Relation between the changes in physical activity and body-mass index during adolescence: a multicentre longitudinal study

• Published in: The Lancet (British edition) Vol. 366; no. 9482; pp. 301 - 307
• Main Authors: Kimm, Sue YS, Glynn, Nancy W, Obarzanek, Eva, Kriska, Andrea M, Daniels, Stephen R, Barton, Bruce A, Liu, Kiang
• Format: Journal Article
• Language: English
• Published: London Elsevier Ltd 23.07.2005; Lancet; Elsevier Limited
• Subjects: Adolescent; Adult; African Continental Ancestry Group; Biological and medical sciences; Body Mass Index; Child; Child development; Correlation analysis; Energy Intake; Energy Metabolism; European Continental Ancestry Group; Exercise; Female; General aspects; Humans; Longitudinal Studies; Medical sciences; Obesity; Obesity - prevention & control; Physical fitness; Physical growth; Skinfold Thickness; Weight; United States > US; Human; Physical exercise; Medicine; Body mass index; Follow up study; Adolescent; Change
• ISSN: 0140-6736; 1474-547X
• DOI: 10.1016/S0140-6736(05)66837-7

The role of physical activity in preventing obesity during adolescence remains unknown. We examined changes in activity in relation to changes in body-mass index (BMI) and adiposity in a cohort of 1152 black and 1135 white girls from the USA, who were followed up prospectively from ages 9 or 10 to 18 or 19 years. BMI and sum of skinfold thickness were assessed annually, whereas habitual activity was assessed at years 1 (baseline), 3, 5, and 7–10. Each girls' overall activity status was categorised as active, moderately active, or inactive. Longitudinal regression models examined associations between changes in activity and in overall activity status with changes in BMI and in sum of skinfold thickness. Each decline in activity of 10 metabolic equivalent [MET]-times per week was associated with an increase in BMI of 0·14 kg/m 2 (SE 0·03) and in sum of skinfold thickness of 0·62 mm (0·17) for black girls, and of 0·09 kg/m 2 (0·02) and 0·63 mm (0·13) for white girls. At ages 18 or 19 years, BMI differences between active and inactive girls were 2·98 kg/m 2 (p<0·0001) for black girls and 2·10 kg/m 2 (p<0·0001) for white girls. Similar results were apparent for sum of skinfold thickness. For moderately active girls, changes in BMI and sum of skinfold thickness were about midway between those for active and inactive girls. Changes in activity levels of US girls during adolescence significantly affected changes in BMI and adiposity. Thus, preventing the steep decline in activity during adolescence is an important method to reduce obesity.