Increased capillary density in skeletal muscle is not associated with impaired insulin sensitivity induced by bed rest in healthy young men

• Published in: Applied physiology, nutrition, and metabolism Vol. 43; no. 12; pp. 1334 - 1340
• Main Authors: Montero, David, Oberholzer, Laura, Haider, Thomas, Breenfeldt-Andersen, Andreas, Dandanell, Sune, Meinild-Lundby, Anne-Kristine, Maconochie, Hannah, Lundby, Carsten
• Format: Journal Article
• Language: English
• Published: Canada NRC Research Press 01.12.2018; Canadian Science Publishing NRC Research Press
• Subjects: Adult; bed rest; Bed Rest - adverse effects; Biopsy; Blood Glucose - physiology; Body Composition - physiology; Body weight; Body Weight - physiology; Capillaries - physiopathology; capillarisation du muscle squelettique; Capillarity; Development and progression; Diabetes therapy; Fasting; Glucose; Glucose metabolism; glucose tolerance; Glucose tolerance test; Health aspects; Homeostasis; Humans; Insulin; Insulin resistance; Insulin Resistance - physiology; insulinorésistance; Male; Medical research; Mens health; Metabolism; Muscle, Skeletal - blood supply; Muscle, Skeletal - physiopathology; Musculoskeletal system; Neovascularization, Pathologic - physiopathology; Oxygen Consumption - physiology; Physiological aspects; repos couché; Risk factors; Sedentary behavior; Skeletal muscle; skeletal muscle capillarization; tolérance au glucose; Type 2 diabetes; Young Adult; skeletal muscle capillarization; capillarisation du muscle squelettique; bed rest; glucose tolerance; tolérance au glucose; insulin resistance; insulinorésistance; repos couché
• ISSN: 1715-5312; 1715-5320
• DOI: 10.1139/apnm-2018-0195

Physical inactivity alters glucose homeostasis in skeletal muscle, potentially developing into overt metabolic disease. The present study sought to investigate the role of skeletal muscle capillarization in glucose tolerance and insulin sensitivity (IS) using a classic human model of physical inactivity. Thirteen healthy males (age = 23 ± 2 years) underwent 4 days of full-time supervised and diet-controlled bed rest. Oral glucose tolerance test, indices of IS (quantitative insulin sensitivity check index (QUICKI), Matsuda index), as well as skeletal muscle biopsies with measurement of fiber type distribution, fiber cross-sectional area (FCSA), capillary-to-fiber ratio (C/F ratio), and capillary density (CD) were assessed prior to and after bed rest. Body weight and composition were unaltered by bed rest. Fasting glucose/insulin ratio (G 0 /I 0 ratio) (−25%, P = 0.016), QUICKI (−7%, P = 0.023), and Matsuda index (−24%, P = 0.003) diminished with bed rest. Skeletal muscle FCSA decreased (−737.4 ± 763.2 μm −2 (−12%), P = 0.005) while C/F ratio was preserved, resulting in augmented CD (+93.9 ± 91.5 capillaries·mm −2 (+37%), P = 0.003) with bed rest. No association was detected between changes in skeletal muscle variables and metabolic outcomes. Independently of bed rest-induced effects, a positive linear relationship was detected between C/F ratio and G 0 /I 0 ratio (β = 17.09, P = 0.021). In conclusion, impaired glucose homeostasis with bed rest is not prevented nor associated with enhanced skeletal muscle capillarization in healthy individuals.