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Although suboptimal bone health has been reported in children and adolescents with low motor competence (LMC), it is not known whether such deficits are present at the time of peak bone mass. We examined the impact of LMC on bone mineral density (BMD) in 1043 participants (484 females) from the Raine Cohort Study. Participants had motor competence assessed using the McCarron Assessment of Neuromuscular Development at 10, 14, and 17 years, and a whole body dual-energy X-ray absorptiometry scan at 20 years. Bone loading from physical activity was estimated from the International Physical Activity Questionnaire at the age of 17. The association between LMC and BMD was determined using general linear models that controlled for sex, age, body mass index, vitamin D status, and prior bone loading. Results indicated LMC status (present in 29.6% males and 21.9% females) was associated with a 1.8 to 2.6% decrease in BMD at all load-bearing bone sites. Assessment by sex showed that the association was mainly in males. Osteogenic potential of physical activity was associated with increased BMD dependent on sex and LMC status, with males with DCD showing a reduced effect from increasing bone loading. As such, although engagement in osteogenic physical activity is associated with BMD, other factors involved in physical activity e.g. diversity, movement quality, may also contribute to BMD differences based upon LMC status. The finding of lower peak bone mass for individuals with LMC may reflect a higher risk of osteoporosis, especially for males, however, further research is required. peerReviewed

Objectives: We investigated the associations of accelerometry-derived osteogenic indices (OIs), moderate-to-vigorous (MVPA), and vigorous intensity physical activity (VPA) with peripheral quantitative computed tomography (pCQT) parameters in 99 adolescents aged 10–13 years. Methods: Bone parameters were assessed at the distal (4%) and shaft (66%) of the tibia using pQCT. Accelerometers were worn on the right hip for 7 consecutive days. OIs were calculated based on acceleration peak histograms either using all of the peaks (OI) or peaks with acceleration ≥5.2 g (HOI). MVPA and VPA were defined using previously published cut-points. Results: HOI was positively associated with total area (Partial correlation= 0.22, 95% CI=0.01 to 0.41), cortical area (CoA) (0.33, 95% CI=0.13 to 0.50), and stress strain index (SSI) (0.29, 95% CI=0.09 to 0.47) of tibial shaft and with total density at the distal tibia (0.23, 95% CI=0.02 to 0.42). OI was positively associated with CoA (0.31, 95% CI=0.11 to 0.49) and SSI (0.26, 95% CI=0.05 to 0.44) of tibial shaft. MVPA was positively associated with CoA (0.28, 95% CI=0.07 to 0.46) of the tibial shaft. Conclusions: OI and HOI were positively associated with pQCT parameters while MVPA and VPA demonstrated less consistent associations with them. peerReviewed

Purpose: Moderate-to-vigorous physical activity (MVPA) positively influences bone mineral content (BMC) in prepubertal children, but it is unknown whether this relationship is partially mediated by free leptin index. The aim of this study was to examine whether the relationship between MVPA and total body less head (TBLH) BMC is mediated or moderated by free leptin index in prepubertal children. Methods: We performed a cross-sectional analysis on 401 children (194 girls) from baseline examinations of the Physical Activity and Nutrition in Childhood Study. We applied the four-way decomposition mediation analysis method to assess whether free leptin index, measured from fasted blood samples, mediated the relationship between accelerometer-measured MVPA and TBLH BMC measured by dual-energy X-ray absorptiometry. Results: MVPA had a positive controlled direct effect on TBLH BMC in girls and boys (β = 0.010 to 0.011, p &lt, 0.05). There was no mediation or interaction between MVPA, free leptin index and TBLH BMC in girls or boys (β = −0.000 to 0.001, p &gt, 0.05). Conclusion: Our study indicates that MVPA positively influences TBLH BMC through pathways not related to free leptin index in predominantly normal-weight prepubertal children, likely primarily through mechanical loading. The relationships between MVPA, free leptin index and TBLH BMC may be influenced by other factors such as pubertal status and adiposity, so it is unknown whether these observations extend to overweight and obese children at different stages of puberty.

Summary A 12-month exercise program reversibly prevented hip bone loss in premenopausal women with early breast cancer. The bone-protective effect was maintained for 2 years after the end of the program but was lost thereafter. Purpose Breast cancer survivors are at an increased risk for osteoporosis and fracture. This 5-year follow-up of a randomized impact exercise intervention trial evaluated the maintenance of training effects on bone among breast cancer patients. Methods Five hundred seventy-three early breast cancer patients aged 35–68 years and treated with adjuvant therapy were allocated into a 12-month exercise program or a control group. Four hundred forty-four patients (77%) were included in the 5-year analysis. The exercise intervention comprised weekly supervised step aerobics, circuit exercises, and home training. Areal bone mineral density (aBMD) was measured by dual-energy X-ray absorptiometry. Physical activity was estimated in metabolic equivalent (MET) hours per week and physical performance assessed by 2-km walking and figure-8 running tests. Results In premenopausal patients, the 12-month exercise program maintained femoral neck (FN) and total hip (TH) aBMD for 3 years, but the protective effect was lost thereafter. The mean FN aBMD change in the exercise and control groups was − 0.2% and − 1.5% 1 year, − 1.1% and − 2.1% 3 years and − 3.3% versus − 2.4% 5 years after the beginning of the intervention, respectively. Lumbar spine (LS) bone loss was not prevented in premenopausal women and no training effects on aBMD were seen in postmenopausal women. The main confounding element of the study was the unexpected rise in physical activity among patients in the control group. The physical performance improved among premenopausal women in the exercise group compared with the controls. Conclusion The 12-month exercise program prevented FN and TH bone loss in premenopausal breast cancer patients for 3 years. The bone-protective effect was reversible and lost thereafter. Electronic supplementary material The online version of this article (10.1007/s00198-020-05611-w) contains supplementary material, which is available to authorized users.

This study aimed to investigate the associations of competitive sport participation in adolescence and age at menarche (AAM) with body composition, femoral neck bone mineral density (BMD), physical performance, and physical activity (PA) in middle-aged women. 1098 women aged 47&ndash, 55 years formed the sample of this retrospective study. Participants self-reported their PA level at age 13&ndash, 16 years and AAM. The protocol also included dual-energy X-ray absorptiometry, physical performance tests, and accelerometer-measured PA. Participants were divided into three groups according to their PA level at the age of 13&ndash, 16 (no exercise, regular PA, and competitive sport) and according to their AAM (&le, 12, 13, and &ge, 14 years). After adjusting for potential confounding factors, participation in competitive sport at age 13&ndash, 16 was associated with higher midlife lean mass and BMD, and better physical performance compared to groups with no exercise or regular PA. Individuals with AAM &ge, 14 years had lower midlife BMI and fat mass than participants in the other AAM groups and pre- and perimenopausal women with AAM &ge, 14 years had lower BMD than those with AAM &le, 12. The findings indicate that participation in competitive sport in adolescence is associated with healthier body composition, higher BMD, and better physical performance in midlife, but BMD might be impaired if menarche occurs late.

Objectives: Developmental coordination disorder (DCD) compromises bone health purportedly due to lower levels of physical activity. The potential of an exercise intervention to improve bone health parameters in adolescents with DCD has not previously been studied. This study thus aimed to determine the impact of a multimodal exercise intervention on bone health in this population at-risk of secondary osteoporosis. Methods: Twenty-eight adolescents (17 male, 11 female) aged between 12-17 years (Mage=14.1) with DCD participated in a twice weekly, 13-week generalised multimodal exercise intervention. Peripheral quantitative computed tomography scans of the tibia (4% and 66%) were performed over a six month period. Generalised estimating equations were used to examine the impact of fitness measures on bone parameters over time. Results: An overall improvement trend was observed for bone health, with significant increases at the 66% tibial site for bone mass (4.12% increase, dcohen=0.23, p=0.010) and cortical area (5.42% increase, η2 =12.09, p=0.014). Lower body fitness measures were significantly associated with improvements in bone health parameters, tempered by the degree of motor impairment. Conclusion: A multimodal exercise intervention may be effective in improving bone health of adolescents with DCD. Given the impact of motor impairments, gains may be greater over an extended period of study. peerReviewed

Background Dynamic high-intensity physical activity is thought to be beneficial for older adults’ bone health. Traditional volume-based processing of accelerometer-measured physical activity data, quantified on a minute-per-minute basis, may average out sporadic high impact activity, whereas accelerometer data processing approaches based on identifying impacts can capture also these potentially beneficial short activity bursts. We investigated the associations between habitual physical activity and proximal femur bone traits among sedentary older adults utilizing three different numerical treatments of accelerometer-data to examine, if impact-based processing approaches are more suitable to assess bone loading than volume-based processing of physical activity data among older adults. Methods This cross-sectional study utilized the baseline data from the PASSWORD-study (n=284, mean ± SD age 74 ± 4 years, 57 % women). Total femur bone mineral content (BMC) and bone mineral density (BMD), femoral neck BMC, BMD, section modulus and minimal width (MNW) were measured with dual energy x-ray absorptiometry. Physical activity was measured for seven consecutive days with a tri-axial accelerometer. Raw acceleration data was processed in three different ways and quantified as i) mean daily minutes in sedentary, light and moderate-to-vigorous-intensity activity, ii) mean daily number of acceleration peaks divided into low (1.5 g to 2.0 g), medium (2.0 g to 2.5 g) and high (> 2.5 g) impacts, and iii) mean daily osteogenic index, which is a summary score calculated from log-transformed number of impact peaks in 32 intensity bands (≥ 1.3 g). Associations between physical activity measures and each bone trait were estimated with multiple linear regression adjusted with covariates (age, sex, weight, height, smoking, physical function, medication). Results Participants recorded on average 10 h sedentary, 2.5 hrs light and 32 min moderate-to-vigorous activity, and 3937 low, 494 medium and 157 high impacts per day. Mean osteogenic index score was 173. Light physical activity was positively associated with all bone traits (beta = 0.147 to 0.182, p