title: A 6-year exercise program improves skeletal traits without affecting fracture risk: a prospective controlled study in 2621 children.
abstract: Most pediatric exercise intervention studies that evaluate the effect on skeletal traits include volunteers and follow bone mass for less than 3 years. We present a population-based 6-year controlled exercise intervention study in children with bone structure and incident fractures as endpoints. Fractures were registered in 417 girls and 500 boys in the intervention group (3969 person-years) and 835 girls and 869 boys in the control group (8245 person-years), all aged 6 to 9 years at study start, during the 6-year study period. Children in the intervention group had 40 minutes daily school physical education (PE) and the control group 60 minutes per week. In a subcohort with 78 girls and 111 boys in the intervention group and 52 girls and 54 boys in the control group, bone mineral density (BMD; g/cm(2) ) and bone area (mm(2) ) were measured repeatedly by dual-energy X-ray absorptiometry (DXA). Peripheral quantitative computed tomography (pQCT) measured bone mass and bone structure at follow-up. There were 21.7 low and moderate energy-related fractures per 1000 person-years in the intervention group and 19.3 fractures in the control group, leading to a rate ratio (RR) of 1.12 (0.85, 1.46). Girls in the intervention group, compared with girls in the control group, had 0.009 g/cm(2) (0.003, 0.015) larger gain annually in spine BMD, 0.07 g (0.014, 0.123) larger gain in femoral neck bone mineral content (BMC), and 4.1 mm(2) (0.5, 7.8) larger gain in femoral neck area, and at follow-up 24.1 g (7.6, 40.6) higher tibial cortical BMC (g) and 23.9 mm(2) (5.27, 42.6) larger tibial cross-sectional area. Boys with daily PE had 0.006 g/cm(2) (0.002, 0.010) larger gain annually in spine BMD than control boys but at follow-up no higher pQCT values than boys in the control group. Daily PE for 6 years in at study start 6- to 9-year-olds improves bone mass and bone size in girls and bone mass in boys, without affecting the fracture risk.
authors.affiliation: Clinical and Molecular Osteoporosis Research Unit, Department of Clinical Sciences and Orthopedics, Lund University, and Skåne University Hospital, Malmö, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Detter
authors.forename: Björn E
authors.initials: BE
authors.lastname: Rosengren
authors.forename: Magnus
authors.initials: M
authors.lastname: Dencker
authors.forename: Mattias
authors.initials: M
authors.lastname: Lorentzon
authors.forename: Jan-Åke
authors.initials: JÅ
authors.lastname: Nilsson
authors.forename: Magnus K
authors.initials: MK
authors.lastname: Karlsson
mesh_terms: D015502:Absorptiometry, Photon; D061725:Accelerometry; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D016022:Case-Control Studies; D002648:Child; D015444:Exercise / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000503:physiopathology*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D009043:Motor Activity; D011446:Prospective Studies; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology
keywords: BONE MINERAL CONTENT (BMC); BONE MINERAL DENSITY (BMD); BONE SIZE; BOYS; CHILDREN; CONTROLLED; EXERCISE; FRACTURE; GIRLS; GROWTH; PHYSICAL ACTIVITY; PROSPECTIVE; pQCT