Increasing weight-bearing physical activity and calcium intake for bone mass growth in children and adolescents: a review of intervention trials

Sex differences in physical activity dose-response effects on site-specific bone mineral density during childhood and adolescence

Physical activity (PA) serves as a modifiable determinant of bone mineral density (BMD). However, sex- and site-specific dose-response relationships remain poorly defined. Leveraging data from the National Health and Nutrition Examination Survey (NHANES 2011-2014), this cross-sectional study investigated sex-specific associations between accelerometer-derived PA (volume and intensity) and site-specific BMD in 2,659 children and adolescents aged 8-19 years. BMD assessment was conducted via dual-energy X-ray absorptiometry, and PA was quantified using monitor-independent movement summary units (MIMS). Linear and nonlinear analyses revealed distinct patterns: boys exhibited stronger linear associations between PA volume and BMD at weight-bearing sites (e.g., pelvis, arms, and legs; β = 0.003-0.004, P < 0.05), and girls demonstrated nonlinear thresholds (e.g., volume threshold: 15.0 × 103 MIMS/day). Both sexes had intensity-driven thresholds (~ 45-49 MIMS/min), with diminishing returns above these values (β = 0.010 in boys; stagnation in girls). Directional trends suggest the greater BMD gains per standard deviation (SD) increase in PA for boys compared with that for girls across most skeletal regions (e.g., total body less head: 0.131 SD vs. 0.106 SD for intensity). However, statistical significance (P < 0.05) was observed only for arm BMD responses. Mechanistic analyses highlighted the corresponding biomechanical principles, with weight-bearing regions showing stronger PA-BMD links than nonweight-bearing sites (e.g., spine). These findings underscore the importance of prioritizing high-intensity, weight-bearing activities, particularly for girls, to optimize skeletal health during growth. Public health strategies should focus on achieving, rather than exceeding, the identified daily 60 min intensity thresholds (~ 45-49 MIMS/min) through school- and community-based interventions.

Effect of Calcium and Vitamin D Supplementation (Dairy vs. Pharmacological) on Bone Health of Underprivileged Indian Children and Youth with Type-1 Diabetes: A Randomized Controlled Trial

BACKGROUND

Bone health is affected by chronic childhood disorders including type-1 diabetes mellitus (T1DM). We conducted this randomized controlled trial with the objective of investigating the effect of 1-year supplementation of vitamin-D with milk or with pharmacological calcium on bone mass accrual in underprivileged Indian children and youth with T1DM.

METHODS

5 to 23year old (n = 203) underprivileged children and youth with T1DM were allocated to one of three groups: Milk (group A-received 200 ml milk + 1000 international unit (IU) vitamin-D3/day), Calcium supplement (group B-received 500 mg of calcium carbonate + 1000 IU of vitamin-D3/day) or standard of care/control (group C). Anthropometry, clinical details, biochemistry, diet (3-day 24-h recall), physical activity (questionnaires adapted for Indian children) and bone health parameters (using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography- DXA and pQCT respectively) were evaluated at enrolment and end of 12 month intervention.

RESULTS

Total body less head(TBLH) bone mineral content (BMC(g)) and bone mineral density (BMD(gm/cm2)) were significantly higher at end of study in girls in both supplemented groups (TBLHBMC-A-1011.8 ± 307.8, B-983.2 ± 352.9, C-792.8 ± 346.8. TBLHBMD-A-± 0.2, B-0.8 ± 0.2, C-0.6 ± 0.2, p < 0.05). Z score of lumbar spine bone mineral apparent density of supplemented participants of both sexes was significantly higher than controls (Boys- A-0.7 ± 1.1, B-0.6 ± 1.4, C- -0.7 ± 1.1; Girls- A-1.1 ± 1.1, B-0.9 ± 3.4, C- -1.7 ± 1.3, p < 0.05). A significantly higher percentage increase was found in cortical thickness in girls in both supplemented groups (A-17.9 ± 28.6, B-15.3 ± 16.5, C-7.6 ± 26.2); the differences remained after adjusting for confounders.

CONCLUSION

Supplementation with milk or pharmacological calcium (+vitaminD3) improved bone outcomes-particularly geometry in children with T1DM with more pronounced effect in girls. Pharmacological calcium may be more cost effective in optimising bone health in T1DM in resource limited settings.

Osteoporosis in Childhood Cancer Survivors: Physiopathology, Prevention, Therapy and Future Perspectives

The improvement of chemotherapy, radiotherapy, and surgical interventions, together with hematopoietic stem cell transplantation, increased childhood cancer survival rate in the last decades, reaching 80% in Europe. Nevertheless, anti-cancer treatments are mainly responsible for the onset of long-term side effects in childhood cancer survivors (CCS), including alterations of the endocrine system function and activity. In particular, the most frequent dysfunction in CCS is a metabolic bone disorder characterized by low bone mineral density (BMD) with increased skeletal fragility. BMD loss is also a consequence of a sedentary lifestyle, malnutrition, and cancer itself could affect BMD, thus inducing osteopenia and osteoporosis. In this paper, we provide an overview of possible causes of bone impairment in CCS in order to propose management strategies for early identification and treatment of skeletal fragility in this population.

Alteration of osteoclast activity in childhood cancer survivors: Role of iron and of CB2/TRPV1 receptors

Childhood cancer survivors (CCS) are predisposed to the onset of osteoporosis (OP). It is known that iron overload induces osteoclasts (OCs) overactivity and that the iron chelator Deferasirox (DFX) can counteract it. The Cannabinoid Receptor type 2 (CB2) and the transient receptor potential vanilloid type-1 (TRPV1) are potential therapeutic targets for OP. In this study we isolated OCs from peripheral blood of 20 CCS and investigated osteoclast biomarkers expression and iron metabolism evaluating iron release by OCs and the expression of several molecules involved in its regulation. Moreover, we analyzed the effects of CB2 and TRPV1 stimulation in combination with DFX on osteoclast activity and iron metabolism. We observed, for the first time, an osteoclast hyperactivation in CCS suggesting a role for iron in its development. Moreover, we confirmed the well-known role of CB2 and TRPV1 receptors in bone metabolism, suggesting the receptors as possible key biomarkers of bone damage. Moreover, we demonstrated a promising synergism between pharmacological compounds, stimulating CB2 or inhibiting/desensitizing TRPV1 and DFX, in counteracting osteoclast overactivity in CCS to improve their quality of life.

Physical Activity in Late Prepuberty and Early Puberty Is Associated With High Bone Formation and Low Bone Resorption

Background

Physical activity (PA) increases bone mass, especially in late prepuberty and early puberty, but it remains unclear if and how PA affects both bone formation and bone resorption.

Materials and Methods

We included 191 boys and 158 girls aged 7.7 ± 0.6 (mean ± SD) in a population-based PA intervention study. The intervention group (123 boys and 94 girls) received daily physical education (PE) in school (40 min/day; 200 min/week) from study start and during the nine compulsory school years in Sweden. The controls (68 boys and 64 girls) received the national standard of 1–2 classes PE/week (60 min/week). During the intervention, blood samples were collected at ages 9.9 ± 0.6 (n = 172; all in Tanner stages 1–2) and 14.8 ± 0.8 (n = 146; all in Tanner stages 3–5) and after termination of the intervention at age 18.8 ± 0.3 (n = 93; all in Tanner stage 5) and 23.5 ± 0.7 (n = 152). In serum, we analyzed bone formation markers [bone-specific alkaline phosphatase (bALP), osteocalcin (OC), and N-terminal propeptide of collagen type 1 (PINP)] and bone resorption markers [C-terminal telopeptide cross links (CTX) and tartrate-resistant acid phosphatase (TRAcP 5b)]. Linear regression was used to compare age and sex-adjusted mean differences between intervention children and controls in these markers.

Results

Two years after the intervention was initiated (at Tanner stages 1–2), we found higher serum levels of bALP and OC, and lower serum levels of TRAcP 5b in the intervention compared with the control group. The mean difference (95% CI) was for bALP: 13.7 (2.1, 25.3) μg/L, OC: 9.1 (0.1, 18.1) μg/L, and TRAcP 5b: −2.3 (−3.9, −0.7) U/L. At Tanner stages 3–5 and after the intervention was terminated, bone turnover markers were similar in the intervention and the control children.

Conclusion

Daily school PA in the late prepubertal and early pubertal periods is associated with higher bone formation and lower bone resorption than school PA 1–2 times/week. In late pubertal and postpubertal periods, bone formation and resorption were similar. Termination of the intervention is not associated with adverse bone turnover, indicating that PA-induced bone mass benefits gained during growth may remain in adulthood.

Exercise and Childhood Cancer-A Historical Review

Simple Summary

Childhood cancer survivors are at risk of developing important adverse effects, but there is growing evidence that physical exercise could help in this regard. The present review summarizes the history of pediatric exercise oncology and the main milestones achieved along the way. Overall, physical exercise appears to be safe and beneficial even during the most aggressive phases of pediatric cancer treatment and can represent an effective coadjuvant therapy for attenuating cancer-related adverse effects.

Abstract

Childhood cancer survivors are at risk of developing important adverse effects, many of which persist for years after the end of treatment. The implementation of interventions aiming at attenuating tumor/treatment-associated adverse effects is therefore a major issue in pediatric oncology, and there is growing evidence that physical exercise could help in this regard. The present review aims to summarize the main milestones achieved in pediatric exercise oncology. For this purpose, we conducted a systematic review of relevant studies written in English in the electronic database PubMed (from inception to 14 August 2021). This review traces the field of pediatric exercise oncology throughout recent history based on three fundamental pillars: (i) exercise during childhood cancer treatment; (ii) exercise during/after hematopoietic stem cell transplantation; and (iii) exercise after childhood cancer treatment. Accumulating evidence––although still preliminary in many cases––supports the safety and potential benefits of regular exercise (with no major contraindications in general) in the childhood cancer continuum, even during the most aggressive phases of treatment. Exercise can indeed represent an effective coadjuvant therapy for attenuating cancer-related adverse effects.

Nutritional intake and bone health

Osteoporotic or fragility fractures affect one in two women and one in five men who are older than 50. These events are associated with substantial morbidity, increased mortality, and an impaired quality of life. Recommended general measures for fragility fracture prevention include a balanced diet with an optimal protein and calcium intake and vitamin D sufficiency, together with regular weight-bearing physical exercise. In this narrative Review, we discuss the role of nutrients, foods, and dietary patterns in maintaining bone health. Much of this information comes from observational studies. Bone mineral density, microstructure-estimated bone strength, and trabecular and cortical microstructure are positively associated with total protein intake. Several studies indicate that fracture risk might be lower with a higher dietary protein intake, provided that the calcium supply is sufficient. Dairy products are a valuable source of these two nutrients. Hip fracture risk appears to be lower in consumers of dairy products, particularly fermented dairy products. Consuming less than five servings per day of fruit and vegetables is associated with a higher hip fracture risk. Adherence to a Mediterranean diet or to a prudent diet is associated with a lower fracture risk. These various nutrients and dietary patterns influence gut microbiota composition or function, or both. The conclusions of this Review emphasise the importance of a balanced diet including minerals, protein, and fruit and vegetables for bone health and in the prevention of fragility fractures.

Combined effects of physical activity and calcium on bone health in children and adolescents: a systematic review of randomized controlled trials

BACKGROUND

A better understanding of the role of exercise and nutrition in bone health is significant for preventing osteoporosis. The aim of this review was to assess the combined effects of physical activity and calcium intake on improving bone mineral density in children and adolescents.

METHODS

A search of electronic databases (MedLine, ISI Web of Science, Science Direct) and the literature references were performed. Randomized controlled trials published between 1997 and 2017, evaluating the effect of both physical activity and calcium intake intervention on bone mineral density or bone mineral content among children aged 3-18 years were selected. The Improved Jadad Rating Scale was used to assess the methodological quality of the included studies. Study characteristics were summarized in accordance with the review's PICO criteria. Changes in bone mineral content were detected at several different bone sites.

RESULTS

A total of nine studies involving 908 participants were included in this review. The combined intervention of physical activity and calcium increased bone mineral in children and adolescents, especially when baseline calcium intake level was low and among participants on the stage of early puberty.

CONCLUSIONS

Regular physical activity combined with high level of calcium intake is beneficial for bone health in young population. Further research is needed to evaluate the dose-response associations and long-term effects of the interaction between physical activity and calcium intake.

Skeletal loading score is associated with bone microarchitecture in young adults

Physical activity that involves high strain magnitudes and high rates of loading is reported to be most effective in eliciting an osteogenic bone response. Whether a history of participation in osteogenic activities during youth, as well as current participation in osteogenic activities, contributes to young adult bone microarchitecture and strength is unknown.

PURPOSE

We determined the association between a new skeletal loading (SkL) score reflecting physical activity from age 11 to adulthood, the bone specific physical activity questionnaire (BPAQ) and bone microarchitecture in young Black and White men and women.

METHODS

We conducted a cross-sectional study of young ([mean ± SD] 23.7 ± 3.3 years) Black (n = 51 women, n = 31 men) and White (n = 50 women, n = 49 men) adults. Microarchitecture and estimated bone strength (by micro-finite element analysis) were assessed at the ultradistal tibia using high-resolution peripheral quantitative computed tomography (HR-pQCT). Physical activity questionnaires were administered and a SkL score was derived based on ground reaction force, rate of loading, frequency, duration, and life period of participation per activity from age 11 onwards. BPAQ score was also calculated. We used multiple linear regression to determine associations between both SkL score and BPAQ score and bone outcomes, adjusting for age, height, weight, sex, and race.

RESULTS

We found that SkL score, which accounts for current and historical physical activity, was significantly associated with most cortical bone parameters at the tibia including area, area fraction, porosity, thickness, and tissue mineral density (R² = 0.27-0.55, all p < 0.01). Further, trabecular thickness, separation, number, and bone mineral density (R² = 0.22-0.32, all p < 0.01), as well as stiffness and failure load (R² = 0.63-0.65, all p < 0.01), were associated with the SkL score. The BPAQ was also significantly associated with most bone parameters, but to a lesser degree than SkL score.

CONCLUSION

These findings suggest that among young adults, greater amounts of osteogenic physical activity, as assessed by the SkL score and BPAQ are associated with improved bone microarchitecture and strength. With the potential to predict bone parameters in young adults, these scores may ultimately serve to identify those most vulnerable to fracture.

Effect of assisted walking-movement in patients with genetic and acquired neuromuscular disorders with the motorised Innowalk device: an international case study meta-analysis

People with physical disabilities (PD) suffer from consequences due to lack of physical activity and consequently, are at increased risk of chronic diseases. We aimed to evaluate the ability of a motorised assistive device for dynamic standing with weight-bearing in addition to standard state-of-the-art therapy to improve clinical outcome in a meta-analysis of available studies. A total of 11 studies were identified from different European countries analysing the effect of the dynamic device Innowalk. Raw data of nine studies were pooled including a total of 31 patients observed between 2009 and 2017. Standardised questionnaires and physical outcomes were examined in this exploratory meta-analysis. We recorded patients' characteristics, duration, intensity, and location of usage as well as general clinical outcomes and improvement of passive range of motion (PROM). The analysed population consisted in 90% cases of patients younger than 18 years of age. Patients were severely disabled individuals (aged 8 (6-10) years; 58% male; 67% non-ambulatory, 86% cerebral palsy). A total of 94% used the Innowalk in a home-based or day-care setting. For nearly all individuals (94%), improvements were recorded for: walking or weight-bearing transfer (n = 13), control/strength of the trunk or head (n = 6), joint mobility (n = 14), sleep (n = 4 out of 6/67%), or muscle strength (n = 17), vital functions (n = 16), bowel function (n = 10), attention/orientation (n = 2). PROM of the hip (flexion, abduction, and adduction) significantly (p < 0.001 for multiple comparisons) increased after 1 month (p < 0.05 flexion, adduction) and further after 5 months (p < 0.05 each) in contrast (p < 0.05 each) to a control group with state-of-the-art therapy. Similarly, PROM showed a trend towards improvement in dorsal extension of the ankle (p = 0.07). In summary, this is the first report of a novel device with additional benefit to standard therapy for severe PD. These intriguing results warrant the planned prospective randomised controlled trial to prove the concept and mechanism of action of this device.

Relationship between physical activity, dietary intake and bone parameters in 10-12 years old Hungarian boys and girls

OBJECTIVES

Physical activity (PA) and adequate macro- and micronutrient intake have favourable influence on the bone status. The aim of this study was to analyse the relationships among PA, anthropometric data, dietary intake and ultrasound bone characteristics in children.

METHODS

10-12 years old Hungarian children (N = 123, 59 girls, 64 boys) provided physical activity, diet, anthropometric and bone data. PA was measured with accelerometer (Actigraph GT3X+). Diet was evaluated with three-day, 24-hour food recall. Calcaneal quantitative ultrasound (QUS) bone parameters were registered with Sonost3000 bone densitometer.

RESULTS

Nutrition and anthropometry did not differ by gender. The values of broadband ultrasound attenuation (BUA) were significantly higher in boys. Girls spent significantly more time being sedentary, boys had greater light, moderate, vigorous, and moderate to vigorous physical activity (MVPA) levels. The children accumulated more than twice the suggested amount of public health guidelines for MVPA. QUS parameters correlated significantly with vigorous physical activity in boys, and with age, height, weight, fat percentage, and body mass index (BMI) for both genders. There was no significant relationship between nutrition and QUS; however, inadequate vitamin K intake correlated with less favourable bone parameters. Multiple linear regression analysis confirmed the importance of vigorous PA - speed of sound (SOS): β = 0.358, p = 0.006; BUA: β = 0.340, p = 0.007; bone quality index (BQI): β = 0.377, p = 0.002; vitamin K intake - SOS: β = 0.256, p = 0.025; BUA: β = 0.235, p = 0.033; BQI: β = 0.295, p = 0.007; BMI - SOS: β = 0.207, p = 0.064; BUA: β = 0.455, p < 0.001; BQI: β = 0.284, p = 0.008; and age - SOS: β = 0.450, p < 0.001; BUA: β = 0.318, p = 0.004; BQI: β = 0.444, p < 0.001).

CONCLUSIONS

Changes in the characteristics of ultrasound bone parameters among 10-12 years old children mainly depended on the amount of intense PA, adequate vitamin K intake and anthropometric variables related to age.

Frequency and duration of vigorous physical activity bouts are associated with adolescent boys' bone mineral status: A cross-sectional study

PURPOSE

Vigorous physical activity (VPA) has been proven to promote osteogenesis in adolescents; however the specifics of the optimal pattern of frequency and duration of VPA are unknown. The main goal of the present study was to analyze the associations of different length of VPA bouts with bone health.

METHODS

180 healthy male adolescents (11-13 years) had their bone mineral content and density assessed by dual-energy X-ray absorptiometry scans at the whole body, femoral neck (FN) and lumbar spine and their physical activity measured by an accelerometer during one week.

RESULTS

VPA was the intensity with the strongest associations with bone mineral parameters especially at the FN. Subjects whose longest VPA bout was 5 min or above had higher FN bone mineral density (BMD) than those who did not complete any 5-min bout and these differences were greater with participants who reached 15 consecutive minutes of VPA (>15': 0.977 ± 0.020 g/cm2; 5'-15': 0.907 ± 0.009 g/cm2; <5': 0.876 ± 0.009 g/cm2; all p < 0.05). When comparing the relevance of VPA bouts and volume of physical activity, the group with low volume and having a VPA bout had better FN BMD compared to the group with high volume but no VPA bout. Additionally, the group with both high volume and VPA bout showed better FN BMD than the rest of the groups.

CONCLUSIONS

VPA may be the most effective activity intensity to improve bone mineral density and content of adolescent boys, with greater benefits if VPA periods either long or frequent.

Are consumption of dairy products and physical activity independently related to bone mineral density of 6-year-old children? Longitudinal and cross-sectional analyses in a birth cohort from Brazil

OBJECTIVE

To evaluate cross-sectional and longitudinal associations of consumption of dairy products and physical activity (PA) with bone mineral density (BMD).

DESIGN

Cohort study with children from the 2004 Pelotas (Brazil) Birth Cohort.

SETTING

Pelotas, a medium-sized Brazilian city.

SUBJECTS

The study started in 2004 and mothers/children were interviewed/measured periodically from birth to age 6 years. PA was measured by maternal proxy at 4 and 6 years and by accelerometry at 6 years. Consumption of dairy products was measured using 24 h food recall (at 4 years) and FFQ (at 6 years). Total-body and lumbar-spine BMD (g/cm2) were measured by dual-energy X-ray absorptiometry.

RESULTS

At 6 years, BMD was measured in 3444 children and 2636 children provided data on objectively measured PA by accelerometry. Consumption of dairy products at 4 years was associated with higher lumbar-spine BMD at 6 years in boys, while current consumption was positively associated with BMD in both sexes (P < 0·001). PA assessed by maternal report at 4 and 6 years of age was associated with higher BMD at 6 years in boys. PA assessed by accelerometry was positively related to total-body and lumbar-spine BMD in boys and lumbar-spine BMD in girls. We did not find evidence for an interaction between PA and consumption of dairy products on BMD.

CONCLUSIONS

We observed positive and independent longitudinal and cross-sectional associations between consumption of dairy products and PA with BMD in the total body and at the lumbar spine in young children.

Multiscale investigation on the effects of additional weight bearing in combination with low-magnitude high-frequency vibration on bone quality of growing female rats

This study aimed to explore the effects of additional weight bearing in combination with low-magnitude high-frequency vibration (LMHFV; 45 Hz, 0.3 g) on bone quality. One hundred twenty rats were randomly divided into ten groups; namely, sedentary (SED), additional weight bearing in which the rat wears a backpack whose weight is x% of the body weight (WBx; x = 5, 12, 19, 26), basic vibration (V), and additional weight bearing in combination with LMHFV in which the rat wears a backpack whose weight is x% of the body weight (Vx; x = 5, 12, 19, 26). The experiment was conducted for 12 weeks, 7 days per week, and 15 min per day. A three-point bending mechanical test, micro computed tomography, and a nanoindentation test were used. Serum samples were analyzed chemically. Failure load in V19 rats was significantly lower than that in SED rats (P < 0.05). Vx (x = 5, 12, 19, 26) rats showed poor microarchitectures. The content of tartrate-resistant acid phosphatase 5b was significantly higher in Vx (x = 5, 12, 19, 26) rats than that in SED rats (P < 0.05). V26 rats demonstrated comparatively better nanomechanical properties of materials than the other vibrational groups. Additional weight bearing in combination with LMHFV negatively affected the macromechanical properties and microarchitecture of bone. Heavy additional weight bearing, such as 26% of body weight, in combination with LMHFV was able to improve the nanomechanical properties of growing bone material compared with LMHFV. A combined mechanical stimulation was used, which may provide useful information to understand the mechanism of this mechanical stimulation on bone.

Evidence for Genetic Risk Contributing to Long-Term Adverse Treatment Effects in Childhood Cancer Survivors

Survivors of childhood cancer are at increased risk for therapy-related morbidities and mortality. Although the demographic and clinical factors predicting the risk for long-term effects of cancer therapy are well known, the impact of genetic risk for specific late effects is less clearly defined. Here, we review the extant literature and recent research describing genetic modifiers to risk for the more common late effects of childhood cancer therapy. Results of this research support the need for clinical trials that attempt to further refine risk prediction by incorporating genetic testing into existing algorithms that are primarily based on clinical and demographic factors. Confirmation of genetic predisposition, as defined by reproducibility and prospective validation, would permit therapeutic modification and discussion of individualized survivor care plans even at initial cancer diagnosis.

Pregnancy-associated transient osteoporosis of the hip: results of a case-control study

The etiology and underlying mechanisms of transient of osteoporosis of the hip (TOH) during pregnancy are still unclear, since no systematic analyses exist. Our results support the hypothesis that TOH is a multifactorial disease, which is associated with immobility, dental problems, and lack of exercise in childhood.

INTRODUCTION

Pregnancy-associated transient osteoporosis of the hip (TOH) is a rare but severe form of osteoporosis, which may affect a subgroup of women in the last trimester of pregnancy or immediately postpartum. Common symptoms include acute pain of the hip(s) due to bone marrow edema or even hip fractures. The exact underlining mechanisms of this disorder are still unknown since no published systematic analyses exist.

METHODS

Out of a total of 52 TOH patients, 33 TOH patients could be matched with 33 healthy controls according to age, region, and gravity. The aim of this retrospective case-control study was to evaluate the risk factors for TOH in a homogenous population of women.

RESULTS

The baseline characteristics of the two study groups were similar. Overall, 12.1% of the TOH patients sustained a hip fracture. Expectedly, 90.9% of the TOH patients complained about pain of the hip (p ≤ 0.001). TOH patients suffered more frequently from severe dental problems during childhood (p = 0.023) and performed less often sports before and after puberty (p ≤ 0.001), whereas the frequency of immobilization during pregnancy was threefold higher compared to the control group (p = 0.007). We found a significant increase of the TOH risk in patients with dental problems in childhood (OR 3.7; CI 1.3-10.7) as well as in patients with lack of exercise during childhood (OR 4.2; CI 1.3-12.9).

CONCLUSIONS

Our results support the hypothesis that pregnancy-associated TOH is a multifactorial disease, to which several individual factors may contribute. Hereby, we found significant associations with immobility, dental problems, and lack of exercise in childhood.

Exercise for Bone in Childhood-Hitting the Sweet Spot

PURPOSE

The goal of the current work is to challenge the enduring notion that prepuberty is the optimum timing for maximum bone response to exercise in childhood and to present the evidence that early puberty is a more potently receptive period.

METHOD

The relevant literature is reviewed and the causes of the misconception are addressed in detail.

RESULTS

Contrary to prevailing opinion, ample evidence exists to suggest that the peripubertal years represent the developmental period during which bone is likely to respond most robustly to exercise intervention.

CONCLUSION

Public health initiatives that target bone-specific exercise interventions during the pubertal years are likely to be the most effective strategy to harness the increased receptiveness of the growing skeleton to mechanical loading.

Systematic review on evidence-based adolescent nutrition interventions

Adolescence is a critical stage in the life cycle, and adequate nutrition is necessary for the proper growth and development of individuals and their offspring. Here, we comprehensively review all published systematic reviews (through October 2016) on adolescents (10-19 years) and women of reproductive age, including pregnant women, which targeted interventions related to nutrition. For interventions where there was no existing systematic review on adolescents, we reviewed primary studies/trials. We included interventions on micronutrient supplementation (iron, folic acid, iron-folic acid (IFA), calcium, vitamin D, vitamin A, zinc, iodine, and multiple micronutrients), food/protein energy supplementation, nutrition education for pregnant adolescents, obesity prevention and management, and management of gestational diabetes. We identified a total of 35 systematic reviews, of which only five were conducted on adolescents, and 107 primary studies on adolescents. Our review suggests that iron alone, IFA, zinc, and multiple micronutrient supplementation in adolescents can significantly improve serum hemoglobin concentration. While zinc supplementation in pregnant adolescents showed improvements in preterm birth and low birth weight, we found a paucity of trials on calcium, vitamin D, vitamin A, and iodine supplementation. We found limited evidence on food/protein energy supplementation in adolescents. Interventions to prevent and manage obesity showed a nonsignificant impact on reducing body mass index. This review underscores the importance of adolescent nutrition interventions. It is imperative that countries design nutritional interventions, particularly for adolescents.

The Effectiveness of Interventions on Sustained Childhood Physical Activity: A Systematic Review and Meta-Analysis of Controlled Studies

BACKGROUND

Increased physical activity (PA) has been associated with a reduction in non-communicable disease risk factors and outcomes. However, interventions to increase childhood PA typically produce small to negligible effects. Recent reviews are limited due to lack of post-intervention follow-up measurement. This review aimed to examine measured effects at least six months post-intervention.

METHODS AND FINDINGS

We searched PubMed, MEDLINE, EMBASE, PsychINFO, ScienceDirect, SportDiscus and Google Scholar between 1st January 1991 and 1st November 2014 for controlled studies reporting six-month post-intervention measurement for children aged 5 to 18 years. 14 studies met inclusion criteria; 12 reported moderate-to-vigorous PA (MVPA) (n = 5790) and 10 reported total PA (TPA) (n = 4855). We calculated overall effect estimates and 95% CI's using random effects modelling with inverse variance weighting. Mean difference was calculated for MVPA, with standardised mean difference calculated to TPA due to measurement variation. Meta-regression assessed heterogeneity by continuous level variables. Negligible mean difference in MVPA existed in favour of the intervention group, amounting to 1.47 (95% CI -1.88, 4.82) mins/day compared to controls, while no difference was recorded on TPA. Sub-group analyses revealed males (2.65 mins/day: 95% CI 2.03, 3.27) reported higher levels of MVPA than females (-0.42 mins/day: 95% CI -7.77, 6.94), community settings (2.67 mins/day: 95% CI 2.05, 3.28) were more effective than school settings (1.70 mins/day: 95% CI -4.84, 8.25), and that treatment (4.47 mins/day: 95% CI -0.81, 9.76) demonstrated greater effects than population approaches (1.03 mins/day: 95% CI -2.54, 4.60). Meta-regression revealed no significant differences by factor on pooled effects. Significant heterogeneity existed between studies and potential for small study effects was present.

CONCLUSIONS

Improved PA levels subsequent to intervention were not maintained six month post-intervention. A potentially useful avenue of future research is to specifically explore community treatment of high risk individuals.

REVIEW REGISTRATION

PROSPERO CRD42014007545.

Prediction of bone mineral density and content from measures of physical activity and sedentary behavior in younger and older females

BACKGROUND

Little is known regarding the extent to which physical activity (PA) and sedentary behavior (SB) influence bone mineral content (BMC) and bone mineral density (BMD) in females across the lifespan.

METHODS

Data from 2232 females aged 12 years and older collected as part of the 2007-2008 National Health and Nutrition Examination Survey were analyzed. Categories of PA and SB were used to predict femoral and spinal BMD and BMC in four age groups (G1: 12-17; G2: 18-39; G3: 40-64; G4: ≥ 65 years). Self-reported PA categories included sufficient moderate-to-vigorous recreational PA (S-MVRPA) and insufficient MVRPA (I-MVRPA).

RESULTS

G1 females who accumulated S-MVRPA displayed greater femoral and spinal BMC and BMD compared to G1 females who displayed I-MVRPA. For G4 females, higher levels of SB were associated with lower femoral BMC and BMD.

CONCLUSIONS

These findings highlight the importance of engaging in sufficient moderate-to-vigorous physical activity during adolescence and reducing sedentary behavior in older adults to improve bone health in females.

Effects of weight-bearing activities on bone mineral content and density in children and adolescents: a meta-analysis

Osteoporosis and associated fractures are a major health concern in Western industrialized nations. Exercise during growth is suggested to oppose the involutional bone loss later in life by increasing peak bone mass. The primary aim of the present meta-analysis was to provide a robust estimate of the effect of weight-bearing activities (WBAs) on bone mineral content (BMC) and areal bone mineral density (aBMD), during childhood and adolescence. To locate relevant studies up to June 2012, computerized searches of multiple bibliographic databases and hand searches of key journals and reference lists were performed. Results were extracted by two independent reviewers. The quality of the included trials was assessed via the Physiotherapy Evidence Database (PEDro) score. The study group effect was defined as the difference between the standardized mean change for the treatment and control groups divided by the pooled pretest SD. From 109 potentially relevant studies, only 27 met the inclusion criteria. The analyzed training programs were capable of significantly increasing BMC and aBMD during growth. However, the weighted overall effect sizes (ESs) for changes in BMC (ES 0.17; 95% confidence interval [CI], 0.05-0.29; p < 0.05) and aBMD (ES 0.26; 95% CI, 0.02-0.49) were small. Stepwise backward regression revealed that more than one-third of the observed variance (r(2)  = 0.35) between subgroups of the BMC dataset could be explained by differences in the amount of habitual calcium intake per day (beta 0.54, p < 0.01) and the maturational stage (beta -0.28, p < 0.01) at baseline. No significant moderators were identified for aBMD, possibly due to the small number of trials investigating WBAs on aBMD. The results of this meta-analysis conclude that WBAs alongside high calcium intake provide a practical, relevant method to significantly improve BMC in prepubertal children, justifying the application of this exercise form as an osteoporosis prophylaxis in this stage of maturity.

Effects of calcium and training on the development of bone density in children with Down syndrome

In this study we examined the effects of physical training and calcium intake on the development of bone mineral density (BMD) in children with Down syndrome (DS). A total of 48 children with DS (age 7-12 years old) matched for age and BMD were assigned to four groups exercise and calcium intake (Ex(+)Ca(+)), calcium intake-no-exercise (Ex(-)Ca(+)), exercise no-calcium intake (Ex(+)Ca(-)) and non-exercise-no-calcium intake (Ex(-)Ca(-)). The training protocol included 45 min of weight bearing exercise performed 3 sessions per week in addition to dietary calcium rich food intake of enriched cow milk with vitamin D containing 200 mg calcium per serving or no enriched dietary supplement for a duration of 4 months. Data analysis was performed on data by using t-test, one-way ANOVA analysis and Tukey post hoc tests to determine the main and combined effects of training and calcium regiment on BMD. All groups showed greater femoral neck BMD after 4 months. The increase in femoral neck BMD in the Ex(+)Ca(+) group was 5.96% greater than the Ex(+)Ca(-) group (p<0.01). The effect of training was greater than calcium intake alone. The Ex(+)Ca(-) group achieved 3.52% greater BMD than Ex(-)Ca(+) group (p<0.01). In this study, all the experimental groups had greater BMD than the no-calcium-no-exercise group that served as the control group (p<0.01). It was concluded that additional weight bearing exercise and calcium supplementation resulted in a greater increase in BMD in children with DS.

A family-centered lifestyle intervention to improve body composition and bone mass in overweight and obese children 6 through 8 years: a randomized controlled trial study protocol

BACKGROUND

Childhood obesity gives rise to health complications including impaired musculoskeletal development that associates with increased risk of fractures. Prevention and treatment programs should focus on nutrition education, increasing physical activity (PA), reducing sedentary behaviours, and should monitor bone mass as a component of body composition. To ensure lifestyle changes are sustained in the home environment, programs need to be family-centered. To date, no study has reported on a family-centered lifestyle intervention for obese children that aims to not only ameliorate adiposity, but also support increases in bone and lean muscle mass. Furthermore, it is unknown if programs of such nature can also favorably change eating and activity behaviors. The aim of this study is to determine the effects of a 1 y family-centered lifestyle intervention, focused on both nutrient dense foods including increased intakes of milk and alternatives, plus total and weight-bearing PA, on body composition and bone mass in overweight or obese children.

METHODS/DESIGN

The study design is a randomized controlled trial for overweight or obese children (6-8 y). Participants are randomized to control, standard treatment (StTx) or modified treatment (ModTx). This study is family-centred and includes individualized counselling sessions on nutrition, PA and sedentary behaviors occurring 4 weeks after baseline for 5 months, then at the end of month 8. The control group receives counselling at the end of the study. All groups are measured at baseline and every 3 months for the primary outcome of changes in body mass index Z-scores. At each visit blood is drawn and children complete a researcher-administered behavior questionnaire and muscle function testing. Changes from baseline to 12 months in body fat (% and mass), waist circumference, lean body mass, bone (mineral content, mineral density, size and volumetric density), dietary intake, self-reported PA and sedentary behaviour are examined.

DISCUSSION

This family-centered theory-based study permits for biochemical and physiological assessments. This trial will assess the effectiveness of the intervention at changing lifestyle behaviours by decreasing adiposity while enhancing lean and bone mass. If successful, the intervention proposed offers new insights for the management or treatment of childhood obesity.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01290016.

Altitude, pasture type, and sheep breed affect bone metabolism and serum 25-hydroxyvitamin D in grazing lambs

This study aimed to investigate the bone development of two mountain sheep breeds during natural summer grazing either in the lowlands or on different characteristic alpine pastures. Pasture types differed in topographic slope, plant species composition, general nutritional feeding value, Ca and P content, and Ca:P ratio of herbage. Twenty-seven Engadine sheep (ES) lambs and 27 Valaisian Black Nose sheep (VS) lambs were divided into four groups of 6 to 7 animals per breed and allocated to three contrasting alpine pasture types and one lowland pasture type. The lambs were slaughtered after 9 wk of experimental grazing. The steep alpine pastures in combination with a high (4.8) to very high (13.6) Ca:P ratio in the forage decreased total bone mineral content as measured in the middle of the left metatarsus of the lambs from both breeds, and cortical bone mineral content and cortical bone mineral density of ES lambs. Breed × pasture type interactions occurred in the development of total and cortical bone mineral content, and in cortical thickness, indicating that bone metabolism of different genotypes obviously profited differently from the varying conditions. An altitude effect occurred for 25-hydroxyvitamin D with notably higher serum concentrations on the three alpine sites, and a breed effect led to higher concentrations for ES than VS. Despite a high variance, there were pasture-type effects on serum markers of bone formation and resorption.

Self-reported recreational exercise combining regularity and impact is necessary to maximize bone mineral density in young adult women: a population-based study of 1,061 women 25 years of age

Recreational physical activity in 25-year-old women in Sweden increases bone mineral density (BMD) in the trochanter by 5.5% when combining regularity and impact. Jogging and spinning were especially beneficial for hip BMD (6.4-8.5%). Women who enjoyed physical education in school maintained their higher activity level at age 25.

INTRODUCTION

The aims of this study were to evaluate the effects of recreational exercise on BMD and describe how exercise patterns change with time in a normal population of young adult women.

METHODS

In a population-based study of 1,061 women, age 25 (±0.2), BMD was measured at total body (TB-BMD), femoral neck (FN-BMD), trochanter (TR-BMD), and spine (LS-BMD). Self-reported physical activity status was assessed by questionnaire. Regularity of exercise was expressed as recreational activity level (RAL) and impact load as peak strain score (PSS). A permutation (COMB-RP) was used to evaluate combined endurance and impacts on bone mass.

RESULTS

More than half of the women reported exercising on a regular basis and the most common activities were running, strength training, aerobics, and spinning. Seventy percent participated in at least one activity during the year. Women with high RAL or PSS had higher BMD in the hip (2.6-3.5%) and spine (1.5-2.1%), with the greatest differences resulting from PSS (p < 0.001-0.02). Combined regularity and impact (high-COMB-RP) conferred the greatest gains in BMD (FN 4.7%, TR 5.5%, LS 3.1%; p < 0.001) despite concomitant lower body weight. Jogging and spinning were particularly beneficial for hip BMD (+6.4-8.5%). Women with high-COMB-RP scores enjoyed physical education in school more and maintained higher activity levels throughout compared to those with low scores.

CONCLUSION

Self-reported recreational levels of physical activity positively influence BMD in young adult women but to maximize BMD gains, regular, high-impact exercise is required. Enjoyment of exercise contributes to regularity of exercising which has short- and long-term implications for bone health.

Bone health: part 2, physical activity

Mechanical loading is a crucial factor for maintaining skeletal health. Physical activities, exercise, and sports provide a wealth and variety of mechanical loads to bones, through muscle forces, ground reaction forces, and other contact or impact forces. Weightbearing activities can be effective exercises to enhance bone health-particularly, those that involve jumping and impact loads (with greater strain magnitudes, rates, and frequencies). Physical activity appears to be acutely beneficial for enhancing bone health in the early pubertal period and in older age, such as in postmenopausal women. In preparing this article, PubMed, Web of Science, and relevant edited books (English language) were reviewed from 1961 to present.

Weight-Bearing Physical Activity among Girls and Mothers: Relationships to Girls’ Weight Status

OBJECTIVE

To assess weight-bearing physical activity (WBPA) barriers, benefits, self-efficacy, social influence, and behaviors [WBPA and physical activity (PA)] among girls and their mothers according to girls' weight status (nonoverweight vs. overweight).

RESEARCH METHODS AND PROCEDURES

Participants were 9- to 11-year-old girls (n = 295) and their mothers who participated in the baseline assessment of a nutrition and PA intervention trial. Girls' and mothers' WBPA attitudes and mothers' WBPA behaviors were self-reported on questionnaires. Girls' WBPA and total PA behaviors were self-reported using a structured interview (Physical Activity Checklist Interview). Stature and weight were measured by standardized anthropometrics. Overweight status was based on BMI.

RESULTS

Compared with nonoverweight girls, overweight girls were significantly more likely to report barriers to WBPA participation and perceive social influence from family and friends to do more WBPA. They were also significantly less likely to report self-efficacy regarding WBPA and to believe that they did enough WBPA. Compared with mothers of nonoverweight girls, mothers of overweight girls were significantly more likely to report that it is difficult to persuade their daughters to do more WBPA and significantly less likely to report that WBPA was fun for their daughters. Girls' overweight status was not associated with girls' reports of minutes spent per week in PA or WBPA.

DISCUSSION

The present study's findings of lower WBPA self-efficacy, lack of enjoyment of WBPA, and higher perceived social influence to do WBPA among overweight girls suggest that efforts are needed to promote physical competencies and positive perceptions of PA among overweight girls.

Impact of social marketing in the prevention of childhood obesity

Obesity, mainly childhood obesity, is a worldwide concern. Childhood obesity continues to adulthood, and it is associated with multiple noncommunicable diseases. One important aspect in the fight against obesity is prevention, the earlier, the better. Social marketing is a novel concept being increasingly used as an approach to address social problems and more and more included in the community-based interventions aiming to change unhealthy behaviors. Although there is limited evidence of its effectiveness, it seems that when conscientiously applied, social marketing principles may be useful to change behaviors and thus better health outcomes.

Bone density in post-pubertal adolescent survivors of childhood brain tumors

BACKGROUND

Childhood cancer survivors are at high risk for reduced bone mineral density (BMD). Our objective was to determine whether post-pubertal adolescent survivors of brain tumors, whose tumor or treatments placed them at risk for pituitary hormone deficiencies, have low BMD near time of peak bone mass accrual, and to assess risk factors for decreased BMD.

PROCEDURE

Chart review of 36 post-pubertal adolescents with history of tumor or radiation therapy (RT) of the hypothalamic-pituitary area who had undergone BMD screening via dual-energy X-ray absorptiometry (DXA).

RESULTS

Age at DXA was 16.9 ± 1.9 years (mean ± SD). Time since diagnosis was 8.5 ± 3.6 years. Median BMD Z scores were -0.95 (range -2.7 to 1.7) at the femoral neck, -1.20 (-3.6 to 1.8) at the hip, and -0.90 (-3.7 to 1.8) at the spine. Bone mineral apparent density (BMAD) Z scores were -0.23 (-2.7 to 1.9) at the femoral neck and -0.45 (-3.0 to 2.3) at the spine. Those with history of ≥1 fracture had lower BMD Z scores of the femoral neck, total hip, and spine (P < 0.05). Those with treated GH deficiency (GHD) had a higher BMD Z-score at the femoral neck, total hip, and spine (P < 0.05) than those not treated. There was no difference in BMD with respect to treatment with chemotherapy, cranial or spinal RT, or hypogonadism. Spontaneous menarche and regular periods did not correlate with BMD.

CONCLUSIONS

In post-pubertal adolescent survivors of childhood brain tumors, fracture history and untreated GHD are risk factors for decreased BMD.

Bone mineral density changes after physical training and calcium intake in students with attention deficit and hyper activity disorders

In this study we investigate the effects of weight bearing exercise and calcium intake on bone mineral density (BMD) of students with attention deficit and hyper activity (ADHD) disorder. For this reason 54 male students with ADHD (age 8-12 years old) were assigned to four groups with no differences in age, BMD, calcium intake, and physical activity: exercise groups with or without calcium supplementation (Ex+Ca+ and Ex+Ca-) and non-exercise groups with or without calcium supplementation (Ex-Ca+ and Ex-Ca-). The intervention involved 50 min of weight bearing exercise performed 3 sessions a week and/or the addition of dietary calcium rich food using enriched cow milk with vitamin D containing 250 mg calcium per serving, over 9 months. Paired-samples t-test, one way ANOVA analysis, and Tukey tests were used to determine the main and combined effects of training and calcium on BMD. All groups showed greater femoral neck BMD after 9 months. The increase in femoral neck BMD was significantly different between all groups (p < 0.05). Ex+Ca+ group has greater increase in BMD than other groups. Apparently, the effect of training was greater than calcium intake (p < 0.05). These results help to provide more evidence for public health organizations to deal with both exercise and nutrition issues in children with ADHD disorder for the achievement of peak BMD.

Epigenetic influences in the developmental origins of osteoporosis

Osteoporosis is a major public health problem due to consequent fragility fractures; data from the UK suggest that up to 50% of women and 20% men aged 50 years will have an osteoporosis-related fracture in their remaining lifetime. Skeletal size and density increase from early embryogenesis through intrauterine, infant, childhood and adult life to reach a peak in the third to fourth decade. The peak bone mass achieved is a strong predictor of later osteoporosis risk. Epidemiological studies have demonstrated a positive relationship between early growth and later bone mass, both at peak and in later life, and also with reduced risk of hip fracture. Mother-offspring cohorts have allowed the elucidation of some of the specific factors in early life, such as maternal body build, lifestyle and 25(OH)-vitamin D status, which might be important. Most recently, the phenomenon of developmental plasticity, whereby a single genotype may give rise to different phenotypes depending on the prevailing environment, and the science of epigenetics have presented novel molecular mechanisms which may underlie previous observations. This review will give an overview of these latter developments in the context of the burden of osteoporosis and the wider data supporting the link between the early environment and bone health in later life.

Tracking of appendicular bone mineral density for 6 years including the pubertal growth spurt: Japanese Population-based Osteoporosis kids cohort study

Bone development up to early adulthood plays an important role in determining the risk of osteoporosis later in life. However, bone development in children has not been fully documented by longitudinal studies in Japanese children. The purpose of this study is to determine the degree of tracking of areal bone mineral density (aBMD) from pre-puberty to 6-year follow-up, and to determine the target period to achieve maximal peak aBMD. This study was conducted as the pediatric part of a larger cohort study, the Japanese Population-based Osteoporosis (JPOS) study. Of 448 children aged 9-12 years who completed the baseline survey, 225 participated in the follow-up study 6 years later (follow-up rate: 50.2%). aBMD at the forearm was measured using dual-energy X-ray absorptiometry. aBMD values in pre-pubertal children at baseline showed a significant tracking correlation with aBMD obtained at 6-year follow-up in both genders (boys r = 0.655, girls r = 0.759). Although boys and girls in the lowest quartile of aBMD pre-pubertally had greater annual increases in aBMD from pre-puberty to 6-year follow-up than those in other aBMD quartiles, they still showed the lowest mean aBMD at 6-year follow-up. Children with lower pre-pubertal aBMD showed greater increases in BMD up until 6-year follow-up, but the increase was not great enough to catch up with other children. About 50% of the variance in aBMD at 6-year follow-up was determined by the aBMD achieved during the pre-pubertal period. Activities that increase aBMD are important not only for children during puberty, but also for younger pre-pubertal children.

Biopsychosocial variables associated with substantial bone mineral density loss during the use of depot medroxyprogesterone acetate in adolescents: adolescents who lost 5% or more from baseline vs. those who lost less than 5%

BACKGROUND

It is unclear why some adolescents experience substantial bone mineral density (BMD) loss, while others experience a minimal decrease during depot medroxyprogesterone acetate (DMPA) use. We examined biopsychosocial factors in adolescents who experienced ≥5% BMD loss from baseline compared with adolescents who experienced <5% BMD loss during DMPA use.

STUDY DESIGN

A multicenter, prospective, nonrandomized study of 181 female adolescents who initiated DMPA for contraception was conducted. BMD (by dual-energy X-ray absorptiometry) and serum estradiol were measured at initiation and every 6 months for 240 weeks of DMPA use.

RESULTS

Half of participants experienced BMD loss of ≥5% from baseline at the hip, and a quarter experienced BMD loss of ≥5% at the lumbar spine (BMD substantial losers, SL). Hip and lumbar spine BMD-SL received a significantly greater number of DMPA injections than non-SL (p<.001). Decreased estradiol levels did not statistically differ between BMD loss subgroups. Hip BMD-SL had significantly lower baseline body mass index (BMI) than non-SL (p=.002), and there was an inverse relationship between weight gain and degree of BMD loss. Mean calcium intake was significantly lower (p<.05) in hip BMD-SL, and reported alcohol use was significantly higher (p<.05) in lumbar spine BMD-SL compared with non-SL.

CONCLUSIONS

BMD loss of ≥5% was more common at the hip than at the lumbar spine among adolescents using DMPA. Decreased serum estradiol levels did not correlate with magnitude of BMD loss. Lower BMI and calcium intake and greater alcohol use were associated with greater BMD loss in adolescents using DMPA.

The relationships among bone health, insulin-like growth factor-1 and sex hormones in adolescent female athletes

The aim of this study was to determine the relationships of bone mineral density (BMD) and content (BMC) with insulin-like growth factor-1 (IGF-1), IGF-binding protein-3 (IGFBP-3) and estradiol in pubertal female athletes. The participants were 170 healthy adolescent girls (13-15 years) who participated in competitive extramural athletic programs, i.e., sports games (n = 49), track sprinting (n = 24), rhythmic gymnastics (n = 23), swimming (n = 24) and cross-country skiing (n = 17). The control group (n = 33) consisted of girls who took part only in compulsory physical education classes at school. The whole-body BMD and femoral neck and lumbar spine BMD and BMC were measured using DXA, and the volumetric BMD was calculated. Venous blood samples to determine the concentration of IGF-1, IGFBP-3 and estradiol were drawn after an overnight fasting. After adjusting for age, body height and body mass, the relationships among BMD variables, IGF-1 and the IGF-1/IGFBP-3 molar ratio remained significant only in the rhythmic gymnast group. BMDs at the femoral neck and lumbar spine were also related to estradiol levels (r = 0.45-0.60; p < 0.05) only in the rhythmic gymnast group. No relationships were found among the measured BMD, IGF axis and estradiol in other athletic groups. Only BMC at the femoral neck remained associated with the IGF-1/IGFBP-3 molar ratio in the rhythmic gymnast group after adjusting for age, body height and body mass. Stepwise multiple regression analysis indicated that IGF-1 and estradiol together explained 42.6% (R(2) x 100) of total variance in the femoral neck BMD and IGF-1 alone 35.4% (R(2) x 100) of the total variance in the femoral neck BMC only in the rhythmic gymnast group. We conclude that femoral neck and lumbar spine BMD correlated with IGF-1, IGF-1/IGFBP-3 molar ratio and estradiol in rhythmic gymnasts. No relationships were found between bone parameters and the hormones used in other athletic groups.

Factors associated with low bone mass in the hemodialysis patients--a cross-sectional correlation study

BACKGROUND

Low bone mass is common in end-stage renal disease patients, especially those undergoing hemodialysis. It can lead to serious bone health problems such as fragility fractures. The purpose of this study is to investigate the risk factors of low bone mass in the hemodialysis patients.

METHODS

Sixty-three subjects on hemodialysis for at least 6 months were recruited from a single center for this cross-sectional study. We collected data by questionnaire survey and medical records review. All subjects underwent a bone mineral density (BMD) assay with dual-energy x-ray absorptiometry at the lumbar spine and right hip. Data were statistically analyzed by means of descriptive analysis, independent t test and one way analysis of variance for continuous variables, Pearson product-moment correlation to explore the correlated factors of BMD, and stepwise multiple linear regression to identify the predictors of low bone mass.

RESULTS

Using WHO criteria as a cutoff point, fifty-one subjects (81%) had a T-score lower than -1, of them 8 subjects (13%) had osteoporosis with the femoral neck most commonly affected. Regarding risk factors, age, serum alkaline phosphatase (ALP) level, and intact parathyroid hormone (iPTH) level had significant negative correlations with the femoral neck and lumbar spine BMD. On the other hand, serum albumin level, effective exercise time, and body weight (BW) had significant positive correlations with the femoral neck and lumbar spine BMD. Age, effective exercise time, and serum albumin level significantly predicted the femoral neck BMD (R(2) x 0.25), whereas BW and the ALP level significantly predicted the lumbar spine BMD (R(2) x 0.20).

CONCLUSION

This study showed that advanced age, low BW, low serum albumin level, and high ALP and iPTH levels were associated with a low bone mass in the hemodialysis patients. We suggest that regular monitoring of the femoral neck BMD, maintaining an adequate serum albumin level and BW, and undertaking an exercise program are important to improve bone health in the patients undergoing hemodialysis.

Impact of dairy products and dietary calcium on bone-mineral content in children: results of a meta-analysis

OBJECTIVE

Although calcium is essential for maintaining bone health in children, the optimum dietary intake of calcium in this age group, particularly in the form of dairy foods, is not well defined. A meta-analysis was conducted to examine the impact of dietary calcium/dairy supplementation on bone mineral content in this age group.

METHODS

Data were pooled from randomized controlled intervention trials and observational studies using previously described methods. The outcome of interest was a summary mean difference bone mineral content. Sensitivity analyses were employed to evaluate any observed statistical heterogeneity and to examine the influence of specific study characteristics on the summary estimate of effect.

RESULTS

Initially combining data from twenty-one randomized controlled trials (RCTs) using total body bone mineral content (TB-BMC) as the outcome of interest, yielded a non-statistically significant increase in TB-BMC of 2 g (supplemented versus controls). These data demonstrated substantial statistical heterogeneity with sensitivity analyses revealing that among study subjects with normal or near normal baseline dietary calcium/dairy intakes, supplemental dairy/calcium showed little impact on bone mineral content. Sensitivity analyses suggested that baseline calcium intake could potentially account for the statistical heterogeneity. Pooling the three reports utilizing low intake subjects yielded a statistically significant summary mean BMC of 49 g (24.0-76-6). Pooling two RCTs using calcium/dairy supplement plus vitamin D was also associated with an increase in lumbar spine BMC of, on average, 35 g (-6.8-41.8). The lack of data using BMC measurements at other anatomic sites as well as sparse data from non-randomized studies, precluded further statistical pooling.

CONCLUSION

Increased dietary calcium/dairy products, with and without vitamin D, significantly increases total body and lumbar spine BMC in children with low base-line intakes.

Development and reliability testing for measures of psychosocial constructs associated with adolescent girls' calcium intake

Early adolescence is an important period for assuring adequate calcium intake to achieve optimal bone health. This study was conducted to develop a measure of psychosocial constructs likely to be associated with young adolescent girls' consumption of high-calcium foods and to evaluate the test-retest reliability and factor structure of the measure. Methods involved: (a) generating a pool of items; (b) a cross-sectional pretest of the survey with a small group; (c) longitudinal administration of the revised survey with a larger group; and (d) statistical analysis to determine psychometric properties of the measures. Seventeen girls completed the pretest and debriefing, and 217 girls participated in the pilot test and test-retest (completion rate 95%). The study took place in Hawaii in late 2002. Coefficient alpha was used to test internal consistency and test-retest reliabilities were calculated. Cluster analyses of the items were performed to evaluate the factor structure of the measure. The resulting measure was a 55-item questionnaire to assess key psychosocial variables in three categories: Social and Environmental Factors (Availability, Social Influence); Attitudes and Preferences (Health Benefits; Preferences; Taste; Weight; Tolerance; Convenience); and Knowledge. The survey had high internal consistency reliability (alpha>.75) and good test-retest reliability (0.73 to 0.78 except for Knowledge, where Spearman's rho=0.41). The study developed a measure with high internal consistency and test-retest reliability to assess constructs that can be used in descriptive, prospective, and intervention research and as possible explanatory or mediating variables.

Bone mineral density deficits in survivors of childhood cancer: long-term follow-up guidelines and review of the literature

The development of curative therapy for most pediatric malignancies has produced a growing population of childhood cancer survivors who are at increased risk for a variety of health problems resulting from their cancer or its treatment. Because of the fact that many treatment-related sequelae may not become clinically apparent until the survivor attains maturity or begins to age, the ability of primary care providers to anticipate late effects of treatment is essential for providing timely interventions that prevent or correct these sequelae and their adverse effects on quality of life. Altered bone metabolism during treatment for childhood cancer may interfere with attainment of peak bone mass, potentially predisposing to premature onset of and more severe complications related to osteopenia and osteoporosis. Bone mineral deficits have been reported after treatment for a variety of pediatric malignancies and represent morbidity that can be reduced or prevented through lifestyle changes and attention to other common cancer-related sequelae such as hypogonadism. The Children's Oncology Group long-term follow-up guidelines for survivors of childhood, adolescent, and young adult cancers provide risk-based surveillance recommendations that are based on expert opinion and review of the scientific literature for potential late effects of pediatric cancer therapy including osteopenia. This review summarizes the existing literature that has defined characteristics of cancer survivors at risk for bone mineral deficits and contributed to the surveillance and counseling recommendations outlined in the Children's Oncology group long-term follow-up guidelines.

Physical activity, calcium intake and bone health in children and adolescents

Osteoporosis is a serious and potentially debilitating disease, which can lead to a variety of health complications and a diminished quality of life. Consequently, the development of bone mineral density (BMD) and content (BMC) during childhood and adolescence is of great importance, as it may attenuate the effects and incidence of osteoporosis later in life. Identifying the mechanisms by which bones are strengthened early in life is crucial. This review highlights research examining factors that influence BMD and BMC in children and adolescents. While a sizeable amount of variation in BMD and BMC in children and adolescents can be attributed to genetic factors and body size, studies have also shown the positive influence of physical activity and calcium intake on bone development. Research supporting the role of these modifiable factors varies according to age, sex and the bone site studied. During the pubertal years, large gains in BMD and BMC are evident. However, physical activity and calcium intake are also important to the development of BMD and BMC during the prepubertal years. Thus, actions taken throughout childhood may exert a great impact on BMD and BMC, and overall bone health as an adult.

Bone mass accretion rates in pre- and early-pubertal South African black and white children in relation to habitual physical activity and dietary calcium intakes

AIM

To examine bone mass changes in 321 black and white South African children in relation to habitual physical activity (PA) levels and calcium intakes.

METHODS

Children underwent two bone mass scans at ages nine and 10 years using dual X-Ray absorptiometry. PA levels and calcium intakes were assessed using questionnaires. Data were analyzed by regressing change in bone mineral content (BMC) and bone area (BA) from age nine to 10, against BA (for BMC), height and body weight. The residuals were saved and called residualized BMCGAIN and BAGAIN. Residualized values provide good indication of weight, height and BA-matched accumulation rates.

RESULTS

White children had significantly higher PA levels and calcium intakes than black children. Most active white males had significantly higher residualized BMCGAIN and BAGAIN at the whole body, hip and spine but not at the radius, than those who were less active. Most active white females had significantly higher residualized BAGAIN at all sites except the radius than less-active girls. No such effects were seen in black children. There was no interactive effect on residualized BMCGAIN for calcium intake and PA (except at the spine in white girls).

CONCLUSION

Bone mass and area gain is accentuated in pre- and early-pubertal children with highest levels of habitual physical activity. Limited evidence of an effect of dietary calcium intakes on BMC was found.

Effects of calcium supplementation on bone density in healthy children: meta-analysis of randomised controlled trials

OBJECTIVES

To assess the effectiveness of calcium supplementation for improving bone mineral density in healthy children and to determine if any effect is modified by other factors and persists after supplementation stops.

DESIGN

Meta-analysis.

DATA SOURCES

Electronic bibliographic databases, hand searching of conference proceedings, and contacting authors for unpublished data.

REVIEW METHODS

We included randomised placebo controlled trials of calcium supplementation in healthy children that lasted at least three months and had bone outcomes measured after at least six months of follow-up. Two reviewers independently extracted data and assessed quality. Meta-analyses predominantly used fixed effects models with outcomes given as standardised mean differences.

RESULTS

We included 19 studies involving 2859 children. Calcium supplementation had no effect on bone mineral density at the femoral neck or lumbar spine. There was a small effect on total body bone mineral content (standardised mean difference 0.14, 95% confidence interval 0.01 to 0.27) and upper limb bone mineral density (0.14, 0.04 to 0.24). This effect persisted after the end of supplementation only at the upper limb (0.14, 0.01 to 0.28). There was no evidence that sex, baseline calcium intake, pubertal stage, ethnicity, or level of physical activity modified the effect.

CONCLUSIONS

The small effect of calcium supplementation on bone mineral density in the upper limb is unlikely to reduce the risk of fracture, either in childhood or later life, to a degree of major public health importance.

Calcium supplementation for improving bone mineral density in children

BACKGROUND

Clinical trials have shown that calcium supplementation in children can increase bone mineral density (BMD) although this effect may not be maintained. There has been no quantitative systematic review of this intervention.

OBJECTIVES

. To determine the effectiveness of calcium supplementation for improving BMD in children. . To determine if any effect varies by sex, pubertal stage, ethnicity or level of physical activity, and if any effect persists after supplementation is ceased.

SEARCH STRATEGY

We searched CENTRAL, (Cochrane Central Register of Controlled Trials) (Issue 3, 2005), MEDLINE (1966 to 1 April 2005), EMBASE (1980 to 1 April 2005), CINAHL (1982 to 1 April 2005), AMED (1985 to 1 April 2005), MANTIS (1880 to 1 April 2005) ISI Web of Science (1945 to 1 April 2005), Food Science and Technology Abstracts (1969 to 1 April 2005) and Human Nutrition (1982 to 1 April 2005). Conference abstract books (Osteoporosis International, Journal of Bone and Mineral Research) were hand-searched.

SELECTION CRITERIA

Randomised controlled trials of calcium supplementation (including by food sources) compared with placebo, with a treatment period of at least 3 months in children without co-existent medical conditions affecting bone metabolism. Outcomes had to include areal or volumetric BMD, bone mineral content (BMC), or in the case of studies using quantitative ultrasound, broadband ultrasound attenuation and ultrasonic speed of sound, measured after at least 6 months of follow-up.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data including adverse events. We contacted study authors for additional information.

MAIN RESULTS

The 19 trials included 2859 participants, of which 1367 were randomised to supplementation and 1426 to placebo. There was no heterogeneity in the results of the main effects analyses to suggest that the studies were not comparable. There was no effect of calcium supplementation on femoral neck or lumbar spine BMD. There was a small effect on total body BMC (standardised mean difference (SMD) +0.14, 95% CI+0.01, +0.27) and upper limb BMD (SMD +0.14, 95%CI +0.04, +0.24). Only the effect in the upper limb persisted after supplementation ceased (SMD+0.14, 95%CI+0.01, +0.28). This effect is approximately equivalent to a 1.7% greater increase in supplemented groups, which at best would reduce absolute fracture risk in children by 0.1-0.2%per annum. There was no evidence of effect modification by baseline calcium intake, sex, ethnicity, physical activity or pubertal stage. Adverse events were reported infrequently and were minor.

AUTHORS' CONCLUSIONS

While there is a small effect of calcium supplementation in the upper limb, the increase in BMD which results is unlikely to result in a clinically significant decrease in fracture risk. The results do not support the use of calcium supplementation in healthy children as a public health intervention. These results cannot be extrapolated to children with medical conditions affecting bone metabolism.

Physical activity and strength of the femoral neck during the adolescent growth spurt: a longitudinal analysis

Loading of the femoral neck (FN) is dominated by bending and compressive stresses. We hypothesize that adaptation of the FN to physical activity would be manifested in the cross-sectional area (CSA) and section modulus (Z) of bone, indices of axial and bending strength, respectively. We investigated the influence of physical activity on bone strength during adolescence using 7 years of longitudinal data from 109 boys and 121 girls from the Saskatchewan Paediatric Bone and Mineral Accrual Study (PBMAS). Physical activity data (PAC-Q physical activity inventory) and anthropometric measurements were taken every 6 months and DXA bone scans were measured annually (Hologic QDR2000, array mode). We applied hip structural analysis to derive strength and geometric indices of the femoral neck using DXA scans. To control for maturation, we determined a biological maturity age defined as years from age at peak height velocity (APHV). To account for the repeated measures within individual nature of longitudinal data, multilevel random effects regression analyses were used to analyze the data. When biological maturity age and body size (height and weight) were controlled, in both boys and girls, physical activity was a significant positive independent predictor of CSA and Z of the narrow region of the femoral neck (P < 0.05). There was no independent effect of physical activity on the subperiosteal width of the femoral neck. When leg length and leg lean mass were introduced into the random effects models to control for size and muscle mass of the leg (instead of height and weight), all significant effects of physical activity disappeared. Even among adolescents engaged in normal levels of physical activity, the statistically significant relationship between physical activity and indices of bone strength demonstrate that modifiable lifestyle factors like exercise play an important role in optimizing bone strength during the growing years. Physical activity differences were explained by the interdependence between activity and lean mass considerations. Physical activity is important for optimal development of bone strength.

Dietary calcium and bone mineral density in premenopausal women with systemic lupus erythematosus

The primary objective of this study was to determine the relationship between dietary calcium intake and bone mineral density (BMD) in premenopausal women with systemic lupus erythematosus (SLE) on corticosteroids (CS). The secondary aim was to identify other risk factors for osteoporosis in these patients. A cross-sectional sample of patients attending the SLE Clinic at a teaching hospital was recruited. BMD was measured using dual-energy X-ray absorptiometry. Daily dietary calcium intake was assessed using a structured validated food frequency questionnaire, in which patients were asked to estimate their food intake based on their recent 2-month dietary habits. Sixty subjects were recruited with a mean age of 33.70+/-8.46 years. The median duration of CS use was 5.5 years (range 0.08-24). The median cumulative dose of steroids was 17.21 g (range 0.16-91.37). The median daily dietary calcium intake was 483 mg (range 78-2101). There was no significant correlation between calcium intake and BMD, even after correcting for CS use. There were also no correlations between BMD and the duration of SLE, cumulative CS use, duration of CS use, smoking, alcohol intake, and SLE disease activity index score. Twenty-eight (46.7%) patients had normal BMD, 28 (46.7%) had osteopenia, and four (6.6%) had osteoporosis. Duration of SLE significantly correlated with cumulative CS dosage. In conclusion, 6.7% of these Asian premenopausal SLE women had osteoporosis and only 46.7% had normal BMD. Daily dietary calcium intake did not correlate with BMD.

A mother-based intervention trial for osteoporosis prevention in children

OBJECTIVE

To assess whether a lifestyle intervention delivered to mothers might impact on osteoporosis preventive behaviors in their children.

METHODS

We performed a 2-year randomized controlled trial of individualized bone mineral density feedback with either an osteoporosis information leaflet, or small group education, in a population-based sample of 354 mothers from Southern Tasmania, Australia in 2000-02. Main outcomes were maternal report of calcium intake and physical activity change in their children.

RESULTS

Receiving small group education was associated with mothers' report of increasing children's calcium intake (odds ratio 2.3, 95% confidence interval 1.4, 3.8), as was low t-score feedback (odds ratio 2.0, 95% confidence interval 1.2, 3.3). Mothers who increased their own physical activity were more often reported increasing both physical activity (odds ratio 2.7, 95% confidence interval 1.5, 5.0) and calcium intake in their children (odds ratio 2.2, 95% confidence interval 1.3, 3.7). Mothers who commenced calcium supplements more often reported increasing children's calcium intake (odds ratio 2.6, 95% confidence interval 1.0, 6.7) but not physical activity.

CONCLUSIONS

Both bone mineral density feedback and small group education delivered to mothers are effective at inducing maternally reported osteoporosis preventive behavior change in their children. These results require confirmation by studies with objective outcome measures.

Effects of calcium, dairy product, and vitamin D supplementation on bone mass accrual and body composition in 10-12-y-old girls: a 2-y randomized trial

BACKGROUND

Little is known about the relative effectiveness of calcium supplementation from food or pills with or without vitamin D supplementation for bone mass accrual during the rapid growth period.

OBJECTIVE

The purpose was to examine the effects of both food-based and pill supplements of calcium and vitamin D on bone mass and body composition in girls aged 10-12 y.

DESIGN

This placebo-controlled intervention trial randomly assigned 195 healthy girls at Tanner stage I-II, aged 10-12 y, with dietary calcium intakes <900 mg/d to 1 of 4 groups: calcium (1000 mg) + vitamin D3 (200 IU), calcium (1000 mg), cheese (1000 mg calcium), and placebo. Primary outcomes were bone indexes of the hip, spine, and whole body by dual-energy X-ray absorptiometry and of the radius and tibia by peripheral quantitative computed tomography.

RESULTS

With the use of intention-to-treat or efficacy analysis, calcium supplementation with cheese resulted in a higher percentage change in cortical thickness of the tibia than did placebo, calcium, or calcium + vitamin D treatment (P = 0.01, 0.038, and 0.004, respectively) and in higher whole-body bone mineral density than did placebo treatment (P = 0.044) when compliance was >50%. With the use of a hierarchical linear model with random effects to control for growth velocity, these differences disappeared.

CONCLUSIONS

Increasing calcium intake by consuming cheese appears to be more beneficial for cortical bone mass accrual than the consumption of tablets containing a similar amount of calcium. Diverse patterns of growth velocity may mask the efficacy of supplementation in a short-term trial of children transiting through puberty.

Increasing weight-bearing physical activity and calcium-rich foods to promote bone mass gains among 9-11 year old girls: outcomes of the Cal-Girls study

Background

A two-year, community-based, group-randomized trial to promote bone mass gains among 9–11 year-old girls through increased intake of calcium-rich foods and weight-bearing physical activity was evaluated.

Methods

Following baseline data collection, 30 5th-grade Girl Scout troops were randomized to a two-year behavioral intervention program or to a no-treatment control group. Evaluations were conducted at baseline, one year, and two years. Measures included bone mineral content, density, and area (measured by DXA), dietary calcium intake (24-hour recall), and weight-bearing physical activity (physical activity checklist interview). Mixed-model regression was used to evaluate treatment-related changes in bone mineral content (g) for the total body, lumbar spine (L1-L4), proximal femur, one-third distal radius, and femoral neck. Changes in eating and physical activity behavioral outcomes were examined.

Results

Although the intervention was implemented with high fidelity, no significant intervention effects were observed for total bone mineral content or any specific bone sites. Significant intervention effects were observed for increases in dietary calcium. No significant intervention effects were observed for increases in weight-bearing physical activity.

Conclusion

Future research needs to identify the optimal dosage of weight-bearing physical activity and calcium-rich dietary behavior change required to maximize bone mass gains in pre-adolescent and adolescent girls.

The relationship of dietary and lifestyle factors to bone mineral indexes in children

OBJECTIVE

To identify factors related to children's bone mineral indexes at age 8 years, and to assess bone mineral indexes in the same children at ages 6 and 8 years.

DESIGN

Bone mineral content (BMC [g]) and bone mineral density (BMD; calculated as g/cm 2 ) were measured by dual-energy x-ray absorptiometry (DEXA) in children and their mothers when the children were 8 years of age. A subset of children had an earlier DEXA assessment at age 6 years. Children's dietary intake, height, weight, and level of sedentary activity were assessed as part of a longitudinal study from ages 2 months to 8 years.

SUBJECTS/SETTING

Fifty-two healthy white children (25 male, 27 female) and their mothers. Main outcome measures Children's total BMC and BMD at age 8 years.

STATISTICAL ANALYSES PERFORMED

Correlations and stepwise multiple regression analyses.

RESULTS

Factors positively related to children's BMC at age 8 years included longitudinal intakes (ages 2 to 8 years) of protein, phosphorus, vitamin K, magnesium, zinc, energy, and iron; height; weight; and age ( P < or = .05). Factors positively related to children's BMD at age 8 years included longitudinal intakes of protein and magnesium ( P < or = .05). Female sex was negatively associated with BMC and BMD at age 8 years ( P < or = .05). Children's bone mineral indexes at ages 6 and 8 years were strongly correlated ( r =0.86, P < .0001 for BMC; r =0.92, P <.0001 for BMD).

CONCLUSIONS

Because many nutrients are related to bone health, children should consume a varied and nutrient-dense diet.

Potential benefits of physical activity for children with acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) is the most common form of paediatric leukaemia. The survival rate in children with ALL has improved significantly over the past several years, which makes quality of life an important focus for researchers. Some of the side effects of treatment (i.e. osteoporosis and obesity) are not realized until years after conclusion of therapy. Few studies have addressed the impact of physical activity (PA) on the side effects that occur during treatment of children with ALL. This paper discusses the increased risk for both osteoporosis and obesity due to treatment for ALL and suggests ways that PA may attenuate bone loss and risk of obesity by discussing what is known about effects of PA in healthy children and children with other chronic diseases. Recommendations will be made for PA interventions and future research in children with ALL.