The Effect of a 12-Week Aerobic Treadmill Exercise on Markers of Glucose Metabolism

Pre-screening- potential participants interested in participating in the proposed research study will be required to perform a pre-screening to assess eligibility. Interested participants will e-mail the research team at TheATEAMstudy@gmail.com and will be contacted by one of the research team members via telephone to discuss the basics of the study and, if the participant is interested, schedule them for an orientation session.

Orientation- following signature of the informed consent by both the participant and the person who obtained the informed consent, a demographics questionnaire and medical history questionnaire will be administered to assess overall health. Following acquisition of the participant's medical history questionnaire, height and weight, will be measured, and from this BMI will be calculated. If the participant is eligible following testing and measurements at orientation, they will be scheduled for a series of baseline visits.

Baseline visits- baseline visit testing will consist of three visits.

At baseline visit 1, participants will come in and have the CGM device placed. For the CGM, a Dexcom G4 Platinum Professional monitor (Dexcom Company, San Diego, CA) will be used. This particular monitor has been approved by the US Food and Drug Administration for use up to 7 consecutive days. This device has a small implantable catheter that will be placed ~2cm to participant preferred side of the umbilicus, a transmitter, and a receiver. This device collects interstitial fluid glucose concentrations every 5 minutes, 24-hours a day, for 7 days. Alongside the CGM for monitoring of blood glucose, each participant will be required to handle a standard glucometer that employs lancets for finger sticks to gain a quick and simple measurement 2 times/day to ensure that there is no drift in the CGM readings. During this visit an actigraph monitor (wGT3X+, Actigraph, LLC, Pensacola, FL) will be placed on the participant's non-dominant or preferred wrist. This Actigraph wGT3X+ monitor is a device that measures activity patterns in an XYZ-directional pathway. It will be worn for 7 consecutive days concurrently with the CGM to aid in the establishment of wake time. A sleep diary will be utilized to aid in the determination of self-report sleep duration, which will include time in bed, sleep time, wake time, and time out of bed. By utilizing a sleep diary in combination with the actigraph monitor, it will allow for ease of interpretation when analyzing the actigraph monitor raw data by providing an estimate as to what sleep/wake time may be. Self-report food intake will be completed via MyFitnessPal (Under Armour™ Connected Fitness, Baltimore, MD), or a standard food diary if necessary, for not only types of food consumed to assess for the effects of meal content, but also time of consumption to assess postprandial blood glucose concentrations for 7 consecutive days. Following this, participants will be scheduled for baseline visit 2.

At baseline visit 2, ~12-24-hours post-baseline visit 1, following a 12-hour fast a 30-minute resting metabolic rate (RMR) test followed by a fasting blood draw and subsequent 120-minute OGTT will be completed. A 30-minute RMR test will be performed to measure oxygen consumption and energy expenditure at rest. For the RMR testing, a Parvo Medics TrueOne 2400 unit (Parvo Medics TrueOne 2400, Salt Lake City, UT), which will be calibrated each time being used, will be utilized. Each participant will have a clear, plastic hood placed over their head while they lay flat on their back resting, without falling asleep for ~30 minutes in a quiet, dimly lit room. After the 30-minute RMR, a fasting blood draw will take place and blood samples will be aliquoted and frozen in a standard VWR -80oC freezer until all blood samples are collected. Participants will then consume a standard 75 gram glucose drink and perform a 2-hour OGTT. Glucose concentration during OGTT will be collected by the CGM device and time points pre-, and 30-,60-,90-, and 120-minutes post-consumption will be used for analysis. Participants will be asked to be as sedentary as possible during this time period as to not disturb the natural uptake and/or clearance of blood glucose that occurs at rest. Upon completion of these tests participants will be scheduled for their baseline visit day 3, ~5-6 days post-baseline visit day 2. During this time period participants will be informed to maintain their normal daily life patterns and to continue to monitor their diet and sleep up until baseline visit 3.