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

Skeletal Loading: Lean and Bone Mass Development in Young Elite Male Gymnasts, Swimmers, and Nonathletes Aged 6-24 Years

BACKGROUND

Exercise optimizes peak bone mass accrual, particularly if the loading is high magnitude and distributed in abnormal directions. Little is known about the influence of early intense training in sport during peak bone mass accrual, especially in boys.

METHODS

Ninety-eight males aged 6-24 years (gymnasts, swimmers, and controls) completed the bone-specific physical activity questionnaire and a 7-day exercise diary. Dual-energy X-ray absorptiometry determined bone mineral properties of the total body (less head) and lumbar spine (LS, L1-L4) and total lean mass. Subgroup analyses were conducted for juniors (prepubescent), adolescents (11-16 y), and seniors (17-24 y).

RESULTS

Lean mass was positively associated with total body less head and LS bone outcomes in all 3 age groups (R2 = .632-.770, P < .05), and bone-specific physical activity questionnaire scores were associated with LS bone mineral density in adolescents and seniors (R2 = .440 and .591, P < .05). Senior gymnasts had significantly higher LS bone mineral density (in grams per square centimeter) and Z-scores than swimmers (P = .004) and controls (P = .012).

CONCLUSIONS

Elite gymnastics is associated with superior peak bone mass accrual in young males. The benefits appear more pronounced during young adulthood compared with prepuberty, potentially reflecting an extended time course for bone adaptation.

Correlation between physical activity and adolescent idiopathic scoliosis: a systematic review

BACKGROUND

The multifactorial aetiology of scoliosis is well known. Physical activity is considered both a treatment and causative factor for idiopathic scoliosis; however, evidence for a causal relationship between physical activity levels and idiopathic scoliosis in adolescents is conflicting. Therefore, we aimed to summarise the current evidence regarding the association between adolescent idiopathic scoliosis and physical activity and further to assess whether the relationship is dose dependent.

METHODS

PubMed, Cochrane, Scopus, and Web of Science databases were searched from 1991 to July 2022 using the following main keywords: adolescent idiopathic scoliosis, physical activity, and risk factors, supplemented with manual searches, secondary citations, and reference searches. The quality of the included literature was evaluated using the Scale for Reporting Observational Studies in Enhanced Epidemiology guidelines.

RESULTS

Eight studies were included in this review, of which six reported an association between adolescent idiopathic scoliosis and physical activity levels and two reported no association. One British study reported reduced physical function early in life as a new risk factor for scoliosis onset.

CONCLUSIONS

Physical activity is strongly associated with adolescent idiopathic scoliosis. Physical activity should be encouraged as it plays an important role in the prevention of adolescent idiopathic scoliosis. Further research is needed to determine the dose-dependent relationship between physical activity and prevention of adolescent idiopathic scoliosis.

Risk factors associated with low bone mineral density in children with idiopathic scoliosis: a scoping review

BACKGROUND

Children with idiopathic scoliosis (IS) have a high risk of osteoporosis and IS with low bone mineral density (BMD) are susceptible to curve progression. This review aims to explore the risk factors of low BMD in children with IS.

METHODS

Studies were retrieved from 5 databases that were published up to January 2022. Search terms are keywords in titles or abstracts, including subject headings related to "Scoliosis", "Bone Mineral Density", and "Risk Factors". Observational studies on risk factors of low BMD in children with IS were enrolled in this review. The number of studies, sample size, outcome measures, research type, endocrine, and lifestyle-related factors, gene/signal pathway, and other contents were extracted for qualitative analysis.

RESULTS

A total of 56 studies were included in this scoping review. Thirty studies involved genetic factors that may affect BMD, including the Vitamin-D receptor gene, RANK/RANKL signal pathway, the function of mesenchymal stem cells, Runx2, Interleukin-6 (IL-6), and miR-145/β-catenin pathway. Eight studies mentioned the influence of endocrine factors on BMD, and the results showed that serum levels of IL-6, leptin and its metabolites, and ghrelin in children with IS were different from the age-matched controls. In addition, there were 18 articles on lifestyle-related factors related to low BMD in children with IS, consisting of physical activity, calcium intake, Vitamin D level, and body composition.

CONCLUSIONS

Genetic, endocrine, and lifestyle-related factors might relate to low BMD and even osteoporosis in IS. To prevent osteoporosis, the effectiveness of regular screening for low BMD risk factors in children with IS needs to be investigated. Additionally, clear risk factors suggest strategies for bone intervention. Future studies should consider the effectiveness of calcium and vitamin D supplements and physical activity in BMD improvement.

Compositional and functional properties of milk and dairy products derived from cows fed pasture or concentrate-based diets

Worldwide milk production is predominantly founded on indoor, high-concentrate feeding systems, whereas pasture-based feeding systems are most common in New Zealand and Ireland but have received greater attention recently in countries utilizing conventional systems. Consumer interest in 'pasture-fed' dairy products has also increased, arising from environmental, ethical, and nutritional concerns. A substantial body of research exists describing the effect of different feeding strategies on the composition of milk, with several recent studies focusing on the comparison of pasture- and concentrate-based feeding regimes. Significant variation is typically observed in the gross composition of milk produced from different supplemental feeds, but various changes in the discrete composition of macromolecular components in milk have also been associated with dietary influence, particularly in relation to the fatty acid profile. Changes in milk composition have also been shown to have implications for milk and dairy product processability, functionality and sensory properties. Methods to determine the traceability of dairy products or verify marketing claims such as 'pasture-fed' have also been established, based on compositional variation due to diet. This review explores the effects of feed types on milk composition and quality, along with the ultimate effect of diet-induced changes on milk and dairy product functionality, with particular emphasis placed on pasture- and concentrate-based feeding systems.

Does Sex Dimorphism Exist in Dysfunctional Movement Patterns during the Sensitive Period of Adolescence?

This study aimed to investigate sex difference in the functional movement in the adolescent period. Seven hundred and thirty adolescents (365 boys) aged 16-17 years participated in the study. The participants performed standardized Functional Movement Screen™ (FMS^TM) protocol and a t-test was used to examine sex differences in the total functional movement screen score, while the chi-square test was used to determine sex differences in the proportion of dysfunctional movement and movement asymmetries within the individual FMS^TM tests. Girls demonstrated higher total FMS^TM score compared to boys (12.7 ± 2.3 and 12.2 ± 2.4, respectively; p = 0.0054). Sex differences were present in several individual functional movement patterns where boys demonstrated higher prevalence of dysfunctional movement compared to girls in patterns that challenge mobility and flexibility of the body (inline lunge: 32% vs. 22%, df = 1, p = 0.0009; shoulder mobility: 47% vs. 26%, df = 1, p < 0.0001; and active straight leg raise: 31% vs. 9%, df = 1, p < 0.0001), while girls underperformed in tests that have higher demands for upper-body strength and abdominal stabilization (trunk stability push-up: 81% vs. 44%, df = 1, p < 0.0001; and rotary stability: 54% vs. 44%, df = 1, p = 0.0075). Findings of this study suggest that sex dimorphisms exist in functional movement patterns in the period of mid-adolescence. The results of this research need to be considered while using FMS^TM as a screening tool, as well as the reference standard for exercise intervention among the secondary school-aged population.

Growth of cortical bone thickness and trabecular bone density in Japanese children

BACKGROUND

The acquisition of a high bone density at a young age is a strategy to prevent fractures/falls later in life. We therefore decided to investigate the increases in cortical thickness (CoTh) and trabecular bone density (TBD) of children.

METHODS

Subjects comprised 1314 students (678 boys and 636 girls) aged between 12 and 18 years. Lifestyle factors were examined with a self-administered questionnaire (sleep times, exercise habits, and calcium intake). Bone growth was assessed based on CoTh and TBD using an ultrasonic bone densitometer. Height, weight, and body fat percentage were also measured.

RESULTS

Increases in CoTh and TBD occurred earlier in girls than in boys. Calcium intake was not sufficient at any of the ages examined, and sleep times were shorter than those recommended by the National Sleep Foundation. Increases in CoTh and TBD occurred subsequent to increases in height. Although increases in CoTh were observed with age in both sexes, TBD increased in boys until the age of 17 years and in girls until the age of 15 years. At 18 years of age, the young adult mean value was greater than 100% for CoTh but lower than 100% for TBD. A multivariate analysis identified age, body mass index (BMI), and exercise as independent positive factors for CoTh, while body fat percentage was an independent negative factor. Age and BMI were independent positive factors for TBD in both sexes, whereas body fat percentage was a positive factor in boys only.

CONCLUSIONS

The study found that CoTH and TBD varied with age and differed in increase in boys and girls; related factors of bone increase could also be found. The results of this study may contribute to the acquisition of high bone density in children and adolescents.

Physical activity and health in Chinese children and adolescents: expert consensus statement (2020)

China is experiencing significant public health challenges related to social and demographic transitions and lifestyle transformations following unprecedented economic reforms four decades ago. Of particular public health concern is the fourfold increase in overweight and obesity rates in the nation's youth population, coupled with the low prevalence of adolescents meeting recommended levels of physical activity. Improving the overall health of China's more than 170 million children and adolescents has become a national priority. However, advancing nationwide health initiatives and physical activity promotion in this population has been hampered by the lack of a population-specific and culturally relevant consensus on recommendations for achieving these ends. To address this deficiency and inform policies to achieve Healthy China 2030 goals, a panel of Chinese experts, complemented by international professionals, developed this consensus statement. The consensus was achieved through an iterative process that began with a literature search from electronic databases; in-depth reviews, conducted by a steering committee, of the resulting articles; and panel group evaluations and discussions in the form of email correspondence, conference calls and written communications. Ultimately, the panel agreed on 10 major themes with strong scientific evidence that, in children and adolescents aged 6-17, participating in moderate to vigorous physical activities led to multiple positive health outcomes. Our consensus statement also (1) highlights major challenges in promoting physical activity, (2) identifies future research that addresses current knowledge gaps, and (3) provides recommendations for teachers, education experts, parents and policymakers for promoting physical activity among Chinese school-aged children and adolescents. This consensus statement aligns with international efforts to develop global physical activity guidelines to promote physical activity and health and prevent lifestyle-related diseases in children and adolescents. More importantly, it provides a foundation for developing culturally appropriate and effective physical activity interventions, health promotion strategies and policy initiatives to improve the health of Chinese children and adolescents.

Human skeletal physiology and factors affecting its modeling and remodeling

Human skeleton is a living tissue that performs structural and metabolic functions. It is not only the largest storehouse for calcium and other essential ions but also a depot for toxic chemicals faced by human body throughout life. Skeletal modeling starts at conception and then throughout life undergoes constant remodeling to adopt its shape and strength according to human needs. With the passage of time, like other tissues in the body, bones also bear the brunt of life and in this life long process loses its strength and vitality. Multiple genetic and environmental factors play an integral part in its formation, strength, and decline.

Correlation Between Bone Density and Lumbar Compression Fractures

Objectives: Bone densitometry is widely used to evaluate osteoporosis; however, it is pointed out that bone density may be high in the case of fractures, deformities, and osteosclerotic changes. The present study evaluated bone density measured at our hospital and evaluated its correlation with the presence or absence of lumbar spine fractures. Methods: Bone density of the lumbar spine and femur was measured in 185 patients from July 2017 to June 2019 at our hospital, and the presence or absence of a lumbar spine compression fracture was evaluated on the basis of the image. Information regarding age, sex, lumbar bone density, presence or absence of lumbar fracture, number of lumbar fractures, and grade of lumbar fracture was also statistically evaluated. Results: Analysis was performed for 185 patients (20 males and 165 females, average age 76.9 ± 7.5 years). The bone density was 0.830 ± 0.229 of compression fractured bodies (number of vertebral bodies were 132) and 0.765 ± 0.178 g/cm³ of noncompression fractured bodies (number of vertebral bodies was 608). Discussion: The presence of lumbar fractures significantly increases bone density. For diagnosing osteoporosis, both bone density and the possibility of lumbar spine fractures must be considered.

Beat osteoporosis - nourish and exercise skeletons (BONES): a group randomized controlled trial in children

BACKGROUND

Lifelong healthy habits developed during childhood may prevent chronic diseases in adulthood. Interventions to promote these habits must begin early. The BONES (Beat Osteoporosis - Nourish and Exercise Skeletons) project assessed whether early elementary school children participating in a multifaceted health behavior change, after-school based intervention would improve bone quality and muscular strength and engage in more bone-strengthening behaviors.

METHODS

The 2-year BONES (B) intervention included bone-strengthening physical activity (85 min/week), educational materials (2 days/week), and daily calcium-rich snacks (380 mg calcium/day) delivered by after-school program leaders. BONES plus Parent (B + P) included an additional parent education component. From 1999 to 2004, n = 83 after-school programs (N = 1434 children aged 6-9 years) in Massachusetts and Rhode Island participated in a group randomized trial with two intervention arms (B only, n = 25 programs; B + P, n = 33) and a control arm (C, n = 25). Outcome measures (primary: bone quality (stiffness index of the calcaneus) and muscular strength (grip strength and vertical jump); secondary: bone-strengthening behaviors (calcium-rich food knowledge, preference, and intake; and physical activity level (metabolic equivalent time (MET) score, and weight-bearing factor (WBF) score)) were recorded at baseline, and after years one and two. Analyses followed an intent-to-treat protocol, and focused on individual subjects' trajectories along the three time points adjusting for baseline age and race via a mixed-effects regression framework. Analyses were performed with and without sex stratification.

RESULTS

Children in B + P increased bone stiffness compared to C (p = 0.05); No significant changes were observed in muscle strength, food knowledge, or vertical jump. Children in B + P showed significant improvement in their MET and WBF scores compared to C (p < 0.01) with a stronger effect in boys in both B and B + P (all p < 0.01).

CONCLUSION

After-school programs, coupled with parental engagement, serving early elementary school children are a potentially feasible platform to deliver bone-strengthening behaviors to prevent osteoporosis in adulthood, with some encouraging bone and physical activity outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00065247. Retrospectively registered. First posted July 22, 2003.

Calcaneal Broadband Ultrasound Attenuation and Speed of Sound Measurements in a Population of Nigerian Children: Reference Data and the Influence of Sociodemographic Variables

OBJECTIVES

The aim of our study was to establish a reference database of calcaneal broadband ultrasound attenuation (BUA) and the speed of sound (SOS) in a healthy Nigerian population of children aged 6 to 14 years and also to investigate the influence of sociodemographic and anthropometric variables on them.

METHODS

The BUA and SOS of 1016 healthy children were measured by quantitative ultrasound densitometry. Height and weight were measured with a stadiometer and weighing balance, respectively, whereas the sociodemographic parameters of the participants were collected on a semistructured questionnaire. A multiple regression model using stepwise selection and Pearson correlation coefficients were used to examine the relationship between the ultrasound parameters and sociodemographic and anthropometric parameters. Comparisons between various age groups were made by analysis of variance.

RESULTS

The mean BUA and SOS ± SD of the participants were 60.57 ± 16.21 dB/MHz and 1563.48 ± 21.74 m/s, respectively, for boys and 58.18 ± 15.16 dB/MHz and 1560.03 ± 22.32 m/s for girls. The BUA in both sexes was positively influenced by age and weight (P < .05), whereas only the father's educational status was its predictor (P < .05) in the boys. For the girls, the family size and mother's educational status were predictors of the BUA (P < .05). The SOS was marginally influenced by age and family size in the boys (P < .05), whereas the father's educational status was the predictor in the girls.

CONCLUSIONS

The established BUA and SOS values in this study are baseline values, and further study, which would also involve data from a large number of Nigerian children, would be needed to support their effectiveness as reference values.

Diagnosis of osteoporotic vertebral fractures in children

Osteoporosis is a generalised disorder of the skeleton with reduced bone density and abnormal bone architecture. It increases bone fragility and renders the individual susceptible to fractures. Fractures of the vertebrae are common osteoporotic fractures. Vertebral fractures may result in scoliosis or kyphosis and, because they may be clinically silent, it is imperative that vertebral fractures are diagnosed in children accurately and at an early stage, so the necessary medical care can be implemented. Traditionally, diagnosis of osteoporotic vertebral fractures has been from lateral spine radiographs; however, a small number of studies have shown that dual energy x-ray absorptiometry is comparable to radiographs for identifying vertebral fractures in children, while allowing reduced radiation exposure. The diagnosis of vertebral fractures from dual energy x-ray absorptiometry is termed vertebral fracture assessment. Existing scoring systems for vertebral fracture assessment in adults have been assessed for use in children, but there is no standardisation and observer reliability is variable. This literature review suggests the need for a semiautomated tool that (compared to the subjective and semiquantitative methods available) will allow more reliable and precise detection of vertebral fractures in children.

The interactions of physical activity, exercise and genetics and their associations with bone mineral density: implications for injury risk in elite athletes

Low bone mineral density (BMD) is established as a primary predictor of osteoporotic risk and can also have substantial implications for athlete health and injury risk in the elite sporting environment. BMD is a highly multi-factorial phenotype influenced by diet, hormonal characteristics and physical activity. The interrelationships between such factors, and a strong genetic component, suggested to be around 50-85% at various anatomical sites, determine skeletal health throughout life. Genome-wide association studies and case-control designs have revealed many loci associated with variation in BMD. However, a number of the candidate genes identified at these loci have no known associated biological function or have yet to be replicated in subsequent investigations. Furthermore, few investigations have considered gene-environment interactions-in particular, whether specific genes may be sensitive to mechanical loading from physical activity and the outcome of such an interaction for BMD and potential injury risk. Therefore, this review considers the importance of physical activity on BMD, genetic associations with BMD and how subsequent investigation requires consideration of the interaction between these determinants. Future research using well-defined independent cohorts such as elite athletes, who experience much greater mechanical stress than most, to study such phenotypes, can provide a greater understanding of these factors as well as the biological underpinnings of such a physiologically "extreme" population. Subsequently, modification of training, exercise or rehabilitation programmes based on genetic characteristics could have substantial implications in both the sporting and public health domains once the fundamental research has been conducted successfully.

Modifiable factors associated with bone health in Malaysian adolescents utilising calcaneus quantitative ultrasound

Maximizing bone mineral accrual to attain an optimal peak bone mass (PBM), particularly during adolescence, appears to be an effective protective strategy in the prevention of osteoporosis. This study aimed to evaluate the influence of physical activity (PA), fat mass (FM), lean mass (LM), body mass index (BMI), calcium, or combination of vitamin D supplement intake, smoking and alcohol drinking status on bone health assessed by calcaneus quantitative ultrasound (QUS) in a healthy adolescent population. The participants comprised of 920 male and female secondary school adolescents aged 15–17 years old. Quantitative ultrasound measurements of the left heel were performed using Lunar Achilles EX II, which included results of broadband ultrasound attenuation (BUA), speed of sound (SOS), and a calculated stiffness index (SI). Multivariable linear regression analyses revealed that—PA was positively associated with all three QUS indices in both genders; BMI was positively associated with SI and SOS in females; LM was positively associated with BUA in both genders; and FM was negatively associated with SI in females. These variables accounted for 32.1%, 21.2% and 29.4% of females’ SOS, BUA and SI variances (p<0.001), respectively and 23.6%, 15.4% and 17.2% of males’ SOS, BUA and SI variances (p<0.001), respectively. Promoting health benefits from physical activity could influence bone status and consequently improve PBM, which is a potent protective determinant against osteoporosis in adulthood.

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.

Occlusal disharmony-induced stress causes osteopenia of the lumbar vertebrae and long bones in mice

Excessive exposure to glucocorticoids causes osteoporosis in children and adults. Occlusal disharmony is known to induce an increase in serum corticosteroid levels in murine models, but the influence of occlusal disharmony-induced stress on the bone mass during the growth period has not yet been clarified. The purpose of this study was to investigate whether occlusal disharmony-induced stress decreases bone mass. Five-week-old C57BL/6J male mice were used. A 0.5-mm increase in the vertical height of occlusion was used to induce occlusal disharmony for a period of 7 days. Serum corticosterone levels were significantly higher on post-induction day 7, with radiological evidence of osteopenia of the third lumbar vertebra and long bones of the hind limbs. Osteopenia was associated with a reduction of the mechanical properties of the tibia and femur, with significant suppression of bone formation parameters and an increase in bone resorption parameters, as evaluated by bone histomorphometric analysis of the tibial/femur metaphysis. Our findings at the level of bones were supported by our assessment of serum markers of systemic metabolism. Therefore, occlusal disharmony-induced stress may lead to osteopenia and reduce the mechanical strength of bone through an increase in serum glucocorticoid levels in mice.

Diet and Exercise: a Match Made in Bone

PURPOSE OF REVIEW

Multiple dietary components have the potential to positively affect bone mineral density in early life and reduce loss of bone mass with aging. In addition, regular weight-bearing physical activity has a strong positive effect on bone through activation of osteocyte signaling. We will explore possible synergistic effects of dietary components and mechanical stimuli for bone health by identifying dietary components that have the potential to alter the response of osteocytes to mechanical loading.

RECENT FINDINGS

Several (sub)cellular aspects of osteocytes determine their signaling towards osteoblasts and osteoclasts in response to mechanical stimuli, such as the osteocyte cytoskeleton, estrogen receptor α, the vitamin D receptor, and the architecture of the lacunocanalicular system. Potential modulators of these features include 1,25-dihydroxy vitamin D3, several forms of vitamin K, and the phytoestrogen genistein. Multiple dietary components potentially affect osteocyte function and therefore may have a synergistic effect on bone health when combined with a regime of physical activity.

Pregnancy-associated osteoporosis: a case-control study

The etiology and underlying mechanisms of pregnancy-associated osteoporosis (PAO) are still unknown, since no systematic analyses exist. Our results indicate that PAO is a heterogeneous, rare but severe disease including a substantial number of fractures with a significant delay from first symptom to diagnose.

INTRODUCTION

Pregnancy-associated osteoporosis (PAO) is a rare but severe type of premenopausal osteoporosis. Most common symptom includes acute lower back pain due to vertebral fracture predominantly occurring in the last trimester of pregnancy or immediately postpartum. The exact underlining mechanisms and risk factors of PAO are still unknown, and up to date, there are no published systematic analyses.

METHODS

We identified 102 PAO patients and matched them with 102 healthy controls according to age, region, and gravidity to evaluate risk factors in a large and homogenous population of women.

RESULTS

The baseline characteristics and anthropometric data of the two study groups were similar. Eighty-eight percent of the patients with PAO suffered from one or more fractures with a mean of 3.3 fractures per patient. The most common fracture site was the thoracolumbar spine, whereas 29, 37, 48, and 35% of the patients reported fractures at TH11, TH12, L1, and L2, respectively. PAO patients suffered more frequently from excessive dental problems in childhood (p < 0.001). The control group performed significantly more frequently sports both before (p < 0.002) and after puberty (p < 0.01). Compared to the controls, the patients with PAO reported twice as often severe diseases during pregnancy (p < 0.029). Hereby, the frequency of immobilization was twice as often in the PAO group compared to that in the control group (p < 0.005).

CONCLUSIONS

Our results indicate that PAO is a heterogeneous, rare but severe disease including a substantial number of fractures with a significant delay from first symptom to diagnose. Increased awareness is warranted to immediately start effective treatment.

Adequate calcium intake during long periods improves bone mineral density in healthy children. Data from the Childhood Obesity Project

BACKGROUND

Bone mineralization can be influenced by genetic factors, hormonal status, nutrition, physical activity and body composition. The association of higher calcium (Ca) intake or Ca supplementation with better bone mineral density (BMD) remains controversial. Furthermore, it has been speculated that maintaining long-term adequate Ca intake rather than having a brief supplementation period is more effective. The aim of the study was to prospectively analyse the influence of adequate Ca intake on BMD at 7 years of age in European children.

METHODS

Data from the Childhood Obesity Project were analysed in a prospective longitudinal cohort trial. Dietary intake was recorded using 3-day food records at 4, 5 and 6 years of age. The probability of adequate intake (PA) of Ca was calculated following the American Institute of Medicine guidelines for individual assessments, with FAO, WHO and United Nations University joint expert consultation dietary recommendations. Children were categorised as having high Ca PA (PA >95%) or not (PA <95%). At 7 years, whole body (WB) and lumbar spine (LS) BMD were measured in the Spanish subsample by dual-energy x-ray absorptiometry. Internal BMD z-scores were calculated; BMD below -1 z-score were considered to indicate osteopenia, and BMD z-scores below -2, "low bone mineral density for age".

RESULTS

BMD was measured in 179 children. Ca intake at 6 years was positively correlated with LS BMD at 7 years (R = 0.205, p = 0.030). A Ca increase of 100 mg/day explained 19.4% (p = 0.011) of the LS BMD z-score variation, modifying it by 0.089 (0.021, 0.157) units. Children with Ca PA >95% at 5 and 6 or from 4 to 6 years of age showed higher BMD z-scores at the LS and WB levels than children with Ca PA <95% (p < 0.001 and p < 0.05 for LS and WB BMD, respectively). Ca PA >95% maintained over 2 years explained 26.3% of the LS BMD z-score variation (p < 0.001), increasing it by 0.669 (0.202, 1.137). PA >95% maintained over 3 years explained 24.9% of the LS BMD z-score variation, increasing it by 0.773 (0.282, 1.264). The effects of Ca adequacy on WB BMD were similar. Children with PA >95% over 2 years had an Odds ratio of 13.84 and 12 for osteopenia at the LS and WB levels, respectively (p = 0.001).

CONCLUSIONS

Long periods of adequate Ca intake in childhood increase BMD and reduce osteopenia risk. The Childhood Obesity Project clinical trial (CHOP) was registered at clinicaltrials.gov as NCT00338689.

Dietary intakes in children born small for gestational age and appropriate for gestational age: A longitudinal study

Children born small for gestational age (SGA) have an increased risk of cardiovascular disease (CVD) and associated risk factors in later life; however, little is known about their dietary intakes. The objective of this study was to assess dietary intakes in SGA and appropriate for gestational age (AGA) at 3.5, 7, and 11 years. The Auckland Birthweight Collaborative Study is a longitudinal case-control study of children born at term (n = 871). Children were assessed at 3.5 (n = 550), 7 (n = 591), and 11 (n = 620) years of age. Diet was assessed using a 24-hr record-assisted recall. Reported dietary intakes were analyzed and compared with the Australian and New Zealand Nutrient Reference Values. Compared with AGA, median energy intakes were significantly lower in SGA at 3.5 years (4.2 MJ [IQR, 3.0 to 5.8] vs. 5.4 MJ [IQR, 3.9 to 6.5]; p < .0001) but not at 7 and 11 years. Inadequate dietary intakes of micronutrients were more prevalent among SGA at 3.5 years and 11 years of age. A large proportion of SGA and AGA children consumed more than the recommended amounts of saturated fats, sugars, and sodium. There was no association of dietary intake and socio-demographic factors. This study reveals that dietary intake in 3.5-year-old children born SGA is lower in energy and a variety of micronutrients compared with dietary intake in AGA. These intakes may however be appropriate given their BMI z-scores. High intakes of sodium, saturated fat, and sugars are a concern for all children in this cohort.

Abnormal Bone Mechanical and Structural Properties in Adolescent Idiopathic Scoliosis: A Study with Finite Element Analysis and Structural Model Index

Previous studies found adolescent idiopathic scoliosis (AIS) is associated with low bone mineral density (BMD) and abnormal bone quality, whilst the association between AIS and their bone strength is unknown. From high-resolution peripheral quantitative computed tomography-generated images, bone mechanical properties can be evaluated with finite element analysis (FEA), and trabecular rod-plate configuration related to trabecular bone strength can be quantified by structure model index (SMI). This study aimed to compare trabecular configuration and bone mechanical properties between AIS and the controls. 95 AIS girls aged 12-14 years and 97 age- and gender-matched normal controls were recruited. Bilateral femoral necks and non-dominant distal radius were scanned by dual-energy X-ray absorptiometry for areal BMD and HR-pQCT for SMI and FEA, respectively. Subjects were further classified into osteopenic and non-osteopenic group based on their areal BMD. Bone mechanical properties (stiffness, failure load and apparent modulus) were calculated using FEA. Linear regression model was used for controlling age, physical activity and calcium intake. AIS was associated with lower failure load and apparent modulus after adjusting for age, whereas AIS was associated with lower apparent modulus after adjusting for all confounders. Osteopenic AIS was associated with more rod-like trabeculae when compared with non-osteopenic AIS, whereas no difference was detected between osteopenic and non-osteopenic controls. This might be the result of abnormal regulation and modulation of bone metabolism and bone modelling and remodelling in AIS which will warrant future studies with a longitudinal design to determine the significance of micro-architectural abnormalities in AIS.

The influence of dairy consumption, sedentary behaviour and physical activity on bone mass in Flemish children: a cross-sectional study

Background

This cross-sectional study aimed to look for an association in young children between whole body bone mineral content (BMC) and areal bone mineral density (aBMD) and dairy consumption as well as sedentary behaviour (SB) and physical activity (PA). Moreover, we investigated whether there was an interaction effect between dairy consumption and SB or PA on BMC and aBMD.

Methods

Healthy children (6-12 years) were recruited from primary schools. Body composition and whole body bone mass were measured with dual-energy X-ray absorptiometry (DXA), dairy consumption was assessed with a food frequency questionnaire (FFQ) and PA and SB with an accelerometer. In total, 272 children underwent a DXA scan. Complete FFQ data were available for 264 children and 210 children had matching data from accelerometry recordings. Regression analyses were used to study the associations between (1) BMC and aBMD and (2) dairy consumption, SB and PA, adjusting for age, gender, pubertal stage, height and body composition.

Results

Dairy consumption was positively associated with whole body BMC and aBMD (absolute value as well as z-score), after correction for relevant confounders. SB was negatively associated with aBMD z-score and light PA was positively associated with both BMC and aBMD z-score. No gender differences were found. Moreover, an interaction effect between vigorous PA (VPA) and dairy consumption on aBMD (z-score) and BMC z-score was found, indicating that children with both high VPA and high dairy consumption had higher values for BMC and aBMD of the whole body minus the head.

Conclusion

Already at young age, PA and dairy consumption positively influence whole body bone mass assessed by DXA. Moreover, this study indicates clearly that SB is negatively associated with whole body bone density. Promoting regular PA and sufficient dairy consumption in young children and limiting SB can be expected to positively influence their bone mass accumulation, which can help in the prevention of osteoporosis later in life.

A systematic literature review with meta-analyses of within- and between-day differences in objectively measured physical activity in school-aged children

Background

Targeting specific time periods of the day or week may enhance physical activity (PA) interventions in youth. The most prudent time segments to target are currently unclear.

Objectives

To systematically review the literature describing differences in young people’s objectively measured PA on weekdays vs. weekends, in school vs. out of school, weekends vs. out of school and lesson time vs. break time.

Methods

Electronic databases were searched for English-language, cross-sectional studies of school-aged children (4–18 years) reporting time-segment-specific accelerometer-measured PA from 01/1990 to 01/2013. We meta-analysed standardised mean differences (SMD) between time segments for mean accelerometer counts per minute (TPA) and minutes in moderate-to-vigorous PA (MVPA). SMD is reported in units of standard deviation; 0.2, 0.5 and 0.8 represent small, moderate and large effects. Heterogeneity was explored using meta-regression (potential effect modifiers: age, sex and study setting).

Results

Of the 54 included studies, 37 were eligible for meta-analyses. Children were more active on weekdays than weekends [pooled SMD (95 % CI) TPA 0.14 (0.08; 0.20), MVPA 0.42 (0.35; 0.49)]. On school days, TPA was lower in school than out of school; however, marginally more MVPA was accumulated in school [TPA −0.24 (−0.40; −0.08), MVPA 0.17 (−0.03; 0.38)]. TPA was slightly lower on weekends than out of school on school days, but a greater absolute volume of MVPA was performed on weekends [TPA −0.10 (−0.19; −0.01), MVPA 1.02 (0.82; 1.23)]. Heterogeneity between studies was high (I² 73.3–96.3 %), with 20.3–53.1 % of variance between studies attributable to potential moderating factors.

Conclusions

School-aged children are more active on weekdays than weekend days. The outcome measure influences the conclusions for other comparisons. Findings support the tailoring of intervention strategies to specific time periods.

Electronic supplementary material

The online version of this article (doi:10.1007/s40279-014-0215-5) contains supplementary material, which is available to authorized users.

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.

Association between bone mineralization, body composition, and cardiorespiratory fitness level in young Australian men

The critical age for attainment of peak bone mineralization is however 20-30 yr, but few studies have investigated bone mineralization and its association with body composition and cardiorespiratory fitness level in young men. This study aimed to investigate relationships between age, bone mineral measurements, body composition measurements, and cardiorespiratory fitness level in a group of young healthy Australian men. Thirty-five healthy men aged 18-25 yr had anthropometric measures, body composition, and cardiorespiratory fitness level assessed. Bone mineral content was significantly associated with height, body mass and lean mass, and bone mineral density positively correlated with lean mass and body mass. Bone mineral measurements did not correlate with fat mass, percentage of fat mass, or cardiorespiratory fitness level. Age was directly correlated with total body mass, body fat, and percentage of fat mass. Body mineral measurements correlated with lean mass but not with fat mass or with cardiorespiratory fitness in this group of young healthy men. Positive association between body fat and age in such young group suggests that more studies with young men are warranted and may help inform strategies to optimize increase in bone mineral measurements.

Combat sports practice favors bone mineral density among adolescent male athletes

The aim of this study was to determine the impact of combat sports practice on bone mineral density (BMD) and to analyze the relationship between bone parameters and anthropometric measurements, bone markers, and activity index (AI). In other words, to detect the most important determinant of BMD in the adolescent period among combat sports athletes. Fifty athletes engaged in combat sports, mean age 17.1±0.2 yr, were compared with 30 sedentary subjects who were matched for age, height, and pubertal stage. For all subjects, the whole-body BMD, lumbar spine BMD (L2-L4), and BMD in the pelvis, arms, and legs was measured by dual-energy X-ray absorptiometry, and anthropometric measurements were evaluated. Daily calcium intake, bone resorption, and formation markers were measured. BMD measurements were greater in the combat sports athletes than in the sedentary group (p<0.01). Weight, body mass index, and lean body mass were significantly correlated with BMD in different sites. Daily calcium consumption lower than daily calcium intake recommended in both athletes and sedentary group. AI was strongly correlated with all BMD measurements particularly with the whole body, legs, and arms. Negative correlations were observed between bone markers and BMD in different sites. The common major predictor of BMD measurements was AI (p<0.0001). AI associated to lean body mass determined whole-body BMD until 74%. AI explained both BMD in arms and L2-L4 at 25%. AI associated to height can account for 63% of the variance in BMD legs. These observations suggested that the best model predicting BMD in different sites among adolescent combat sports athletes was the AI. Children and adolescents should be encouraged to participate in combat sports to maximize their bone accrual.

Bone mineral density and vitamin D status in ambulatory and non-ambulatory children with cerebral palsy

This study assessed distal femur and lumbar spine bone mineral density (BMD) Z-scores in children with cerebral palsy. BMD z-score was lower in non-ambulatory than in ambulatory children. Somewhat surprisingly, among ambulatory children, those with better walking abilities had higher BMD z-score than those with more impaired walking ability.

INTRODUCTION

Children with cerebral palsy (CP) have increased risk for low bone mineral density (BMD). The aim was to explore the difference in BMD at the distal femur and lumbar spine between ambulatory and non-ambulatory children with CP and the relationship between vitamin D status and BMD.

METHODS

Fifty-one children (age range 8-18 years; 20 girls) with CP participated. Their BMD Z-scores were measured in the lumbar spine and the distal femur using dual X-ray absorptiometry, and 25-hydroxy-vitamin D (25-OHD) concentrations were measured in serum. Children with GMFCS level I-III were defined as 'walkers' while children with level IV-V were defined as 'non-walkers.

RESULTS

Non-walkers had lower mean BMD Z-scores (range -1.7 to -5.4) than walkers at all sites (range -0.8 to -1.5). Among walkers, BMD Z-scores at the distal femur were lower in those with GMFCS level II than with level I (p values < 0.004). A similar difference was found between the affected and unaffected limb in children with hemiplegia. Mean 25-OHD concentration was 45 nmol/L (SD = 18); lower in walkers (mean = 41 nmol/L; SD = 18) than in non-walkers (mean = 53 nmol/L; SD = 19; p = 0.041). There were no correlations between 25-OHD and BMD z-scores.

CONCLUSIONS

The main predictor of low BMD Z-scores in the distal femur was the inability to walk, but the results suggest that the degree of the neuromotor impairment may also be a significant predictor. Vitamin D status did not correlate with BMD z-scores.

Physical activity from adolescence to young adulthood and bone mineral density in young adults from the 1982 Pelotas (Brazil) Birth Cohort

OBJECTIVE

To evaluate a prospective association between physical activity (PA) and bone mineral density (BMD) in young adults.

METHOD

Total body (TB), lumbar spine (LS) and femoral neck (FN) BMD were measured in participants from the 1982 Pelotas Birth Cohort by dual-energy X-ray absorptiometry at 30 y. PA was evaluated at 15, 18 (males) and 23 y.

RESULTS

3454 young adults were scanned (DXA) at least at one anatomical site. In males, PA at 15 y was associated with LS density (β=0.061 g/cm(2); 95% confidence interval (CI): 0.015; 0.108). A positive dose-response effect was found for the association between PA at 18 y and BMD. Males in the two highest quartiles of PA at 23 y had significantly greater BMD at all anatomical sites than males in the lowest quartile. We observed greater BMD at 30 y in boys who were active at least in one of the assessments (18 or 23 y) compared to inactive boys at both ages. Females in the highest quartile of PA at 23 y showed greater FN density at 30 y (β=0.020; 95%CI: 0.001; 0.039).

CONCLUSIONS

A physically active pattern is important to BMD across the first three decades of life. Potential beneficial effects of PA were not entirely lost with advancing age in male young adults.

Effects of weight-bearing exercise on bone health in girls: a meta-analysis

BACKGROUND

Because growing bone possesses a greater capacity to adapt to mechanical loading than does mature bone, it is important for girls to engage in weight-bearing activities, especially since the prevalence of osteoporosis among older women is considerably higher than that of older men. In recent years, the osteogenic potential of weight-bearing activities performed by children and adolescents has received increasing attention and accumulating evidence suggests that this type of activity may improve bone health prior to adulthood and help prevent osteoporosis later in life.

OBJECTIVE

Because previous interventions have varied with respect to the exercise parameters studied and sometimes produced conflicting findings, this meta-analysis was undertaken to evaluate the impact of weight-bearing exercise on the bone health of female children and adolescents and quantify the influence of key moderating variables (e.g. pubertal stage, exercise mode, intervention strategy, exercise duration, frequency of exercise, programme length and study design) on skeletal development in this cohort.

METHODS

A comprehensive literature search was conducted using databases such as PubMed, MEDLINE, CINAHL, Web of Science, Physical Education Index, Science Direct and ProQuest. Search terms included 'bone mass', 'bone mineral', 'bone health', 'exercise' and 'physical activity'. Randomized- and non-randomized controlled trials featuring healthy prepubertal, early-pubertal and pubertal girls and measurement of areal bone mineral density (aBMD) or bone mineral content (BMC) using dual energy x-ray absorptiometry were examined. Comprehensive Meta-Analysis software was used to determine weighted mean effect sizes (ES) and conduct moderator analyses for three different regions of interest [i.e. total body, lumbar spine (LS), and femoral neck].

RESULTS

From 17 included studies, 72 ES values were retrieved. Our findings revealed a small, but significant influence of weight-bearing exercise on BMC and aBMD of the LS (overall ES 0.19; 95% confidence interval (CI) 0.05, 0.33 and overall ES 0.26, 95% CI 0.09, 0.43, respectively) and BMC of the femoral neck (ES 0.23; 95% CI 0.10, 0.36). For both aBMD and BMC, overall ES was not affected by any moderator variables except frequency of exercise, such that weight-bearing activity performed for more than 3 days per week resulted in a significantly greater ES value for LS aBMD compared with programmes lasting 3 or fewer days per week [Cochran's Q statistic (Qbetween) = 4.09; p < 0.05].

CONCLUSION

The impact of weight-bearing activities seems to be site specific, and a greater frequency of weight-bearing activities is related to greater aBMD of LS in growing girls. Future investigations are warranted to better understand the dose-response relationship between weight-bearing activity and bone health in girls and explore the mediating role of pubertal status in promoting skeletal development among female youth.

Fracture patterns and bone mass in South African adolescent-mother pairs: the Birth to Twenty cohort

The associations of fracture prevalence and bone mass in adolescents with maternal fracture history and bone mass have not been investigated previously in South Africa. Maternal bone mass has a significant inverse association with their adolescents' fracture rates and bone mass across all ethnic groups.

INTRODUCTION

Differences in fracture rates and bone mass between families and individuals of different ethnic origins may be due to differing lifestyles and/or genetic backgrounds. This study aimed to assess associations of fracture prevalence and bone mass in adolescents with maternal fracture history and bone mass, and sibling fracture history.

METHODS

Data from 1,389 adolescent-biological mother pairs from the Birth to Twenty longitudinal study were obtained. Questionnaires were completed on adolescent fractures until 17/18 years of age and on sibling fractures. Biological mothers completed questionnaires on their own fractures prior to the age of 18 years. Anthropometric and bone mass data on adolescent-biological mother pairs were collected.

RESULTS

An adolescent's risk of lifetime fracture decreased with increasing maternal lumbar spine (LS) bone mineral content (BMC; 24 % reduction in fracture risk for every unit increase in maternal LS BMC Z-score) and increased if they were white, male, or had a sibling with a history of fracture. Adolescent height, weight, male gender, maternal bone area and BMC, and white ethnicity were positive predictors of adolescent bone mass. White adolescents and their mothers had a higher fracture prevalence (adolescents 42 %, mothers 31 %) compared to the black (adolescents 20 %, mothers 6 %) and mixed ancestry (adolescents 20 %, mothers 16 %) groups.

CONCLUSION

Maternal bone mass has a significant inverse association with their adolescent off-springs' fracture risk and bone mass. Furthermore, there is a strong familial component in fracture patterns among South African adolescents and their siblings.

Milk consumption during teenage years and risk of hip fractures in older adults

IMPORTANCE

Milk consumption during adolescence is recommended to promote peak bone mass and thereby reduce fracture risk in later life. However, its role in hip fracture prevention is not established and high consumption may adversely influence risk by increasing height.

OBJECTIVES

To determine whether milk consumption during teenage years influences risk of hip fracture in older adults and to investigate the role of attained height in this association.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study over 22 years of follow-up in more than 96,000 white postmenopausal women from the Nurses' Health Study and men aged 50 years and older from the Health Professionals Follow-up Study in the United States.

EXPOSURES

Frequency of consumption of milk and other foods during ages 13 to 18 years and attained height were reported at baseline. Current diet, weight, smoking, physical activity, medication use, and other risk factors for hip fractures were reported on biennial questionnaires.

MAIN OUTCOMES AND MEASURES

Cox proportional hazards models were used to calculate relative risks (RRs) of first incidence of hip fracture from low-trauma events per glass (8 fl oz or 240 mL) of milk consumed per day during teenage years.

RESULTS

During follow-up, 1226 hip fractures were identified in women and 490 in men. After controlling for known risk factors and current milk consumption, each additional glass of milk per day during teenage years was associated with a significant 9% higher risk of hip fracture in men (RR = 1.09; 95% CI, 1.01-1.17). The association was attenuated when height was added to the model (RR = 1.06; 95% CI, 0.98-1.14). Teenage milk consumption was not associated with hip fractures in women (RR = 1.00 per glass per day; 95% CI, 0.95-1.05).

CONCLUSIONS AND RELEVANCE

Greater milk consumption during teenage years was not associated with a lower risk of hip fracture in older adults. The positive association observed in men was partially mediated through attained height.

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.

Effect of vitamin D replacement on hip structural geometry in adolescents: a randomized controlled trial

BACKGROUND

We have shown in a randomized controlled trial that vitamin D increases bone mass, lean mass and bone area in adolescent girls, but not boys. These increments may translate into improvements in bone geometry and therefore bone strength. This study investigated the impact of vitamin D on hip geometric dimensions from DXA-derived hip structural analyses in adolescents who participated in the trial.

METHODS

167 girls (mean age 13.1 years) and 171 boys (mean age 12.7 years) were randomly assigned to receive weekly placebo oil or vitamin D3, at doses of 1400 IU or 14,000 IU, in a double blind placebo-controlled 1-year trial. DXA images were obtained at baseline and one year, and hip images were analyzed using the hip structural analysis (HSA) software to derive parameters of bone geometry. These include outer diameter (OD), cross sectional area (CSA), section modulus (Z), and buckling ratio (BR) at the narrow neck (NN), intertrochanteric (IT), and shaft (S) regions. Analysis of Covariance (ANCOVA) was used to examine group differences for changes of bone structural parameters.

RESULTS

In the overall group of girls, vitamin D supplementation increased aBMD (7.9% and 6.8% in low and high doses, versus 4.2% in placebo) and reduced the BR of NN (6.1% and 2.4% in low and high doses, versus 1.9% in placebo). It also improved aBMD (7.9% and 5.2% versus 3.6%) and CSA (7.5% and 5.1% versus 4.1%) of the IT and OD of the S (2.4% and 2.5% versus 0.8% respectively). Significant changes in the OD and BR of the NN, in the overall group of girls remained, after adjusting for lean mass, and were unaffected with further adjustments for lifestyle, pubertal status, and height measures. Conversely, boys did not exhibit any significant changes in any parameters of interest. A dose effect was not detected and subgroup analyses revealed no beneficial effect of vitamin D by pubertal stage.

CONCLUSIONS

Vitamin D supplementation improved bone mass and several DXA-derived structural bone parameters, in adolescent girls, but not boys. This occurred at a critical site, the femoral neck, and if maintained through adulthood could improve bone strength and lower the risk of hip fractures.

The role of physical activity and diet on bone mineral indices in young men: a cross-sectional study

Background

Osteoporotic fractures are a significant cause of morbidity and mortality, particularly in developed countries. Increasing peak bone mass in young people may be the most important primary prevention strategy to reduce the risk of osteoporosis. This study aimed to examine the relationship between dietary factors and physical activity on bone mineralization in young men.

Methods

Thirty-five healthy men aged 18–25 y had anthropometric measures, body composition, resting metabolic rate, blood pressure, blood lipids, food intake, physical activity and cardiorespiratory fitness assessed.

Results

Participants who consumed more than 1000 mg/d of calcium were taller and had higher levels of whole body mineral content than participants who consumed less than 1000 mg/d of calcium. Similarly, participants who expended more than 20% of total daily energy engaged in moderate- to vigorous-intensity physical activity had higher cardiorespiratory fitness and higher levels of body mass adjusted bone mineral content than participants who did not meet this level of energy expenditure. There were no differences in blood pressure or blood lipids between participants in calcium or in physical activity energy expenditure categories.

Conclusions

A high intake of dietary calcium and high daily energy expenditure engaged in moderate- to vigorous-intensity physical activity were positively associated with bone mineralization in young men, particularly in the lumbar region.

Vitamin C and zinc intakes are related to bone macroarchitectural structure and strength in prepubescent girls

The extent to which nutrient intake may influence bone structure and strength during maximal rates of skeletal growth remains uncertain. We examined the relationship of dietary intake of micronutrients and bone macroarchitectural structure in young girls. This cross-sectional analysis included baseline data from 363 fourth- and sixth-grade girls enrolled in the Jump-In study. Nutrient intake was assessed using the Harvard Youth/Adolescent Food Frequency Questionnaire. Volumetric BMD (vBMD), bone geometry, and strength were measured by peripheral quantitative computed tomography. Correlations and regression modeling assessed relations between usual nutrient intake and bone parameters. In fourth-grade girls, metaphyseal and diaphyseal area and circumferences as well as diaphyseal strength were associated with vitamin C intake (r = 0.15-0.19, p < 0.05). Zinc intake was correlated with diaphyseal vBMD (r = 0.15-0.16, p < 0.05). Using multiple linear regression to adjust for important covariates, we observed significant independent associations for vitamin C and zinc with bone parameters. For every milligram per day of vitamin C intake trabecular area increased by 11 %, cortical strength improved by 14 %, and periosteal and endosteal circumferences increased by 5 and 8.6 %, respectively. For every milligram per day of zinc intake, cortical vBMD increased by <1 %. No significant associations were observed in sixth-grade girls. Results of this study suggests that vitamin C and zinc intake are positively associated with objective measures of bone geometry, size, and strength in fourth-grade girls. This indicates that potential differences in micronutrient and bone associations at various age-associated stages of bone maturation may be indicative of competing hormonal influences.

Association between the stress fracture and bone metabolism/quality markers in lacrosse players

Background

Overuse injury including stress fracture is a serious problem for athletes. Recently, the importance of bone metabolism and quality as factors preventing overuse injury has been increasingly recognized. Hence, we hypothesized that markers of bone metabolism and quality are related to overuse injuries.

Methods

The subjects, which were elite university lacrosse players (male, n = 35; age, 19.8 ± 1.1; female, n = 49; age, 20.0 ± 1.0), were divided into a stress fracture group and a control group. We measured the subjects’ physical characteristics (height, weight, body mass index, and body fat) and bone architecture was evaluated using quantitative ultrasound. Bone alkaline phosphatase, N-telopeptide cross-link of type I collagen, tartrate-resistant acid phosphatase 5b (TRAP-5b), homocysteine, and pentosidine were measured from blood samples obtained from all subjects.

Results

No significant difference was observed between groups with respect to height, weight, body mass index, and body fat, as well as quantitative ultrasound. Further, there were no significant differences in the levels of bone alkaline phosphatase, N-telopeptide cross-link of type I collagen, or TRAP-5b between stress fracture and control groups in all subjects and in male subjects. However, a significant increase in TRAP-5b level was observed in the stress fracture group compared with the control in the female subjects (409.9 ± 209.3 and 318.6 ± 81.6 mU/dL, respectively; P < 0.05). Homocysteine and pentosidine did not differ between groups.

Conclusion

These results suggest that osteoclast activity of female athletes with stress fractures may be enhanced by TRAP-5b.

Bone health in children with cerebral palsy and epilepsy

Children with disabilities that limit mobility are at increased risk for osteoporosis. In the United States, 10 million people have osteoporosis and 34 million people are estimated to be at risk of acquiring this condition. Typically, bone fragility and osteoporosis have been associated with older adults; however, these problems can also affect children. The childhood and adolescent years are critically important in producing healthy bone mass. Yet cerebral palsy and epilepsy, which are both chronic disorders that frequently coexist, are predictors of muscular and skeletal compromise. Nurse practitioners should be aware of recommendations for promoting and achieving optimal bone health in children with these disabilities and screening patients who are at risk of sustaining fractures.

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.

Physical activity and bone mineral density in adolescents with vitamin D deficiency

INTRODUCTION

Studies have shown that physical activity (PA) is superior to many other environmental factors in determining bone mineral density (BMD), but none has examined the independent relationship between PA and vitamin D status.

PURPOSE

The aim of this study was to assess the relationship among amount of PA, vitamin D (25(OH)D), and BMD.

METHODS

A total of 166 female ballet dancers and sedentary adolescents were divided by tertiles of serum levels of 25(OH)D (< 11.3, 11.3-14.9, and > or = 15 ng·mL(-1)). Diet, PA, and menstruation were assessed by questionnaires; BMD was measured in three sites by dual-energy x-ray absorptiometry.

RESULTS

Across 25(OH)D tertiles, there were no differences in mean participant age, weight, height, PA, calcium and energy intake, BMD, or parathyroid hormone. PA was positively associated with BMD in participants with vitamin D deficiency. Multivariable regression analysis, controlling for age, body mass index, parathyroid hormone, and bone turnover markers, showed that total body, femoral neck, and lumbar spine BMD were all positively related to PA, with regression coefficients increasing as vitamin D levels dropped across tertiles.

CONCLUSIONS

PA is positively related to BMD in vitamin D-deficient female adolescents and with increasing magnitude as serum vitamin D levels drop. These findings suggest that PA may counteract the detrimental effect of marked vitamin D deficiency on bone mass.

Familial correlation of bone mineral density, birth data and lifestyle factors among adolescent daughters, mothers and grandmothers

This study aimed to clarify the relationship between skeletal or lifestyle factors among Japanese daughter-mother, mother-grandmother and daughter-grandmother pairs. We performed a cross-sectional study in a cohort of Japanese adolescent daughters (12-18 years of age), their mothers (339 pairs) and grandmothers on their mothers' side (34 pairs). Gestational age, birth weight, age at menarche and presence of menarche or menopause were surveyed in the participants. Height, body weight and lumbar 2-4 bone mineral density (BMD) were measured. Dietary intake and current physical activity were assessed by using questionnaires. Gestational age and age at menarche were significantly correlated among daughters, mothers and grandmothers (P < 0.001). BMD was significantly correlated between daughters and mothers (P < 0.001), while it was not significantly correlated between daughters and grandmothers or between mothers and grandmothers. Dietary intake of calcium and vitamin D, and the frequency, duration and intensity of current physical activity were significantly correlated between daughters and mothers (P < 0.05), although no significant correlation was found between daughters and grandmothers, or between mothers and grandmothers. The parameters for exercise indicated a positive correlation for BMD in the daughters and the mothers, but not in the grandmothers. The results suggested that estrogen deficiency decreases familial correlation for BMD after menopause. Achieving high BMD through exercise may be important for prevention of postmenopausal osteoporosis in premenopausal low-height mothers.

Influence of muscle fitness test performance on metabolic risk factors among adolescent girls

BACKGROUND

The purpose of this study was to examine the association between muscular fitness (MF), assessed by 2 components of Fitnessgram test battery, the Curl-Up and Push-Ups tests and the metabolic risk score among adolescent girls.

METHODS

A total of 229 girls (aged 12-15 years old) comprised the sample of this study. Anthropometric data (height, body mass, waist circumference) were collected. Body mass index (BMI) was also calculated. Muscular strength was assessed taking into account the tests that comprised the FITNESSGRAM test battery, i.e. the curl-up and the push-up. Participants were then categorized in one of 3 categories according the number of tests in which they accomplished the scores that allow them to be classified in health or above health zone. The blood pressure [BP], fasting total cholesterol [TC], low density lipoprotein-cholesterol [LDL-C], high density lipoprotein-cholesterol [HDL-C], triglycerides [TG], glucose, and a metabolic risk score (MRS) were also examined. Physical Activity Index (PAI) was obtained by questionnaire.

RESULTS

Higher compliance with health-zone criteria (good in the 2 tests), adjusted for age and maturation, were positive and significantly (p </= 0.05) associated with height (r = 0.19) and PAI (r = 0.21), while a significant but negative association was found for BMI (r = -0.12); WC (r = -0.19); TC (r = -0.16); TG (r = -0.16); LDL (r = -0.16) and MRS (r = -0.16). Logistic regression showed that who were assigned to MF fittest group were less likely (OR = 0.27; p = 0.003) to be classified overweight/obese and less likely (OR = 0.26; p = 0.03) to be classified as having MRS. This last association was also found for those whom only performed 1 test under the health zone (OR = 0.23; p = 0.02).

CONCLUSIONS

Our data showed that low strength test performance was associated with increased risk for obesity and metabolic risk in adolescent girls even after adjustment for age and maturation.

Psychosocial factors influencing calcium intake and bone quality in middle school girls

Calcium intake has been associated with promoting bone health in children and adolescents, thus preventing osteoporosis later in life. Behavior change such as increased calcium intake, as well as physiological factors such as bone quality, may be facilitated by psychosocial and environmental factors. The purpose of this study was to identify pathways by which psychosocial factors influence calcium intake and bone quality in middle school girls. The study design was cross-sectional. Baseline data from the Incorporating More Physical Activity and Calcium in Teens (IMPACT) study, collected in 2001-2003, were used. IMPACT was a 1.5-year nutrition and physical activity intervention study, designed to improve bone density in 717 middle school girls in Texas. Main outcome measures were calcium intake determined using mean milligrams of calcium consumed per day and number of glasses of milk consumed per day, and bone quality determined using a calcaneal stiffness index. Confirmatory factor analysis and path analysis were performed to identify the direct and indirect pathways used by various psychosocial factors such as knowledge, self-efficacy, outcome expectations, and milk availability at home, to influence calcium intake and bone quality. Results showed that knowledge of osteoporosis and calcium-rich foods had an indirect effect on calcium intake, with outcome expectations as the mediating variable (beta=.035 and beta=.03, respectively; P<0.05). Calcium self-efficacy had a significant indirect effect on calcium intake, with outcome expectations as the mediator (beta=.085, P<0.05). None of the variables significantly influenced bone quality. Thus, several direct and indirect pathways used to influence calcium intake among adolescent girls were identified. These findings are critical for the development of effective interventions to promote calcium intake in this population.

Systematic review of the health benefits of physical activity and fitness in school-aged children and youth

Background

The purpose was to: 1) perform a systematic review of studies examining the relation between physical activity, fitness, and health in school-aged children and youth, and 2) make recommendations based on the findings.

Methods

The systematic review was limited to 7 health indicators: high blood cholesterol, high blood pressure, the metabolic syndrome, obesity, low bone density, depression, and injuries. Literature searches were conducted using predefined keywords in 6 key databases. A total of 11,088 potential papers were identified. The abstracts and full-text articles of potentially relevant papers were screened to determine eligibility. Data was abstracted for 113 outcomes from the 86 eligible papers. The evidence was graded for each health outcome using established criteria based on the quantity and quality of studies and strength of effect. The volume, intensity, and type of physical activity were considered.

Results

Physical activity was associated with numerous health benefits. The dose-response relations observed in observational studies indicate that the more physical activity, the greater the health benefit. Results from experimental studies indicate that even modest amounts of physical activity can have health benefits in high-risk youngsters (e.g., obese). To achieve substantive health benefits, the physical activity should be of at least a moderate intensity. Vigorous intensity activities may provide even greater benefit. Aerobic-based activities had the greatest health benefit, other than for bone health, in which case high-impact weight bearing activities were required.

Conclusion

The following recommendations were made: 1) Children and youth 5-17 years of age should accumulate an average of at least 60 minutes per day and up to several hours of at least moderate intensity physical activity. Some of the health benefits can be achieved through an average of 30 minutes per day. [Level 2, Grade A]. 2) More vigorous intensity activities should be incorporated or added when possible, including activities that strengthen muscle and bone [Level 3, Grade B]. 3) Aerobic activities should make up the majority of the physical activity. Muscle and bone strengthening activities should be incorporated on at least 3 days of the week [Level 2, Grade A].

Assessment of bone mineral density and risk factors in children completing treatment for acute lymphoblastic leukemia

BACKGROUND

Reduced bone mineral density and increased fracture risk have been reported in children with cancer. In this study, we aimed to determine the growth and bone mineral density (BMD) of the children off chemotherapy for acute lymphoblastic leukemia, and the probable risk factors.

PROCEDURE

The age, anthropometric measurements, lumbar spine BMDs were recorded in 70 children. The risk factors on BMD; daily calcium intake, the time interval from the completion of the chemotherapy, cranial radiotherapy, cumulative steroid dose, decrease in physical activity were investigated. Serum calcium, phosphate, alkaline phosphates, magnesium, insulin-like growth factor-1 (IGF-1) and 25 (OH) vitamin D levels were determined.

RESULTS

The mean height percentile at the time of diagnosis was decreased from the value of 53 to a value of 47 at the beginning of the study (P=0.071). Of them; 44% had osteoporosis, 41% had osteopenia, and the rest had normal BMD. BMD z-scores were decreased during the first 2 years from the completion of the treatment. There was a positive correlation between BMD z-scores and daily calcium intake (CC=0.366, P=0.0015). A negative correlation was determined between the time spent on TV and computers and BMD z-scores (CC=-0.464, P=0.0019). Serum IGF-1 and 25 (OH) vitamin D levels of patients were significantly lower than controls (P=0.033).

CONCLUSIONS

Our data revealed that 85% of the survivors had bone mineralization defect. BMDs and z scores were decreased during the first 2 years from the completion of the treatment and then gradually began to increase. The most important risk factor for decreased BMD was low daily calcium intake. Therefore, patients and their families should be encouraged to take sufficient amount of calcium. Prophylactic vitamin D may also be supplemented.

Pediatric Hodgkin lymphoma survivors at negligible risk for significant bone mineral density deficits

BACKGROUND

We hypothesized that pediatric Hodgkin lymphoma (HL) survivors would have bone mineral density (BMD) deficits compared to their peers because of osteotoxic chemotherapy during the time of greatest BMD accretion.

METHODS

We retrospectively reviewed records of HL survivors returning for follow-up between 1990 and 2002. Of the 133 eligible survivors, 109 who underwent quantitative computed tomography (QCT) comprised the study group. QCT-determined BMD Z-scores were correlated with patient characteristics and therapeutic exposures by Wilcoxon rank sum or Chi-square tests. Logistic regression models were used to explore risk factors for diminished BMD.

RESULTS

The study cohort was half male (50.5%) and 85.3% reported their race as white. Participants were representative of all survivors potentially eligible for study, except that more study participants were female, had hypothyroidism, and had received cyclophosphamide. Median age at diagnosis was 15.1 years (range, 3.1-20.7 years); median time between diagnosis and QCT was 7.5 years (range, 5.0-12.4 years). The proportion of HL survivors with BMD below the mean did not significantly differ from the general population (P = 0.503). However, those with BMD -1.5 SD and BMD -2.0 SD or lower (14.7% and 7.3%, respectively) exceeded that in the general population (6.7% and 2.3%, respectively; P < 0.001 for both degrees of severity). Males, diagnosed at 14 years or older, were at 6.5 times higher risk than females (OR 95% CI: 1.24-34.14; P = 0.027) for BMD deficits.

CONCLUSIONS

Overall, pediatric HL survivors had negligible BMD deficits. Male gender was associated with an increased risk of developing BMD deficits.

Psychosocial, environmental and behavioral factors associated with bone health in middle-school girls

The purpose of this study was to identify the psychosocial, environmental and behavioral factors associated with calcium intake, physical activity and bone health in a cohort of adolescent girls. Baseline data (N = 718 girls, mean age: 11.6 +/-0.4 years) from the Incorporating More Physical Activity and Calcium in Teens (IMPACT) study conducted in Texas, 2001-03, were utilized for the analyses. Hierarchical linear regression was used to examine the associations of interest. Confounders adjusted for included ethnicity, menarchal status, body mass index and lactose intolerance. Several psychosocial and behavioral factors were significantly associated with bone quality. These included knowledge of calcium content of foods (beta = 0.08, P = 0.016), self-efficacy toward consuming calcium-rich foods (beta = 0.16, P = 0.047), physical activity self-efficacy (beta = 0.20, P = 0.002), physical activity outcome expectations (beta = 0.5, P = 0.004), family encouragement to do physical activity (beta = 0.96, P = 0.027), friend engagement in physical activity (beta = 1.3, P = 0.001) and participation in sports teams (beta = 1.7, P < 0.001). Self-efficacy, social support and participation in sports teams appear to be strongly associated with bone health in adolescent girls. Future health education/health promotion programs need to address these factors for effective primary prevention of osteoporosis in this population.