What is in Fact the Contribution of Reducing Time Spent in Sedentary Behaviors on Daily Energy Expenditure? A Doubly Labeled Water Study
Condition: Risk Reduction Behavior
Study type: Interventional

Summary: 
      The main purposes of this randomized cross-over trial are to test if a 3h/day reduction of
      time spent in sedentary behaviour (SB) through breaking up hourly and shifting it for
      standing and walking behaviours would substantially increase total (TEE) and PA energy
      expenditure (PAEE) compared to a week of habitual prolonged SB, in male and female
      overweight/obese inactive (which do not attained MVPA recommendations) and sedentary desk
      workers. Specifically using an experiment design our main aims are: a) to determine the
      impact of reducing SB on TEE and PAEE; b) to analyse the independent effects of interrupting
      SB through breaks and the overall reduction in SB on TEE and PAEE; c) To analyse the
      determinants for the overall reduction in SB; d) If the changes occurred in TEE and PAEE were
      dependent on specific covariates.
    

Detailed description: 
      There is enough information about exercise physiology to support the well-documented public
      health guidelines promoting at least 150 minutes of moderate-to vigorous physical activity
      (MVPA)(1). However there is an emergence of inactivity physiology studies. If we divide a day
      into periods of MVPA, light intensity PA (LIPA), sedentary behavior and sleep we observe a
      large proportion of the time taken up by time spent sitting, such as TV viewing, car driving
      and computer use. In fact, evidence exists that excessive time spent in sedentary behavior
      (SB) is a health risk that is not mitigated by performing half an hour of MVPA per day (2,
      3). Life expectancy at birth may increase by ~2y if SB is reduced to <3h/day (4) whereas
      prospective associations exist between SB with mortality and morbidity (2, 3). Short term
      experimental studies indicate that physical inactivity affects energy balance and is
      considered conducive to weight gain (5, 6). A decrease in PA has a considerable ability to
      decrease total energy expenditure (TEE) without any compensatory changes in energy intake,
      which generate a positive energy balance. The extent to which reducing and breaking up SB
      over sustained periods of time considerably increases TEE has never been investigated under
      free-living conditions.

      Our hypothesis are that, a daily 3h reduction of SB during 1-week, either by increasing the
      number of breaks and by shifting SB to low intensity physical activity (LIPA), mainly through
      standing and walking activities, would substantially increase physical activity energy
      expenditure (PAEE) in male and female overweight/obese inactive computer desk workers
      compared to 1-week of usual prolonged SB. Prior to intervention, number of steps/day and PA
      were assessed through the use of a pedometer and accelerometer to respectively identify the
      habitual daily steps and to assure participants are inactive (<30 min/day of MVPA and ~ 5000
      steps/day). Eligible participants were enrolled in a crossover experiment with two conditions
      performed in a random order: intervention (3h-reduction in SB) and control (habitual SB),
      both under free-living conditions. Each condition last for 1 week and participants were
      instructed to keep the same eating patterns while wearing an accelerometer, pedometer, a
      combined accelerometer and heart rate device, and an inclinometer (activpal). Doubly labeled
      water (DLW) was administered in both conditions to assess TEE, indirect calorimetry was
      employed to measure resting energy expenditure (REE), and PAEE subtracted from the sum of REE
      and thermogenic effect of food (assumed as 10% of TEE). Body composition was assessed at
      baseline and in the last day of the intervention week with DXA and participants wore the
      devices 24 hours a day during the two weeks and did the food records in three days in each
      week. In practice, at the workplace, our intervention to reduce SB include a software that
      hourly alert the participants to break up SB for approximately 7 minutes through adopting
      walking behaviors (~30-60 minutes/day) while during transportation, home/domestic, and
      leisure time contexts, an individual goal for number of steps/day was set based on an
      expected step cadence for ambulatory activities (~90-120 minutes/day). Also a number of
      strategies to break up SB were transmitted to the participants in the several contexts for
      accomplishing their goals.

      At the workplace, daily breaks were automatically generated and registered through the
      software. Daily adherence in breaking up SB was supervised using phone calls during the day
      as well as compliance with the individual steps/day goal, self-registered in a diary at the
      end of the day. During the control week, supervision was performed to assure that
      participants remained inactive with a similar SB and number of steps/day, as observed at
      baseline.

      During the trial, a 3-day food intake record was collected and analyzed at each condition. We
      anticipate that by using objective measures of transitions from sitting to standing and
      stepping, we will provide important methodological information, as sedentary time comprises a
      large proportion of waking hours and small changes may go undetected using self-report SB. A
      unique aspect of the present study is the utilization of state of-the-art technologies to
      investigate differences in daily EE and activity patterns in overweight/obese individuals.

      The results of this project may have remarkable public health relevance. Most of the
      population weight gain in the past could have been avoided if a negative energy balance of
      100 Kcal/day was achieved. We expect that our findings reveal a meaningful difference in
      energy expenditure by breaking up SB. We anticipated a public health message emphasizing
      "standing and walking more" as a simple approach to prevent weight gain and the rise of
      obesity in developed countries. This project may also contribute to disclose innovative
      energy balance -based methodologies for designing long-term intervention studies examining
      the effect of breaking up sedentary time on health-related parameters.
    

Intervention name(s): Reduction of sedentary time by breaking it with low intensity physical activity
Intervention type(s): Behavioral
Intervention description(s): One 5-10 minute break per hour during the work day using a software that alert the participant, and perform 6000 steps above the baseline number of steps/day (previously evaluated), by adopting several domain specific strategies, during 7 days.
Other intervention name(s): LIPA; breaks
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Sedentary Behavior; Breaks; Workplace; Energy Expenditure; Physical activity; doubly labeled water