Fatty Acid Metabolism and Insulin Sensitivity After Exercise in Obesity

Alterations in fatty acid mobilization and oxidation may be primary adaptations responsible
for the improvements in metabolic health after a single session of endurance exercise. The
investigators will determine the effect of a single session of endurance exercise on
whole-body fatty acid mobilization and oxidation, IMTG concentration and the expression of
factors that regulate these processes in skeletal muscle of 11 women with abdominal obesity
(age: 18-45y). In addition, the investigators will evaluate how these factors, and exercise,
effect insulin signalling and insulin sensitivity. Every effort will be made to recruit
subjects from ethnic and minority groups. Before participating in the study, subjects will
be informed of all the procedures and potential risks, and they will sign an informed
consent form approved by The University of Michigan Institutional Review Board. Eligible
volunteers will participate in three separate trials, in a randomized order. In two trials
subjects will eat exactly the same amount of calories, except in one trial they will
exercise (eucaloric + exercise) and in the other trial they will remain sedentary
(hypercaloric). In a third trial subjects will again remain sedentary but instead they will
ingest appropriate calories to maintain caloric balance (eucaloric + sedentary). By doing
this the investigators are also able to investigate the effect of acute caloric
perturbations on insulin sensitivity, because it is possible that the enhanced insulin
sensitivity evident after exercise, as compared to the sedentary state, is due to caloric
deficit and not the exercise bout, per se.