Identification of Exercise-induced Myokines Regulating the Muscle-adipose Signaling Axis

Acute exercise stimulates a cascade of responses within the human body. Not only do tissues work in an autonomous manner, but they also secrete factors mediating interorgan communication. Recent human research identified >600 proteins secreted into the circulation following an acute bout of exercise, many of which are predicted to derive from the skeletal muscle and target the adipose tissue. Indeed, human studies have validated the effect exercise-induced myokines have upon adipose physiology, most notably IL-6. While insightful, identification of myokines and their tissue of target (i.e. adipose tissue) remains extremely challenging in humans. This is largely due to the need for tissue collection from multiple sites (skeletal muscle and adipose tissue) and at multiple timepoints (before and after exercise). To address these challenges, This study will implement an acute bout of exercise in a human cohort, followed by tissue collection and in-depth secretome and tissue protein analysis. This study will accomplish these goals through tissue and blood collection at multiple timepoints before and after exercise followed by in-depth proteome and transcriptome analysis.

For the first in-person visit, participants will arrive to The Rockefeller University Hospital between 8:00am to 10:00am in a non-fasted state. All participants will be asked to keep track of their food consumption both the night prior to and the day of the visit. Participants will be asked to consume their breakfast 2-hours prior to arrival, and will be asked to eat their habitual breakfast. Participants will be asked to refrain from intense physical activity 48 hours prior to the testing day, any caffeinated beverages the day of arrival, and any alcoholic beverages for 24-hours prior to arrival.

Height, weight, resting heart rate, blood pressure, and body composition, will be measured. Blood will be collected from the upper arm for blood chemistry analyses including HbA1c (%), Cholesterol (mg/dl), LDL-cholesterol (mg/dl), HDL-cholesterol (mg/dl), Triglyceride (mg/dl), Complete blood count (CBC), and High sensitivity C-reactive protein (hsCRP). An additional 20mL of blood will be drawn from the arm for protein identification through the use of proteomics. Subcutaneous adipose from the lower abdomen will be collected following blood collection.

Following a minimum of one week from fat sample collection, participants will take part in a maximal aerobic consumption (VO2max) test between 8:00am-10:00am. Participants will arrive in a non-fasted state, but all participants will be asked to keep track of their food consumption the night prior to, and the morning of, the VO2max test. When possible, the investigators will recommend the participants to consume the identical dinner/breakfast to that consumed prior to the first in-person visit. Participants will be asked to consume their breakfast 2-hours prior to arrival. Additionally, participants will be asked to refrain from intense physical activity 48 hours prior to the testing day, any caffeinated beverages the day of arrival, and any alcoholic beverages for 24-hours prior to arrival.

For VO2max testing, participants will take part in a general warm up consisting of walking on a motorized treadmill for 5 minutes followed by performing a graded exercise test (GXT) on a motorized treadmill while wearing a one-way, non-rebreathing Hans Rudolph 7450 series V2 mask that allows for the evaluation of all expired air which is calibrated prior to each test. Volume of ventilated expired air as well as oxygen and carbon dioxide concentrations of expired air will be determined using a commercial metabolic cart (Parvo Medics' TrueOne® 2400, Parvo, UT). Specifically, the investigators will incorporate the Ellestad Protocol to determine the participants VO2max. The Ellestad Protocol is divided into 8 phases which gradually increases in speed and incline throughout the test. To confirm that the VO2max test is eliciting a metabolic response, lactate measurements through the use of a finger prick will be taken both before and immediately following the exercise test. Additionally, participants will wear a light-weight heart rate monitoring device (Polar) strapped around the upper torso during testing to track heart rate throughout exercise.