This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In individuals with impaired glucose tolerance, exacerbated post-prandial glycemic excursions occur with higher levels of both glucose and insulin in the blood for longer periods of time. Increasing evidence suggests that these exacerbated post-prandial excursions are closely associated with, and may be pre-disposing for, many of the complications associated with diabetes and insulin resistance, including atherosclerosis, myocardial infarction, and stroke. Exercise has been shown to reduce the risks associated with insulin resistance and is an effective means of reducing glycemic excursions and increasing insulin sensitivity. In the present study, we will examine the dose-response relationship between intensity of exercise at equal caloric output and the resultant glycemic effects, with the ultimate aim of identifying the minimum effective exercise intensity for the reduction of post-prandial glycemic excursions. Abdominally obese subjects (BMI >30, waist circumference >80 cm for women and >94 cm for men) will be tested on the GCRC on 5 occasions: (1) - a baseline VO2 Peak / LT protocol to determine exercise intensities and (4) randomly assigned sessions at rest and at 3 differing exercise intensities (low, moderate, intense - exercise duration will vary so that caloric expenditure can be constant for each exercise session at 250 kcal). During tests 2-5, seventy five grams of glucose will be administered 1 h after the onset of exercise. Blood samples will be collected at -30, -20 -10, 0, and at 5-10 minute intervals after the onset of exercise for 240 min and assayed for glucose, insulin and c-peptide. Glucose and insulin rate of change and area under the curve will be calculated. Minimal modeling will be used to assess glucose disposal and insulin sensitivity, and c-peptide minimal model will be used to evaluate -cell function. Repeated measures ANCOVA with covariate SI will be used to examine differences among conditions.
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