Growth is the opportune time to modify bone accrual. While bone adaptation is known to be dependent on local loading and consequent deformations (strain) of bone, little is known about the effects of sex, and bone-specific physical activity on location-specific cross-sectional bone geometry during growth. To provide more insight we examined bone traits at different locations around tibial cross sections, and along the tibia between individuals who vary in terms of physical activity exposure, sex, and pubertal status. Data from 304 individuals aged 5-29 years (172 males, 132 females) were examined. Peripheral quantitative computed tomography (pQCT) was applied at 4%, 14%, 38%, and 66% of tibial length. Maturity was established by estimating age at peak height velocity (APHV). Loading history was quantified with the bone-specific physical activity questionnaire (BPAQ). Comparisons, adjusted for height, weight and age were made between sex, maturity, and BPAQ tertile groups. Few to no differences were observed between sexes or BPAQ tertiles prior to APHV, whereas marked sexual dimorphism and differences between BPAQ tertiles were observed after APHV. Cross-sectional location-specific differences between BPAQ tertiles were not evident prior to APHV, whereas clear location-specificity was observed after APHV. In conclusion, the skeletal benefits of physical activity are location-specific in the tibia. The present results indicate that the peri- or post-pubertal period is likely a more favourable window of opportunity for enhancing cross-sectional bone geometry than pre-puberty. Increased loading during the peri-pubertal period may enhance the bone of both sexes.

This study aimed to determine the effects of school-based, bone-focused exercise interventions on bone, fat, and lean mass in children by systematically reviewing and meta-analyzing the literature. Potentially relevant articles were identified by searching electronic databases. Abstracts were included if they described the effects of an in-school exercise intervention for children 5-17 yr old compared with controls and presented baseline and follow-up results for bone, fat, and lean measures. Identified studies were systematically reviewed for methodological quality. Meta-analyses were performed for whole body, lumbar spine, and femoral neck bone mineral content (BMC), fat, and lean mass. Sixteen eligible trials were identified including eight randomized controlled trials, three clinical controlled trials, and five nonrandomized, nonmatched studies. The quality analysis revealed two studies had low, nine had medium, and five had a high risk of bias. Meta-analyses revealed a small positive effect of bone-targeted exercise on whole body BMC (standardized mean difference [SMD] = 0.483, 95% CI = 0.132-0.833), femoral neck BMC (SMD = 0.292, 95% CI = -0.022 to 0.607), lumbar spine BMC (SMD = 0.384, 95% CI = 0.193-0.575), fat mass (SMD = -0.248, 95% CI = -0.406 to -0.089), and lean mass (SMD = 0.159, 95% CI = -0.076 to 0.394). Beneficial effects of school-based, bone-targeted exercise were observed for bone and fat, but not for lean mass. Excluding trials with high risk of bias strengthened that effect. Considerable study heterogeneity may have obscured effects on lean mass. The effects observed for bone and fat support the pursuit of brief, jumping-focused interventions to reduce fat as well as enhance musculoskeletal tissue in school age children.

Our goal was to test the effect of a brief, novel bone- and fat-targeted exercise program on bone, muscle, and fat in healthy pre and peripubertal boys. We conducted a 10-min, 3/wk capoeira and jumping exercise intervention for 9 months with year 5 and 6 school boys. Anthropometrics, maturity, heart rate, blood pressure, maximal vertical jump, aerobic capacity and calcaneal broadband ultrasound attenuation and stiffness index (BUA and SI; Achilles, GE) were assessed. Bone, lean and fat tissue (DXA; XR800, Norland), and parameters of bone geometry (pQCT, XCT3000, Stratec) were measured from a subsample of 36 boys. Of 188 boys (10.6 ± 0.5 yr) who consented, 172 completed all testing; 104 exercisers (EX) and 68 controls (CON). 30 EX and 6 CON participants underwent DXA and pQCT measures. EX improved BUA (+4.3% vs. +2.1%, p = .035), waist circumference (+2.8% vs. +6.2%, p = .001), heart rate (-5.3% vs. +1.5%, p = .005), maximal vertical jump (+12.2% vs. −0.3%, p = .001) and estimated maximal oxygen consumption (+9.1% vs. +1.2%, p = .001) compared with CON. Three 10-min sessions of capoeira and jumping per week improved calcaneal bone and metabolic health of pre and peripubertal boys over the course of a school year with little disruption to the academic schedule.

Objectives: The aim of the current study was to assess whether calcaneal broadband ultrasound attenuation (BUA) can predict whole body and regional dual-energy x-ray absorptiometry (DXA)-derived bone mass in healthy, Australian children and adolescents at different stages of maturity. Methods: A total of 389 boys and girls across a wide age range (four to 18 years) volunteered to participate. The estimated age of peak height velocity (APHV) was used to classify children into pre-, peri-, and post-APHV groups. BUA was measured at the non-dominant heel with quantitative ultrasonometry (QUS) (Lunar Achilles Insight, GE), while bone mineral density (BMD) and bone mineral content (BMC) were examined at the femoral neck, lumbar spine and whole body (DXA, XR-800, Norland). Associations between BUA and DXA-derived measures were examined with Pearson correlations and linear regression. Participants were additionally ranked in quartiles for QUS and DXA measures in order to determine agreement in rankings. Results: For the whole sample, BUA predicted 29% of the study population variance in whole body BMC and BMD, 23% to 24% of the study population variance in lumbar spine BMC and BMD, and 21% to 24% of the variance in femoral neck BMC and BMD (p < 0.001). BUA predictions were strongest for the most mature participants (pre-APHV R² = 0.03 to 0.19; peri-APHV R² = 0.05 to 0.17; post-APHV R² = 0.18 to 0.28) and marginally stronger for girls (R² = 0.25-0.32, p < 0.001) than for boys (R² = 0.21-0.27, p < 0.001). Agreement in quartile rankings between QUS and DXA measures of bone mass was generally poor (27.3% to 38.2%). Conclusion: Calcaneal BUA has a weak to moderate relationship with DXA measurements of bone mass in children, and has a tendency to misclassify children on the basis of quartile rankings. Cite this article: B. K. Weeks, R. Hirsch, R. C. Nogueira, B. R. Beck. Is calcaneal broadband ultrasound attenuation a valid index of dual-energy x-ray absorptiometry-derived bone mass in children? Bone Joint Res 2016;5:538–543. DOI: 10.1302/2046-3758.511.BJR-2016-0116.R1.

Purpose: To determine the 12-month maintenance of a 9-month, thrice-weekly, 10-minute high-intensity exercise program, delivered in schools, on bone and other health-related performance variables in prepubertal children. Methods: All participants (N = 311) of the CAPO kids trial (testing times T1–T2) were contacted to undergo retesting (T3) of all original measures—including weight, standing and sitting height, calcaneal broadband ultrasound attenuation (Achilles, GE), and stiffness index (Achilles, GE)—waist circumference, resting heart rate, blood pressure, vertical jump, and aerobic capacity. Maturity was determined by estimating age of peak height velocity using sex-specific regression equations. Results: A total of 240 children [12.3 (0.6) y old] were included in the current study (77% of initial follow-up sample at T2). Between the T2 and T3 time points, both exercise (EX) group and control (CON) group increased broadband ultrasound attenuation (EX: 5.6%, P ≤ .001; CON: 6.5%, P ≤ .001), stiffness index (EX: 7.3%, P ≤ .001; CON: 5.2%, P ≤ .001), vertical jump (EX: 5.9%, P ≤ .001; CON: 6.3%, P ≤ .001), estimated maximal oxygen consumption (EX: 13.3%, P ≤ .001; CON: 12.1%, P ≤ .001), and reduced waist circumference (EX: −5.2%, P ≤ .001; CON: −5.6%, P ≤ .001), with no between-group differences in the magnitude of those changes. No differences were detected in absolute values between groups at T3. Conclusion: Although the statistically significant differences observed between groups following the intervention were no longer significant 1 year after withdrawal of the intervention, the between-group similarities in growth trajectories of those parameters could suggest that some benefit of the intervention for bone health, waist circumference, and physical performance endured.