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

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.