title: The influence of maturation, body size and physical self-perceptions on longitudinal changes in physical activity in adolescent girls.
abstract: The aim of this study was to adopt a longitudinal design to explore the direct effects of both absolute and relative maturation and changes in body size on physical activity, and explore if, and how, physical self-perceptions might mediate this effect. We recruited 208 girls (11.8 ± 0.4 years) at baseline. Data were collected at three subsequent time points, each 6 months apart. At 18 months, 119 girls remained in the study. At each time point, girls completed the Physical Activity Questionnaire for Children, the Pubertal Development Scale (from which, both a measure of relative and absolute maturation were defined) and the Physical Self-Perception Profile, and had physical size characteristics assessed. Multilevel modelling for physical activity indicated a significant negative effect of age, positive effect for physical condition and sport competence and positive association for relatively early maturers. Absolute maturation, body mass, waist circumference and sum of skinfolds did not significantly contribute to the model. Contrary to common hypotheses, relatively more mature girls may, in fact, be more active than their less mature peers. However, neither changes in absolute maturation nor physical size appear to directly influence changes in physical activity in adolescent girls.
authors.affiliation: a The Institute for Sport, Physical Education and Health Sciences, The Moray House School of Education, St Leonard's Land , The University of Edinburgh , Holyrood Road, Edinburgh EH8 8AQ , Scotland.
authors.forename: Samantha
authors.initials: S
authors.lastname: Fawkner
authors.forename: Joan
authors.initials: J
authors.lastname: Henretty
authors.forename: Ann-Marie
authors.initials: AM
authors.lastname: Knowles
authors.forename: Alan
authors.initials: A
authors.lastname: Nevill
authors.forename: Ailsa
authors.initials: A
authors.lastname: Niven
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001828:Body Image; D015992:Body Mass Index; D049628:Body Size; D002648:Child; D015444:Exercise; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D010809:Physical Fitness; D012649:Self Concept; D012741:Sexual Maturation; D013177:Sports; D011795:Surveys and Questionnaires