Association between sedentary behavior and bone mass in adolescents

Short bouts and long-term exercise reduce sedentary-induced bone loss and microstructural changes by modulating bone formation and resorption in healthy young male rats

Although the toxic effect of Sedentary behavior (SED) on bone health has been demonstrated in the previous study, the underlying mechanisms of SED, or break SED to bone health remain unclear. In this study, we aim to investigate the effects of sedentary behavior (SED) on bone health, as well as the potential favor effects of moderate to vigorous physical activity (MVPA) and periodic interruptions of SED. To simulate SED, we used small Plexiglas cages (20.0 × 9.0 × 10.0 cm) to restrict animal movement. Short bursts of exercise to break SED and continuous long-term exercise were also designed. After an 8-weeks period of SED, we observed decreased bone mass and bone microstructure. Specifically, there was a notable decrease in the bone mineral density (BMD), bone surface (BS) and cortical thickness (Ct.Th) significantly reduced in cortical bone. In the trabecular bone, parameters such as trabecular separation (Tb.Sp), trabecular number (Tb.N), BS, connectivity density (Conn.D), BS/BV, bone volume/tissue volume (BV/TV), degree of anisotropy (DA), and structural model index (SMI) were also significantly reduced. In addition, we detected an increase in serum tartrate-resistant acid phosphatase (TRAP) levels in SED rats at both 4 and 8 weeks. At 8 weeks, the osteoclast number and surface with TRAP-staining were significantly increased, however, the OPG mRNA and proteins level were significantly decreased. After daily short bouts exercise and long-term exercise, we observed improvements in bone mass and microstructure. These improvements included increasing BMD and BV/TV of cortical bone, and improving Conn.D, BV/TV, DA and SMI of trabecular. Meanwhile, we found that, at 4 and 8 weeks, there was an increase in serum ALP. At 8 weeks, the mineralized nodules surface with Alizarin Red S-staining, and OPG mRNA and proteins level in bone tissue were significantly increased. Our findings suggest that SED leads to alterations in the bone mass and microstructure, which are associated with the changes in the OPG protein and bone remodeling. Exercise, whether in short daily bouts or continuous long-term sessions, can ameliorate the harmful effects of SED. Similarly, the changes in bone mass and microstructure from exercise are also associated with the changes in the OPG protein and bone remodeling by upregulated osteoblast activity to bone formation. Overall, our findings indicate the importance of physical activity in maintaining bone health and preventing the negative impacts of prolonged SED.

Association between sedentary behavior and bone mass, microstructure and strength in children, adolescents and young adults: a systematic review

Sedentary behavior (SED) research is currently receiving increasing attention in the field of public health. While it has been shown to have negative effects on cardiovascular or metabolic health, there is limited knowledge regarding the relationship between SED and bone health in children, adolescents, and young adults. Thus, the purpose of this review is to investigate the associations between SED and bone health status, specifically bone mass, microstructure, and strength. A comprehensive literature search was conducted across five electronic databases, including EMBASE, PubMed, Medline, Cochrane, Web of Science and CNKI. The inclusion criteria were as follows: healthy participants aged 24 years or younger, with measured SED and measured bone outcomes. The quality of the included articles was assessed using the National Institute of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. After excluding, the final sample included 25 cross-sectional, 9 observational and 2 both cross-sectional and longitudinal studies. Among these, seven were rated as 'high quality', twenty-three were rated as 'moderated quality', and six were rated as 'low quality' according to the quality assessment criteria. After summarizing the evidence, we found no strong evidence to support an association between BMC or BMD and SED, even when considering gender or adjusting for moderate-to-vigorous physical activity (MVPA). However, a strong level of evidence was found indicating a negative relationship between objectively measured SED and cortical bone mineral density (Ct.BMD) in the tibia or stiffness index (SI) in the Calcaneus across all age groups. While the association between adverse bone health outcomes and SED still cannot be confirmed due to insufficient evidence, these findings suggest that bone microstructure and strength may be more sensitive to SED than bone mass. Thus, further evidence is needed to fully understand the connection between sedentary behavior and bone health, particularly regarding the relationship between SED and bone strength.

Description of bone health in adolescents and young persons with Klinefelter syndrome - results from a pilot study

BACKGROUND

In adults with Klinefelter syndrome (KS), impaired bone health with reduced bone mineral density (BMD) has been described even in the presence of testosterone replacement therapy. The aim of the present study was to characterize bone health in young patients with KS.

PATIENTS AND METHODS

20 participants aged 16.10 ± 4.28 years with KS (7 with testosterone replacement therapy) were included in the KliBONE study (DRKS 00024870). Medical history, clinical, radiographic and biochemical parameters of bone health and metabolism were obtained. Radiographic bone health index (BHI) was assessed via automated digital X-ray radiogrammetry of the left hand or via dual energy X-ray absorptiometry (DXA) of the lumbar spine and left femur in participants ≥ 16 years. Peripheral blood mononuclear cells were differentiated into osteoclasts and quantified in 7 participants and 7 healthy controls.

RESULTS

Mean BHI SDS was - 1.42 ± 1.22 and mean BMD z-score at the lumbar vertebrae (L1-4) was - 0.92 ± 1.00. 25-OH-vitamin D levels < 20 ng/ml were detected in 8/20. Other parameters of bone metabolism (bone-specific alkaline phosphatase, PTH, ß-crosslaps and osteocalcin) were within age-appropriate reference ranges. Serum leptin SDS was elevated (mean 2.15 ± 1.19). The number of osteoclasts in participants with KS did not differ from that of controls.

CONCLUSION

BHI SDS and BMD z-scores were lower than expected in young individuals with KS despite age-appropriate bone turnover markers and no apparent pathology in osteoclast differentiation. The cause of the early-onset bone phenotype requires further investigation.

Problematic video gaming is negatively associated with bone mineral density in adolescents

Adolescent bone health may be negatively impacted by problematic video gaming (PVG) due to factors such as prolonged screen time, poor sleep quality, and increased depression. Although sedentary behaviors have been linked to decreased bone mass, there is limited research on how PVG impacts bone health. We aimed to evaluate the association between PVG and bone mineral density (BMD) in adolescents by comparing the BMD z-scores of adolescents with and without PVG and by identifying PVG-related risk factors that may affect low BMD scores. This cross-sectional study took place between May 2019 and August 2021 with 110 adolescents who played video games for at least two hours per day. Data on screen time, game genre, tobacco, alcohol, caffeine consumption, and vigorous physical activity status were recorded. PVG was assessed using the Internet Gaming Disorder-Short Form (IGDS9-SF), with scores ≤ 16 comprising the control group and > 16 the PVG group. Sleep quality was assessed by Pittsburgh Sleep Quality Index, and depression was evaluated by Children's Depression Inventory. Dual-energy X-ray absorptiometry measurements of femoral neck and lumbar spine BMD were compared between the two groups. The mean age of the participants was 14.2 ± 1.8 years, and 86.4% were males. The PVG group exhibited lower femoral neck z-scores (p = 0.013) and a higher proportion of adolescents with low femoral neck BMD risk (27.8% vs 9.7%, p = 0.041). Lumber spine z-scores did not differ (p = 0.271). Despite poorer depressive symptoms and sleep quality in the PVG group, they were not associated with low BMD risk (OR 1.02, 95% CI 0.97-1.08, p = 0.398 and OR 1.00, 95% CI 0.87-1.18, p = 0.972, respectively). Among all PVG-related risk factors, video game time (aOR = 1.22, 95% CI = 1.06-1.41, p = 0.006) and vigorous physical activity amount (aOR = 2.86, 95% CI = 0.93-8.76, p = 0.080) showed the strongest associations with femoral neck z-scores.  Conclusion: The results of this study, showing a negative association between PVG and femoral neck BMD in adolescents, underscore the importance evaluating, monitoring, and supporting lower extremity bone health in adolescents with PVG. What is Known: • Adolescents with problematic video gaming are at risk for depression, impaired sleep; sedentary lifestyle; consumption of tobacco, alcohol, and drugs; and high caffeine intake. • These risk factors might lead to compromised bone health. What is New: • Problematic video gaming is associated with the low femoral neck bone mineral density risk in adolescents. • Extended video game time and reduced physical activity are found to be the primary risk factors.

Role of lifestyle factors in mediating the effect of educational attainment on bone mineral density: a Mendelian randomization study

We performed two-step multivariable Mendelian randomization analysis to explore the mediating role of lifestyle factors in educational attainment (EA) and bone mineral density (BMD). Summary statistics from genome-wide association studies of European lineages were used. Coffee intake and processed-meat intake mediated the association between EA and BMD.

PURPOSE

This study aimed to explore the causal relationship between educational attainment (EA) and bone mineral density (BMD), as well as the potential mediating roles of lifestyle factors in the expected EA-BMD relationship. By identifying modifiable lifestyle factors, we hope to provide relevant information to prevent osteoporosis or low BMD in the less educated population.

METHODS

Using summary statistics from genome-wide association studies (GWAS) of major European lineages, one- and two-sample Mendelian randomization (MR) analyses were performed to estimate the association between EA (in the social sciences genetic association consortium (SSGAC) involving 766,345 individuals and in the UK Biobank (UKB) involving 293,723 individuals) and BMD (in the Genetic Factors for Osteoporosis Consortium involving 426,824 individuals selected from the UKB). The EA variable in both consortia were expressed by years of schooling completed. Two-step multivariable MR was used to assess the mediating roles of eight lifestyle-related factors (moderate-to-vigorous physical activity, watching television, computer using, smoking initiation, coffee intake, alcohol intake frequency, tea intake, and processed-meat intake) in the EA and BMD association, and the corresponding mediating proportion was calculated. Meta-analysis was used to present a pooled estimate.

RESULTS

A total of 317 and 73 independent single-nucleotide polymorphisms (SNPs) of GWAS significance (P < 5.0 × 10-8) were selected as instrumental variables (IVs) for EA in the SSGAC and UKB, respectively. A total of 513 SNPs were selected as IVs for the BMD. The results of one- and two-sample MR revealed that the genetically predicted BMD increased by 0.094 and 0.047 g/cm2, respectively, in response to each SD increment of genetically predicted schooling years. Among the eight candidate mediators, coffee intake and processed-meat intake were potential mediators revealed by the two-step multivariable MR analysis, mediating 26.87% and 23.92% of EA's effect on BMD, respectively. Meta-analysis showed consistent findings. Results of sensitivity analysis indicated the robustness of our findings.

CONCLUSION

We elucidated the causal protective effect of EA on BMD and the mediating roles of coffee intake and processed-meat intake. Intervening with these factors can potentially reduce the burden of bone density loss or osteoporotic fractures among the less educated population.

Correlation between sedentary activity, physical activity and bone mineral density and fat in America: National Health and Nutrition Examination Survey, 2011-2018

We compared the relationship between sedentary activity (SA) and physical activity (PA) with bone mineral density (BMD) and body fat percentage in the United States and found a negative association between SA and BMD and a positive association with body fat percentage. A positive association between PA and BMD and a negative association with body fat percentage. SA and PA are associated with changes in skeletal parameters and body fat percentage, and we aimed to investigate and compare the relationship between SA, PA and bone mineral density (BMD) and body fat percentage in men and women. We assessed the relationship between SA, PA and BMD and body fat percentage in 9787 Americans aged 20-59 years (mean age 38.28 ± 11.39 years) from NHANES 2011-2018. BMD and body fat percentage were measured by dual-energy X-ray bone densitometry (DXA). We used multiple linear regression models to examine the relationships between SA, PA and lumbar spine BMD and total body fat percentage, adjusted for a large number of confounding factors. After adjusting for race/ethnicity, age, alcohol and smoking behavior, body mass index (BMI), total protein, blood calcium, blood uric acid, cholesterol, blood phosphorus, vitamin D, and blood urea nitrogen, SA was negatively associated with lumbar spine BMD (β = - 0.0011 95% CI - 0.0020 to - 0.0002, P = 0.022), and SA was positively associated with total fat percentage (β = PA was positively associated with lumbar BMD (β = 0.0046 95% CI 0.0010 to 0.0082, P = 0.012) and there was a negative association between PA and body fat percentage (β = - 1.177 95% CI - 1.326 to -1.027, P < 0.001). Our results show that physical activity is a key component of maintaining bone health in both men and women and is strongly associated with lower body fat percentages. Sedentary activity is negatively correlated with bone density and is strongly associated with an increase in body fat percentage. Healthcare policy makers should consider reducing sedentary activity and increasing physical activity when preventing osteoporosis and obesity.

Effects of cheerleading practice on advanced glycation end products, areal bone mineral density, and physical fitness in female adolescents

Background: Exercise has been widely reported to promote bone health, but it is unknown whether is associated with a reduction in advanced glycosylation end products (AGEs). This study aimed to investigate the effects of 14 weeks of cheerleading exercise on areal bone mineral density (aBMD) and AGEs.

Methods: In this study, 46 female teenagers (age, 19.52 ± 1.21 years; body mass index, 20.15 ± 2.47 kg/m²) were randomly divided into a cheerleading group (CHE, n = 21) and a control group (CON, n = 25). The CHE group was subjected to cheerleading practice twice a week for 14 weeks; the CON group maintained their daily routine. Dual-energy X-ray absorptiometry was used to measure aBMD, and autofluorescence (AF) values were used to reflect AGEs. Physical fitness testing all-in-one machines are used to test body composition, cardiorespiratory fitness, muscle fitness and flexibility. A mixed ANOVA model was used to examine the effect of the intervention on each outcome. A multiple mediation model with covariates for physical activity and eating behaviors was performed to explore the mediators between cheerleading exercise and aBMD.

Results: After 14 weeks of cheerleading practice, 1) aBMD increased significantly in both groups with significantly higher increases in the CHE group (p < 0.05). 2) AGEs significantly decreased in the CHE group (−2.7%), but not in the CON group (p > 0.05). 3) Vertical jumps and sit-ups significantly increased in the CHE group (p < 0.05), but not in the CON group (p > 0.05). 4) ΔAF values was significantly negatively correlated with Δ aBMD (r = −0.302, p < 0.05). 5) ΔAF values mediated the effect of exercise on the aBMD (indirect effect: 0.0032, 95% CI 0.0002–0.0079).

Conclusion: Cheerleading practice improved aBMD and physical fitness and reduced AGEs accumulation in female adolescents. The effect of exercise on aBMD was partially mediated by AGEs.

Comparison of bone mineral density according to domains of sedentary behavior in children and adolescents

BACKGROUND

Somatic maturation and the age at onset of puberty are closely related to bone mineral density (BMD), and are potential confounders of the associations between physical activity, sedentary behavior (SB) and BMD in adolescents. Thus the aim was compare BMD at different anatomical sites according to different domains of SB.

METHODS

The sample consisted of 88 young people (54 boys and 34 girls; 9.5 ± 1.5 years). The self-reported SB was measured by the time spent on TV, computer, video game and smartphone. BMD at each location and throughout the body was assessed by DEXA. Physical activity was assessed by a questionnaire. The comparison of the different types of BMD sites according to the SB levels for each screen device and the total SB were analyzed by Covariance Analysis (ANCOVA).

RESULTS

Whole-body BMD was higher in young people with low total SB (Total BMD = 0.957 ± 0.042) than in those with moderate (Total BMD = 0.921 ± 0.053) and high SB (Total BMD = 0.929 ± 0.051) (p-value = 0.011). Children and adolescents with low total SB had higher BMD legs (0.965 ± 0.056) than young people with high total SB (BMD legs = 0.877 ± 0.209), but this relationship was attenuated when the analyzes were adjusted for physical activity (p-value = 0.068).

CONCLUSION

Adolescents with high sedentary behavior tend to have lower whole body bone mineral density than those with low sedentary behavior.

Relationship Between Muscle Strength, Body Composition and Bone Mineral Density in Adolescents

Adolescence is an important period for the acquisition of bone mass, which can be enhanced by several factors. This study aimed examine the relationships of handgrip strength, free-fat mass, and fat mass with bone mineral density in adolescents. 118 adolescents (60 girls), aged 10 to 14 years, participated in the study. Information on sex, age, handgrip strength, free-fat mass, fat mass and bone mineral density were collected. Multiple linear regression analyses were conducted to examine possible relationships between bone mineral density and handgrip strength, free-fat mass and fat mass. There was a relation between handgrip strength and free-fat mass with bone mineral density in both sexes. Fat mass was correlated with bone mineral density only in girls (r= 0.314, p< 0.014). The final models, adjusted for sexual maturation, included free-fat mass (girls - β= 0.419, p< 0.001; boys - β= 0.455; p< 0.001) and handgrip strength (girls - β= 0.358, p< 0.05; boys - β= 0.325; p< 0.05) and these variables together explained 51.8% and 62.9% of the variation of bone mineral density, in girls and boys, respectively. Handgrip strength and free-fat mass were positively associated with bone mineral density. A sex-specific difference indicated that higher levels of free-fat mass are of paramount importance for both sexes.

Screen Time and Bone Status in Children and Adolescents: A Systematic Review

Introduction: Technological advances over the last 2 decades have led to an increase in the time spent by children and youth engaged in screen-based activities, and growing recognition of deleterious effects on health. In this systematic review of cohort and cross-sectional studies, we assess current data on the relationship between screen time and bone status in children and teenagers. Methods: We searched PUBMED and SCOPUS databases for studies of children and adolescents that assessed screen time and bone status, determined by measuring bone mineral content or density, bone stiffness index, bone speed of sound, bone broadband ultrasound attenuation, or frame index. Searches were limited to studies published between 1900 and 2020, and performed in accordance with Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. The studies included were evaluated using the Newcastle-Ottawa quality assessment scale. Results: Ten cohort and cross-sectional studies including pediatric population were selected. The combined study population was 20,420 children/adolescents, of whom 18,444 participated in cross-sectional studies. Four studies assessed the effects of total screen time, seven the consequences of TV viewing time, and six the effects of recreational computer use on bone health. Our findings indicate an inverse association between total and weekly screen time and bone health in children and adolescents. In 57% of the studies included also a negative correlation between television viewing time and bone status was observed, while recreational computer time did not have a significant impact on bone health. According to the only four studies that included dietetic factors, no relevant differences were found between calcium intake and screen time or bone broadband ultrasound attenuation and bone speed of sound. Conclusions: Review of the literature of the past three decades provides strong support for comprehensive education of screen time on bone status. The findings of this systematic review support a negative association between screen time and bone status in children and adolescents, with a different impact when considering the different technological devices. As peak bone mass in adolescents is the strongest predictor of osteoporosis risk, strategies aimed at improving bone health should incorporate conscious use of digital technology.