A 3-year physical activity intervention program increases the gain in bone mineral and bone width in prepubertal girls but not boys: the prospective copenhagen school child interventions study (CoSCIS).
The aim of this study was to evaluate the effect of increasing the amount of time spent in physical education classes on bone mineral accrual and gain in bone size in prepubertal Danish children. A total of 135 boys and 108 girls, aged 6-8 years, were included in a school-based curriculum intervention program where the usual time spent in physical education classes was doubled to four classes (180 min) per week. The control group comprised age-matched children (62 boys and 76 girls) recruited from a separate community who completed the usual Danish school curriculum of physical activity (90 min/week). Dual-energy X-ray absorptiometry was used to evaluate bone mineral content (BMC; g), bone mineral density (g/cm(2)), and bone width at the calcaneus and distal forearm before and after 3 years of intervention. Anthropometrics and Tanner stages were evaluated on the same occasions. General physical activity was measured with an accelerometer worn for 4 days. In girls, the intervention group had a 12.5% increase (P = 0.04) in distal forearm BMC and a 13.2% increase (P = 0.005) in distal forearm scanned area compared with girls in the control group. No differences were found between the intervention and control groups in boys. Increasing the frequency of physical education classes for prepubertal children is associated with a higher accrual of bone mineral and higher gain in bone size after 3 years in girls but not in boys.
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.
Comment In: J Bone Miner Res. 2014 Jun;29(6):1322-424764102
The river Iset belongs to the Techa-Iset-Tobol-Irtysh-Ob system contaminated by liquid radioactive wastes from Mayak plutonium facility in 1949-1956. This study represents the first retrospective analysis of postmortem measurements of 90Sr in bones from residents of the Iset riverside settlements in 1960-1982. It was shown that 90Sr concentration in bones of residents lived in settlements located downstream from the Techa river mouth (Shadrinsk, Isetskoye, Yalutorovsk) was 5 times higher than average 90Sr concentration in bones of the Russian residents. There was not statistically significant difference in accumulated 90Sr in bones between residents of the considered Iset' settlements indicating similar levels of 90Sr ingestion. Dietary 90Sr intake was reconstructed from the measurements of the radionuclide in bones. Total 90Sr dietary intake in 1950-1975 was 68 kBq; and 90% of the intake occurred in 1950-1961. In 1960s, 90Sr-contamination of the diet in settlements located downstream from the Techa river mouth was mostly (by 70%) due to global fallouts. Absorbed dose in the red bone marrow cumulated over 25 years of exposure was equal to 14 (4.7-42) mGy.