Overweight children have a greater proportion of fat mass relative to muscle mass in the upper limbs than in the lower limbs: implications for bone strength at the distal forearm

Muscle-to-Bone and Soft Tissue-to-Bone Ratio in Children and Adolescents with Obesity

OBJECTIVES

To explore the total and regional muscle-to-bone ratio in children and adolescents with obesity and compare the muscle-to-bone ratio (MBR) and soft tissue-to-bone ratio (SBR) to their peers with normal weight or overweight.

STUDY DESIGN

A total of 219 male and female pediatrics (mean age=12.3±2.5 years) participated in this study. Body composition was assessed with a total body dual X-ray absorptiometry. The MBR was calculated by dividing lean mass by bone mineral content. The SBR was determined by dividing the soft tissue mass (i.e., lean mass+fat mass) by bone mineral content. Differences in total and regional body composition measures between body mass index (BMI) percentile groups was assessed by ANOVA.

RESULTS

The obesity group had significantly higher MBR compared to the normal weight group for total (19.24±1.56 vs. 18.26±1.64), arm (17.11±1.67 vs. 15.88±1.81), and leg (18.41±1.68 vs. 16.62±1.55). Similarly, the obesity group had significantly higher MBR in the leg (18.41±1.68) compared to the overweight group (17.24±1.45). However, the overweight group was not significantly different from the normal weight or the obesity group for total and arm MBR. The total, arm, and leg SBR was significantly different between all BMI groups. Across the entire sample, MBR and SBR were negatively associated with high-density lipoprotein. SBR was positively associated with insulin, HOMA-IR, low-density lipoprotein, very low-density lipoprotein, triglycerides, and systolic blood pressure.

CONCLUSIONS

Children with obesity had a higher MBR and SBR compared to their normal weight peers. In addition, there were significant associations between SBR, higher levels of insulin, atherogenic lipoproteins, and increased systolic blood pressure. Thus, SBR may be useful as a marker for increased cardiometabolic disease risk, though more research in this area is warranted.

Fibroblast Growth Factor 21 Levels and Bone Mineral Density in Metabolically Healthy and Metabolically Unhealthy Obese Children

OBJECTIVE

The harmful or beneficial effect of obesity on bone mineral density (BMD) remains controversial in children and adolescents. Fibroblast growth factor 21 (FGF21) is a metabolic factor that plays a specific role in the regulation of carbohydrate and lipid metabolism. However, the role of FGF21 in bone metabolism appears paradoxical and is complex. To determine whether serum FGF21 level was associated with BMD in obese children and adolescents.

METHODS

The study was conducted with the participation of children and adolescents aged 8-18 years. Ninety-eight obese children were included in the study group and 44 children were included in the control group. BMD, in addition to the routine obesity workup, which includes fasting blood glucose, fasting insulin levels, lipid profile, and liver enzymes; serum FGF21 levels have been analyzed.

RESULTS

The mean age of the obese group (n=98) was 13.34±2.24 years and the mean age of controls (n=44) was 13.48±2.87 years. Based on International Diabetes Federation criteria, 15 of 98 (15.3%) patients were metabolically unhealthy. FGF21 levels were 193.54±139.62 mg/dL in the obese group and 158.69±151.81 mg/dL in the control group (p=0.06). There was no difference between the FGF21 and BMD z-score values of girls and boys in the obese and control groups (p>0.05).

CONCLUSION

BMD-z-score was increased in obese children compared to healthy control. Moreover, BMD-z-score tended to be higher when more metabolic risk factors were present. However, there was no significant relationship between FGF21 levels and BMD z-score values in obese children.

Forearm Fractures in Overweight-Obese Children and Adolescents: A Matter of Bone Density, Bone Geometry or Body Composition?

Forearm fractures in children and adolescents are associated with increased body mass index (BMI). This bone site is non-weight-bearing and therefore is appropriate to explore the effect of BMI on bone mineral density (BMD) and bone geometry, avoiding the confounding effect of increased weight-associated mechanical loading. The aim of this review was to summarize available evidence on bone indices and body composition assessed by peripheral quantitative computed tomography (pQCT) or dual X-ray absorptiometry (DXA) at the forearm level in overweight (Ow) or obese (Ob) subjects. We conducted a review of the literature according to the PICOS model. A total of 46 studies were identified following the literature search. A final number of 12 studies were included in this review. pQCT studies evidenced that Ow and Ob children typically have normal or increased volumetric BMD (vBMD), total bone area and cortical area, with normal or reduced cortical thickness at the forearm. Outcomes from DXA evaluations are less conclusive. In almost all the studies fat mass and lean mass area at the forearm are increased. A higher fat-to-lean mass ratio has been observed in few studies. Bone strength was reported as normal or increased compared to normal weight peers. In Ow or Ob children-adolescents, vBMD, bone size and bone strength are not reduced compared to normal weight peers. The local higher fat-to-lean mass ratio may give a mismatch between bone strength and the load experienced by the distal forearm during a fall, resulting in increased risk of forearm fractures.

Development and Trial of a Prototype Device for Sensorimotor Therapy in Patients with Distal Radius Fractures

This study examined the clinical feasibility of a prototype device (development name: Ghost) for facilitating range of motion (RoM) recovery in the acute phase in patients with distal radius fractures (DRF). The Ghost device involves the administration of a combination of vibratory and visual stimuli. We divided the patients into the Ghost (n = 10) and control group (n = 4; tendon vibration only) groups. The experimental interventions were administered between the day after surgery and day 7 postoperatively. Traditional hand therapy was provided to both groups once daily from day 7 until day 84 postoperatively and once a week from day 84 until the end of the intervention period. Because vibratory stimulation makes the patient focus on wrist flexion, the primary outcome was the arc of wrist flexion-extension on the injured side, which was measured on days 7, 14, 28, 42, 56, 70, and 84. Analysis of covariance was applied using a bootstrap method to evaluate changes over time and compare them between the groups. Analyses was performed after stratification by age and body mass index. Both interventions improved RoM over time in patients with DRF. Results showed that Ghost has greater efficacy for improving wrist RoM in DRF patients than vibration alone. Treatment with Ghost can result in good RoM improvement during the acute phase of DRF in young patients and those with and normal or low body mass index. Further study is needed to verify our findings and assess the extent of RoM recovery.

Age and sex effects in physical fitness components of 108,295 third graders including 515 primary schools and 9 cohorts

Children's physical fitness development and related moderating effects of age and sex are well documented, especially boys' and girls' divergence during puberty. The situation might be different during prepuberty. As girls mature approximately two years earlier than boys, we tested a possible convergence of performance with five tests representing four components of physical fitness in a large sample of 108,295 eight-year old third-graders. Within this single prepubertal year of life and irrespective of the test, performance increased linearly with chronological age, and boys outperformed girls to a larger extent in tests requiring muscle mass for successful performance. Tests differed in the magnitude of age effects (gains), but there was no evidence for an interaction between age and sex. Moreover, "physical fitness" of schools correlated at r = 0.48 with their age effect which might imply that "fit schools" promote larger gains; expected secular trends from 2011 to 2019 were replicated.

Association between maternal smoking and child bone mineral density: a systematic review and meta-analysis

Maternal smoking during pregnancy has detrimental effects on fetal development. The current review examined the differences in offspring's bone mineral density (BMD) between mothers smoked during pregnancy and those who did not. A systematic review and meta-analysis on the studies investigating the influence of maternal smoking during pregnancy on children or neonates' bone measures published up to October 30, 2018, was performed. BMD results measured at different body sites were pooled and then fixed or random effect models were used based on the presence of heterogeneity. The desired pooled effect size was the offspring's BMD mean difference with 95% confidence interval between smoker and non-smoker mothers. Sensitivity analysis was performed for birth weight and current weight, two important mediator/confounders causing heterogeneity. Overall, eight studies consisting of 17,931 participants aged from infancy to 18 years were included. According to the fixed effect model, the mean of BMD in offspring whose mothers smoked during pregnancy was 0.01 g/cm² lower than those with non-smoker mothers (95% CI = - 0.02 to - 0.002). However, subgroup meta-analysis adjusted for birth weight and current weight demonstrated no significant mean difference between BMD of children with smoker and non-smoker mothers (d = 0.06, 95% CI = -0.04 to 0.16, p value = 0.25 and d = - 0.005, 95% CI = - 0.01 to 0.004, p value = 0.28, respectively). According to available studies, it is suggested that maternal smoking during pregnancy does not have direct effect on the offspring's BMD. Instead, this association might be confounded by other factors such as placental weight, birth weight, and current body size of children.

Skeletal Muscle Composition and Glucose Levels in Children Who Are Overweight and Obese

BACKGROUND

Skeletal muscle is overlooked in the realm of insulin resistance in children who are overweight and obese despite the fact that it accounts for the most glucose disposal.

OBJECTIVES

Therefore, this study examined fasted glucose levels and muscle cross-sectional area and echo intensity (EI) via ultrasound images of the first dorsal interosseous, vastus lateralis, and rectus femoris in children who are normal weight and overweight and obese aged 8-10 years.

METHODS

In total, 13 males (age = 9.0 [0.7] y) and 7 females (age = 9.0 [0.8] y) volunteered for this study. Independent samples t tests and effect sizes (ESs) were used to examine potential differences in skeletal muscle composition and glucose concentrations.

RESULTS

There were no significant differences between groups for glucose concentration (P = .07, ES = 0.86); however, the children who were overweight and obese had significantly greater EI (P < .01, ES = 0.98-1.63) for the first dorsal interosseous, vastus lateralis, and rectus femoris and lower cross-sectional area when normalized to EI when collapsed across muscles (P < .04, ES = 0.92). Glucose concentrations correlated with EI and cross-sectional area/EI for the vastus lateralis (r = .514 to -.593) and rectus femoris (r = .551 to -.513), but not the first dorsal interosseous.

DISCUSSION

There is evidence that adiposity-related pathways leading to insulin resistance and skeletal muscle degradation are active in young children who are overweight and obese.

Arachidonic acid status negatively associates with forearm bone outcomes and glucose homeostasis in children with an overweight condition or obesity

Long-chain polyunsaturated fatty acids are implicated in musculoskeletal health in adults. This study examined whether fatty acid status relates to bone health outcomes in children with overweight condition or obesity (body mass index z score, 3.1 ± 0.1; age, 9.0 ± 0.2 years; n = 108). Nondominant forearm bone density (distal one-third), geometry (4% site), and soft tissue composition (66%) were assessed using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Red blood cell (RBC) fatty acid profile and indices of glucose homeostasis were measured. Differences in outcomes among RBC arachidonic acid (AA, C20:4n-6) tertiles were tested using mixed-model ANOVA. Ultra-, mid-, and total-distal forearm bone mineral content, adjusted for sex, age, percentage body fat, race, and forearm length, were 10% to 13% greater in children in the first AA tertile relative to the third. Children in the second tertile had the highest bone cross-sectional area and estimated strength at the 66% radius. Muscle cross-sectional area was 15% lower in the third tertile compared with the first, along with higher fasting insulin concentrations (27%) and homeostasis model of assessment estimate of insulin resistance (31%). Higher RBC AA status aligns with deficits in forearm bone mass, geometry, and muscle mass in children with excess adiposity and early signs of insulin resistance. Novelty Higher arachidonic acid status is associated with lower forearm bone mass in children with overweight condition or obesity. Children with higher arachidonic acid status had increased fasting insulin concentrations and indices of insulin resistance.

Intergenerational changes in adiposity and fat distribution from 1982 to 2011 in male children and adolescents from Kolkata (India)

BACKGROUND

India, as a developing country, is subjected to numerous socioeconomic changes. They can significantly influence human development and be mirrored by the secular trends regarding the adiposity and body fat distribution.

OBJECTIVES

The aim of the study was to examine the intergenerational changes of adiposity and body fat distribution in Bengali boys, between 1982 and 2011.

METHODS

The study group consisted of 2064 Bengali boys, aged 7-16, from the middle-class families, examined in two cross-sectional surveys in 1982-83 and 2005-2011. Triceps, biceps, subscapular and suprailiac skinfolds were measured. Their sum and the mean percentage of every skinfold were calculated. The percentage of body fat (%BF) was assessed using Slaughter's equations.

RESULTS

Positive secular trend, significant for most of the age groups, was observed for %BF and sum of skinfolds. It was also present for suprailiac and subscapular skinfolds.

CONCLUSIONS

Adiposity has significantly changed over the past three decades. The results confirm that the measurements of skinfold thickness are a great tool to relatively easily and accurately assess body adiposity in countries such as India. Moreover, further analysis of these trends can help to identify possible negative changes as well as establish their causes in a particular population.

The Bones of Children With Obesity

Excess adiposity in childhood may affect bone development, ultimately leading to bone frailty. Previous reports showing an increased rate of extremity fractures in children with obesity support this fear. On the other hand, there is also evidence suggesting that bone mineral content is higher in obese children than in normal weight peers. Both adipocytes and osteoblasts derive from multipotent mesenchymal stem cells (MSCs) and obesity drives the differentiation of MSCs toward adipocytes at the expense of osteoblast differentiation. Furthermore, adipocytes in bone marrow microenvironment release a number of pro-inflammatory and immunomodulatory molecules that up-regulate formation and activation of osteoclasts, thus favoring bone frailty. On the other hand, body adiposity represents a mechanical load, which is beneficial for bone accrual. In this frame, bone quality, and structure result from the balance of inflammatory and mechanical stimuli. Diet, physical activity and the hormonal milieu at puberty play a pivotal role on this balance. In this review, we will address the question whether the bone of obese children and adolescents is unhealthy in comparison with normal-weight peers and discuss mechanisms underlying the differences in bone quality and structure. We anticipate that many biases and confounders affect the clinical studies conducted so far and preclude us from achieving robust conclusions. Sample-size, lack of adequate controls, heterogeneity of study designs are the major drawbacks of the existing reports. Due to the increased body size of children with obesity, dual energy absorptiometry might overestimate bone mineral density in these individuals. Magnetic resonance imaging, peripheral quantitative CT (pQCT) scanning and high-resolution pQCT are promising techniques for the accurate estimate of bone mineral content in obese children. Moreover, no longitudinal study on the risk of incident osteoporosis in early adulthood of children and adolescents with obesity is available. Finally, we will address emerging dietary issues (i.e., the likely benefits for the bone health of polyunsaturated fatty acids and polyphenols) since an healthy diet (i.e., the Mediterranean diet) with balanced intake of certain nutrients associated with physical activity remain the cornerstones for achieving an adequate bone accrual in young individuals regardless of their adiposity degree.

Adiposity is not beneficial to bone mineral density in 0-5 year old Chinese children: The Jiangsu bone health study

OBJECTIVE

Data on obesity in relation to bone mineral density(BMD) in infants and preschool children were sparse in China. The objective of this study was to examine the associations between body mass index (BMI) and BMD.

SUBJECTS AND METHODS

This was a large population-based multicenter study in which the representative children aged 0-5 years were recruited from 13 Children's Health Care Centers by a stratified cluster random-sampling method in Jiangsu Province, China. BMD was measured by using quantitative ultrasound. The association of BMD with BMI and obesity were evaluated using multiple linear regression and logistic regression analysis taking into account the effects of confounders. The relations between age, weight, height, BMI and BMD were analyzed by using Pearson's correlation and further tested using partial correlation in the additive model.

RESULTS

A total of 5,289 children (2786 boys and 2503 girls) were recruited. The BMD was positively linear relation with age, length/height, and was inversely linear relation with BMI (r=0.711, P<0.001; r=0.727, P<0.001; r=-0.318, P<0.001, respectively). The BMD gradually increased when the weight was in the range within 21.2kg, but started to gain slowlyand even decreased when the weight was over 21.2kg. After adjusting for confounders, compared with control group, children with obesityhad higher odds of low BMD (OR 95%CI: 2.73 (1.57, 4.76), P<0.001), the speed of sound (SOS)value in children with obesity was lower 47.45 (β=-47.45, 95%CI=-85.07, -9.83, P=0.013).

CONCLUSIONS

Adiposity was not advantageous for bone mineral density in 0-5-year-old Chinese children.

Comparison of mandibular cortical bone among obese, overweight, and normal weight adolescents using panoramic mandibular index and mental index

OBJECTIVE

The objective of this study is to evaluate the mental index (MI) and panoramic mandibular index (PMI) of a group of adolescent patients in different body mass index (BMI) percentile.

MATERIAL AND METHODS

Subjects were divided into three different groups in accordance to their BMI percentile status: normal weight (35 subjects; mean age, 14.81 ± 2.12 years), overweight (32 subjects; mean age, 14.77 ± 2.56 years), and obese (33 subjects; mean age, 14.06 ± 2.59 years) groups. Mental index (MI) and panoramic mandibular index (PMI) were assessed on panoramic radiographs.

RESULTS

There were statistically significant differences in PMI and MI that were observed among groups (p < 0.0001 and p < 0.001, respectivel). MI and PMI are higher in overweight and obese individuals than in normal-weight.

CONCLUSIONS

Mandibular cortex was found thicker in patients who are obese and overweight compared to normal weight patients. We can suggest that young obese individuals' bone structure can be take in consideration in orthodontic or dental surgical treatment planning.

CLINICAL RELEVANCE

Dense cortical bone may cause some difficulties in orthodontic and surgical treatment. Clinicians should understand obesity and overweight-related jaw bone changes and consider these factors to treat their patients.

Distal Radius Fractures: Does Obesity Affect Fracture Pattern, Treatment, and Functional Outcomes?

BACKGROUND

Distal radius fractures (DRFs) are 16% of fractures treated by orthopedic surgeons. Obesity's influence on DRF complexity has not been studied. This study was undertaken to determine if body mass index (BMI) affects DRF pattern, treatment, and functional outcomes.

METHODS

Part 1 was a retrospective review of patients who sustained a DRF after a fall from standing height with no prior reduction or treatment. Radiographs were classified as "simple" or "complex." Part 2 consisted of contacting patients from Part 1 and obtaining a Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) score. Retrospective review also identified patients who failed initial nonoperative treatment. Fracture pattern, failure of nonoperative treatment, and QuickDASH scores were compared with BMI at the time of injury.

RESULTS

For Part 1, 130 patients (132 wrists) were identified. Average age was 57 years, 77% were female, and average BMI was 28.2 kg/m². Each point increase in BMI increased the chance of having a complex DRF (odds ratio = 1.07). Part 2 identified 50 patients who completed a QuickDASH at an average of 4.6 years after injury. Those with a BMI <25 kg/m² (n = 15) had an average QuickDASH score of 37; patients with a BMI ≥25 kg/m² (n = 35) had an average QuickDASH score of 18. Increasing BMI was suggestive of a lower QuickDASH score ( P = .08). No significant difference was found with respect to BMI and failure of nonoperative treatment.

CONCLUSIONS

A higher BMI increases the odds of a complex DRF. Despite more complex fractures, overweight patients may experience less disability after sustaining a DRF.

The Impact of Childhood Obesity on Skeletal Health and Development

Increased risk of fracture identified in obese children has led to a focus on the relationship between fat, bone, and the impact of obesity during skeletal development. Early studies have suggested that despite increased fracture risk, obese children have a higher bone mass. However, body size corrections applied to account for wide variations in size between children led to the finding that obese children have a lower total body and regional bone mass relative to their body size. Advances in skeletal imaging have shifted the focus from quantity of bone in obese children to evaluating the changes in bone microarchitecture that result in a change in bone quality and strength. The findings suggest that bone strength in the appendicular skeleton does not appropriately adapt to an increase in body size which results in a mismatch between bone strength and force from falls. Recent evidence points to differing influences of fat compartments on skeletal development-visceral fat may have a negative impact on bone which may be related to the associated adverse metabolic environment, while marrow adipose tissue may have an independent effect on trabecular bone development in obese children. The role of brown fat has received recent attention, demonstrating differences in the influence on bone mass between white and brown adipose tissues. Obesity results in a shift in growth and pubertal hormones as well as influences bone development through the altered release of adipokines. The change in the hormonal milieu provides an important insight into the skeletal changes observed in childhood obesity.

Anthropometric variations in different BMI and adiposity levels among children, adolescents and young adults in Kolkata, India

The objective of the study was to analyse selected anthropometric features of children, adolescents and young adults from middle-class families in Kolkata, India, by BMI and adiposity categories. Standardized anthropometric measurements of 4194 individuals (1999 male and 2195 female) aged 7-21 were carried out between the years 2005 and 2011. The results were compared by BMI and adiposity categories. Statistical significance was assessed using two-way-ANOVA and linear regression analysis was performed. The study population could be differentiated in terms of BMI and adiposity categories for all examined anthropometric characteristics (p ≤ 0.001). After taking age into consideration, differences were observed for males in the case of body height and humerus breadth in BMI and adiposity categories, and for femur breadth in the case of adiposity categories. For females, differences were noted in body height measurements in BMI and adiposity categories, a sum of skinfold thicknesses in BMI categories, and upper-arm and calf circumferences in adiposity categories. The patterns of differences in the BMI categories were found to be similar to those in adiposity categories. The linear regression analysis results showed that there was a significant relationship between BMI and body fat ratio in the examined population. Underweight individuals, and those with low adiposity, were characterized by lower extremity circumferences and skeletal breadths. These features reached highest values in overweight/obese persons, characterized by high body fat. However, the differences observed between each BMI and adiposity category, in most cases, were only present in early childhood.

Relative contributions of lean and fat mass to bone strength in young Hispanic and non-Hispanic girls

BACKGROUND

With the high prevalence of childhood obesity, especially among Hispanic children, understanding how body weight and its components of lean and fat mass affect bone development is important, given that the amount of bone mineral accrued during childhood can determine osteoporosis risk later in life. The aim of this study was to assess the independent contributions of lean and fat mass on volumetric bone mineral density (vBMD), geometry, and strength in both weight-bearing and non-weight-bearing bones of Hispanic and non-Hispanic girls.

METHODS

Bone vBMD, geometry, and strength were assessed at the 20% distal femur, the 4% and 66% distal tibia, and the 66% distal radius of the non-dominant limb of 326, 9- to 12-year-old girls using peripheral quantitative computed tomography (pQCT). Total body lean and fat mass were measured by dual-energy x-ray absorptiometry (DXA). Multiple linear regression was used to assess the independent relationships of fat and lean mass with pQCT bone measures while adjusting for relevant confounders. Potential interactions between ethnicity and both fat and lean mass were also tested.

RESULTS

Lean mass was a significant positive contributor to all bone outcomes (p < 0.05) with the exception of vBMD at diaphyseal sites. Fat mass was a significant contributor to bone strength at weight bearing sites, but did not significantly contribute to bone strength at the non-weight bearing radius and was negatively associated with radius cortical content and thickness. Bone measures did not significantly differ between Hispanic and non-Hispanic girls, although there was a significant interaction between ethnicity and fat mass with total bone area at the femur (p = 0.02) and 66% tibia (p = 0.005) as well as bone strength at the femur (p = 0.03).

CONCLUSION

Lean mass is the main determinant of bone strength for appendicular skeletal sites. Fat mass contributes to bone strength in the weight-bearing skeleton but does not add to bone strength in non-weight-bearing locations and may potentially be detrimental. Bone vBMD, geometry, and strength did not differ between Hispanic and non-Hispanic girls; fat mass may be a stronger contributor to bone strength in weight-bearing bones of Hispanic girls compared to non-Hispanic.

Long-term changes in fat distribution in children and adolescents aged 3-18 from Krakow (Poland), within the last 30 years (from 1983 to 2010)

In Poland, even in the late twentieth century, the problem of obesity was not significant. However, recent studies have shown an increase in the prevalence of overweight and obesity. Socioeconomic changes, in last decades, approached Poland to Western Europe. A lifestyle of Poles (physical activity and diet) have changed radically. The aim of the study was to investigate changes in adiposity in children and adolescents over the last decades. Two cross-sectional studies were made in 1983 and 2010. The analysis included 10,324 children and adolescents aged 3-18 living in Krakow (Poland). Data on selected skinfolds (triceps, subscapular, abdominal, suprailiac, calf) were collected and compared between the series of studies. The total body fat (sum of 5 skinfolds) was higher in contemporary boys. In girls, there were not noticed such changes. In both sexes, the adiposity of triceps and supscapular region decreased. In the case of abdominal skinfold - there were no significant changes in boys, while contemporary girls had a smaller abdominal adiposity. In boys, there were noticed reduction in suprailiac skinfold thickness. In the case of girls, the reverse trend was reported - contemporary girls were characterized by higher suprailiac adiposity. Children studied in 2010 were characterized by greater calf skinfold. Changes in adiposity are worrying, especially in boys. The priority should therefore be effective prevention and intervention programs. They can prevent further deepening of the problem among Polish children, by the time it will be as severe as in Western Europe.

Examination of muscle composition and motor unit behavior of the first dorsal interosseous of normal and overweight children

We examined differences between normal weight (NW) and overweight (OW) children aged 8–10 yr in strength, muscle composition, and motor unit (MU) behavior of the first dorsal interosseous. Ultrasonography was used to determine muscle cross-sectional area (CSA), subcutaneous fat (sFAT), and echo intensity (EI). MU behavior was assessed during isometric muscle actions at 20% and 50% of maximal voluntary contraction (MVC) by analyzing electromyography amplitude (EMGRMS) and relationships between mean firing rates (MFR), recruitment thresholds (RT), and MU action potential amplitudes (MUAPsize) and durations (MUAPtime). The OW group had significantly greater EI than the NW group ( P = 0.002; NW, 47.99 ± 6.01 AU; OW, 58.90 ± 10.63 AU, where AU is arbitrary units) with no differences between groups for CSA ( P = 0.688) or MVC force ( P = 0.790). MUAPsize was larger for NW than OW in relation to RT ( P = 0.002) and for MUs expressing similar MFRs ( P = 0.011). There were no significant differences ( P = 0.279–0.969) between groups for slopes or y-intercepts from the MFR vs. RT relationships. MUAPtime was larger in OW ( P = 0.015) and EMGRMS was attenuated in OW compared with NW ( P = 0.034); however, there were no significant correlations ( P = 0.133−0.164, r = 0.270−0.291) between sFAT and EMGRMS. In a muscle that does not support body mass, the OW children had smaller MUAPsize as well as greater EI, although anatomical CSA was similar. This contradicts previous studies examining larger limb muscles. Despite evidence of smaller MUs, the OW children had similar isometric strength compared with NW children.

NEW & NOTEWORTHY Ultrasound data and motor unit action potential sizes suggest that overweight children have poorer muscle composition and smaller motor units in the first dorsal interosseous than normal weight children. Evidence is presented that suggests differences in action potential size cannot be explained by differences in subcutaneous fat alone.

Obesity Increases Risk of Loss of Reduction After Casting for Diaphyseal Fractures of the Radius and Ulna in Children: An Observational Cohort Study

OBJECTIVES

To determine if high body mass index (BMI) increases the risk of loss of reduction (LOR) following closed reduction and casting for displaced concomitant fractures of the radial and ulnar shafts in pediatric patients.

DESIGN

Retrospective cohort study.

SETTING

A single, tertiary care, urban children's hospital.

PATIENTS/PARTICIPANTS

Pediatric patients 2-18 years of age with closed, displaced, concomitant diaphyseal fractures of the radius and ulna (OTA/AO 22-A3) who underwent closed reduction and casting at the study site.

MAIN OUTCOME MEASURES

BMI percentile of ≥95 was defined as obese. For nonobese patients, BMI percentile of ≥85 was defined as overweight. BMI percentile category, fracture angulation, sex, age, fracture location, and number of follow-up visits were recorded. Radiographs and health records were reviewed to note clinical and radiographic cases of LOR. The primary outcome was LOR (clinical or radiographic).

RESULTS

Overall, 124 subjects (74 male and 50 female subjects) underwent acceptable closed reduction and casting. Median patient age was 7.6 years (range, 2.2-17.8 years). There were 14 cases of LOR. LOR rates were 7.2%, 16.7%, and 44.4% for the nonoverweight, overweight, and obese cohorts, respectively (P = 0.005). Regression analysis revealed that LOR was positively associated with higher BMI category (odds ratio for overweight 4.49; P = 0.082; odds ratio for obese 7.52; P = 0.020) and patient age in years (odds ratio, 1.38; P = 0.001).

CONCLUSIONS

Given the high risk of LOR in overweight and obese children with displaced concomitant fractures of the radial and ulnar shafts, our findings suggest that attentive and frequent follow-up is warranted. In these patients, the initial reduction should be closely scrutinized, and a lower threshold for surgical fixation may be considered.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Obese Versus Normal-Weight Late-Adolescent Females have Inferior Trabecular Bone Microarchitecture: A Pilot Case-Control Study

Though still a topic of debate, the position that skeletal health is compromised with obesity has received support in the pediatric and adult literature. The limited data relating specifically to trabecular bone microarchitecture, however, have been relatively inconsistent. The aim of this pilot cross-sectional case-control study was to compare trabecular bone microarchitecture between obese (OB) and normal-weight (NW) late-adolescent females. A secondary aim was to compare diaphyseal cortical bone outcomes between these two groups. Twenty-four non-Hispanic white females, ages 18-19 years, were recruited into OB (n = 12) or NW (n = 12) groups based on pre-specified criteria for percent body fat (≥32 vs. <30, respectively), body mass index (>90th vs. 20th-79th, respectively), and waist circumference (≥90th vs. 25th-75th, respectively). Participants were also individually matched on age, height, and oral contraceptive use. Using magnetic resonance imaging, trabecular bone microarchitecture was assessed at the distal radius and proximal tibia metaphysis, and cortical bone architecture was assessed at the mid-radius and mid-tibia diaphysis. OB versus NW had lower apparent trabecular thickness (radius and tibia), higher apparent trabecular separation (radius), and lower apparent bone volume to total volume (radius; all P < 0.050). Some differences in radius and tibia trabecular bone microarchitecture were retained after adjusting for insulin resistance or age at menarche. Mid-radius and mid-tibia cortical bone volume and estimated strength were lower in the OB compared to NW after adjusting for fat-free soft tissue mass (all P < 0.050). These trabecular and cortical bone deficits might contribute to the increased fracture risk in obese youth.

Differences in bone mineral density between normal-weight children and children with overweight and obesity: a systematic review and meta-analysis

OBJECTIVE

This study examines the differences in bone mineral density between normal-weight children and children with overweight or obesity.

METHODS

A systematic review and meta-analysis of observational studies (published up to 22 June 2016) on the differences in bone mineral density between normal-weight children and overweight and obese children was performed. Results were pooled when possible and mean differences (MDs) were calculated between normal-weight and overweight and normal-weight and obese children for bone content and density measures at different body sites.

RESULTS

Twenty-seven studies, with a total of 5,958 children, were included. There was moderate and high quality of evidence that overweight (MD 213 g; 95% confidence interval [CI] 166, 261) and obese children (MD 329 g; 95%CI [229, 430]) have a significantly higher whole body bone mineral content than normal-weight children. Similar results were found for whole body bone mineral density. Sensitivity analysis showed that the association was stronger in girls.

CONCLUSIONS

Overweight and obese children have a significantly higher bone mineral density compared with normal-weight children. Because there was only one study included with a longitudinal design, the long-term impact of childhood overweight and obesity on bone health at adulthood is not clear.

Effects of Habitual Physical Activity and Fitness on Tibial Cortical Bone Mass, Structure and Mass Distribution in Pre-pubertal Boys and Girls: The Look Study

Targeted weight-bearing activities during the pre-pubertal years can improve cortical bone mass, structure and distribution, but less is known about the influence of habitual physical activity (PA) and fitness. This study examined the effects of contrasting habitual PA and fitness levels on cortical bone density, geometry and mass distribution in pre-pubertal children. Boys (n = 241) and girls (n = 245) aged 7-9 years had a pQCT scan to measure tibial mid-shaft total, cortical and medullary area, cortical thickness, density, polar strength strain index (SSIpolar) and the mass/density distribution through the bone cortex (radial distribution divided into endo-, mid- and pericortical regions) and around the centre of mass (polar distribution). Four contrasting PA and fitness groups (inactive-unfit, inactive-fit, active-unfit, active-fit) were generated based on daily step counts (pedometer, 7-days) and fitness levels (20-m shuttle test and vertical jump) for boys and girls separately. Active-fit boys had 7.3-7.7 % greater cortical area and thickness compared to inactive-unfit boys (P < 0.05), which was largely due to a 6.4-7.8 % (P < 0.05) greater cortical mass in the posterior-lateral, medial and posterior-medial 66 % tibial regions. Cortical area was not significantly different across PA-fitness categories in girls, but active-fit girls had 6.1 % (P < 0.05) greater SSIpolar compared to inactive-fit girls, which was likely due to their 6.7 % (P < 0.05) greater total bone area. There was also a small region-specific cortical mass benefit in the posterior-medial 66 % tibia cortex in active-fit girls. Higher levels of habitual PA-fitness were associated with small regional-specific gains in 66 % tibial cortical bone mass in pre-pubertal children, particularly boys.

Timing of low bone mineral density and predictors of bone mineral density trajectory in children on long-term warfarin: a longitudinal study

We studied bone mineral density (BMD) of children exposed to long-term warfarin. BMD Z-scores ≤ -2.0 were estimated to occur in less than one fifth of the patients after 10 years of warfarin exposure, and BMI and growth hormone deficiency predicted BMD changes over time. These predictors can help identify high-risk patients.

INTRODUCTION

Children with chronic diseases are at increased risk of developing thrombosis, which may require long-term warfarin therapy. Warfarin could further jeopardize the bone health of a population already at risk for bone fragility. Our objective was to investigate the occurrence and timing of low bone mineral density (BMD) and the predictors that influence BMD trajectory in children receiving warfarin for >1 year.

METHODS

We analyzed the results of an institutional protocol that includes dual-energy X-ray absorptiometry, with or without spinal X-rays and laboratory biomarkers, as required.

RESULTS

Low BMD (age, sex, race, and height-for-age-Z-score adjusted BMD Z-score ≤ -2.0) was detected in 13 % (9/70) of the patients at some point during their follow-up; these patients were more likely to have complex underlying medical conditions and low body mass index (BMI) percentile. BMD Z-scores remained within normal range in 87 % of children. Survival analysis showed that the estimated 10-year abnormal BMD-free rate for the entire group was 81 % (95 % confidence interval [CI] 69 to 93 %). Trajectory analysis revealed that BMI percentiles at baseline and growth hormone deficiency (GHD) were associated with lower BMD Z-scores at the first assessment, whereas baseline BMI percentile was the only predictor of BMD Z-score over time.

CONCLUSIONS

Our findings identified BMI and GHD as risk factors influencing BMD in children exposed to long-term warfarin, creating an opportunity for early detection and intervention in these patients.

Effects of a Specialist-Led, School Physical Education Program on Bone Mass, Structure, and Strength in Primary School Children: A 4-Year Cluster Randomized Controlled Trial

This 4-year cluster randomized controlled trial of 365 boys and 362 girls (mean age 8.1 ± 0.3 years) from grade 2 in 29 primary schools investigated the effects of a specialist-taught physical education (PE) program on bone strength and body composition. All children received 150 min/week of common practice (CP) PE from general classroom teachers but in 13 schools 100 min/week of CP PE was replaced by specialized-led PE (SPE) by teachers who emphasized more vigorous exercise/games combined with static and dynamic postural activities involving muscle strength. Outcome measures assessed in grades 2, 4, and 6 included: total body bone mineral content (BMC), lean mass (LM), and fat mass (FM) by DXA, and radius and tibia (4% and 66% sites) bone structure, volumetric density and strength, and muscle cross-sectional area (CSA) by pQCT. After 4-years, gains in total body BMC, FM, and muscle CSA were similar between the groups in both sexes, but girls in the SPE group experienced a greater gain in total body LM (mean 1.0 kg; 95% CI, 0.2 to 1.9 kg). Compared to CP, girls in the SPE group also had greater gains in cortical area (CoA) and cortical thickness (CoTh) at the mid-tibia (CoA, 5.0% [95% CI, 0.2% to 1.9%]; CoTh, 7.5% [95% CI, 2.4% to 12.6%]) and mid-radius (CoA, 9.3% [95% CI, 3.5% to 15.1%]; CoTh, 14.4% [95% CI, 6.1% to 22.7%]), whereas SPE boys had a 5.2% (95% CI, 0.4% to 10.0%) greater gain in mid-tibia CoTh. These benefits were due to reduced endocortical expansion. There were no significant benefits of SPE on total bone area, cortical density or bone strength at the mid-shaft sites, nor any appreciable effects at the distal skeletal sites. This study indicates that a specialist-led school-based PE program improves cortical bone structure, due to reduced endocortical expansion. This finding challenges the notion that periosteal apposition is the predominant response of bone to loading during the prepubertal and early-pubertal period.

The Association Between Weight Status and Pediatric Forearm Fractures Resulting From Ground-Level Falls

OBJECTIVE

The purpose of our study was to evaluate the hypothesis that pediatric forearm fractures resulting from ground-level falls are associated with increased weight status (weight for age/sex percentile ≥ 95th) in comparison with those resulting from major trauma.

METHODS

This is a retrospective case-control study nested within a case series of 929 children, ages 0 to 17 years, with self-identified residence in Washington, DC, who were treated for isolated forearm fractures in an urban, academic pediatric emergency department between 2003 and 2006. Multivariable logistic regression was performed to test for the association of weight status with mechanism of injury while controlling for sex, age, race/ethnicity, bone fractured, and season.

RESULTS

Of 929 forearm fractures, there were 226 (24.3%) with ground-level falls and 54 (5.8%) with major trauma. Compared with children with forearm fractures resulting from major trauma, ground-level fall cases were significantly older (10.4 [3.4] vs 7.4 [4.2] years, P < 0.05), had greater adjusted odds of having a weight for age/sex of 95th percentile or higher (odds ratio, 2.7; 95% confidence interval, 1.2-6.5), and had significantly more radius-only fractures (odds ratio, 2.3; 95% confidence interval, 1.2-4.7). These groups did not differ in sex, race/ethnicity, or injury season.

CONCLUSIONS

Ground-level falls are a common mechanism of pediatric forearm fracture and are significantly associated with increased weight status and radius-only fractures. These results suggest the need for further investigation into obesity and bone health in pediatric patients with forearm fractures caused by ground-level falls.

Childhood obesity, bone development, and cardiometabolic risk factors

Osteoporosis and obesity are both major public health concerns. It has long been considered that these are distinct disorders rarely found in the same individual; however, emerging evidence supports an important interaction between adipose tissue and the skeleton. Whereas overweight per se may augment bone strength, animal studies suggest that the metabolic impairment that accompanies obesity is detrimental to bone. Obesity during childhood, a critical time for bone development, likely has profound and lasting effects on bone strength and fracture risk. This notion has received little attention in children and results are mixed, with studies reporting that bone strength development is enhanced or impaired by obesity. Whether obesity is a risk factor for osteoporosis or childhood bone health, in general, remains an important clinical question. Here, we will focus on clarifying the controversial relationships between childhood obesity and bone strength development, and provide insights into potential mechanisms that may regulate the effect of excess adiposity on bone.

Measurement of muscle and fat in postmenopausal women: precision of previously reported pQCT imaging methods

Peripheral quantitative computed tomography (pQCT) imaging has been used to quantify muscle area and density as well as intermuscular adipose tissue (IMAT) and subcutaneous adipose tissue (SAT) area in the lower and upper limb. Numerous protocols have been reported to derive these soft-tissue outcomes, but their precision has not been assessed in community-dwelling postmenopausal women. The objective of this study was to compare the precision of previously reported analysis protocols for quantifying muscle area and density, as well as IMAT and SAT area in postmenopausal women. Six image analysis protocols using two available software suites (Stratec XCT, BoneJ) were identified from the pQCT literature. Analysis protocols were applied to a sample of 35 older female adults (mean age 73.7; SD 7.2 years), randomly selected from a population based-cohort and scanned twice within an average of 9.7 (SD 3.6) days. Relative precision was calculated as absolute values and as a percentage of the sample mean (root mean square coefficient of variation; CV%RMS). Soft-tissue outcomes across protocols were compared on their log-transformed coefficients of variation using multilevel linear models and Tukey contrasts. For most protocols, CV%RMS for muscle area, density, and SAT area ranged between 2.1 and 3.7%, 0.7 and 1.9%, and 2.4 and 6.4%, respectively. Precision for IMAT area varied considerably, from 3 to 42%. Consideration of these study results will aid in the selection of appropriate image analysis protocols for pQCT-derived soft-tissue outcomes in postmenopausal women.

Is high weight status associated with pediatric forearm fractures requiring anatomic reduction?

BACKGROUND

High weight status is associated with increased forearm fracture risk but its relationship to severity of fracture has not been evaluated. We compared the epidemiology of children's forearm fractures treated with fracture reduction to those not treated with reduction, hypothesizing that high weight status would be significantly associated with need for reduction.

METHODS

This is a case-control study including Washington, DC children, ages 2 to 17 years, treated for isolated forearm fractures in an urban, tertiary care pediatric emergency department from 2003 to 2006. Descriptive statistics and logistic regression were conducted to compare patients with forearm fracture reductions to nonintervention controls.

RESULTS

Of 888 forearm fractures, 330 (37.2%) required reduction (cases) whereas 558 (64.8%) did not (controls). Cases were more likely than controls to be male [adjusted odds ratio, 1.67 (95% confidence interval, 1.11-2.50)] and to have experienced a more severe mechanism of trauma [adjusted odds ratio, 2.11 (95% confidence interval, 1.14-3.90)]. The groups did not differ in weight status, age, or race/ethnicity.

CONCLUSIONS

The need for reduction among children with forearm fractures is significantly associated with male sex and major mechanisms of trauma but not with high weight status. Strategies to reduce severe forearm fractures should focus on preventing major mechanisms of trauma.

The Relation between Visceral and Subcutaneous Fat to Bone Mass among Egyptian Children and Adolescents

BACKGROUND: The relation between fat distribution and bone mass is still being debated in children and adolescents.AIM: To verify the influence of both visceral and subcutaneous fat on bone mass among Egyptian children and adolescents.SUBJECTS AND METHODS: The study involved 78 (38 boys and 40 girls) individuals from children (42) and adolescents (36), aged 8-17 years. They were divided into 2 age groups: children group (20 boys and 22 girls) aged 8-12 years and adolescent group (18 boys and 18 girls) aged 13-17 years. Anthropometric measurements, visceral and subcutaneous fat (measured by ultrasound), body composition, BMD and BMC (Measured by DXA), were attempted.RESULTS: Among children, significant positive correlations between visceral fat; in males; and subcutaneous fat; in females; with total BMC, BMD and its Z-score were revealed. After exclusion of age effect, the association between visceral fat in females with total BMD and its Z-score and lumbar BMD-Z-score became significant.  For adolescents, no correlation was observed between either visceral or subcutaneous fat with any parameter of bone mass.CONCLUSIONS: Visceral and subcutaneous fat had significant positive association with bone mass in children; males and females respectively. On the contrary such association disappeared during adolescence.

Body composition during childhood and adolescence: relations to bone strength and microstructure

CONTEXT

Numerous studies have examined the association of body composition with bone development in children and adolescents, but none have used micro-finite element (μFE) analysis of high-resolution peripheral quantitative computed tomography images to assess bone strength.

OBJECTIVE

This study sought to examine the relations of appendicular lean mass (ALM) and total body fat mass (TBFM) to bone strength (failure load) at the distal radius and tibia.

DESIGN, PARTICIPANTS, AND SETTING

This was a cross-sectional study of 198 healthy 8- to <15-year-old boys (n = 109) and girls (n = 89) performed in a Clinical Research Unit.

RESULTS

After adjusting for bone age, height, fracture history, ALM, and TBFM, multiple linear regression analyses in boys and girls, separately, showed robust positive associations between ALM and failure loads at both the distal radius (boys: β = 0.92, P < .001; girls: β = 0.66, P = .001) and tibia (boys: β = 0.96, P < .001; girls: β = 0.66, P < .001). By contrast, in both boys and girls the relationship between TBFM and failure load at the distal radius was virtually nonexistent (boys: β = -0.07; P = .284; girls: β = -0.03; P = .729). At the distal tibia, positive, albeit weak, associations were observed between TBFM and failure load in both boys (β = 0.09, P = .075) and girls (β = 0.17, P = .033).

CONCLUSIONS

Our data highlight the importance of lean mass for optimizing bone strength during growth, and suggest that fat mass may have differential relations to bone strength at weight-bearing vs non-weight-bearing sites in children and adolescents. These observations suggest that the strength of the distal radius does not commensurately increase with excess gains in adiposity during growth, which may result in a mismatch between bone strength and the load experienced by the distal forearm during a fall. These findings may explain, in part, why obese children are over-represented among distal forearm fracture cases.

Quantitative computer tomography in children and adolescents: the 2013 ISCD Pediatric Official Positions

In 2007, International Society of Clinical Densitometry Pediatric Positions Task Forces reviewed the evidence for the clinical application of peripheral quantitative computed tomography (pQCT) in children and adolescents. At that time, numerous limitations regarding the clinical application of pQCT were identified, although its use as a research modality for investigation of bone strength was highlighted. The present report provides an updated review of evidence for the clinical application of pQCT, as well as additional reviews of whole body QCT scans of the central and peripheral skeletons, and high-resolution pQCT in children. Although these techniques remain in the domain of research, this report summarizes the recent literature and evidence of the clinical applicability and offers general recommendations regarding the use of these modalities in pediatric bone health assessment.

Vitamin D supplementation, body weight and human serum 25-hydroxyvitamin D response: a systematic review

PURPOSE

There is considerable variation in incremental circulating 25-hydroxyvitamin D (25OHD) levels on vitamin D supplements, even when similar age groups and identical vitamin D doses are compared. We therefore aimed to investigate the importance of body weight for the dose-response relation in circulating 25OHD.

METHODS

We performed a systematic review of randomized placebo-controlled vitamin D supplementation trials in all age groups ≥10 years to clarify the influence of body weight and other parameters on incremental circulating 25OHD levels (difference between baseline and in-study values) in vitamin D-deficient and non-deficient individuals.

RESULTS

We included 144 cohorts from 94 independent studies, published from 1990 to November 2012, in our systematic review. There was a logarithmic association between vitamin D dose per kg body weight per day and increment in circulating 25OHD. In multivariable regression analysis, vitamin D dose per kg body weight per day could explain 34.5% of variation in circulating 25OHD. Additional significant predictors were type of supplement (vitamin D2 or vitamin D3), age, concomitant intake of calcium supplements and baseline 25OHD, explaining 9.8, 3.7, 2.4 and 1.9%, respectively, of the variation in circulating 25OHD.

CONCLUSIONS

This systematic review demonstrates that body weight is an important predictor of variation in circulating 25OHD in cohorts on vitamin D supplements. Our model provides an estimate of the daily vitamin D dose that is necessary for achieving adequate circulating 25OHD levels in vitamin D-insufficient or vitamin D-deficient individuals/cohorts with different body weights and ages.

Physical education and blood lipid concentrations in children: the LOOK randomized cluster trial

Background and Objectives

Elevated blood lipids during childhood are predictive of dyslipidemia in adults. Although obese and inactive children have elevated values, any potentially protective role of elementary school physical education is unknown. Our objective was to determine the effect of a modern elementary school physical education (PE) program on the blood lipid concentrations in community-based children.

Methods

In this cluster-randomized controlled trial, 708 healthy children (8.1±0.3 years, 367 boys) in 29 schools were allocated to either a 4-year intervention program of specialist-taught PE (13 schools) or to a control group of the currently practiced PE conducted by generalist classroom teachers. Fasting blood lipids were measured at ages 8, 10, and 12 years and intervention and control class activities were recorded.

Results

Intervention classes included more fitness work and more moderate and vigorous physical activity than control classes (both p<0.001). With no group differences at baseline, the percentage of 12 year-old boys and girls with elevated low density lipoprotein cholesterol (LDL-C, >3.36mmol.L⁻¹,130 mg/dL) was lower in the intervention than control group (14% vs. 23%, p = 0.02). There was also an intervention effect on mean LDL-C across all boys (reduction of 9.6% for intervention v 2.8% control, p = 0.02), but not girls (p = 0.2). The intervention effect on total cholesterol mirrored LDL-C, but there were no detectable 4-year intervention effects on high-density lipoprotein cholesterol or triglycerides.

Conclusions

The PE program delivered by specialist teachers over four years in elementary school reduced the incidence of elevated LDL-C in boys and girls, and provides a means by which early preventative practices can be offered to all children.

Trial Registration

Australia New Zealand Clinical Trial Registry ANZRN12612000027819 https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=347799.

Bone size and bone strength are increased in obese male adolescents

CONTEXT

Controversy exists on the effect of obesity on bone development during puberty.

OBJECTIVE

Our objective was to determine differences in volumetric bone mineral density (vBMD) and bone geometry in male obese adolescents (ObAs) in overlap with changes in bone maturation, muscle mass and force development, and circulating sex steroids and IGF-I. We hypothesized that changes in bone parameters are more evident at the weight-bearing site and that changes in serum estradiol are most prominent.

DESIGN, SETTING, AND PARTICIPANTS

We recruited 51 male ObAs (10-19 years) at the entry of a residential weight-loss program and 51 healthy age-matched and 51 bone-age-matched controls.

MAIN OUTCOME MEASURES

vBMD and geometric bone parameters, as well as muscle and fat area were studied at the forearm and lower leg by peripheral quantitative computed tomography. Muscle force was studied by jumping mechanography.

RESULTS

In addition to an advanced bone maturation, differences in trabecular bone parameters (higher vBMD and larger trabecular area) and cortical bone geometry (larger cortical area and periosteal and endosteal circumference) were observed in ObAs both at the radius and tibia at different pubertal stages. After matching for bone age, all differences at the tibia, but only the difference in trabecular vBMD at the radius, remained significant. Larger muscle area and higher maximal force were found in ObAs compared with controls, as well as higher circulating free estrogen, but similar free testosterone and IGF-I levels.

CONCLUSIONS

ObAs have larger and stronger bones at both the forearm and lower leg. The observed differences in bone parameters can be explained by a combination of advanced bone maturation, higher estrogen exposure, and greater mechanical loading resulting from a higher muscle mass and strength.

Geometric indices of hip bone strength in obese, overweight, and normal-weight adolescent girls

The aim of this study was to compare hip bone strength indices in obese, overweight, and normal-weight adolescent girls using hip structure analysis (HSA). This study included 64 postmenarcheal adolescent girls (14 obese, 21 overweight, and 29 normal weight). The 3 groups (obese, overweight, and normal weight) were matched for maturity (years since menarche). Body composition and bone mineral density (BMD) of whole body, lumbar spine, and proximal femur were assessed by dual-energy X-ray absorptiometry (DXA). To evaluate hip bone strength, DXA scans were analyzed at the femoral neck (FN) at its narrow neck (NN) region, the intertrochanteric (IT), and the femoral shaft (FS) by the HSA program. Cross-sectional area and section modulus were measured from hip BMD profiles. Total hip BMD and FN BMD were significantly higher in obese and overweight girls in comparison with normal-weight girls (p < 0.05). However, after adjusting for weight, using a one-way analysis of covariance, there were no significant differences among the 3 groups regarding HSA variables. This study suggests that in obese and overweight adolescent girls, axial strength and bending strength indices of the NN, IT, and FS are adapted to the increased body weight.

Distinct relationships of intramuscular and subcutaneous fat with cortical bone: findings from a cross-sectional study of young adult males and females

CONTEXT

Intracellular fat within muscle and visceral tissue has been suggested to adversely influence bone development.

OBJECTIVE

The aim of the study was to evaluate associations between im fat, as reflected by muscle density as measured by peripheral quantitative computed tomography, and cortical bone parameters in young adults.

DESIGN/SETTING/PARTICIPANTS

We conducted a cross-sectional analysis of 1703 males and 2243 females aged 17.8 years from the Avon Longitudinal Study of Parents and Children.

OUTCOME MEASURES

We measured cortical bone parameters from midtibial peripheral quantitative computed tomography scans.

RESULTS

Muscle density (inversely related to im fat) was inversely associated with periosteal circumference (PC) (beta = -0.07 [95% confidence interval (CI), -0.1, -0.04]), cortical bone mineral density (BMDC) (beta = -0.21 [95% CI, -0.26, -0.17]), and cortical thickness (CT) (beta = -0.37 [95% CI, -0.42, -0.33]) (males and females combined, adjusted for age, height, gender, and muscle cross-sectional area). In contrast, sc fat area was positively associated with PC (beta = 0.10 [95% CI, 0.07, 0.12]), but no association was seen with BMDC or CT. To examine the role of candidate intermediary metabolic pathways, analyses were repeated after adjustment for insulin, C-reactive protein, and β-C-telopeptides of type I collagen. Whereas similar associations were observed after adjustment for insulin and C-reactive protein, the association between muscle density and BMDC was partially attenuated by adjustment for β-C-telopeptides of type I collagen (beta = -0.14 [95% CI, -0.20, -0.08]).

CONCLUSION

Although im and sc fat were both positively associated with cortical bone mass, the nature of these relationships differed in that im fat was predominantly associated with CT and BMDC, whereas sc fat was mainly associated with PC. These relationships were largely independent of candidate metabolic pathways, such as altered bone resorption, insulin resistance, or inflammation.

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.

Origins of balance disorders during a daily living movement in obese: can biomechanical factors explain everything?

Obese people suffer from postural deficits and are more subject to falls than their lean counterpart. To improve prevention and post-fall rehabilitation programs, it seems important to better understand the posturo-kinetic disorders in daily life situations by determining the contribution of some key factors, mainly morphological characteristics and physical activity level, in the apparition of these disorders. Twelve severe android obese and eight healthy non obese adults performed a reaching task mobilizing the whole body. To further determine the origin of the postural and motor behavior differences, non obese individuals also performed an experimental session with additional constraints which simulated some of the obese morphological characteristics. Impact of the sedentary lifestyle was also studied by dissociation of the obese in two subgroups: physically « active » and physically « inactive ». Movement kinetics and kinematics were characterized with an optoelectronic system synchronized to a force platform. The mechanical equilibrium pattern was evaluated through the displacements of the Centre of Mass (CoM) and the centre of foot pressure within the Base of Support (BoS). Results showed that obesity decreased movement speed (≈-23%, p<0.01), strongly increased CoM displacement (≈+30%, p<0.05) and induced an important spatio-temporal desynchronization (≈+40%, p<0.05) of the focal and postural components of the movement during the transition between the descending and ascending movements. The role of some morphological characteristics and of physical activity on obese patients' postural control disorder is discussed and set back in the more general context of overall factors contributing to postural deficits with obesity.

How does bone quality differ between healthy-weight and overweight adolescents and young adults?

BACKGROUND

Overweight youth have greater bone mass than their healthy-weight peers but sustain more fractures. However, it is unclear whether and how excess body fat influences bone quality in youth.

QUESTIONS/PURPOSES

We determined whether overweight status correlated with three-dimensional aspects of bone quality influencing bone strength in adolescent and young adult females and males.

METHODS

We categorized males (n=103; mean age, 17 years) and females (n=85; mean age, 18 years) into healthy-weight and overweight groups. We measured lean mass (LM) and fat mass (FM) with dual-energy x-ray absorptiometry (DXA). We used high-resolution peripheral quantitative CT to assess the distal radius (7% site) and distal tibia (8% site). Bone quality measures included total bone mineral density (Tt.BMD), total area (Tt.Ar), trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), separation (Tb.Sp), and thickness (Tb.Th). We used multiple regression to compare bone quality between healthy-weight and overweight adolescents adjusting for age, ethnicity, limb length, LM, and FM.

RESULTS

Overweight males had higher (10%-21%) Tt.BMD, BV/TV, and Tb.N and lower Tb.Sp at the tibia and lower Tt.Ar at the radius than healthy-weight males. No differences were observed between overweight and healthy-weight females. LM attenuated the differences in bone quality between groups in males while FM negatively predicted Tt.BMD, BV/TV, Tb.N, and Tb.Th.

CONCLUSIONS

Our data suggest overweight males have enhanced bone quality compared with healthy-weight males; however, when group differences are interpreted in the context of the mechanostat theory, it appears bone quality of overweight adolescents adapts to LM and not to greater FM.

Adenovirus 36, adiposity, and bone strength in late-adolescent females

Adenovirus 36 (Ad36) is the only adenovirus to date that has been linked with obesity in humans. Our previous studies in late-adolescent females suggest that excess weight in the form of fat mass is associated with lower cortical bone strength. The purpose of this study was to assess the relationship between Ad36-specific antibodies, adiposity, and bone strength in our sample of late-adolescent females. A cross-sectional study of 115 females aged 18 to 19 years was performed. Participants were classified according to adiposity by dual-energy X-ray absorptiometry (body fat percentage as normal-fat [ < 32% body fat; n = 93] or high-fat [ ≥ 32% body fat; n = 22]), and according to the presence of Ad36-specific neutralizing antibodies. Peripheral quantitative computed tomography measured bone parameters at the 4% (trabecular bone) and 20% (cortical bone) site, and muscle cross-sectional area (MCSA) at the 66% site, from the distal metaphyses of the radius and the tibia. Bone strength was determined from volumetric bone mineral density and bone geometry to calculate bone strength index (BSI; trabecular site) and polar strength-strain index (SSI; cortical site). After adjustment for MCSA and limb length, radial SSI was lower in Ad36+  versus Ad36- subjects from the high-fat group (p < 0.03), but not the normal-fat group. No significant differences were observed between groups in tibial SSI or BSI. These data support an association of adiposity and cortical bone strength at the radius with the presence of neutralizing antibodies to Ad36 in late-adolescent females.

Longitudinal relationships between whole body and central adiposity on weight-bearing bone geometry, density, and bone strength: a pQCT study in young girls

Longitudinal relationships between adiposity (total body and central) and bone development were assessed in young girls. Total body and android fat masses were positively associated with bone strength and density parameters of the femur and tibia. These results suggest adiposity may have site-specific stimulating effects on the developing bone.

INTRODUCTION

Childhood obesity may impair bone development, but the relationships between adiposity and bone remain unclear. Failure to account for fat pattern may explain the conflicting results.

PURPOSE

Longitudinal associations of total body fat mass (TBFM) and android fat mass (AFM) with 2-year changes in weight-bearing bone parameters were examined in 260 girls aged 8-13 years at baseline. Peripheral quantitative computed tomography was used to measure bone strength index (BSI, square milligrams per quartic millimeter), strength-strain index (SSI, cubic millimeters), and volumetric bone mineral density (vBMD, milligrams per cubic centimeter) at distal metaphyseal and diaphyseal regions of the femur and tibia. TBFM and AFM were assessed by dual-energy x-ray absorptiometry.

RESULTS

Baseline TBFM and AFM were positively associated with the change in femur BSI (r = 0.20, r = 0.17, respectively) and femur trabecular vBMD (r = 0.19, r = 0.19, respectively). Similarly, positive associations were found between TBFM and change in tibia BSI and SSI (r = 0.16, r = 0.15, respectively), and femur total and trabecular vBMD (r = 0.12, r = 0.14, respectively). Analysis of covariance showed that girls in the middle thirds of AFM had significantly lower femur trabecular vBMD and significantly higher tibia cortical vBMD than girls in the highest thirds of AFM. All results were significant at p < 0.05.

CONCLUSIONS

Whereas baseline levels of TBFM and AFM are positive predictors of bone strength and density at the femur and tibia, higher levels of AFM above a certain level may impair cortical vBMD growth at weight-bearing sites. Future studies in obese children will be needed to test this possibility.

A trial of sugar-free or sugar-sweetened beverages and body weight in children

BACKGROUND

The consumption of beverages that contain sugar is associated with overweight, possibly because liquid sugars do not lead to a sense of satiety, so the consumption of other foods is not reduced. However, data are lacking to show that the replacement of sugar-containing beverages with noncaloric beverages diminishes weight gain.

METHODS

We conducted an 18-month trial involving 641 primarily normal-weight children from 4 years 10 months to 11 years 11 months of age. Participants were randomly assigned to receive 250 ml (8 oz) per day of a sugar-free, artificially sweetened beverage (sugar-free group) or a similar sugar-containing beverage that provided 104 kcal (sugar group). Beverages were distributed through schools. At 18 months, 26% of the children had stopped consuming the beverages; the data from children who did not complete the study were imputed.

RESULTS

The z score for the body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) increased on average by 0.02 SD units in the sugar-free group and by 0.15 SD units in the sugar group; the 95% confidence interval (CI) of the difference was -0.21 to -0.05. Weight increased by 6.35 kg in the sugar-free group as compared with 7.37 kg in the sugar group (95% CI for the difference, -1.54 to -0.48). The skinfold-thickness measurements, waist-to-height ratio, and fat mass also increased significantly less in the sugar-free group. Adverse events were minor. When we combined measurements at 18 months in 136 children who had discontinued the study with those in 477 children who completed the study, the BMI z score increased by 0.06 SD units in the sugar-free group and by 0.12 SD units in the sugar group (P=0.06).

CONCLUSIONS

Masked replacement of sugar-containing beverages with noncaloric beverages reduced weight gain and fat accumulation in normal-weight children. (Funded by the Netherlands Organization for Health Research and Development and others; DRINK ClinicalTrials.gov number, NCT00893529.).

Total and regional relationship between lean and fat mass with increasing adiposity--impact for the diagnosis of sarcopenic obesity

BACKGROUND/OBJECTIVE

Besides the effect of age used to define sarcopenia, there is need to understand the impact of adiposity on the relationship between lean (fat-free mass, FFM) and fat mass (FM) in order to diagnose sarcopenic obese phenotypes. More importantly, the regional distribution of skeletal muscle (SM) to adipose tissue (AT) or the composition of FFM (that is, SM proportion of lean mass) may also depend on adiposity.

SUBJECTS/METHODS

In a large database (n=1737) of healthy males and females (age 11-84 years, BMI 13.5-52.5 kg/m(2)) we investigated changes in the relationship between FFM and FM (normalized by height as fat-free mass index and fat mass index: FFMI and FMI, kg/m(2) assessed by densitometry) with increasing adiposity and age. In a subgroup (n=263) we analyzed the relationship between regional SM and (i) AT (by magnetic resonance imaging) or (ii) lean soft tissue (by dual X-ray absorptiometry) with increasing adiposity.

RESULTS

The relationship between lean and FM was influenced by adiposity, age and gender. With increasing adiposity, SM/AT declined faster at the trunk in men and at the extremities in women. The contribution of appendicular SM to lean soft tissue of arms and legs tended to decrease at a higher adiposity in both genders (FMI >6.97 kg/m(2) in women; FMI>7.77 kg/m(2) in men).

CONCLUSION

Besides age and gender, adiposity and body region should be considered when evaluating the normal relationship between lean and FM, SM/FFM and SM/AT.

Bone mineral density and vitamin D status among African American children with forearm fractures

OBJECTIVE

To determine whether African American children with forearm fractures have decreased bone mineral density and an increased prevalence of vitamin D deficiency (serum 25-hydroxyvitamin D level ≤ 20 ng/mL) compared with fracture-free control patients.

METHODS

This case-control study in African American children, aged 5 to 9 years, included case patients with forearm fracture and control patients without fracture. Evaluation included measurement of bone mineral density and serum 25-hydroxyvitamin D level. Univariable and multivariable analyses were used to test for associations between fracture status and 2 measures of bone health (bone mineral density and 25-hydroxyvitamin D level) while controlling for other potential confounders.

RESULTS

The final sample included 76 case and 74 control patients. There were no significant differences between case and control patients in age, gender, parental education level, enrollment season, outdoor play time, height, or mean dietary calcium nutrient density. Cases were more likely than control patients to be overweight (49.3% vs 31.4%, P = .03). Compared with control patients, case patients had lower whole body z scores for bone mineral density (0.62 ± 0.96 vs 0.98 ± 1.09; adjusted odds ratio 0.38 [0.20-0.72]) and were more likely to be vitamin D deficient (47.1% vs 40.8%; adjusted odds ratio 3.46 [1.09-10.94]).

CONCLUSIONS

These data support an association of lower bone mineral density and vitamin D deficiency with increased odds of forearm fracture among African American children. Because suboptimal childhood bone health also negatively impacts adult bone health, interventions to increase bone mineral density and correct vitamin D deficiency are indicated in this population to provide short-term and long-term benefits.

The influence of age at menarche on cross-sectional geometry of bone in young adulthood

Elucidating the somatic and maturational influences on the biomechanical properties of bone in children is crucial for a proper understanding of bone strength and quality in childhood and later life, and has significant potential for predicting adult fracture and osteoporosis risks. The ability of a long bone to resist bending and torsion is primarily a function of its cross-sectional geometric properties, and is negatively impacted by smaller external bone diameter. In pubescent girls, elevated levels of estrogen impede subperiosteal bone growth and increase endosteal bone deposition, resulting in bones averaging a smaller external and internal diameter relative to boys. In addition, given a well-documented secular trend for an earlier menarche, the age at which the rate of subperiosteal bone deposition decreases may also be younger in more recent cohorts of girls. In this study we examined the relationship between pubertal timing and subsequent bone strength in girls. Specifically, we investigated the effects of age at menarche on bone strength indicators (polar moment of inertia and section modulus) determined from cross-sectional geometry of the second metacarpal (MC2) using data derived from serial hand-wrist radiographs of female participants (N=223) in the Fels Longitudinal Study, with repeated measures of MC2 between the ages of 7 and 35 years. Using multivariate regression models, we evaluated the effects of age at menarche on associations between measures of bone strength in early adulthood and the same measures at a prepubertal age. Results indicate that later age at menarche is associated with stronger adult bone (in torsion and bending) when controlling for prepubertal bone strength (R(2) ranged between 0.54 and 0.70, p<0.001). Since cross-sectional properties of bone in childhood may have long lasting implications, they should be considered along with pubertal timing in assessing risk for future fracture and in clinical recommendations.

SECULAR TRENDS IN BODY COMPOSITION AND FREQUENCY OF OVERWEIGHT AND OBESITY IN BOYS AGED 3–18 FROM KRAKOW, POLAND, WITHIN THE LAST 30 YEARS (FROM 1983 TO 2010)

The aim of this study was to examine the changes in body composition (fatness and muscle and bone mass) and BMI in three cohorts of boys living in Krakow, Poland, over the last 30 years, and to assess how overweight and obesity frequencies have developed over the period. The anthropological survey was conducted in 2010, and comprised 1863 boys from Krakow aged 3–18 years. The analysis compared the latest measurements of selected skinfold thicknesses, BMI, total body muscle mass and bone mass with the results of surveys from 1983 (N=1934) and 2000 (N=2323). The frequency of overweight and obesity was assessed for the last survey series, and their trends determined for the years 1983–2000 and 2000–2010. The analysis of fat tissue distribution showed that the boys from the 2010 cohort, as compared with those examined in 2000, had a higher trunk adiposity, as manifested by greater thickness of subscapular and suprailiac skinfold thicknesses, and boasted a larger muscle mass and lower bone mass. The survey results also showed that, from 1983 to 2000, the percentage of overweight boys increased slightly (from 11.69% to 12.48%), whereas the frequency of obesity did not change. Over the last decade, the percentage of overweight people has increased to 15.94%, and the frequency of obesity has doubled, equalling 4.94% in 2010. The last decade has seen a minor trend in boys towards increased trunk adiposity, muscle mass, BMI and prevalence of overweight and obesity, and a slight decrease in bone mass.