Obesity
Conditions
Keywords
physical activity, relative reinforcing value, sedentary behavior, obesity
Brief summary
The primary aim is to examine how reduction in sedentary behaviors influences physical activity and energy intake.
Detailed description
Many youth find television, videos and computer games to be very reinforcing, and they choose to be sedentary rather than physically active. Sedentary behaviors can influence energy balance and body weight by reducing physical activity and increasing energy intake. Research from our laboratory has shown that reducing sedentary behavior can increase physical activity and decrease energy intake, but there is substantial variability in the response of youth to reductions in sedentary behavior. The present proposal is designed to extend our research and explore theoretical models that may help understand why youth vary in their response to increase physical activity when targeted sedentary behaviors are reduced. We hypothesize that the increase in physical activity when sedentary behaviors are reduced is related to the relative reinforcing value (RRV) of physical activity to sedentary behaviors. The RRV of physical activity is a measure of the motivation to be active in youth, and overweight youth who are inactive find physical activity relatively less reinforcing than less overweight youth. We predict that RRV of physical activity will be positively related to the substitution of total physical activity and physical activity in the moderate to vigorous intensity range for sedentary behaviors when targeted sedentary behaviors are reduced. To test this hypothesis, we will study 60 overweight and at risk for overweight 8-12 year-old youth who differ in the RRV of physical activity to sedentary behavior, with equal numbers of boys and girls, in 3 phases: baseline, and reduce television watching from baseline by 25 percent and 50 percent. Each phase will be implemented for three weeks. Order of experimental phases will be counterbalanced across subjects. It is also predicted that reducing sedentary behavior will reduce energy intake and dietary fat intake, and the reduction in energy intake will be greatest for youth with stronger association between eating with television watching and other targeted sedentary behaviors. Liking and outcome expectancy of physical activity will be studied as additional predictors of substitution of physical activity for reductions in sedentary behaviors. Developing a better understanding of why obese youth increase physical activity or decrease energy intake when sedentary behaviors are reduced is important for the treatment of pediatric obesity.
Interventions
DEVICETelevision reduction device
A TV allowance helps turn off the television when the time limits have been met.
Sponsors
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
State University of New York at Buffalo
Study design
Intervention model
SEQUENTIAL
Primary purpose
OTHER
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
8 Years to 12 Years
Healthy volunteers
Yes
Inclusion criteria
* above the 85th BMI percentile * reside in one primary household * engage in at least 18 hours of sedentary behavior a week
Exclusion criteria
* none
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Physical Activity | 3 days | Actigraph activity monitors were used to record physical activity over 3 days, in addition to a weekly physical activity diary. Acti-graph counts were used to estimate energy expenditure during waking hours. Counts per minute describes the average rate of counts, with 0 being at rest and higher numbers indicating more vigorous physical activity. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Energy Intake | 3 days | Resting metabolic rate was calculated using the activity data from accelerometer (Actigraph) collection. Resting metabolic rate was used to calculate estimated daily energy expenditure. Daily energy expenditure and weight change over the study period was used to estimate energy intake. If weight was stable of the nine weeks, assume energy intake = energy expenditure. A gain of a pound was estimated as equivalent to a positive balance of 3500 calories and a loss of a pound was estimated as equivalent to a negative balance of 3500 calories. |
Countries
United States
Participant flow
Recruitment details
Families were recruited from the Buffalo NY area. 460 families were interested in screening for the study with 271 ineligible families, 4 families who were no longer interested and 28 families who withdrew from phone screen, for a total of 157 families eligible for an orientation appointment.
Pre-assignment details
Prior to enrolling in the protocol, families completed an orientation, at which eligibility and interest were assessed. Families who enrolled, first completed three weeks of monitoring on the Television reduction device to determine eligibility (at least 18 hours/week of screen use) and compliance with physical activity accelerometer use.
Participants by arm
| Arm | Count |
|---|---|
| Usual Sedentary Children were asked to maintain their usual targeted sedentary behaviors (TV, video game, computer use) measured by a television reduction device (TV Allowance) | 56 |
| Total | 56 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| 25% Reduction of Sedentary Activity | Protocol Violation | 4 |
| 25% Reduction of Sedentary Activity | Withdrawal by Subject | 1 |
Baseline characteristics
| Characteristic | Usual Sedentary |
|---|---|
| Age, Continuous | 10.7 Years STANDARD_DEVIATION 1.2 |
| Body Mass Index | 25.0 kg/m^2 STANDARD_DEVIATION 4.2 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 3 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 52 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 1 Participants |
| Height | 57.4 Inches STANDARD_DEVIATION 3.7 |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 0 Participants |
| Race (NIH/OMB) Black or African American | 6 Participants |
| Race (NIH/OMB) More than one race | 8 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 42 Participants |
| Sex: Female, Male Female | 29 Participants |
| Sex: Female, Male Male | 27 Participants |
| Weight | 118.8 lbs STANDARD_DEVIATION 30.5 |
| zBMI | 1.8 z-score STANDARD_DEVIATION 0.4 |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 61 |
| other Total, other adverse events | 0 / 61 |
| serious Total, serious adverse events | 0 / 61 |
Outcome results
Primary
Physical Activity
Actigraph activity monitors were used to record physical activity over 3 days, in addition to a weekly physical activity diary. Acti-graph counts were used to estimate energy expenditure during waking hours. Counts per minute describes the average rate of counts, with 0 being at rest and higher numbers indicating more vigorous physical activity.
Time frame: 3 days
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Usual Sedentary | Physical Activity | 576.9 counts/minute of physical activity | Standard Error 23.8 |
| 25% Sedentary Reduction | Physical Activity | 572.4 counts/minute of physical activity | Standard Error 25.6 |
| 50% Sedentary Reduction | Physical Activity | 555.7 counts/minute of physical activity | Standard Error 24.3 |
Secondary
Energy Intake
Resting metabolic rate was calculated using the activity data from accelerometer (Actigraph) collection. Resting metabolic rate was used to calculate estimated daily energy expenditure. Daily energy expenditure and weight change over the study period was used to estimate energy intake. If weight was stable of the nine weeks, assume energy intake = energy expenditure. A gain of a pound was estimated as equivalent to a positive balance of 3500 calories and a loss of a pound was estimated as equivalent to a negative balance of 3500 calories.
Time frame: 3 days
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Usual Sedentary | Energy Intake | 2106.4 calories/day | Standard Error 65.7 |
| 25% Sedentary Reduction | Energy Intake | 2173.5 calories/day | Standard Error 65.2 |
| 50% Sedentary Reduction | Energy Intake | 2144.3 calories/day | Standard Error 74.6 |