| 1. |
- Detter, Fredrik, et al.
(författare)
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A 3-year school-based exercise intervention improves muscle strength - a prospective controlled population-based study in 223 children
- 2014
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Ingår i: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Background: Intense physical activity (PA) improves muscle strength in children, but it remains uncertain whether moderately intense PA in a population-based cohort of children confers these benefits. Methods: We included children aged 6-9 years in four schools where the intervention school increased the school curriculum of PA from 60 minutes/week to 40 minutes/school day while the control schools continued with 60 minutes/week for three years. We measured muscle strength, as isokinetic Peak Torque (PT) (Nm) of the knee flexors in the right leg at speeds of 60 degrees/second and 180 degrees/second, at baseline and at follow-up, in 47 girls and 76 boys in the intervention group and 46 girls and 54 boys in the control group and then calculated annual changes in muscle strength. Data are provided as means with 95% confidence intervals. Results: Girls in the intervention group had 1.0 Nm (0.13, 1.9) and boys 1.9 Nm (0.9, 2.9) greater annual gain in knee flexor PT at 60 degrees/second, than girls and boys in the control group. Boys in the intervention group also had 1.5 Nm (0.5, 2.5) greater annual gain in knee flexors PT at 180 degrees/second than boys in the control group. Conclusion: A 3-year moderately intense PA intervention program within the school curriculum enhances muscle strength in both girls and boys.
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| 2. |
- Detter, Fredrik, et al.
(författare)
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A 5-Year Exercise Program in Pre- and Peripubertal Children Improves Bone Mass and Bone Size Without Affecting Fracture Risk.
- 2013
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 1432-0827 .- 0171-967X. ; 92:4, s. 385-393
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Tidskriftsartikel (refereegranskat)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.
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| 3. |
- Detter, Fredrik, et al.
(författare)
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A Six-Year Exercise Program Improves Skeletal Traits without Affecting Fracture Risk - a Prospective Controlled Study in 2621 Children
- 2014
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Ingår i: Journal of bone and mineral research. - : Wiley. - 0884-0431 .- 1523-4681. ; 29:6, s. 1325-1336
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Tidskriftsartikel (refereegranskat)abstract
- Most pediatric exercise intervention studies, that evaluates the effect on skeletal traits include volunteers and follow bone mass for less than three years. We present a population-based six-year controlled exercise intervention study in children with also 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 6-9 years at study start, during the six-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 sub-cohort with 78 girls and 111 boys in the intervention group and 52 girls and 54 boys in the control group, bone mineral density (g/cm2 ) and bone area (mm2 ) 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 19.8 fractures in the control group, leading to a Rate Ratio (RR) of 1.12 (0.85, 1.46). Girls in the intervention group, in comparison with girls in the control group, had 0.009 g/cm2 (0.003, 0.015) larger gain annually in spine BMD, 0.07 g (0.014, 0.123) larger gain in femoral neck BMC and 4.0 mm2 (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 mm2 (5.27, 42.6) larger tibial cross-sectional area. Boys with daily PE had 0.006 g/cm2 (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 six years in at study start 6-9 year old improves bone mass and bone size in girls and bone mass in boys, without affecting the fracture risk. (c) 2014 American Society for Bone and Mineral Research.
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| 4. |
- Detter, Fredrik
(författare)
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The Influence of Physical Activity on Musculoskeletal Characteristics and Fracture Risk at Growth
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Physical Activity (PA) can improve neuromuscular development. A high level of physical activity can perhaps however lead to more fractures. This is a longitudinal population-based exercise intervention study where the school-based physical education (PE) in one school is increased from mean 60 min/week to mean 200 min/ week. We registered fractures in all children during 6 years. We annually measured musculoskeletal traits in a subsample by dual-energy X-ray absorptiometry (DXA) and muscle strength by a Biodex dynamometer. At follow-up we used peripheral computed tomography (pQCT) to assess the appendicular skeleton. The fracture risk was not affected by the intervention, rate ratio 1.12 (0.85, 1.46). Children in the intervention group annually improved their spine BMD more than controls (p<0.05). At follow-up intervention girls had improved 11% in femoral neck BMC and 8% in tibial cortical bone mass (all p<0.05). Intervention children also improved their muscle strength compared to the controls (all p<0.05). This thesis shows that a long-term PA intervention program in school improves the gain in skeletal traits and muscle strength without increasing the fracture risk.
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| 5. |
- Löfgren, Bjarne, et al.
(författare)
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Influence of a 3-Year Exercise Intervention Program on Fracture Risk, Bone Mass, and Bone Size in Prepubertal Children
- 2011
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Ingår i: Journal of Bone and Mineral Research. - : Wiley. - 1523-4681 .- 0884-0431. ; 26:8, s. 1740-1747
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Tidskriftsartikel (refereegranskat)abstract
- Published prospective pediatric exercise intervention studies are short term and use skeletal traits as surrogate endpoints for fractures, whereas other reports infer exercise to be associated with more trauma and fractures. This prospective, controlled exercise intervention study therefore followed both skeletal traits and fracture risk for 36 months. Fractures were registered in children aged 7 to 9 years; there were 446 boys and 362 girls in the intervention group (2129 person-years) and 807 boys and 780 girls in the control group (4430 person-years). The intervention included school physical education of 40 minutes per day for 3 years. The control children achieved the Swedish standard of 60 minutes per week. In a subsample of 76 boys and 48 girls in the intervention group and 55 boys and 44 girls in the control group, bone mineral content (BMC, g) and bone width (cm) were followed in the lumbar spine and hip by dual-energy X-ray absorptiometry (DXA). The rate ratio (RR) for fractures was 1.08 (0.71, 1.62) [ mean (95% confidence interval)]. In the DXA-measured children, there were no group differences at baseline in age, anthropometrics, or bone traits. The mean annual gain in the intervention group in lumbar spine BMC was 0.9 SD higher in girls and 0.8 SD higher in boys (both p<.001) and in third lumbar vertebra width 0.4 SD higher in girls and 0.3 SD higher in boys (both p<.05) than in control children. It is concluded that a moderately intense 3-year exercise program in 7- to 9-year-old children increases bone mass and possibly also bone size without increasing fracture risk. (C) 2011 American Society for Bone and Mineral Research.
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| 6. |
- Tuskan, G A, et al.
(författare)
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The genome of black cottonwood, Populus trichocarpa (Torr. & Gray).
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 313:5793, s. 1596-604
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Tidskriftsartikel (refereegranskat)abstract
- We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.
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