title: Light-load resistance exercise increases muscle protein synthesis and hypertrophy signaling in elderly men.
abstract: The present study investigated whether well-tolerated light-load resistance exercise (LL-RE) affects skeletal muscle fractional synthetic rate (FSR) and anabolic intracellular signaling as a way to counteract age-related loss of muscle mass. Untrained healthy elderly (>65-yr-old) men were subjected to 13 h of supine rest. After 2.5 h of rest, unilateral LL-RE, consisting of leg extensions (10 sets, 36 repetitions) at 16% of 1 repetition maximum (RM), was conducted. Subsequently, the subjects were randomized to oral intake of 4 g of whey protein per hour (PULSE,n= 10), 28 g of whey protein at 0 h and 12 g of whey protein at 7 h postexercise (BOLUS,n= 10), or 4 g of maltodextrin per hour (placebo,n= 10). Quadriceps muscle biopsies were taken at 0, 3, 7, and 10 h postexercise from the resting and the exercised leg of each subject. Myofibrillar FSR and activity of select targets from the mechanistic target of rapamycin complex 1-signaling cascade were analyzed from the biopsies. LL-RE increased myofibrillar FSR compared with the resting leg throughout the 10-h postexercise period. Phosphorylated (T308) AKT expression increased in the exercised leg immediately after exercise. This increase persisted in the placebo group only. Levels of phosphorylated (T37/46) eukaryotic translation initiation factor 4E-binding protein 1 increased throughout the postexercise period in the exercised leg in the placebo and BOLUS groups and peaked at 7 h. In all three groups, phosphorylated (T56) eukaryotic elongation factor 2 decreased in response to LL-RE. We conclude that resistance exercise at only 16% of 1 RM increased myofibrillar FSR, irrespective of nutrient type and feeding pattern, which indicates an anabolic effect of LL-RE in elderly individuals. This finding was supported by increased signaling for translation initiation and translation elongation in response to LL-RE.
authors: Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; jakobagergaard@hotmail.com.|Department of Physical Therapy, University of Utah, Salt Lake City, Utah.
authors: Jakob
authors: J
authors: Agergaard
authors: Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: Jacob
authors: J
authors: Bülow
authors: Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: Jacob K
authors: JK
authors: Jensen
authors: Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.|Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: Søren
authors: S
authors: Reitelseder
authors: Department of Physical Therapy, University of Utah, Salt Lake City, Utah.
authors: Micah J
authors: MJ
authors: Drummond
authors: Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: Peter
authors: 0000-0001-7138-3211
authors: P
authors: Schjerling
authors: Department of Biostatistics, Institute of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; and.
authors: Thomas
authors: T
authors: Scheike
authors: Arla Foods Ingredients Group P/S, Viby, Denmark.
authors: Anja
authors: A
authors: Serena
authors: Institute of Sports Medicine, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Ageing, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.|Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: Lars
authors: L
authors: Holm
mesh_terms: D000368:Aged; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D014176:Protein Biosynthesis; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D055070:Resistance Training; D015398:Signal Transduction / Q000187:drug effects; D016896:Treatment Outcome; D000067816:Whey Proteins / Q000008:administration & dosage*
chemical_list: D009124:Muscle Proteins; D000067816:Whey Proteins; D051057:Proto-Oncogene Proteins c-akt
keywords: hypertrophy; light load; mTORC1 signaling; muscle protein synthesis; resistance exercise; sarcopenia