title: Essential amino acid and carbohydrate supplementation ameliorates muscle protein loss in humans during 28 days bedrest.
abstract: We determined whether essential amino acid and carbohydrate supplementation could offset the catabolic response to prolonged inactivity. Major outcome measures included mixed muscle fractional synthetic rate (FSR), phenylalanine net balance, lean leg mass, and leg extension strength. On d 1 and 28, vastus lateralis muscle biopsies and femoral arterio-venous blood samples were obtained during a primed constant infusion of l-[ring-(2)H(5)]phenylalanine. Net balance and FSR were calculated over 16 h, during which the control group (CON) received a nutritionally mixed meal every 5 h (0830, 1330, and 1830 h). The experimental group (EXP) also consumed 16.5 g essential amino acids and 30 g carbohydrate (1100, 1600, and 2100 h). The dietary regimen was maintained during bedrest. FSR was higher in the EXP group on d 1 (EXP, 0.099 +/- 0.008%/h; CON: 0.075 +/- 0.005%/h) and d 28 (EXP, 0.093 +/- 0.006%/h; CON, 0.055 +/- 0.007%/h). Lean leg mass was maintained throughout bedrest in the EXP group (+0.2 +/- 0.3 kg), but fell in the CON group (-0.4 +/- 0.1 kg). Strength loss was more pronounced in the CON group (EXP, -8.8 +/- 1.4 kg; CON, -17.8 +/- 4.4 kg). Essential amino acid and carbohydrate supplementation may represent a viable intervention for individuals at risk of sarcopenia due to immobility or prolonged bedrest.
authors.affiliation: Metabolism Unit, 815 Market Street, Galveston, Texas 77550, USA. djpaddon@utmb.edu
authors.forename: Douglas
authors.initials: D
authors.lastname: Paddon-Jones
authors.forename: Melinda
authors.initials: M
authors.lastname: Sheffield-Moore
authors.forename: Randall J
authors.initials: RJ
authors.lastname: Urban
authors.forename: Arthur P
authors.initials: AP
authors.lastname: Sanford
authors.forename: Asle
authors.initials: A
authors.lastname: Aarsland
authors.forename: Robert R
authors.initials: RR
authors.lastname: Wolfe
authors.forename: Arny A
authors.initials: AA
authors.lastname: Ferrando
mesh_terms: D000328:Adult; D000601:Amino Acids, Essential / Q000008:administration & dosage*; D001510:Bed Rest; D001786:Blood Glucose / Q000032:analysis; D001823:Body Composition; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D019587:Dietary Supplements; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D008875:Middle Aged; D009124:Muscle Proteins / Q000378:metabolism*; D010649:Phenylalanine / Q000378:metabolism
chemical_list: D000601:Amino Acids, Essential; D001786:Blood Glucose; D004040:Dietary Carbohydrates; D007328:Insulin; D009124:Muscle Proteins; D010649:Phenylalanine