Low Intensity Physical Activity During Sitting on Glycemic Control and Vascular Function in Obese Individuals
Condition: Obesity; Metabolic Syndrome
MeSH terms: Metabolic Syndrome
Study type: Interventional

Summary: 
      Prolonged sitting is a common behavior in contemporary humans. In epidemiological studies,
      increased sitting time has been associated with increased risk for cardiovascular disease and
      all-cause mortality. Recent research has also shown that interrupting sitting time with
      standing prevents the poorer glycemic control. However, studies are lacking which evaluate
      the impact of low intensity physical activity during prolonged sitting on vascular function.
      Whether low intensity physical activity can increase blood flow substantially and prevent
      impairment in vascular function and glycemic control is unknown.

      The purpose of the present study is to evaluate whether increased blood flow during sitting
      via low intensity physical activity (fidgetting) prevents the impairment in vascular function
      and poorer glycemic control associated with prolonged sitting.
    

Detailed description: 
      Experimental Design: Twenty obese subjects with metabolic syndrome will complete 2 study days
      with measures vascular function and glycemic control. On one study day, the subjects will sit
      quietly for 3 hours and on the second study day subjects will sit quietly for 3 hours and
      simultaneously move their legs using fidgetting.

      VISIT 1: All visits will be in Gwynn Hall. On this visit subjects will be consented in the
      following manner: a review of the inclusion/exclusion criteria and discussion of the informed
      consent form including an oral explanation of the study purpose, protocol, and potential
      risks and benefits. Potential subjects will be given time to read the consent form and ask
      questions of the study personnel. After signing the informed consent, the popliteal artery
      will be imaged by Doppler ultrasound to ensure that the subject is a candidate for the study.
      Body composition will be measured and waist measurements will be made. Questionnaires will be
      filled out. Subjects will be asked to fill out a one day food record on the day prior to each
      study visit.

      VISIT 2 and 3: Upon arrival to the laboratory, subjects will be asked to use the bathroom and
      height and weight measurements will be taken. An IV will be placed in a forearm vein.
      Subjects will then be asked to lie down and they will be instrumented for baseline assessment
      of blood pressure and flow-mediated dilation in the popliteal artery.

      Energy expenditure (EE): A ParvoMedics TrueOne2400 metabolic measurement system (Sandy Lake,
      UT) will be used to measure EE. The EE measurement will occur throughout the sitting period
      on both study visits. During the measures, a mask will be placed on their face to collect
      their expired air. The air will be analyzed for O2 and CO2 content. The participants will be
      able to breathe room air normally during the procedure. This measurement will be made prior
      to ingesting the glucose and periodically throughout the sitting period.

      After baseline assessments, the subject will be asked to drink a 75 g glucose drink. On one
      occasion, subjects will then sit in a comfortable chair with minimal movement. On the second
      study day, subjects will sit comfortably in a chair but will continuously move their legs by
      fidgetting. Subjects will be allowed to move their arms (e.g., use computer or read) although
      not vigorously. The rationale for maintaining activity in the legs is to increase muscle
      blood flow and thus increase shear stress. The subject will have access to a bathroom using a
      wheelchair if needed. Every hour, 3 assessments of blood pressure and leg blood flow will be
      made while the subject remains in the sitting position. After the 4-hour sitting period,
      subjects will lie down again for post-sitting assessment blood pressure and flow-mediated
      dilation.

      Following the consumption of the glucose, a small blood sample will be taken every ½ hour for
      3 hours. These samples will be used to measure glucose, insulin, glucagon, and c-peptide.
    

Intervention name(s): Glucose; Fidgetting
Intervention type(s): Dietary Supplement; Behavioral
Intervention description(s): Glucose; low intensity physical activity (fidgetting)
Other intervention name(s): low intensity physical activity
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: The subject will complete one intervention with consumption of 75 g of glucose with fidgeting and one intervention with no glucose consumption with fidgeting.
Masking: None (Open Label)
Primary purpose: Prevention