title: One Week of Bed Rest Leads to Substantial Muscle Atrophy and Induces Whole-Body Insulin Resistance in the Absence of Skeletal Muscle Lipid Accumulation.
abstract: Short (<10 days) periods of muscle disuse, often necessary for recovery from illness or injury, lead to various negative health consequences. The current study investigated mechanisms underlying disuse-induced insulin resistance, taking into account muscle atrophy. Ten healthy, young males (age: 23 ± 1 years; BMI: 23.0 ± 0.9 kg · m(-2)) were subjected to 1 week of strict bed rest. Prior to and after bed rest, lean body mass (dual-energy X-ray absorptiometry) and quadriceps cross-sectional area (CSA; computed tomography) were assessed, and peak oxygen uptake (VO2peak) and leg strength were determined. Whole-body insulin sensitivity was measured using a hyperinsulinemic-euglycemic clamp. Additionally, muscle biopsies were collected to assess muscle lipid (fraction) content and various markers of mitochondrial and vascular content. Bed rest resulted in 1.4 ± 0.2 kg lean tissue loss and a 3.2 ± 0.9% decline in quadriceps CSA (both P < 0.01). VO2peak and one-repetition maximum declined by 6.4 ± 2.3 (P < 0.05) and 6.9 ± 1.4% (P < 0.01), respectively. Bed rest induced a 29 ± 5% decrease in whole-body insulin sensitivity (P < 0.01). This was accompanied by a decline in muscle oxidative capacity, without alterations in skeletal muscle lipid content or saturation level, markers of oxidative stress, or capillary density. In conclusion, 1 week of bed rest substantially reduces skeletal muscle mass and lowers whole-body insulin sensitivity, without affecting mechanisms implicated in high-fat diet-induced insulin resistance.
authors.affiliation: NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastrict, the Netherlands.
authors.forename: Marlou L
authors.initials: ML
authors.lastname: Dirks
authors.affiliation: NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastrict, the Netherlands.
authors.forename: Benjamin T
authors.initials: BT
authors.lastname: Wall
authors.affiliation: NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastrict, the Netherlands.
authors.forename: Bas
authors.initials: B
authors.lastname: van de Valk
authors.affiliation: Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Tanya M
authors.initials: TM
authors.lastname: Holloway
authors.affiliation: Human Health & Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Graham P
authors.initials: GP
authors.lastname: Holloway
authors.affiliation: Department of Physiology, Medical University of Bialystok, Bialystok, Poland.
authors.forename: Adrian
authors.initials: A
authors.lastname: Chabowski
authors.affiliation: NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastrict, the Netherlands.
authors.forename: Gijs H
authors.initials: GH
authors.lastname: Goossens
authors.affiliation: NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre, Maastrict, the Netherlands l.vanloon@maastrichtuniversity.nl.
authors.forename: Luc J C
authors.initials: LJ
authors.lastname: van Loon
mesh_terms: D015502:Absorptiometry, Photon; D000328:Adult; D001510:Bed Rest / Q000009:adverse effects*; D059305:Diet, High-Fat; D015309:Glucose Clamp Technique; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology* / Q000502:physiology*; D009133:Muscular Atrophy / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D052097:Quadriceps Muscle / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D055815:Young Adult