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Physical activity augments bone mineral accrual in young children: The Iowa Bone Development study
Kathleen F Janz1, Julie M Gilmore, Trudy L Burns
1Department of Health and Sport Studies, The University of Iowa, Iowa City, Iowa 52242, USA. kathleen-janz@uiowa.edu
Insights
Maintaining high physical activity levels in childhood significantly boosts bone mineral content (BMC) accrual, especially at the hip and whole body. This highlights the importance of everyday activity for pediatric bone health.
Area of Science:
- Pediatric bone health research
- Childhood physical activity and development
- Skeletal health in pediatrics
Background:
- Bone mineral content (BMC) is crucial for skeletal health.
- Understanding factors influencing BMC accrual in children is essential for long-term bone health.
- Physical activity is a known modulator of bone health.
Purpose of the Study:
- To investigate the association between physical activity and BMC in children over a 3-year period.
- To determine if physical activity enhances BMC accrual during childhood.
- To analyze sex-specific differences in the relationship between physical activity and BMC.
Main Methods:
- A longitudinal study involving 370 children (mean age at baseline 5.3 years, at follow-up 8.6 years).
- Physical activity was objectively measured using 4-day accelerometry.
- Bone mineral content (BMC) was assessed using dual-energy x-ray absorptiometry (DXA).
Main Results:
- Higher physical activity levels were associated with greater follow-up BMC at multiple sites (hip, trochanter, spine, whole body) in boys, and at the trochanter and whole body in girls, after adjusting for baseline BMC and body size.
- Physical activity explained a modest proportion (1%–2%) of the variability in BMC.
- Children with sustained high physical activity accrued significantly more trochanteric BMC (14% increase) and whole-body BMC (5% increase) compared to those with consistently low activity levels.
Conclusions:
- Sustained high levels of everyday physical activity are positively associated with bone mineral content (BMC) accrual in young children.
- The findings suggest that physical activity plays a significant role in enhancing pediatric bone development, particularly at the trochanteric region.
- Promoting regular physical activity in childhood may be a key strategy for optimizing skeletal health and preventing future bone-related issues.
Objectives:
This 3-year follow-up study examined associations between physical activity and bone mineral content (BMC) and whether physical activity augments BMC accrual.
Study Design:
Participants were 370 children (mean age baseline 5.3 years, follow-up 8.6 years). Physical activity was measured using 4-day accelerometry. BMC was measured using dual energy x-ray absorptiometry.
Results:
After adjustment for baseline BMC, age, and body size, mean physical activity predicted follow-up BMC at the hip, trochanter, spine, and whole body in boys and at the trochanter and whole body in girls. The variability in BMC explained by physical activity was modest (1% to 2%). However, based on a general linear model with adjustment for baseline BMC and body size, children who maintained high levels of physical activity accrued, on average, 14% more trochanteric BMC and 5% more whole-body BMC relative to peers maintaining low levels of physical activity.
Conclusions:
This study suggests that maintaining high levels of everyday physical activity contributes to increases in BMC in young children, particularly at the trochanter.
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