title: Concurrent resistance and aerobic exercise stimulates both myofibrillar and mitochondrial protein synthesis in sedentary middle-aged men.
abstract: We determined myofibrillar and mitochondrial protein fractional synthesis rates (FSR), intramuscular signaling protein phosphorylation, and mRNA expression responses after isolated bouts of resistance exercise (RE), aerobic exercise (AE), or in combination [termed concurrent exercise (CE)] in sedentary middle-aged men. Eight subjects (age = 53.3 ± 1.8 yr; body mass index = 29.4 ± 1.4 kg·m(2)) randomly completed 8 × 8 leg extension repetitions at 70% of one repetition-maximum, 40 min of cycling at 55% peak aerobic power output (AE), or (consecutively) 50% of the RE and AE trials (CE). Biopsies were obtained (during a primed, constant infusion of l-[ring-(13)C(6)]phenylalanine) while fasted, and at 1 and 4 h following postexercise ingestion of 20 g of protein. All trials increased mitochondrial FSR above fasted rates (RE = 1.3-fold; AE = 1.5; CE = 1.4; P < 0.05), although only CE (2.2) and RE (1.8) increased myofibrillar FSR (P < 0.05). At 1 h postexercise, phosphorylation of Akt on Ser(473) (CE = 7.7; RE = 4.6) and Thr(308) (CE = 4.4; RE = 2.9), and PRAS40 on Thr(246) (CE = 3.8; AE = 2.5) increased (P < 0.05), with CE greater than AE for Akt Ser(473)-Thr(308) and greater than RE for PRAS40 (P < 0.05). Despite increased phosphorylation of Akt-PRAS40, phosphorylation of mammalian target of rapamycin (Ser(2448)) remained unchanged (P > 0.05), while rpS6 (Ser(235/236)) increased only in RE (10.4) (P < 0.05). CE and AE both resulted in increased peroxisome proliferator receptor-γ coactivator 1-α (PGC1α) expression at 1 h (CE = 2.9; AE = 2.8; P < 0.05) and 4 h (CE = 2.6; AE = 2.4) and PGC1β expression at 4 h (CE = 2.1; AE = 2.6; P < 0.05). These data suggest that CE-induced acute stimulation of myofibrillar and mitochondrial FSR, protein signaling, and mRNA expression are equivalent to either isolate mode (RE or AE). These results occurred without an interference effect on muscle protein subfractional synthesis rates, protein signaling, or mRNA expression.
authors.affiliation: School of Human Movement Studies, Charles Sturt University, Bathurst, New South Wales, Australia.
authors.forename: Cheyne E
authors.initials: CE
authors.lastname: Donges
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Burd
authors.forename: Rob
authors.initials: R
authors.lastname: Duffield
authors.forename: Greg C
authors.initials: GC
authors.lastname: Smith
authors.forename: Daniel W D
authors.initials: DW
authors.lastname: West
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Short
authors.forename: Richard
authors.initials: R
authors.lastname: Mackenzie
authors.forename: Lindsay D
authors.initials: LD
authors.lastname: Plank
authors.forename: Peter R
authors.initials: PR
authors.lastname: Shepherd
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Phillips
authors.forename: Johann A
authors.initials: JA
authors.lastname: Edge
mesh_terms: D002352:Carrier Proteins / Q000096:biosynthesis / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D024101:Mitochondrial Proteins / Q000096:biosynthesis* / Q000378:metabolism; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000502:physiology*; D009210:Myofibrils / Q000378:metabolism / Q000502:physiology*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010766:Phosphorylation / Q000502:physiology; D014176:Protein Biosynthesis / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D006360:Heat-Shock Proteins; D024101:Mitochondrial Proteins; D009124:Muscle Proteins; C486497:PPARGC1A protein, human; C455622:PPARGC1B protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D014157:Transcription Factors