Training Induced Muscle Exosome Release

Numerous studies in humans and animals have shown that aerobic exercise is beneficial to adipose tissue function and whole-body metabolism. Both acute and chronic aerobic exercise enhance adipocyte catecholamine sensitivity in humans and animals. Although relatively few studies have investigated whether adipose adrenergic signaling is affected by resistance exercise (RE), it is known that a single bout of RE can increase circulating NEFA and resting energy expenditure and decrease respiratory quotient for up to 24 hours, indicative of increased adipocyte lipolysis and muscle fatty acid oxidation. Furthermore, the lipolytic response to RE is impaired in obese men. Using synergist ablation, a model of RE in mice, the investigators show that adipose transcriptional responses are exosome-dependent, and that serum exosomes enhance adipocyte catecholamine sensitivity and lipolysis for at least 24 hours. To the investigator's knowledge, this is the first demonstration of a potential mechanism whereby RE imparts metabolic adaptations in adipose. Since adipose metabolic function is crucial for determining whole-body metabolic outcomes, the ability of RE-induced exosomes to improve adipose metabolism has significant clinical implications.

Inclusion criteria

• 18-30 years of age.
• Either BMI <25 or >30.
• Relatively sedentary, reporting no participation in regular (>1 day per week) exercise for at least the past 3 months.
• Non-smoker.

Exclusion criteria

• BMI between 25 and 30.
• Evidence or signs and symptoms for cardiovascular disease (previous heart attack, arrhythmias, angina, shortness of breath, extreme fatigue, unusual pain in neck, jaw, throat, upper abdomen, or back, swelling in feet, legs, or ankles).
• Evidence or signs and symptoms of metabolic syndrome or disorder (diagnosis of diabetes or insulin resistance, elevated BP, high fasting blood sugar, abnormal cholesterol or triglyceride levels).
• Chronic aspirin or NSAID use (unless it can be safely stopped prior to the biopsies), and any other use of an anticoagulant (e.g., Coumadin) or history of bleeding including history of hypo- or hyper-coagulation disorders.
• Neurological, musculoskeletal, or other disorder that would preclude safe participation in the weight lifting tasks and all performance tests.
• Any other medical condition that would interfere with testing or increase one's risk of complications during exercise, as judged by the study physician.
• Any other condition or events considered exclusionary by the PI and/or physician, such as non-compliance.
• Lidocaine allergy (1% lidocaine is the local anesthetic used during the muscle biopsy procedure).
• Pregnancy.