title: A 5-year exercise program in pre- and peripubertal children improves bone mass and bone size without affecting fracture risk.
abstract: We studied the effect in children of an exercise intervention program on fracture rates and skeletal traits. Fractures were registered for 5 years in a population-based prospective controlled exercise intervention study that included children aged 6-9 years at study start, 446 boys and 362 girls in the intervention group and 807 boys and 780 girls in the control group. Intervention subjects received 40 min/school day of physical education and controls, 60 min/week. In 73 boys and 48 girls in the intervention group and 52 boys and 48 girls in the control group, bone mineral density (BMD, g/cm(2)) and bone area (mm(2)) were followed annually by dual-energy X-ray absorptiometry, after which annual changes were calculated. At follow-up we also assessed trabecular and cortical volumetric BMD (g/cm(3)) and bone structure by peripheral computed tomography in the tibia and radius. There were 20.0 fractures/1,000 person-years in the intervention group and 18.5 fractures/1,000 person-years in the control group, resulting in a rate ratio of 1.08 (0.79-1.47) (mean and 95 % CI). The gain in spine BMD was higher in both girls (difference 0.01 g/cm(2), 0.005-0.019) and boys (difference 0.01 g/cm(2), 0.001-0.008) in the intervention group. Intervention girls also had higher gain in femoral neck area (difference 0.04 mm(2), 0.005-0.083) and at follow-up larger tibial bone mineral content (difference 0.18 g, 0.015-0.35), larger tibial cortical area (difference 17 mm(2), 2.4-31.3), and larger radial cross-sectional area (difference 11.0 mm(2), 0.63-21.40). As increased exercise improves bone mass and in girls bone size without affecting fracture risk, society ought to encourage exercise during growth.
authors: Clinical and Molecular Osteoporosis Research Unit, Department of Clinical Sciences and Orthopedics, Skåne University Hospital, Lund University, SE-205 02, Malmö, Sweden. fredrik.detter@med.lu.se
authors: Fredrik T L
authors: FT
authors: Detter
authors: Björn E
authors: BE
authors: Rosengren
authors: Magnus
authors: M
authors: Dencker
authors: J-Å
authors: JÅ
authors: Nilsson
authors: Magnus K
authors: MK
authors: Karlsson
mesh_terms: D015502:Absorptiometry, Photon; D015519:Bone Density / Q000502:physiology; D001846:Bone Development / Q000502:physiology*; D001842:Bone and Bones / Q000033:anatomy & histology*; D002648:Child; D015444:Exercise / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D050723:Fractures, Bone / Q000453:epidemiology*; D006801:Humans; D008297:Male; D009929:Organ Size; D010806:Physical Education and Training / Q000379:methods*; D011446:Prospective Studies; D011627:Puberty / Q000502:physiology*; D011884:Radius / Q000000981:diagnostic imaging; D012307:Risk Factors; D013977:Tibia / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed