The objective of the study is to evaluate the impact of physical activity in obese and nonobese prepubertal children on: 1. biological stress responses during a psychosocial stress test 2. snacking and feeling of hunger in response to the same psychosocial stress test 3. the moderating factor of attachment on the biological stress responses and on snacking Children will be investigated on one study day during 3.5 hours.
Hypotheses In this study, 3 primary hypotheses will be tested. 1. Moderate physical activity during 25 min in children decreases the cortisol levels in response to the Trier Social Stress Test TSST-C (for children). 2. Moderate physical activity during 25 min in children decreases the snacking (calorie consumption when corrected for expenditure and switch in quality of food intake) in response to the Trier Social Stress Test TSST-C (for children). 3. A secure attachment will be a moderating factor for the general increase in cortisol and the snacking in response to the psychosocial stress test (Trier Social Stress Test TSST-C). Secondary objectives: 1. To test if the impact of physical activity on stress responses and snacking differs between obese and non-obese children 2. To test the impact of physical activity on the cardiovascular stress reactivity (blood pressure, heart rate) and the perceived stress (scale) in response to the Trier Social Stress Test TSST-C? 3. To test if the stress reactivity and its modulation by physical activity is different in anxious and in impulsives/labile children 4. To test if serious life events and parental worries and parental educational style influence the stress reactivity
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
50
25 min of physical activity. The placebo arm will have 25 min of reading.
Univeristy of Lausanne, SUPEA
Lausanne, Canton of Vaud, Switzerland
Change in salivary Cortisol and maximal levels of salivary cortisol in response to the TSST stress test over 2 hours
Time frame: 9 months
Snacking (Caloric intake, corrected for energy expenditure)
Measure of caloric intake and measure of choice of high-caloric vs low-caloric food snacking after the TSST stress test
Time frame: 9 months
Moderator effect of attachment (4 different attachment categories), i.e. children with a secure attachment will have lower rises in cortisol compared with children in the other 3 attachment categories
Cortisol levels after the TSST stress test will be lower in children with secure attachment compared to detached, disorganized or preoccupied children (i.e. the 3 other attachment categories).
Time frame: 9 months
Moderator effect of obesity (WHO criteria)
Time frame: 9 months
Cardiovascular reactivity (changes and maximal levels of blood pressure, heart rate)
Time frame: 9 months
Perceived stress (stress scale from 1-7)
Time frame: 9 months
Moderator role of serious life events and parental worries
Time frame: 9 months
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