title: Comparison of structured and unstructured physical activity training on predicted VO2max and heart rate variability in adolescents - a randomized control trial.
abstract: BACKGROUND
  Physical inactivity contributes to many health issues. The WHO-recommended physical activity for adolescents encompasses aerobic, resistance, and bone strengthening exercises aimed at achieving health-related physical fitness. Heart rate variability (HRV) and maximal aerobic capacity (VO2max) are considered as noninvasive measures of cardiovascular health. The objective of this study is to compare the effect of structured and unstructured physical training on maximal aerobic capacity and HRV among adolescents.
  
  
  METHODS
  We designed a single blinded, parallel, randomized active-controlled trial (Registration No. CTRI/2013/08/003897) to compare the physiological effects of 6 months of globally recommended structured physical activity (SPA), with that of unstructured physical activity (USPA) in healthy school-going adolescents. We recruited 439 healthy student volunteers (boys: 250, girls: 189) in the age group of 12-17 years. Randomization across the groups was done using age and gender stratified randomization method, and the participants were divided into two groups: SPA (n=219, boys: 117, girls: 102) and USPA (n=220, boys: 119, girls: 101). Depending on their training status and gender the participants in both SPA and USPA groups were further subdivided into the following four sub-groups: SPA athlete boys (n=22) and girls (n=17), SPA nonathlete boys (n=95) and girls (n=85), USPA athlete boys (n=23) and girls (n=17), and USPA nonathlete boys (n=96) and girls (n=84).
  
  
  RESULTS
  We recorded HRV, body fat%, and VO2 max using Rockport Walk Fitness test before and after the intervention. Maximum aerobic capacity and heart rate variability increased significantly while heart rate, systolic blood pressure, diastolic blood pressure, and body fat percentage decreased significantly after both SPA and USPA intervention. However, the improvement was more in SPA as compared to USPA.
  
  
  CONCLUSIONS
  SPA is more beneficial for improving cardiorespiratory fitness, HRV, and reducing body fat percentage in terms of magnitude than USPA in adolescent individuals irrespective of their gender and sports activities.
authors.affiliation: Department of Physiology, JIPMER, Puducherry.
authors.forename: Vivek Kumar
authors.initials: VK
authors.lastname: Sharma
authors.affiliation: Department of Physiology, Pondicherry Institute of Medical Sciences (PIMS), Kalapet, Puducherry 605014.
authors.forename: Senthil Kumar
authors.initials: SK
authors.lastname: Subramanian
authors.affiliation: Department of Physiology, AIIMS, New Delhi.
authors.forename: Krishnakumar
authors.initials: K
authors.lastname: Radhakrishnan
authors.affiliation: Department of Physiology, JIPMER, Puducherry.
authors.forename: Rajathi
authors.initials: R
authors.lastname: Rajendran
authors.affiliation: Jawahar Navodaya Vidyalaya, Puducherry.
authors.forename: Balasubramanian Sulur
authors.initials: BS
authors.lastname: Ravindran
authors.affiliation: Jawahar Navodaya Vidyalaya, Puducherry.
authors.forename: Vinayathan
authors.initials: V
authors.lastname: Arunachalam
mesh_terms: D000293:Adolescent; D001794:Blood Pressure / Q000502:physiology; D002648:Child; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology; D010100:Oxygen / Q000378:metabolism*; D010809:Physical Fitness / Q000502:physiology*; D013177:Sports / Q000502:physiology
chemical_list: D010100:Oxygen
keywords: VO2max; heart rate variability; maximal aerobic capacity; structured physical activity; unstructured physical activity