of alanine (ALA; isonitrogenous control). Muscle biopsies were taken before, immediately after, and 1, 2 and 4 h after RE and feeding. Muscle protein synthesis (MPS) was measured by incorporation of [1, 2-13C2] leucine into myofibrillar proteins and the phosphorylation of p70S6K1 by immunoblotting. In young men, both area under the curve (AUC; FSR 0-4 h P < 0.05) and peak FSR (0.11 vs. 0.08%.h.-1; P < 0.05) were greater in the SFO + LEU than in the SFO + ALA group, after RE. Similarly, in older men, AUC analysis revealed that post-exercise anabolic responses were greater in the SFO + LEU than SFO + ALA group, after RE (AUC; FSR 0-4 h P < 0.05). Irrespective of age, increases in p70S6K1 phosphorylation were evident in response to both SFO + LEU and SFO + ALA, although greater with leucine supplementation than alanine (fold-change 2.2 vs. 3.2; P < 0.05), specifically in the older men. We conclude that addition of Leucine to a sub-maximal PRO bolus improves anabolic responses to RE in young and older men.
authors.affiliation: University of Nottingham, School of Medicine, Royal Derby Hospital, Derby, DE22 3DT, UK.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Atherton
authors.affiliation: University of Nottingham, School of Medicine, Royal Derby Hospital, Derby, DE22 3DT, UK.
authors.forename: Vinod
authors.initials: V
authors.lastname: Kumar
authors.affiliation: University of Nottingham, School of Medicine, Royal Derby Hospital, Derby, DE22 3DT, UK.
authors.forename: Anna L
authors.initials: AL
authors.lastname: Selby
authors.affiliation: University of Nottingham, School of Medicine, Royal Derby Hospital, Derby, DE22 3DT, UK.
authors.forename: Debbie
authors.initials: D
authors.lastname: Rankin
authors.affiliation: University of Nottingham, School of Medicine, Royal Derby Hospital, Derby, DE22 3DT, UK.
authors.forename: Wulf
authors.initials: W
authors.lastname: Hildebrandt
authors.affiliation: University of Nottingham, School of Medicine, Royal Derby Hospital, Derby, DE22 3DT, UK.
authors.forename: Beth E
authors.initials: BE
authors.lastname: Phillips
authors.affiliation: University of Nottingham, School of Medicine, Royal Derby Hospital, Derby, DE22 3DT, UK; Anaesthetic Department, Derby Hospitals NHS Foundation Trust, Derby, DE22 3DT, UK.
authors.forename: John P
authors.initials: JP
authors.lastname: Williams
authors.affiliation: Unilever Discover R & D, Colworth Science Park, Sharnbrook, MK44 1LQ, UK.
authors.forename: Natalie
authors.initials: N
authors.lastname: Hiscock
authors.affiliation: University of Nottingham, School of Medicine, Royal Derby Hospital, Derby, DE22 3DT, UK. Electronic address: ken.smith@nottingham.ac.uk.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Smith
mesh_terms: D000328:Adult; D000368:Aged; D001628:Beverages; D015992:Body Mass Index; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000097:blood; D006801:Humans; D007930:Leucine / Q000008:administration & dosage* / Q000097:blood; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D009210:Myofibrils / Q000187:drug effects / Q000378:metabolism; D010766:Phosphorylation; D014176:Protein Biosynthesis / Q000187:drug effects; D055070:Resistance Training; D000067816:Whey Proteins / Q000008:administration & dosage; D055815:Young Adult
chemical_list: D004044:Dietary Proteins; D009124:Muscle Proteins; D000067816:Whey Proteins; D007930:Leucine
keywords: Ageing; Exercise; Leucine; Muscle; Protein; Synthesis