title: Influence of maturation on anthropometry and body composition in Japanese junior high school students.
abstract: BACKGROUND
  The purpose of this study was to examine maturity-related differences in anthropometry and body composition in Japanese youth within a single year.
  
  
  METHODS
  Two hundred and ten Japanese youth aged from 13 to 13.99 years participated in this study. Their maturity status was assessed using a self-assessment of stage of pubic hair development. Bioelectrical impedance analysis was used to estimate percent body fat and lean body mass (LBM). Muscle thickness of the anterior thigh, posterior lower leg and rectus abdominis muscles were measured by ultrasound.
  
  
  RESULTS
  For boys, height, body weight, and LBM in less mature groups were lower than that in more mature groups. The maturity-related differences were still significant after adjusting for chronological age. On the other hand, muscle thickness values in the lower extremity and abdomen differed among the groups at different stages of pubic hair development, whereas there was no maturity-related difference in the relative values corrected by LBM, except for those thickness values measured at the abdomen. For girls, only the muscle thickness at the anterior thigh and muscle thickness relative to LBM1/3 at the posterior lower leg was significantly affected by maturity status, but significant maturity-related difference was not found after adjusting for chronological age.
  
  
  CONCLUSIONS
  At least for Japanese boys and girls aged 13 years, maturity status affected body size in boys, but not in girls, and the influence of maturation on the muscularity of the lower extremity and trunk muscles is less in both sexes.
authors.affiliation: National Institute of Fitness and Sport in Kanoya, 1 Shiromizu-cho, Kanoya, Kagoshima 8912393, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Fukunaga
authors.forename: Yohei
authors.initials: Y
authors.lastname: Takai
authors.forename: Takaya
authors.initials: T
authors.lastname: Yoshimoto
authors.forename: Eiji
authors.initials: E
authors.lastname: Fujita
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kanehisa
mesh_terms: D000293:Adolescent; D041923:Adolescent Development / Q000502:physiology*; D000704:Analysis of Variance; D000886:Anthropometry; D001823:Body Composition / Q000502:physiology*; D002648:Child; D015331:Cohort Studies; D005260:Female; D006197:Hair; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D012647:Self-Assessment; D012727:Sex Characteristics; D012741:Sexual Maturation / Q000502:physiology*