Background: Insulin resistance (IR) is associated with metabolic disturbances in several tissues, including increased insulin-stimulated glucose uptake in brain, decreased glucose uptake in adipose tissue and accumulation of fat in and around the myocardium. Whether these disturbances can be normalized by exercise is still uninvestigated. Thus, the aims of this study were to determine the myocardial adiposity in and around myocardium, to elucidate exercise training-induced metabolic adaptations in brain and adipose tissue and to compare the training responses between, sprint interval training (SIT) vs. moderate-intensity continuous training (MICT) in subjects with IR. 
Methods: Middle-aged, sedentary healthy subjects (n=28) and subjects with IR (n=26) were andomized into SIT and MICT interventions for two weeks. Brain and adipose tissue metabolism in terms of glucose uptake and free fatty acid uptake and myocardial adiposity were determined non-invasively using positron emission tomography (PET), computed tomography (CT), magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). 
Results: Two-week of exercise training, both SIT and MICT, decreased epi- and pericardial fat volumes and adipose tissue glucose and fatty acid metabolism similarly in healthy subjects and subjects with IR despite the baseline differences. In short-term, only SIT showed improvements in aerobic capacity, visceral adipose tissue glucose uptake and a decrease in insulin-stimulated brain glucose uptake in IR subjects. 
Conclusions: Exercise training has beneficial effects on adipose tissue volume and metabolism despite the baseline glucose tolerance. This study also showed for the first time, that exercise training can decrease insulin-stimulated brain glucose uptake. These findings further support the therapeutic potential of exercise training in subjects with IR.