Article

Impact Exercise Increases BMC During Growth: An 8-Year Longitudinal Study

Bone Research Laboratory, Department of Nutrition and Exercise Sciences, Oregon State University, Corvallis, Oregon 97331, USA.
Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research (Impact Factor: 6.59). 08/2008; 23(7):986-93. DOI: 10.1359/jbmr.071201
Source: PubMed

ABSTRACT Our aim was to assess BMC of the hip over 8 yr in prepubertal children who participated in a 7-mo jumping intervention compared with controls who participated in a stretching program of equal duration. We hypothesized that jumpers would gain more BMC than control subjects. The data reported come from two cohorts of children who participated in separate, but identical, randomized, controlled, school-based impact exercise interventions and reflect those subjects who agreed to long-term follow-up (N = 57; jumpers = 33, controls = 24; 47% of the original participants). BMC was assessed by DXA at baseline, 7 and 19 mo after intervention, and annually thereafter for 5 yr (eight visits over 8 yr). Multilevel random effects models were constructed and used to predict change in BMC from baseline at each measurement occasion. After 7 mo, those children that completed high-impact jumping exercises had 3.6% more BMC at the hip than control subjects whom completed nonimpact stretching activities (p < 0.05) and 1.4% more BMC at the hip after nearly 8 yr (BMC adjusted for change in age, height, weight, and physical activity; p < 0.05). This provides the first evidence of a sustained effect on total hip BMC from short-term high-impact exercise undertaken in early childhood. If the benefits are sustained into young adulthood, effectively increasing peak bone mass, fracture risk in the later years could be reduced.

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    • "The most significant increases in DXA-measured bone mass were found at the femoral neck in early pubertal children. There are also some prospective studies with longer follow-up time (duration from 6 to 15 years) suggesting long-term skeletal benefits of childhood physical activity [8] [9] [10]. "
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    ABSTRACT: High peak bone mass and strong bone phenotype is known to be partly explained by physical activity during growth but there are few prospective studies on this topic. In this 28-year follow-up of Cardiovascular Risk in Young Finns Study cohort, we assessed whether habitual childhood and adolescence physical activity or inactivity at the age of 3-18 years were associated with adult phenotype of weight-bearing tibia and the risk of low-energy fractures. Baseline physical activity and data on clinical, nutritional and lifestyle factors were assessed separately for females and males aged 3-6-years (N=395-421) and 9-18-years (N=923-965). At the age of 31-46-years, the prevalence of low-energy fractures were assessed with a questionnaire and several tibial traits were measured with pQCT (bone mineral content (BMC; mg), total and cortical cross-sectional areas (mm(2)), trabecular (for the distal site only) and cortical (for the shaft only) bone densities (mg/cm(3)), stress-strain index (SSI; mm(3), for the shaft only), bone strength index (BSI; mg(2)/cm(4), for the distal site only) and the cortical strength index (CSI, for the shaft only)). For the statistical analysis, each bone trait was categorized as below the cohort median or the median and above and the adjusted odds ratios (OR) were determined. In females, frequent physical activity at the age of 9-18-years was associated with higher adulthood values of BSI, total and cortical areas, BMC, CSI and SSI at the tibia independently of many health and lifestyle factors (ORs 0.33-0.53, p≤0.05; P-values for trend 0.002-0.05). Cortical density at the tibial shaft showed the opposite trend (P-value for trend 0.03). Similarly in males, frequent physical activity was associated with higher values of adult total and cortical areas and CSI at the tibia (ORs 0.48-0.53, p≤0.05; P-values for trend 0.01-0.02). However, there was no evidence that childhood or adolescence physical activity was associated with lower risk of low energy fractures during the follow-up. In conclusion, frequent habitual physical activity in adolescence seems to confer benefits on tibial bone size and geometry in adulthood. Copyright © 2015. Published by Elsevier Inc.
    Bone 02/2015; 75. DOI:10.1016/j.bone.2015.02.012 · 4.46 Impact Factor
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    • "Consistent with this theory, prospective in vivo animal loading models have shown that mechanical loads eliciting strain above a specific threshold initiate bone formation that improves bone strength (e.g., Turner et al., 1991; Gross et al., 1997). In growing children, exercise that loads the skeleton leads to long-term increases in bone mineral content (BMC: Gunter et al., 2008). Mechanical loading causes measures of bone strength and stiffness to increase more than measures of bone mass or density (Miller et al., 2007). "
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    • "In children, the gain in height precedes the gain in muscle mass, that precedes the gain in bone mass, suggesting a physiological adaptation of bone to muscle in the growing skeleton (Rauch et al., 2004). If bodily growth and consequently bone mass accrual are to a great extent determined by genetic factors (Parfitt et al., 2004), active children have a greater total body BMD than their inactive peers (Bailey et al., 1999) and an increased hip peak bone mass (Gunter et al., 2008), suggesting a sustained osteotrophic effect of physical activity during growth. Our results are in line with this hypothesis, since physical activity performed during the age of 11–20 years is significantly associated with FN BMD in healthy grown-ups and older men, explaining about 5% of the variance of their FN BMD. "
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