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A 4-year exercise program in children increases bone mass without increasing fracture risk
Bjarne Löfgren1, Magnus Dencker, Jan-Åke Nilsson
1Clinical and Molecular Osteoporosis Research Unit, Department of Clinical Sciences, Lund University, Lund, Sweden. bjarne.lofgren@med.lu.se
Insights
A 4-year school exercise program for children aged 7-9 improved bone development. This study tracked skeletal growth and fracture incidence, finding increased bone mass and size without altering fracture risk.
Area of Science:
- Pediatric exercise science
- Skeletal development research
- Bone health interventions
Background:
- Pediatric exercise studies often lack long-term fracture data.
- Bone traits are frequently used as indirect measures for fractures.
- This study prospectively evaluated skeletal development and fracture incidence over 4 years.
Purpose of the Study:
- To assess the long-term impact of a school-based exercise program on children's skeletal development.
- To investigate the relationship between exercise, bone mass, bone size, and fracture incidence in children.
- To provide long-term fracture data beyond surrogate bone traits.
Main Methods:
- Prospective registration of fractures in 7- to 9-year-old children over 4 years.
- Intervention group: 40 minutes/day of school physical education; Control group: 60 minutes/week.
- Dual-energy radiograph absorptiometry used to monitor bone mineral content and width in a subsample.
Main Results:
- The fracture rate ratio was 1.11, indicating no significant difference between groups.
- Children in the intervention group showed greater annual gains in bone mineral content (girls: 7.0%, boys: 3.3%) and femoral neck width (girls: 1.7%, boys: 0.6%).
- No baseline differences in age, anthropometrics, or bone traits were observed between groups.
Conclusions:
- A 4-year, moderately intense exercise program for children aged 7-9 significantly increased bone mass and size.
- The observed improvements in bone development did not lead to an increased risk of fractures.
- Population-based exercise interventions can positively influence skeletal health in children without compromising safety.
Background:
Most prospective pediatric exercise intervention studies cover <1 year and use bone traits as surrogate end points for fractures. This prospective controlled exercise intervention study therefore followed not only skeletal development but also fracture incidence for 4 years.
Methods:
Fractures were prospectively registered in a cohort of children aged 7 to 9 years, 446 boys and 362 girls in the intervention group (2675 person-years) and 807 boys and 780 girls in the control group (5661 person-years). The intervention included 40 minutes per day of school physical education for 4 years whereas the controls had 60 minutes per week. In a subsample, 73 boys and 48 girls in the intervention and 52 boys and 48 girls in the control group, bone mineral content (g) and bone width (cm) were followed by means of dual-energy radiograph absorptiometry.
Results:
The rate ratio for fractures was 1.11. In the dual-energy radiograph absorptiometry-measured children, there were no group differences at baseline in age, anthropometrics, or bone traits. The mean annual gain in lumbar spine bone mineral content was 7.0% higher in girls and 3.3% higher in boys and in femoral neck width 1.7% higher in girls and 0.6% higher in boys in the intervention than in the control group.
Conclusions:
A population-based moderately intense 4-year exercise program in 7- to 9-year-old children increased bone mass and size without affecting the fracture risk.
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