Impact of aerobic exercise training on age-related changes in insulin sensitivity and muscle oxidative capacity.
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.
Short
Kevin R
KR
Department of Internal Medicine, Division of Endocrinology, Mayo Clinic, Rochester, Minnesota, USA.
Vittone
Janet L
JL
Bigelow
Maureen L
ML
Proctor
David N
DN
Rizza
Robert A
RA
Coenen-Schimke
Jill M
JM
Nair
K Sreekumaran
KS
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
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