Nutrient Timing Following Resistance Exercise
Condition: Type 2 Diabetes
MeSH terms: Diabetes Mellitus
Study type: Interventional

Summary: 
      The purpose of the proposed study is to examine the timing of post-exercise feeding on 15
      hours post-exercise glycemic control and metabolic flexibility and in overweight and obese
      young men with a family history of type 2 diabetes.

      Aim 1 - To determine the temporal effects of post-exercise feeding (i.e., immediate
      post-exercise vs. 3 hours post-exercise) on glycemic control, peripheral insulin sensitivity,
      and metabolic flexibility (as evaluated by sleep RQ) in this same group of participants. We
      hypothesize that a 3 hour delay in nutrient ingestion will promote significantly greater
      improvements in glucose tolerance, metabolic flexibility, and peripheral insulin sensitivity
      both immediately and several hours post-ingestion.
    

Detailed description: 
      The proposed study is cross-sectional and utilizes a within-subject design to study young men
      under two different nutrient timing protocols, which are randomly-ordered and spaced at least
      2 weeks apart.

        1. Participants will be screened for eligibility via phone or email and scheduled for an
           initial visit, in order to consent to the study and undergo some basic baseline
           evaluations. We will rely on participant self-report to verify absence of chronic
           disease or drug use.

        2. After consenting to the study, fasting blood glucose, height, weight, and air
           displacement plethysmography (BodPod®) will be conducted in the Clinical Exercise
           Physiology Laboratory at The George Washington University, in Washington, DC. These
           measures may occur on the same day as consent or at another scheduled time.

        3. After screening, consenting, and baseline assessments, participants will undergo 2
           experimental conditions, which will be randomly-ordered and approximately 2 weeks apart.
           If possible, both of these experimental visits will be scheduled shortly after the
           consent form is signed.

        4. A registered dietitian will instruct participants to eat a standardized (35 kcal∙kg body
           weight-1∙day-1) diet comprising 60% carbohydrate, 20% protein, and 20% fat for 3 days
           prior to both experimental sessions. This instruction will be administered after the
           BodPod® assessment is completed.

        5. Participants will report to the USDA Laboratory chamber at 7:30 AM for the experimental
           sessions. Height, weight blood pressure and heart rate will be measured, then a fasting
           blood sample (5 cc) will be obtained for determination of basal glucose & insulin
           concentrations. A Hidalgo Ambulatory Monitoring Sensor Array Vest (Equivital I: Hidalgo
           Ltd., Cambridge UK) will be worn by all participants measured in the calorimeter for the
           entire 48 period. This device measures heart rate (HR), heat flux, core body
           temperature, posture and physical activity (PA) from a built-in accelerometer.

        6. Then, the sensor portion of the CGMS then will be placed subcutaneously and the CGMS
           calibrated with whole blood using the Accu-Check Advantage (Roche Diagnostics,
           Indianapolis, IL) glucometer. Participants will then enter the whole room calorimeter
           (metabolic chamber) and complete a hunger scale. Hunger will be evaluated 10-20 minutes
           before the start of each meal and 2 hours after the resistance exercise bout. On the
           first day, participants eat a standard breakfast provided by the USDA kitchen at
           approximately 7:45-8:00AM.

        7. Gutierrez or a research assistant will take obtain glucometer readings before and 60
           minutes after each meal to calibrate the the CGMS. These evaluations will occur 4-6
           times over the course of the day.

        8. Standardized meals (lunch at 11:00AM and dinner at 7:00PM) will be provided for subjects
           by the USDA. Blood samples (5 cc each) will be collected prior to and 120 minutes after
           breakfast and lunch; and prior to and 30-, 60-, 90-, and 120-min following the start of
           the evening meal for the determination of post-meal responses in glucose & insulin. A
           trained phlebotomist with at least 50 successful IV catheter placements will place an IV
           catheter into the participant's median antecubital vein before the evening meal to
           facilitate multiple draws after the meal.

        9. On the second day, subjects will awake in the calorimeter at approximately 7:00 AM and a
           fasting blood sample (5 cc) will be obtained for determination of basal concentrations
           of glucose & insulin.

       10. At about 7:30 AM, subjects will eat a standardized breakfast to be consumed by 8:00 AM.
           Two hours after a standardized lunch meal, served at 11:00AM, participants will perform
           one of the following resistance exercise nutrient-timing protocols: immediate
           post-exercise nutrition at approximately 2:00 PM 3 hour post exercise nutrition at
           approximately 5:00 PM). All participants will undergo both experimental conditions at
           different testing sessions.
    

Intervention name(s): Immediate Nutrition; Nutrition 3 hours Post-Bout; Resistance Exercise
Intervention type(s): Dietary Supplement; Dietary Supplement; Other
Intervention description(s): Nutritional supplement consumed either immediately following a 40min resistance exercise bout; Nutritional supplement (600g low-fat chocolate milk) consumed three hours after the exercise bout; A single 40 minute circuit-style bout of resistance exercise
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: nutrition; nutrient; timing; diabetes; family history; dairy