Br J Sports Med 47:71-77 doi:10.1136/bjsports-2011-090704
  • Original articles

Body mass index, fitness and physical activity from childhood through adolescence

Editor's Choice
  1. Olli Simell1,4,7
  1. 1Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland
  2. 2Paavo Nurmi Centre, Sports & Exercise Medicine Unit, Department of Physiology, University of Turku, Turku, Finland
  3. 3Department of Pediatrics, Tampere University Hospital, Tampere, Finland
  4. 4Turku Institute for Child and Youth Research, Turku, Finland
  5. 5Department of Medicine, University of Turku and Turku University Hospital, Turku, Finland
  6. 6Department of Clinical Physiology, University of Turku and Turku University Hospital, Turku, Finland
  7. 7Department of Pediatrics, University of Turku and Turku University Hospital, Turku, Finland
  1. Correspondence to Katja Pahkala, University of Turku, Research Centre of Applied and Preventive Cardiovascular Medicine, Kiinamyllynkatu 10, FI-20520 Turku, Finland; katja.pahkala{at}
  1. Contributors Authors included in the manuscript meet all of the following conditions: (1) substantial contributions to the conception and design, acquisition of data, or analysis and interpretation of data; (2) drafting the article or revising it critically for important intellectual content; and (3) final approval of the version to be published. All authors are responsible for reported research.

  • Received 24 October 2011
  • Accepted 9 May 2012
  • Published Online First 18 July 2012


Background Obesity, sedentary lifestyle and poor cardiorespiratory fitness in childhood may increase the risk of health problems later in life.

Purpose The authors studied the association of early childhood weight status with cardiorespiratory fitness and leisure-time physical activity (LTPA) in adolescence. The stability and associations of LTPA and fitness from childhood through adolescence were also studied.

Methods Body mass index (BMI) was assessed annually since birth in a prospective, longitudinal study. The mean BMI between ages 2 and 7 years indicated weight status at preschool age. Fitness was studied with a shuttle run test at age 9 and with a maximal cycle ergometer test at age 17. The same questionnaire was used to assess LTPA at age 9, 13 and 17. Complete data on preschool BMI, LTPA at ages 13 and 17 and fitness at age 17 years was provided by 351 children, while fitness and LTPA data were available for 74 children at ages 9 and 17.

Results Preschool BMI was inversely associated with fitness in adolescence independently of adolescent LTPA (p=0.0001). Children who had a high preschool BMI but whose weight status was reduced in adolescence had similar fitness in adolescence as the children with a persistently low BMI. Regardless of the fitness level in childhood, the children whose LTPA increased between age 9 and 17 had a similar adolescent fitness level as persistently active subjects.

Conclusions It is important to maintain a healthy body weight and a physically active lifestyle from very childhood through adolescence to improve fitness during adolescence.


  • Funding Finnish Ministry of Education and Culture; Finnish Cultural Foundation; Juho Vainio Foundation; Finnish Cardiac Research Foundation; Academy of Finland (grant number 251360, 206374, 210238, 77841, 34316, and Public Health Challenge Research Programme); Sigrid Juselius Foundation; Special Governmental Grants for Health Sciences Research, Turku University Hospital; Yrjö Jahnsson Foundation; CG Sundell Foundation; Foundation for Pediatric Research and Turku University Foundation.

  • Competing interests None.

  • Ethics approval The Joint Commission on Ethics of the Turku University and the Turku University Central Hospital.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • ▸ References to this paper are available online at

Relevant Article