Sedentary Behavior and Health Outcomes Study
Condition: Sedentary Lifestyle; Metabolic Disturbance; Pediatric Obesity; Physical Activity
MeSH terms: Pediatric Obesity
Study type: Interventional

Summary: 
      This study is a randomized crossover trial to compare the effectiveness of interrupting SB on
      glucose homeostasis in the lab and free-living settings. All participants (N=56) will
      complete one screening visit to determine eligibility, complete at fitness test, and body
      composition analysis by bioelectrical impedance. After 7-21 days, all participants will
      complete two 3-hour in-lab oral glucose tolerance tests (spaced 7-21 days apart). Prior to
      the in-lab OGTT visits, participants will wear an activity monitor for 7 days on the right
      thigh. The experimental conditions for the OGTTs will be: 1) 3-hour OGTT of continuous
      sitting; and 2) 3-hour OGTT with sitting interrupted every 30 minutes with 3-minutes of
      moderate intensity walking on a treadmill. There will be a 7-21 day washout period between
      the OGTT visits. In addition, a subset of participants (N=12) who meet inclusion criteria and
      who successfully complete both OGTT visits will complete a second randomized crossover trial
      in the free-living environment. The experimental conditions for the free-living components
      will be: 1) 4 days of habitual sedentary behaviors; and 2) 4 days of prompted short exercise
      breaks during times in which sedentary behaviors have exceeded 30 minutes. Participants in
      the free-living trial will wear an activity monitor and a continuous glucose monitor.
    

Detailed description: 
      Rationale: Sedentary behavior (SB) can increase risk for type 2 diabetes. Interrupting SB is
      a promising strategy to reduce risk, but the long-term success is not yet clear and data on
      the relationship between in-lab and free-living metabolic responses are lacking. A better
      understanding of the relationship between metabolic responses to sitting and interrupting
      sitting in the lab and in a naturalistic environment will help us design effective and
      targeted intervention strategies to prevent type 2 diabetes in youth.

      Intervention: Participants (28 healthy weight and 28 overweight/obese youth; ages 11-15
      years) from an ongoing longitudinal observational study (HS-12-00446) will complete: a) an
      in-lab randomized crossover trial of acute metabolic responses to prolonged vs. SB
      interruptions; and a subset (N=12) will complete b) two 4-day continuous glucose monitoring
      (CGM) studies of effects of free-living habitual activity vs. SB interruptions on glucose
      homeostasis.

      Objectives/Purpose: The overall goal is to improve metabolic outcomes by interrupting SB in
      youth with small bouts of exercise. The aim of this study is to investigate whether the
      metabolic responses to interrupting sitting are the same in a controlled lab setting and a
      free-living setting. This study will also try to explain why some children respond better to
      these short interruptions in sitting than others by using three years of physical activity,
      body fat, and weight trajectory data from an ongoing study (HS-12-00446).

      Study Population: The study population will consist of participants currently enrolled in the
      Mothers and Their Children's Health (MATCH) Study (PI: Dunton; HS-12-00446; ages 11-15
      years).Eligible participants will have completed 3 years of semi-annual assessments of body
      composition, physical activity, and dietary intake in the MATCH study.

      Study Methodology: This study is a randomized crossover trial to compare the effectiveness of
      interrupting SB on glucose homeostasis in the lab and free-living settings. All participants
      (N=56) will complete one screening visit to determine eligibility, complete at fitness test,
      and body composition analysis by bioelectrical impedance. After 7-21 days, all participants
      will complete two 3-hour in-lab oral glucose tolerance tests (spaced 7-21 days apart). Prior
      to the in-lab OGTT visits, participants will wear an activity monitor for 7 days on the right
      thigh. The experimental conditions for the OGTTs will be: 1) 3-hour OGTT of continuous
      sitting; and 2) 3-hour OGTT with sitting interrupted every 30 minutes with 3-minutes of
      moderate intensity walking on a treadmill. There will be a 7-21 day washout period between
      the OGTT visits. In addition, a subset of participants (N=12) who meet inclusion criteria and
      who successfully complete both OGTT visits will complete a second randomized crossover trial
      in the free-living environment. The experimental conditions for the free-living components
      will be: 1) 4 days of habitual sedentary behaviors; and 2) 4 days of prompted short exercise
      breaks during times in which sedentary behaviors have exceeded 30 minutes. Participants in
      the free-living trial will wear an activity monitor and a continuous glucose monitor.

      Study Arms: Participants will be assigned to receive in random order the continuous sitting
      test at the first visit and the sitting interruptions test on the second visit, or vice
      versa. The order of the free-living conditions will be the same as the in-lab condition
      order.

      Endpoints/Outcomes: The primary endpoints are: insulin, C-peptide, and glucose area under the
      curve (AUC) in the in-lab experiments, and glucose AUC in the free-living experiments.

      Follow-up: Study duration for those completing only the in-lab experiments is a minimum of 17
      days and a maximum of 45 days to complete. For the subset of participants who are
      additionally completing the free-living component, the study duration is a minimum of 25 days
      and a maximum of 53 days.

      Statistical Analyses: The populations for analyses include the full analytical dataset which
      consists of all randomized study participants, with the exception of those participants in
      the parent MATCH study who are not participating in this research study.
    

Intervention name(s): Walking breaks; Sitting only
Intervention type(s): Behavioral; Behavioral
Intervention description(s): In-Lab (full sample): participants will be asked to walk on a treadmill for 3 minutes every 30 minutes at a moderate pace during a 3-hour OGTT Free-living (sub-sample; N=12): participants will be prompted via an ActivPAL vtap monitor to walk for 3 minutes every time sedentary behavior lasts longer than 30 continuous minutes; In-Lab (full sample): participants will remain seated for 3 hours during an OGTT Free-living (sub-sample; N=12): participants will perform their habitual sedentary behaviors
Other intervention name(s): Interrupting sedentary time; Continuous sedentary time
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Participants will complete a randomized crossover study with 2 conditions: sitting continuously for 3 hours vs. interrupting sitting with 3-minute moderate intensity walking breaks every 30 minutes for 3 hours. A subset will then complete a free-living component wearing a continuous glucose monitor that will consist of habitual activity vs. interrupting periods of 30+ sedentary minutes with short activity breaks.
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: sedentary behavior; youth; moderating factors; metabolic outcomes