title: Extracurricular sports activity around growth spurt and improved tibial cortical bone properties in late adolescence.
abstract: OBJECTIVE
  To elucidate whether extracurricular sports activity during rapid growth correlates with improved bone properties in late adolescence, a longitudinal observation was performed among 96 high-school enrollments (46 boys and 50 girls, born in 1981-1982) in metropolitan Tokyo.
  
  
  METHODS
  In each year of high school, tibial cortical speed of sound (TCSOS) was measured by quantitative ultrasonometry, and participation in extracurricular sports activity (ECSA) since primary school was examined by structured questionnaire. We calculated the number of years since peak height velocity (ysPHV) based on annual records of height from 6 to 18 y of age to indicate progression of puberty.
  
  
  RESULTS
  The increase in TCSOS during high school in boys (32.5 m/s) was significantly greater than that in girls (5.4 m/s). The magnitude of positive association between ysPHV and TCSOS attenuated gradually over time. ECSA in grades 7-9 in boys and in grades 4-6 in girls were significant predictors of TCSOS throughout high school, independent of potential confounders.
  
  
  CONCLUSIONS
  The bone benefits of ECSA around the growth spurt are maintainable in subsequent years. The importance of physical activities that are integrated into the ordinary lifestyle of children and adolescents during this crucial period is emphasized.
authors.affiliation: Health Promotion, Graduate School of Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Hui-Jing
authors.initials: HJ
authors.lastname: Shi
authors.forename: Keiko
authors.initials: K
authors.lastname: Nakamura
authors.forename: Masashi
authors.initials: M
authors.lastname: Kizuki
authors.forename: Tomoko
authors.initials: T
authors.lastname: Inose
authors.forename: Kaoruko
authors.initials: K
authors.lastname: Seino
authors.forename: Takehito
authors.initials: T
authors.lastname: Takano
mesh_terms: D000293:Adolescent; D005260:Female; D006801:Humans; D007564:Japan; D016014:Linear Models; D008297:Male; D011627:Puberty / Q000502:physiology; D013177:Sports; D013977:Tibia / Q000254:growth & development* / Q000502:physiology