title: Muscle protein synthetic responses to exercise: effects of age, volume, and intensity.
abstract: We explored the relationships between resistance exercise volume/intensity and muscle myofibrillar protein synthetic (MPS) responses in young and older men. In a crossover design, four groups of six young (24±6 years) and older (70±5 years) men performed two volumes of resistance exercise: either 40% one repetition maximum (1RM) (3 × 14, then 6 × 14 repetitions) or 75% 1RM (3 × 8, then 6 × 8 repetitions), such that at the same volume, work was identical between intensities. Muscle biopsies were taken 0, 1, 2, and 4hours after exercise to measure MPS via myofibrillar bound [1,2-(13)C(2)]leucine and indices of mammalian target of rapamycin signaling by immunoblotting. In younger men, doubling exercise volume produced limited added effects, whereas in older men, it resulted in greater MPS and p70S6 kinase (p70S6K(Thr389)) phosphorylation at both intensities, that is, MPS area under the curve: 75% (1× volume: 0.07±0.01 vs 2× volume: 0.14% ± 0.02% protein synthesized/4hours (p < .001). Doubling exercise volume is a valid strategy to maximize postexercise MPS in ageing.
authors.affiliation: University of Nottingham Graduate Entry Medicine and Health, Derby, UK.
authors.forename: Vinod
authors.initials: V
authors.lastname: Kumar
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Atherton
authors.forename: Anna
authors.initials: A
authors.lastname: Selby
authors.forename: Debbie
authors.initials: D
authors.lastname: Rankin
authors.forename: John
authors.initials: J
authors.lastname: Williams
authors.forename: Kenneth
authors.initials: K
authors.lastname: Smith
authors.forename: Natalie
authors.initials: N
authors.lastname: Hiscock
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Rennie
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000378:metabolism / Q000502:physiology*; D000704:Analysis of Variance; D019540:Area Under Curve; D001707:Biopsy, Needle; D015992:Body Mass Index; D018592:Cross-Over Studies; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology / Q000502:physiology; D009929:Organ Size / Q000502:physiology; D010766:Phosphorylation / Q000502:physiology; D005082:Physical Exertion; D055070:Resistance Training / Q000379:methods*; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D015398:Signal Transduction; D055815:Young Adult
chemical_list: D009124:Muscle Proteins; D038762:Ribosomal Protein S6 Kinases, 70-kDa