Exercise and Insulin Signaling in Human Skeletal Muscle

Study Overview: We are investigating the mechanisms by which exercise improves the response
of skeletal muscle to insulin in lean and obese adults. Participants will complete 4 study
visits consisting of: 1) screening visit, 2) maximal exercise test visit, and then a
randomized order of 3) a resting metabolic study visit, and 4) an exercise metabolic study
visit. Metabolic study visits for resting and exercise conditions will be identical, other
than remaining sedentary or performing exercise. Skeletal muscle biopsy samples will be
collected during resting, immediately post-exercise and during insulin stimulated conditions.

Inclusion Criteria:

- Males or Females

- Aged 18-45 years

- Normal weight (body mass index [BMI] 18-26 kg/m2) or obese (BMI 30-46 kg/m2)

- Sedentary (< 1 hour of planned physical activity per week for ≥ 6 months)

- Weight stable (< 2 kg change in body mass for ≥ 6 months)

- Non-smokers (no tobacco or nicotine use for ≥ 1 year)

Exclusion Criteria:

- Hypertension (systolic blood pressure >140 mmHg, diastolic blood pressure > 90mmHg)

- Chronic health condition including diabetes, cardiovascular disease, treated
hypertension, cancer, anemia, uncontrolled hyper- or hypothyroidism.

- Pregnant, nursing, irregular menses or post-menopausal (if female)

- Hyperglycemia (fasting glucose >126 mg/dl)

- Hypercholesterolemia (fasting LDL>140mg/dl)

- Hemoglobin < 13.0 g/dl (males), < 11.5 g/dl (females)

- Compromised renal function (outside 135-145 mmol/L sodium, 3.5-5.1 mmol/L potassium)

- Lidocaine allergy

- Medications including β-blockers, angiotensin converting enzyme inhibitors, insulin,
thiazolidinediones, metformin, sulfonylureas, chronic non-steroidal anti-inflammatory
use, anti-coagulant (e.g. warfarin), current antibiotics, opiates, monoamine oxidase
inhibitors, benzodiazepines, or others that may impact the study outcomes

- Any physical limitation that prevents a participant from safely completing the
exercise test

- Due to the risks associated with the current protocol, individuals with a diminished
capacity to consent will be excluded. Similarly, due to the need for constant,
accurate participant monitoring during metabolic study activities, participants will
need to clearly understand verbal and written English. Participants who cannot clearly
understand verbal and written English will be excluded.