Objectives. The present study explored factors that underpin increased internalization (i.e., perceived autonomy) in motivation towards exercise over a 1-year period in adolescent girls.
Design. A mixed methods prospective study.
Methods. A total of 107 girls (mean age = 13.28 years) reported their exercise behaviour, exercise goals, and a multidimensional measure of motivation towards exercise on two occasions, 1 year apart. Ten girls reporting increased autonomous motivation were then interviewed.
Results. Two themes were extracted; growing up and seeking challenge. Most participants reported being more interested in exercising for their health as a result of growing up, through having greater understanding of the health-behaviour link and willingness to act now for future health gain. However, their motivation appeared to be only partially internalized, as health was still viewed primarily as a value promoted by respected others (parents, teachers, media). Furthermore, as many girls conflated being healthy with being thin, health for appearance-related weight control was experienced as an extrinsic (controlling) goal. The second theme was more suggestive of autonomous motivation; girls reported valuing exercise for the opportunity it provides to set and achieve personally meaningful challenges, facilitating a sense of competence and achievement.
Conclusions. The findings may have a useful application in suggesting how exercise settings could be manipulated to increase enjoyment and participation during adolescence. In particular, the findings suggest that means of increasing the salience of the rewarding nature of setting and reaching personal challenges in an exercise setting are investigated.