A Randomized-Controlled Lifestyle Intervention to Increase Physical Activity Levels in Adolescents

Study Overview
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Brief Summary
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Students at the age of 14-16 years will be randomized to one intervention arm or one control arm in a 1:1 ratio. Participants of both groups receive a fitness tracker to count the amount of their steps taken. The participants of the intervention arm will commit themselves to a personal goal of steps taken by means of a commitment contract. Achievement of the goal will be rewarded with financial incentives to fulfill the requirements of proper reward medium, according to the Induced Value Theory (Smith, 1976). The duration of the intervention will be 1 year; incentives are provided for 6 months, the remaining 6 months are the follow-up period. The hypothesis is that intensified motivational strategies like the provision of commitment contracts and nudges are effective in increasing the number of steps taken per month compared to a control group.

Detailed Description
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Adolescents age 14 to 16 years visiting schools throughout Tyrol, Austria will be randomized to one intervention arm or a control arm on a class-wise level in a 1:1 ratio. Participants will be invited by the Department of Education in Tyrol and schools will be contacted directly. At the baseline examination cardiovascular risk profiles (including laboratory analysis; anthropometry; a standardized medical interview; and blood pressure, bioelectrical impedance and pulse-wave velocity measurements) are determined and results are communicated in an individual discussion of results. Afterwards, participants of both groups receive a fitness tracker to count the amount of their steps taken. The participants of the intervention arm will commit themselves to a personal goal of steps taken by means of a commitment contract. Achievement of the goal will be rewarded with financial incentives to fulfill the requirements of proper reward medium, according to the Induced Value Theory (Smith, 1976) and nudges (reminders) will be provided to increase motivation. The duration of the intervention will be 1 year; incentives are provided for 6 months, the remaining 6 months are the follow-up period. After 1 year a follow-up examination will be conducted. Economic experiments on time and risk preferences are furthermore carried out at baseline. The hypothesis is that intensified motivational strategies like the provision of commitment contracts and nudges are effective in increasing the number of steps taken per month compared to a control group.

Official Title
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Healthy.Tyrol - A Randomized-Controlled Lifestyle Intervention to Increase Physical Activity Levels in Adolescents

Conditions
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Life Style, Healthy, Life Style

Intervention / Treatment
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* Behavioral: Promotion of physical activity


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 14 - 16 years at baseline Signed informed consent of subjects and legal guardian Exclusion Criteria: Persons, who are suspended upon a court order or upon other legal processes or are accommodated according to the Hospitalization Act, or for whom a custodian is appointed (or appointment is initiated). Persons with impaired power of judgment Persons who are currently engaged in military or community service

Ages Eligible for Study
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Minimum Age: 14 Years
Maximum Age: 16 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Intervention Group<br>Tracking of steps by means of a fitness tracker For the economic experiments on time and risk preferences monetary rewards are used with the amount depending on the decisions of the participants. Participants collect points for transmitting informations about the amount of steps taken on the basis of which they get a small reward (e.g., a skiing ticket) Setting-up of a commitment contract on the individual's goal of monthly steps taken Provision of financial incentives upon achievement of one's goal of steps taken Provision of nudges (reminders) | Behavioral: Promotion of physical activity<br>* Provision of motivational stimuli (commitment contracts, nudges, financial incentives) to increase amount of steps taken<br>|
| No Intervention: Control Group<br>Tracking of steps by means of a fitness tracker For the economic experiments on time and risk preferences monetary rewards are used with the amount depending on the decisions of the participants. Participants collect points for transmitting informations about the amount of steps taken on the basis of which they get a small reward (e.g., a skiing ticket) To keep incentives constant the control group will also receive the flat payment of €10 to disentangle the effects between the contract and financial incentives. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in average number of steps taken per day | Baseline (observation period = first month) versus intervention period (months 2-7) | month 1 versus months 2-7 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in average number of steps taken per day | Baseline (observation period = first month) versus post-intervention period (month 8 - follow-up examination) | month 1 versus month 8 to follow-up examination | 
| Achievement of pre-defined goal of steps (specified as percentage change compared to baseline; 0-50% increase) | percentage of participants in the intervention group achieving their predefined goal (using explanatory variables such as demographic variables, time and risk preferences etc. | month 1 versus months 2-7 | 
| Difference in number of ideal cardiovascular health metrics in the ideal range as defined by the American Heart Association | Between and within group differences | 15 months | 
| Difference in average minutes of moderate to vigorous physical activity per day | Between and within group differences | 15 months | 
| Difference in systolic and diastolic blood pressure | Between and within group differences | 15 months | 
| Difference in body composition as measured by bioeletrical impedance | Between and within group differences | 15 months | 
| Magnitude of commitment (specified as as percentage increase of steps taken by steps of 10 percentage points ranging from 0% - 50%) | Between group differences | 15 months | 
| Difference in visceral abdominal fat-tissue thickness as measured by ultrasonography | Between and within group differences | 15 months | 
| Difference in liver fat and fibrosis as measured by FibroScan | Between and within group differences Liver fat content is assessed by means of the Controlled-Attenuation Parameter [dB/m] and fibrosis by means of transient elastography [kPa]. | 15 months | 
| Predictors of progression of Intima-Media Thickness [µm] | Intima-media thickness is assessed by means of ultrasonography, predictors to be examined include: Blood pressure, lipid parameters, age, sex, liver fat and fibrosis, body composition/BMI, smoking, fasting glucose and CRP. | 15 months | 
| Predictors of progression of pulse-wave velocity [m/s] | pulse-wave velocity is measured using the Vicorder, an oscillometric pulse-wave velocity measurement device, predictors to be examined include: Blood pressure, lipid parameters, age, sex, liver fat and fibrosis, body composition/BMI, smoking, fasting glucose and CRP. | 15 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Lifestyle Intervention, Adolescents, Health Behavior, Financial Incentives, Commitment Contract, Nudges, Cardiovascular Risk Reduction, Primoridal Prevention, Physical Activity