title: Acute exercise reverses starvation-mediated insulin resistance in humans.
abstract: Within 2-3 days of starvation, pronounced insulin resistance develops, possibly mediated by increased lipid load. Here, we show that one exercise bout increases mitochondrial fatty acid (FA) oxidation and reverses starvation-induced insulin resistance. Nine healthy subjects underwent 75-h starvation on two occasions: with no exercise (NE) or with one exercise session at the end of the starvation period (EX). Muscle biopsies were analyzed for mitochondrial function, contents of glycogen, and phosphorylation of regulatory proteins. Glucose tolerance and insulin sensitivity, measured with an intravenous glucose tolerance test (IVGTT), were impaired after starvation, but in EX the response was attenuated or abolished. Glycogen stores were reduced, and plasma FA was increased in both conditions, with a more pronounced effect in EX. After starvation, mitochondrial respiration decreased with complex I substrate (NE and EX), but in EX there was an increased respiration with complex I + II substrate. EX altered regulatory proteins associated with increases in glucose disposal (decreased phosphorylation of glycogen synthase), glucose transport (increased phosphorylation of Akt substrate of 160 kDa), and FA oxidation (increased phosphorylation of acetyl-CoA carboxylase). In conclusion, exercise reversed starvation-induced insulin resistance and was accompanied by reduced glycogen stores, increased lipid oxidation capacity, and activation of signaling proteins involved in glucose transport and FA metabolism.
authors.affiliation: The Swedish School of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Box 5626, 114 86 Stockholm, Sweden. per.frank@gih.se
authors.forename: Per
authors.initials: P
authors.lastname: Frank
authors.forename: Abram
authors.initials: A
authors.lastname: Katz
authors.forename: Eva
authors.initials: E
authors.lastname: Andersson
authors.forename: Kent
authors.initials: K
authors.lastname: Sahlin
mesh_terms: D000328:Adult; D001707:Biopsy, Needle; D031204:Caloric Restriction / Q000009:adverse effects*; D018592:Cross-Over Studies; D042967:Electron Transport Complex I / Q000378:metabolism; D005227:Fatty Acids / Q000097:blood / Q000378:metabolism; D005260:Female; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008931:Mitochondria, Muscle / Q000201:enzymology / Q000378:metabolism; D009043:Motor Activity; D010084:Oxidation-Reduction; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D052097:Quadriceps Muscle / Q000201:enzymology / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D055815:Young Adult
chemical_list: D005227:Fatty Acids; D017382:Reactive Oxygen Species; D006003:Glycogen; D042967:Electron Transport Complex I