Self Determination Theory (SDT), the motivation theory (includes autonomy, competence and relatedness) was used. Therefore the female students in the intervention group were allowed to choose sport centre, type of physical activity and physical activity frequency level (but at least once a week). The research leader supported and encouraged the female students to stay physically active. The female students were members of a sport centre and were able to train by themselves or with other female students in the intervention group.

 

Female students in the control group continued with their ordinary physical education program at the high schools. All female students in the intervention group and in the control group answered questionnaires and carried out physical fitness tests at baseline and at a 6- month follow up and the intervention group also answered questionnaires at a 1-year follow up. Data about level of physical fitness were collected at baseline and at the 6-month follow up.

 

All female students in the intervention and in the control group were tested supervised by the research leader. The physical fitness tests were performed in the same order at both test occasions, and the research leader gave the same verbal encouragement to all female students. The physical fitness tests were tested out on the field at the high schools.