title: A school-based exercise intervention augments bone mineral accrual in early pubertal girls.
abstract: OBJECTIVE
  To evaluate the effects of an elementary school-based physical education exercise intervention program on bone mineral accrual in prepubertal and early pubertal girls.
  
  
  METHODS
  A total of 14 schools were randomly assigned to control (C) and intervention (I) groups. Girls in the I group completed a 10-minute, 3 times per week circuit of varied jumping activities over 7 months. We measured total body, lumbar spine, proximal femur, femoral neck, and trochanteric bone mineral content and areal bone mineral density and estimated femoral neck volumetric bone mineral density at baseline and final measurement in 87 girls in the I group and 90 girls in the C group. Girls were between 8.7 and 11.7 years at baseline. Tanner stage 1 girls were considered prepubertal; Tanner stages 2 and 3 girls were considered early pubertal. We used analysis of covariance (adjusting for baseline bone values, change in size, age, and maturity) to compare 7-month change in bone mineral content, areal bone mineral density, and volumetric bone mineral density between C and I groups within prepubertal and early pubertal girls.
  
  
  RESULTS
  There was no difference in 7-month change in bone parameters between prepubertal I and C groups. Early pubertal girls in the I group gained 1.5% to 3.1% more bone at the femoral neck and lumbar spine than early pubertal girls in the C group (P <.05); gain at other sites did not differ.
  
  
  CONCLUSIONS
  In girls, early puberty may be a particularly opportune time during growth for simple exercise interventions to have a positive effect on bone health.
authors.affiliation: School of Human Kinetics, University of British Columbia, Vancouver, Canada.
authors.forename: K J
authors.initials: KJ
authors.lastname: Mackelvie
authors.forename: H A
authors.initials: HA
authors.lastname: McKay
authors.forename: K M
authors.initials: KM
authors.lastname: Khan
authors.forename: P R
authors.initials: PR
authors.lastname: Crocker
mesh_terms: D015502:Absorptiometry, Photon; D000886:Anthropometry; D001823:Body Composition / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D002648:Child; D002664:Child Nutritional Physiological Phenomena / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000502:physiology; D006801:Humans; D008019:Life Style; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology; D011446:Prospective Studies; D011627:Puberty / Q000502:physiology*; D012572:School Health Services; D013997:Time Factors