title: Impact of aerobic exercise training on age-related changes in insulin sensitivity and muscle oxidative capacity.
abstract: Insulin resistance increases and muscle oxidative capacity decreases during aging, but lifestyle changes-especially physical activity-may reverse these trends. Here we report the effect of a 16-week aerobic exercise program (n = 65) or control activity (n = 37) performed by men and women aged 21-87 years on insulin sensitivity and muscle mitochondria. Insulin sensitivity, measured by intravenous glucose tolerance test, decreased with age (r = -0.32) and was related to abdominal fat content (r = -0.65). Exercise increased peak oxygen uptake (VO(2peak); 10%), activity of muscle mitochondrial enzymes (citrate synthase and cytochrome c oxidase, 45-76%) and mRNA levels of mitochondrial genes (COX4, ND4, both 66%) and genes involved in mitochondrial biogenesis (PGC-1alpha, 55%; NRF-1, 15%; TFAM, 85%). Exercise also increased muscle GLUT4 mRNA and protein (30-52%) and reduced abdominal fat (5%) and plasma triglycerides (25%). None of these changes were affected by age. In contrast, insulin sensitivity improved in younger people but not in middle-aged or older groups. Thus, the muscle mitochondrial response to 4 months of aerobic exercise training was similar in all age-groups, although the older people did not have an improvement in insulin sensitivity.
authors.affiliation: Department of Internal Medicine, Division of Endocrinology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Short
authors.forename: Janet L
authors.initials: JL
authors.lastname: Vittone
authors.forename: Maureen L
authors.initials: ML
authors.lastname: Bigelow
authors.forename: David N
authors.initials: DN
authors.lastname: Proctor
authors.forename: Robert A
authors.initials: RA
authors.lastname: Rizza
authors.forename: Jill M
authors.initials: JM
authors.lastname: Coenen-Schimke
authors.forename: K Sreekumaran
authors.initials: KS
authors.lastname: Nair
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001786:Blood Glucose; D001823:Body Composition; D002950:Citrate (si)-Synthase / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology / Q000517:prevention & control; D015444:Exercise / Q000502:physiology*; D005260:Female; D015870:Gene Expression; D018149:Glucose Intolerance / Q000503:physiopathology / Q000517:prevention & control*; D051275:Glucose Transporter Type 4; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000201:enzymology; D024101:Mitochondrial Proteins; D009004:Monosaccharide Transport Proteins / Q000235:genetics; D009124:Muscle Proteins; D018482:Muscle, Skeletal / Q000378:metabolism*; D051265:NF-E2-Related Factor 1; D009687:Nuclear Proteins / Q000235:genetics; D051266:Nuclear Respiratory Factor 1; D051264:Nuclear Respiratory Factors; D010084:Oxidation-Reduction; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
chemical_list: D001786:Blood Glucose; D004268:DNA-Binding Proteins; D051275:Glucose Transporter Type 4; D007328:Insulin; D008055:Lipids; D024101:Mitochondrial Proteins; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D051265:NF-E2-Related Factor 1; C495633:NRF1 protein, human; D009687:Nuclear Proteins; D051266:Nuclear Respiratory Factor 1; D051264:Nuclear Respiratory Factors; C495692:SLC2A4 protein, human; C499631:TFAM protein, human; D015534:Trans-Activators; D014157:Transcription Factors; C422562:mitochondrial transcription factor A; C111264:peroxisome-proliferator-activated receptor-gamma coactivator-1; D011451:Prostaglandin-Endoperoxide Synthases; D002950:Citrate (si)-Synthase