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Obesity (Silver Spring). 2014 Feb;22(2):451-7. doi: 10.1002/oby.20609. Epub 2013 Oct 16.

Metabolic inflexibility during submaximal aerobic exercise is associated with glucose intolerance in obese older adults.

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  • 1Baltimore Veterans Affairs Geriatric Research, Education and Clinical Center and Research and Development Service, Baltimore, Maryland, USA; Division of Gerontology and Geriatric Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.



People with type 2 diabetes have reduced cardiorespiratory fitness and metabolic impairments that are linked to obesity and often occur prior to the development of type 2 diabetes. We hypothesized that obese, older adults with impaired glucose tolerance (IGT) have lower ability to shift from fat to carbohydrate oxidation when transitioning from rest to submaximal exercise than normal glucose tolerant (NGT) controls.


Glucose tolerance, body composition, and substrate oxidation (measured by RER:respiratory exchange ratio) during submaximal exercise (50% and 60% VO2max ) and insulin infusion (3-hour hyperinsulinemic-euglycemic clamp) were assessed in 23 sedentary, overweight-obese, older men and women.


Obese subjects with NGT (n = 13) and IGT (n = 10) had similar resting RER, but during submaximal exercise those with IGT had a lower RER and less transition to carbohydrate oxidation than the NGT group (P < 0.05). The IGT group also oxidized less carbohydrate during insulin infusion than NGT (P < 0.05). RER at each exercise intensity independently correlated with 120-minute postprandial glucose (r = -0.54 to -0.58, P < 0.05), but not with body composition, VO2max , or RER during insulin infusion.


Obese, older adults have metabolic inflexibility during exercise that is associated with the degree of glucose intolerance independent of age and body composition.

Copyright © 2013 This article is a US government work and, as such, is in the public domain in the United States of America.

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[Available on 2014/8/1]
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