Exercise Training on Brain Insulin Responsiveness

Investigate one acute bout of exercise on the brain insulin responsiveness using functional magnetic resonance imaging in combination with intranasal insulin in healthy participants of normal-weight and overweight/obesity. Two single endurance exercise sessions with different intensities will be evaluated, namely moderate intensity continuous training (MICT) and high-intensity interval training (HIIT). This will be compared to a waiting control condition. In a cross-over design, investigators will compare cerebral response from before to after intranasal insulin administration after a single bout of HIIT or MICT compared to a control condition without exercise. Cerebral response is defined as the cerebral blood flow and resting state functional connectivity in response to intranasal insulin. Secondary outcomes include changes in blood metabolites and proteins and changes in eating behavior.

Inclusion criteria

• BMI between ≥ 19.5 to 39 kg/m2-
• Less than 150 min/week for moderate-intensity physical activity
• Less than 75 min/week for Vigorous- intensity exercise (WHO recommendations for regular physical activity of adults)
• Written consent to participate in the study
• Written consent to be informed about incidental findings

Exclusion criteria

• Type 2 diabetes, cardiovascular diseases such as chronic heart failure, myocardial infarction, status post stroke
• Limitations to participate in ergometer-based exercise (balance and coordination disorders, orthopedic problems, …)
• Insufficient knowledge of the German language
• Persons who cannot legally give consent
• Pregnancy or lactation
• History of severe mental or somatic disorders including neurological diseases (incl. epileptic seizures and migraines)
• Taking psychotropic drugs
• Taking medications that influence glucose metabolism
• Regular use of analgesic drugs
• Taking anticoagulant agents
• Previous bariatric surgery
• Acute infection within the last 4 weeks
• Hemoglobin values less than 12g/dl for women, less than 14 g/dl for men
• Other diseases that in the opinion of the investigator may jeopardize the success of the study or indicate a risk to the volunteer
• Current participation in a lifestyle intervention study or a pharmaceutical study
• Metal implants which cannot be removed as pacemakers, artificial heart valve, electrical devices as insulin pumps, large tattoos, retainer over more than 4 teeth, contraceptive coil, implanted magnetic metal parts as screws or plates after a surgery
• Persons with claustrophobia
• Temperature-sensitive person
• Persons with tinnitus or increased sensitivity to loud sounds