Eight months of regular in-school jumping improves indices of bone strength in adolescent boys and Girls: the POWER PE study

Effects of Implementing 15-Minute Physical Exercise Sessions During Physical Education Classes on Physical Fitness and Anthropometric Indicators in Rural Adolescents

BACKGROUND

The prevalence of overweight, obesity, and low physical fitness is associated with minimal engagement in physical exercise (PEx) and has increasingly affected children and adolescents in rural areas. This study examines the effects of a 15-minute PEx intervention on the levels of physical fitness and anthropometric indicators of overweight and obesity among rural school students.

METHODS

A total of 245 school students (135 boys and 110 girls), aged between 11 and 17 years, were randomly allocated into intervention and comparator groups. The intervention lasted for 12 weeks, comprising 24 PEx sessions. Physical fitness was measured through cardiorespiratory fitness, muscular strength/endurance, handgrip strength, lower limb power, flexibility, speed, and agility. The measured anthropometric indicators of overweight and obesity included body mass index, waist circumference, and the sum of subscapular and triceps skinfolds.

RESULTS

Generalized estimating equations analysis, performed with an intention-to-treat approach, indicated significant group × time interaction (P < .05) for flexibility, muscular strength/endurance, handgrip strength, cardiorespiratory fitness (only for boys), and waist circumference. For these 5 variables, there were no differences between groups at the baseline (P > .05), and the intervention group showed significantly greater improvements compared with the comparator group at the postintervention time (P < .05).

CONCLUSION

An intervention program consisting of 15 minutes of PEx during PE classes, conducted twice a week for 12 weeks, improves cardiorespiratory fitness, flexibility (only for boys), muscular strength/endurance, handgrip strength, body mass index (only for girls), and waist circumference of rural adolescent school students.

Trajectory Analysis of the Four-Year Changes in Body Composition and Bone Mineral Characteristics Among Highly Competitive Male University Long-Distance Runners

OBJECTIVES

This study examined long-term changes in body composition and bone mineral characteristics among male long-distance runners from a high-profile university team, focusing on concerns about impaired musculoskeletal development due to extreme leanness and weight management practices in this population.

METHODS

Trajectory analyses were performed using multilevel modeling of 608 dual-energy x-ray absorptiometry datasets from 109 runners (mean age, height, and weight of 18.0 years, 171.4 cm, and 56.8 kg at baseline, respectively) collected biannually over 4 years.

RESULTS

Linear increases in total and regional lean mass (LM) were observed on average, with the increase in leg LM being double that of arm LM (0.07 vs. 0.03 kg per occasion, respectively). Similarly, total bone mineral density (BMD) and content (BMC) exhibited linear growth on average, with BMD accrual being greater in the legs than in the arms (0.004 vs. 0.001 g/cm2 per occasion, respectively). However, rib BMD and BMC were predicted to decrease. Individually predicted growth rates in total LM were significantly associated with those in total BMD (r = 0.347, p < 0.001) and BMC (r = 0.424, p < 0.001).

CONCLUSIONS

These results indicate site-specific musculoskeletal adaptations to intensive long-distance running training. Moreover, a random slope model accurately captured the trajectories of most dependent variables, highlighting the heterogeneity of training responses. The predictive models developed in this study offer practical strategies for identifying runners at risk of suboptimal physical development, thereby facilitating the development of personalized conditioning programs.

Why should the Next Generation of Youth Guidelines Prioritize Vigorous Physical Activity?

The health benefits of regular physical activity (PA) in youth are well-documented. Yet the adherence rate to PA guidelines among youth worldwide is alarmingly deficient with only 19% of youth worldwide adhering to the World Health Organization guidelines. This is reflective of a global proliferation of a physical inactivity pandemic among youth. The negative consequences of physical inactivity on health are profound, as they threaten to persist into adulthood, exacerbating the burden of preventable health issues. There is persuasive evidence that vigorous PA generates physical fitness and health benefits surpassing those of low- or moderate-intensity activity in youth. In addition, indications show that the adherence rate to vigorous PA among youth exceeds that relative to for low- or moderate-intensity activity. As a result, promoting vigorous PA can help mitigate the global issue of low adherence to PA in youth. Therefore, in this Current Opinion paper, we argue that vigorous PA, compared to low or moderate-intensity activity, holds greater significance for youth's health and physical fitness. Additionally, the potential implications derived from the existing evidence regarding vigorous PA on the current guidelines for youth are discussed.

Interventions to prevent obesity in children aged 12 to 18 years old

BACKGROUND

Prevention of obesity in adolescents is an international public health priority. The prevalence of overweight and obesity is over 25% in North and South America, Australia, most of Europe, and the Gulf region. Interventions that aim to prevent obesity involve strategies that promote healthy diets or 'activity' levels (physical activity, sedentary behaviour and/or sleep) or both, and work by reducing energy intake and/or increasing energy expenditure, respectively. There is uncertainty over which approaches are more effective, and numerous new studies have been published over the last five years since the previous version of this Cochrane Review.

OBJECTIVES

To assess the effects of interventions that aim to prevent obesity in adolescents by modifying dietary intake or 'activity' levels, or a combination of both, on changes in BMI, zBMI score and serious adverse events.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was February 2023.

SELECTION CRITERIA

Randomised controlled trials in adolescents (mean age 12 years and above but less than 19 years), comparing diet or 'activity' interventions (or both) to prevent obesity with no intervention, usual care, or with another eligible intervention, in any setting. Studies had to measure outcomes at a minimum of 12 weeks post baseline. We excluded interventions designed primarily to improve sporting performance.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our outcomes were BMI, zBMI score and serious adverse events, assessed at short- (12 weeks to < 9 months from baseline), medium- (9 months to < 15 months) and long-term (≥ 15 months) follow-up. We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

This review includes 74 studies (83,407 participants); 54 studies (46,358 participants) were included in meta-analyses. Sixty studies were based in high-income countries. The main setting for intervention delivery was schools (57 studies), followed by home (nine studies), the community (five studies) and a primary care setting (three studies). Fifty-one interventions were implemented for less than nine months; the shortest was conducted over one visit and the longest over 28 months. Sixty-two studies declared non-industry funding; five were funded in part by industry. Dietary interventions versus control The evidence is very uncertain about the effects of dietary interventions on body mass index (BMI) at short-term follow-up (mean difference (MD) -0.18, 95% confidence interval (CI) -0.41 to 0.06; 3 studies, 605 participants), medium-term follow-up (MD -0.65, 95% CI -1.18 to -0.11; 3 studies, 900 participants), and standardised BMI (zBMI) at long-term follow-up (MD -0.14, 95% CI -0.38 to 0.10; 2 studies, 1089 participants); all very low-certainty evidence. Compared with control, dietary interventions may have little to no effect on BMI at long-term follow-up (MD -0.30, 95% CI -1.67 to 1.07; 1 study, 44 participants); zBMI at short-term (MD -0.06, 95% CI -0.12 to 0.01; 5 studies, 3154 participants); and zBMI at medium-term (MD 0.02, 95% CI -0.17 to 0.21; 1 study, 112 participants) follow-up; all low-certainty evidence. Dietary interventions may have little to no effect on serious adverse events (two studies, 377 participants; low-certainty evidence). Activity interventions versus control Compared with control, activity interventions do not reduce BMI at short-term follow-up (MD -0.64, 95% CI -1.86 to 0.58; 6 studies, 1780 participants; low-certainty evidence) and probably do not reduce zBMI at medium- (MD 0, 95% CI -0.04 to 0.05; 6 studies, 5335 participants) or long-term (MD -0.05, 95% CI -0.12 to 0.02; 1 study, 985 participants) follow-up; both moderate-certainty evidence. Activity interventions do not reduce zBMI at short-term follow-up (MD 0.02, 95% CI -0.01 to 0.05; 7 studies, 4718 participants; high-certainty evidence), but may reduce BMI slightly at medium-term (MD -0.32, 95% CI -0.53 to -0.11; 3 studies, 2143 participants) and long-term (MD -0.28, 95% CI -0.51 to -0.05; 1 study, 985 participants) follow-up; both low-certainty evidence. Seven studies (5428 participants; low-certainty evidence) reported data on serious adverse events: two reported injuries relating to the exercise component of the intervention and five reported no effect of intervention on reported serious adverse events. Dietary and activity interventions versus control Dietary and activity interventions, compared with control, do not reduce BMI at short-term follow-up (MD 0.03, 95% CI -0.07 to 0.13; 11 studies, 3429 participants; high-certainty evidence), and probably do not reduce BMI at medium-term (MD 0.01, 95% CI -0.09 to 0.11; 8 studies, 5612 participants; moderate-certainty evidence) or long-term (MD 0.06, 95% CI -0.04 to 0.16; 6 studies, 8736 participants; moderate-certainty evidence) follow-up. They may have little to no effect on zBMI in the short term, but the evidence is very uncertain (MD -0.09, 95% CI -0.2 to 0.02; 3 studies, 515 participants; very low-certainty evidence), and they may not reduce zBMI at medium-term (MD -0.05, 95% CI -0.1 to 0.01; 6 studies, 3511 participants; low-certainty evidence) or long-term (MD -0.02, 95% CI -0.05 to 0.01; 7 studies, 8430 participants; low-certainty evidence) follow-up. Four studies (2394 participants) reported data on serious adverse events (very low-certainty evidence): one reported an increase in weight concern in a few adolescents and three reported no effect.

AUTHORS' CONCLUSIONS

The evidence demonstrates that dietary interventions may have little to no effect on obesity in adolescents. There is low-certainty evidence that activity interventions may have a small beneficial effect on BMI at medium- and long-term follow-up. Diet plus activity interventions may result in little to no difference. Importantly, this updated review also suggests that interventions to prevent obesity in this age group may result in little to no difference in serious adverse effects. Limitations of the evidence include inconsistent results across studies, lack of methodological rigour in some studies and small sample sizes. Further research is justified to investigate the effects of diet and activity interventions to prevent childhood obesity in community settings, and in young people with disabilities, since very few ongoing studies are likely to address these. Further randomised trials to address the remaining uncertainty about the effects of diet, activity interventions, or both, to prevent childhood obesity in schools (ideally with zBMI as the measured outcome) would need to have larger samples.

School-based physical activity interventions: which intervention characteristics are associated with participation and retention? A meta-analysis

OBJECTIVE

Many school-based intervention studies are conducted to increase students' physical activity (PA). Recruitment and retention problems potentially impact the robustness of RCT findings. We conducted a meta-analysis to summarize recruitment and retention rates in long-term secondary school-based PA intervention studies and examined associated participant and intervention characteristics.

METHODS

Web of Science, Pubmed, Medline, and PsychInfo were searched until March 20th 2023. We included studies on secondary school-based PA interventions ≥12 weeks, aimed at typically developing adolescents. We abstracted number of schools and students invited, randomized, and participating at follow-up to calculate pooled recruitment and retention rates; participant and intervention characteristics were abstracted to execute subgroup or meta-regression analyses.

RESULTS

Recruitment rates were 51% for invited schools and 80% for invited students, the retention for schools was almost 100% and for students 91%. Interventions with fixed and flexible components, executed in Asia and South America, and from later publication years had higher student recruitment rates. Students' retention rates were lower for interventions which had flexible components, were theory/model-based, used an accelerometer, had a longer intervention duration, and included more females.

CONCLUSION

Recruitment and retention rates in school-based PA interventions are high. Some participant and intervention characteristics influence these rates: flexibility of the intervention, theory/model-based intervention, accelerometer use, intervention duration, continent, and number of females. Researchers should consider these characteristics in intervention development to achieve optimal balance between intervention effectiveness, recruitment, and retention.

Exercise promotes osteogenic differentiation by activating the long non-coding RNA H19/microRNA-149 axis

BACKGROUND

Regular physical activity during childhood and adolescence is beneficial to bone development, as evidenced by the ability to increase bone density and peak bone mass by promoting bone formation.

AIM

To investigate the effects of exercise on bone formation in growing mice and to investigate the underlying mechanisms.

METHODS

20 growing mice were randomly divided into two groups: Con group (control group, n = 10) and Ex group (treadmill exercise group, n = 10). Hematoxylin-eosin staining, immunohistochemistry, and micro-CT scanning were used to assess the bone formation-related indexes of the mouse femur. Bioinformatics analysis was used to find potential miRNAs targets of long non-coding RNA H19 (lncRNA H19). RT-qPCR and Western Blot were used to confirm potential miRNA target genes of lncRNA H19 and the role of lncRNA H19 in promoting osteogenic differentiation.

RESULTS

Compared with the Con group, the expression of bone morphogenetic protein 2 was also significantly increased. The micro-CT results showed that 8 wk moderate-intensity treadmill exercise significantly increased bone mineral density, bone volume fraction, and the number of trabeculae, and decreased trabecular segregation in the femur of mice. Inhibition of lncRNA H19 significantly upregulated the expression of miR-149 and suppressed the expression of markers of osteogenic differentiation. In addition, knockdown of lncRNA H19 significantly downregulated the expression of autophagy markers, which is consistent with the results of autophagy-related protein changes detected in mouse femurs by immunofluorescence.

CONCLUSION

Appropriate treadmill exercise can effectively stimulate bone formation and promote the increase of bone density and bone volume in growing mice, thus enhancing the peak bone mass of mice. The lncRNA H19/miR-149 axis plays an important regulatory role in osteogenic differentiation.

Risk of low bone mineral density in patients with haemophilia: a systematic review and meta-analysis

INTRODUCTION

Patients with haemophilia (PWH) may have lower bone mineral density (BMD). The risk of low BMD in PWH has not been comprehensively analysed. This study aimed to examine the risk of low BMD and changes in BMD in PWH.

METHODS

A comprehensive systematic search was performed in 4 databases: PubMed, Embase, Web of Science, and Cochrane Library. The last search was carried out on 11 December 2022. Review Manager 5.4 and Stata 16 were used for meta-analysis. Odds ratios were calculated by the incidence of low BMD between the haemophilia and control groups in each study. A meta-analysis of the odds ratios for each study was performed to estimate pooled odds ratios. Fixed effects models or random effects models were used to assess outcomes. Heterogeneity was evaluated using Higgins' I2. Subgroup analysis and sensitivity analysis were performed to interpret the potential source of heterogeneity. A funnel plot, Egger's regression test, and the trim-and-fill method were used to assess publication bias.

RESULTS

19 of 793 studies, published between 2004 and 2022, that were identified by search strategy were included in this meta-analysis. The risk for low BMD was approximately four times higher compared to controls. PWH have significantly lower lumbar spine, femoral neck, and total hip BMD. Subgroup analysis showed that the risk of low BMD did not increase significantly in developed countries. Very low heterogeneity was observed in the meta-analysis of the risk of low BMD. The result from Egger's regression test suggested that there may be publication bias. However, the meta-analysis results did not alter after the trim-and-fill correction and the findings were robust.

CONCLUSION

Haemophilia was associated with an increased risk of low BMD. However, the risk of low BMD did not increase significantly in developed countries. And BMD was reduced in PWH, regardless of age, region, or economic ability. For PWH, our concerns should extend beyond bleeding and osteoarthritis to encompass BMD starting at a young age.

Endocrine Health and Health Care Disparities in the Pediatric and Sexual and Gender Minority Populations: An Endocrine Society Scientific Statement

Endocrine care of pediatric and adult patients continues to be plagued by health and health care disparities that are perpetuated by the basic structures of our health systems and research modalities, as well as policies that impact access to care and social determinants of health. This scientific statement expands the Society's 2012 statement by focusing on endocrine disease disparities in the pediatric population and sexual and gender minority populations. These include pediatric and adult lesbian, gay, bisexual, transgender, queer, intersex, and asexual (LGBTQIA) persons. The writing group focused on highly prevalent conditions-growth disorders, puberty, metabolic bone disease, type 1 (T1D) and type 2 (T2D) diabetes mellitus, prediabetes, and obesity. Several important findings emerged. Compared with females and non-White children, non-Hispanic White males are more likely to come to medical attention for short stature. Racially and ethnically diverse populations and males are underrepresented in studies of pubertal development and attainment of peak bone mass, with current norms based on European populations. Like adults, racial and ethnic minority youth suffer a higher burden of disease from obesity, T1D and T2D, and have less access to diabetes treatment technologies and bariatric surgery. LGBTQIA youth and adults also face discrimination and multiple barriers to endocrine care due to pathologizing sexual orientation and gender identity, lack of culturally competent care providers, and policies. Multilevel interventions to address these disparities are required. Inclusion of racial, ethnic, and LGBTQIA populations in longitudinal life course studies is needed to assess growth, puberty, and attainment of peak bone mass. Growth and development charts may need to be adapted to non-European populations. In addition, extension of these studies will be required to understand the clinical and physiologic consequences of interventions to address abnormal development in these populations. Health policies should be recrafted to remove barriers in care for children with obesity and/or diabetes and for LGBTQIA children and adults to facilitate comprehensive access to care, therapeutics, and technological advances. Public health interventions encompassing collection of accurate demographic and social needs data, including the intersection of social determinants of health with health outcomes, and enactment of population health level interventions will be essential tools.

Physical activity in infancy and early childhood: a narrative review of interventions for prevention of obesity and associated health outcomes

In the context of the childhood obesity epidemic, this narrative review aims to explore opportunities to promote physical activity (PA) between birth and age 5 years as well as the health outcomes associated with PA in early childhood. Although early childhood is an ideal time to promote healthy habits, guidelines for PA have often ignored early childhood given the limited evidence for children <5 years old. Herein we discuss and highlight infant, toddler and preschool age interventions to promote PA and prevent obesity both in the short and long-term. We describe novel and modified interventions to promote improved early childhood health outcomes, encompassing cardiorespiratory, muscle, and bone strengthening components necessary for short-term motor development and long-term health. We call for new research aimed at developing and testing innovative early childhood interventions that may be performed in home or childcare settings, monitored by parents or caregivers.

Bone-specific physical activity questionnaire-derived skeletal loading score predicts bone geometry, density, and strength indices: a cross-sectional study

INTRODUCTION

The bone-specific physical activity questionnaire (BPAQ) provides a bone-relevant index of physical activity participation according to the mechanical loads experienced across the life span.

MATERIALS AND METHODS

We aimed to examine relationships between historical bone-relevant physical activity and pQCT-derived parameters of bone strength. We recruited 532 healthy volunteers (277 males, 255 females) across a broad age range (4-97 years). Peripheral quantitative computed tomography (XCT-3000, Stratec, Germany) was used to examine volumetric bone density, area, and strength indices of the non-dominant tibia and radius. Exercise loading history from birth was determined using the past BPAQ (pBPAQ) score. Pearson correlation analysis was used to examine relationships between pBPAQ scores and pQCT parameters.

RESULTS

Independent of sex, pBPAQ scores were associated with total density at the 38% and 66% tibial sites and the 66% radial site (r = 0.145-0.261, p ˂ 0.05), total area at the 38% tibial site and 4% and 66% radial sites (r = 0.129-0.156, p ˂ 0.05), and strength indices at all measured sites (r = 0.123-0.234, p < 0.05).

CONCLUSION

We conclude that, independent of sex, historical bone-relevant physical activity is associated with pQCT-derived indices of bone strength, indicating that pBPAQ captures the characteristics of bone loading history that are likely to be relevant adaptive stimuli. A larger sample is required to examine the influence of age on this relationship.

Impact loading intensifies cortical bone (re)modeling and alters longitudinal bone growth of pubertal rats

Physical exercise is important for musculoskeletal development during puberty, which builds bone mass foundation for later in life. However, strenuous levels of training might bring adverse effects to bone health, reducing longitudinal bone growth. Animal models with various levels of physical exercise were largely used to provide knowledge to clinical settings. Experiments from our previous studies applied different levels of mechanical loading on rat tibia during puberty accompanied by weekly in vivo micro-CT scans. In the present article, we apply 3D image registration-based methods to retrospectively analyze part of the previously acquired micro-CT data. Longitudinal bone growth, growth plate thickness, and cortical bone (re)modeling were evaluated from rats' age of 28-77 days. Our results show that impact loading inhibited proximal bone growth throughout puberty. We hypothesize that impact loading might bring different growth alterations to the distal and proximal growth plates. High impact loading might lead to pathological consequence of osteochondrosis and catch-up growth due to growth inhibition. Impact loading also increased cortical bone (re)modeling before and after the peak proximal bone growth period of young rats, of which the latter case might be caused by the shift from modeling to remodeling as the dominant activity toward the end of rat puberty. We confirm that the tibial endosteum is more mechano-sensitive than the periosteum in response to mechanical loading. To our knowledge, this is the first study to follow up bone growth and bone (re)modeling of young rats throughout the entire puberty with a weekly time interval.

Short-Term Muscle Power Is Related to Lower Limb Muscle Volume in Young Children

PURPOSE

Muscle power is a component of muscular fitness and is proportional to its volume. Reduced muscular fitness in children is linked to negative health outcomes. Associations between muscle volume (MV) and power have not been examined in young children and could reveal important insights into early neuromuscular development.

METHOD

Forty-four children (2-8 y) completed 3 tests of short-term muscular power: repeated anaerobic sprint test, vertical jump, and horizontal jump. MV was assessed using 3D ultrasound for 3 lower limb muscles (rectus femoris, medial gastrocnemius, and tibialis anterior) and summed for across legs. Associations between muscular power and summed MV were assessed using Pearson correlation (r). Sex-based differences in muscular power and MV were assessed using 1-way analysis of covariance.

RESULTS

Moderate-strong associations (r = .57 - .87) were found between muscular power and summed MV. No differences were found between boys and girls for height, weight, MV, or muscular power.

CONCLUSIONS

Young children who have larger lower limb muscles perform better at tasks dependent on short-term muscular power, such as running and jumping, compared with children with smaller muscles. Sex-based differences in short-term muscular power do not exist in young children and reflect similar anthropometry, including lower limb MV.

A comparison of the associations between bone health and three different intensities of accelerometer-derived habitual physical activity in children and adolescents: a systematic review

Positive associations have been identified between bone outcomes and accelerometer-derived moderate (MPA) and vigorous (VPA) physical activity (PA) in youth; however, it remains unclear which intensity is most beneficial. This systematic review aimed to summarise accelerometer-derived methods used to estimate habitual PA in children and adolescents and determine whether the magnitude of association was consistently stronger for a particular intensity (MPA/MVPA/VPA). Observational studies assessing associations between accelerometer-derived MPA and/or MVPA and VPA with bone outcomes in children and adolescents (≤ 18 years) were identified in MEDLINE, EMBASE, Web of Science, SPORTDiscus and the Cochrane Central Register of Controlled Trials. Thirty articles were included (total n = 20,613 (10,077 males), 4-18 years). Chi-square tests determined whether the proportion of significant associations and strongest within-study associations differed significantly between intensities. Results demonstrated that accelerometer methods were highly variable between studies. Of the 570 associations analysed, 186 were significant (p < 0.05). The proportion of within-study strongest associations differed by PA intensity (3 × 2 χ2 = 86.6, p < 0.001) and was significantly higher for VPA (39%) compared to MVPA (5%; 2 × 2 χ2 = 55.3, p < 0.001) and MPA (9%, 2 × 2 χ2 = 49.1, p < 0.001). Results indicated a greater benefit of VPA over MPA/MVPA; however, variability in accelerometer-derived methods used prevents the precise bone-benefitting amount of VPA from being identified. Long epochs and numerous intensity cut-point definitions mean that bone-relevant PA has likely been missed or misclassified in this population. Future research should explore the use of shorter epochs (1 s) and identify bone-specific activity intensities, rather than using pre-defined activity classifications more relevant to cardiovascular health.

The Effects of a Physical Education Intervention Program on the Bone Properties of Second- and Third-Grade Pupils: A Cluster Randomized Controlled Trial

BACKGROUND

Many young children do not participate in sufficient physical activity for promoting optimal bone growth. The objective of this study was to investigate the effect of young children who participated in a school-based intervention program on bone properties. The program included structured physical activity, with a focus on the application of mechanical loads on the upper and lower limbs.

METHODS

A cluster randomized controlled trial was conducted, in which classes were randomly assigned to the intervention or control groups. A total of 295 (50.17% girls) children from the second and third grades from 12 classes in Israel were randomly allocated to an intervention consisting of three 10-minute weekly medium- to high-intensity activities throughout one academic year or to a treatment as usual control group. Bone properties were measured at the distal radius and tibia shaft using speed of sound, before and after the intervention.

RESULTS

Distal radius properties improved significantly for both boys and girls in the intervention group (boys: meanpre = 3769.95, meanpost = 3875.08, Δ = 2.80%; girls: meanpre = 3766.27, meanpost = 3890.83, Δ = 3.30%; d = 1.03); whereas, tibia shaft properties only significantly improved for boys (meanpre = 3663.98, meanpost = 3732.75, Δ = 1.90%; d = 1).

CONCLUSIONS

These findings indicate that distal radius properties of children can be positively affected by a short, easy to implement intervention program that does not require special resources.

Interscholastic Athletics and Bone Strength: The Iowa Bone Development Study

ABSTRACT

Pashkova, A, Hartman, JM, Letuchy, EM, and Janz, KF. Interscholastic athletics and bone strength: the Iowa bone development study. J Strength Cond Res 36(5): 1271-1276, 2022-The objective of this study was to determine the relationship between adolescents' participation in various interscholastic sports and differences in bone strength outcomes. Subjects (N = 380) were recruited from the Iowa Bone Development Study and categorized based on sport participation into 3 power groups: no-power, low-power, and high-power. Sports such as basketball, cheerleading/poms, gymnastics, volleyball, track, football, tennis, and soccer were considered high-power. Peripheral quantitative computed tomography (pQCT) was used to determine bone measures of polar stress-strain index (measure of torsion strength), cortical content (measure of cortical bone size and area at the 66% tibia site), and bone strength index (measure of compression strength based on total bone density and area at the 4% tibia site). Adjusted pairwise comparison for group least squares means high-power sport participation compared with no-power sport participation showed significant differences in all bone strength outcomes for both men and women (p value < 0.01). There was a significant difference in all bone strength measures between low-power and no-power groups for men (p value < 0.05), but not women. Because of decreasing levels of physical activity in late adolescence, the promotion of high-power sports may be particularly important for optimal bone development in the final years before peak bone mass.

Acquisition of peak bone mass

Peak bone mass (PBM) is a key determinant of bone mass and fragility fractures later in life. The increase in bone mass during childhood and adolescence is mainly related to an increase in bone size rather to changes in volumetric bone density. Race, gender, and genetic factors are the main determinants of PBM achievement. Nevertheless, environmental factors such as physical activity, calcium and protein intakes, weight and age at menarche, are also playing an important role in bone mass accrual during growth. Therefore, optimization of calcium and protein intakes and weight-bearing physical activity during growth is an important strategy for optimal acquisition of PBM and bone strength and for contributing to prevent fractures later in life.

Bone mineral density in haemophilia - a multicentre study evaluating the impact of different replacement regimens

AIM

The aim of this study was to investigate if prophylactic treatment in severe haemophilia impact on bone mineral densisty (BMD) in adults with haemophilia A/B.

METHODS

Subjects with haemophilia (n = 120) underwent bone-density measurement and clinical data was collected. BMD in subjects with severe haemophilia on high-dose prophylaxis (n = 41) was compared to BMD in subjects with mild haemophilia (n = 33) and to severe haemophilia treated with intermediate-dose prophylaxis (n = 32) or on-demand replacement therapy (n = 14).

RESULTS

Subjects with severe haemophilia on high-dose prophylaxis showed BMD at total hip comparable to subjects with mild haemophilia (median BMD 955.8 and 977.4 mg/cm² (P = .17), respectively). No difference in BMD was found related to type of prophylactic regimen (median BMD 955.8 and 942.4 mg/cm² , in high-dose and intermediate dose groups, respectively; P = .70). Subjects with severe disease treated on-demand had significantly lower BMD compared to subjects on a high-dose prophylactic regimen (median BMD 771.8 and 955.8 mg/cm² (P = .001), respectively). BMD decreased significantly with age, regardless of severity of haemophilia disease. In a multivariate analysis, adjusted for disease status and age, type of prophylactic regimen was not significantly associated with osteoporosis development.

CONCLUSION

We show that BMD differs in persons with severe haemophilia on propylaxis as compared to those treated on-demand, but that type of prophylactic regimen does not reflect on BMD. The difference between treatment groups was mainly explained by an age difference between groups. However, patients on prophylaxis displayed a high degree of normal BMD not far from mild haemophilia at comparative age.

Circulating Levels of Bone Markers after Short-Term Intense Training with Increased Dairy Consumption in Adolescent Female Athletes

Thirteen female adolescent soccer players (14.3 ± 1.3 years) participated in a cross-over, double-blind trial examining the effects of Greek yogurt (GY) consumption on bone biomarkers during 5 days of intense soccer training. The study took place over two intervention weeks, which consisted of a pre-training assessment day, 5 training days, and a post-training assessment day. Participants completed the GY condition and a carbohydrate isocaloric placebo control pudding condition (CHO) in random order, 4 weeks apart. Morning, fasted, resting blood samples were collected pre- and post-training in each condition. Total osteocalcin (tOC), undercarboxylated osteocalcin (unOC), C-terminal telopeptide of type 1 collagen (CTX), osteoprotegerin (OPG), and receptor activator nuclear factor kappa-β ligand (RANKL) were measured in serum. The results showed no effects for time (pre- to post-training) or condition, and no interaction for tOC, CTX, OPG, RANKL, and the OPG/RANKL ratio. A time-by-condition interaction (p = 0.011) was observed in unOC, reflecting a post-training decrease in the GY, but not the CHO condition (-26% vs. -3%, respectively). However, relative unOC (% of tOC) decreased post-training (-16%), with no differences between conditions. These findings suggest that short-term high-impact intense training had no direct catabolic impact on bone metabolism, with GY adding no benefit beyond that of the isocaloric CHO control pudding.

School-based physical activity programs for promoting physical activity and fitness in children and adolescents aged 6 to 18

BACKGROUND

Physical activity among children and adolescents is associated with lower adiposity, improved cardio-metabolic health, and improved fitness. Worldwide, fewer than 30% of children and adolescents meet global physical activity recommendations of at least 60 minutes of moderate to vigorous physical activity per day. Schools may be ideal sites for interventions given that children and adolescents in most parts of the world spend a substantial amount of time in transit to and from school or attending school.

OBJECTIVES

The purpose of this review update is to summarise the evidence on effectiveness of school-based interventions in increasing moderate to vigorous physical activity and improving fitness among children and adolescents 6 to 18 years of age. Specific objectives are: • to evaluate the effects of school-based interventions on increasing physical activity and improving fitness among children and adolescents; • to evaluate the effects of school-based interventions on improving body composition; and • to determine whether certain combinations or components (or both) of school-based interventions are more effective than others in promoting physical activity and fitness in this target population.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, PsycINFO, BIOSIS, SPORTDiscus, and Sociological Abstracts to 1 June 2020, without language restrictions. We screened reference lists of included articles and relevant systematic reviews. We contacted primary authors of studies to ask for additional information.

SELECTION CRITERIA

Eligible interventions were relevant to public health practice (i.e. were not delivered by a clinician), were implemented in the school setting, and aimed to increase physical activity among all school-attending children and adolescents (aged 6 to 18) for at least 12 weeks. The review was limited to randomised controlled trials. For this update, we have added two new criteria: the primary aim of the study was to increase physical activity or fitness, and the study used an objective measure of physical activity or fitness. Primary outcomes included proportion of participants meeting physical activity guidelines and duration of moderate to vigorous physical activity and sedentary time (new to this update). Secondary outcomes included measured body mass index (BMI), physical fitness, health-related quality of life (new to this update), and adverse events (new to this update). Television viewing time, blood cholesterol, and blood pressure have been removed from this update.  DATA COLLECTION AND ANALYSIS: Two independent review authors used standardised forms to assess each study for relevance, to extract data, and to assess risk of bias. When discrepancies existed, discussion occurred until consensus was reached. Certainty of evidence was assessed according to GRADE. A random-effects meta-analysis based on the inverse variance method was conducted with participants stratified by age (children versus adolescents) when sufficient data were reported. Subgroup analyses explored effects by intervention type.

MAIN RESULTS

Based on the three new inclusion criteria, we excluded 16 of the 44 studies included in the previous version of this review. We screened an additional 9968 titles (search October 2011 to June 2020), of which 978 unique studies were potentially relevant and 61 met all criteria for this update. We included a total of 89 studies representing complete data for 66,752 study participants. Most studies included children only (n = 56), followed by adolescents only (n = 22), and both (n = 10); one study did not report student age. Multi-component interventions were most common (n = 40), followed by schooltime physical activity (n = 19), enhanced physical education (n = 15), and before and after school programmes (n = 14); one study explored both enhanced physical education and an after school programme. Lack of blinding of participants, personnel, and outcome assessors and loss to follow-up were the most common sources of bias.  Results show that school-based physical activity interventions probably result in little to no increase in time engaged in moderate to vigorous physical activity (mean difference (MD) 0.73 minutes/d, 95% confidence interval (CI) 0.16 to 1.30; 33 studies; moderate-certainty evidence) and may lead to little to no decrease in sedentary time (MD -3.78 minutes/d, 95% CI -7.80 to 0.24; 16 studies; low-certainty evidence). School-based physical activity interventions may improve physical fitness reported as maximal oxygen uptake (VO₂max) (MD 1.19 mL/kg/min, 95% CI 0.57 to 1.82; 13 studies; low-certainty evidence). School-based physical activity interventions may result in a very small decrease in BMI z-scores (MD -0.06, 95% CI -0.09 to -0.02; 21 studies; low-certainty evidence) and may not impact BMI expressed as kg/m² (MD -0.07, 95% CI -0.15 to 0.01; 50 studies; low-certainty evidence). We are very uncertain whether school-based physical activity interventions impact health-related quality of life or adverse events.

AUTHORS' CONCLUSIONS

Given the variability of results and the overall small effects, school staff and public health professionals must give the matter considerable thought before implementing school-based physical activity interventions. Given the heterogeneity of effects, the risk of bias, and findings that the magnitude of effect is generally small, results should be interpreted cautiously.

Youth Athlete Development and Nutrition

Adolescence (ages 13–18 years) is a period of significant growth and physical development that includes changes in body composition, metabolic and hormonal fluctuations, maturation of organ systems, and establishment of nutrient deposits, which all may affect future health. In terms of nutrition, adolescence is also an important time in establishing an individual’s lifelong relationship with food, which is particularly important in terms of the connection between diet, exercise, and body image. The challenges of time management (e.g., school, training, work and social commitments) and periods of fluctuating emotions are also features of this period. In addition, an adolescent’s peers become increasingly powerful moderators of all behaviours, including eating. Adolescence is also a period of natural experimentation and this can extend to food choice. Adolescent experiences are not the same and individuals vary considerably in their behaviours. To ensure an adolescent athlete fulfils his/her potential, it is important that stakeholders involved in managing youth athletes emphasize eating patterns that align with and support sound physical, physiological and psychosocial development and are consistent with proven principles of sport nutrition.

The Efficacy of Brief School-Based Exercise Programs in Improving Pubertal Bone Mass and Physical Fitness: A Randomized Controlled Trial

PURPOSE

To examine the effects of three types of school-based exercises on bone health and physical fitness function in Chinese boys and girls.

METHODS

One hundred and seventy-four Chinese boys and girls were randomly assigned into four groups: (1) sham exercise (ShEx); (2) high-impact exercise (HiEx); (3) high-impact exercise with various directions (HiExVi); and (4) high-intensity interval exercise (HiInEx). Speed of sound (SOS) and physical fitness parameters were determined before and after six-month intervention.

RESULTS

At the end of six-month intervention, participants in all groups show an increment of SOS compared with the baseline (p < 0.05), and the changes were higher in HiEx (mean: 38.878 m/s, 95% CI: 32.885~44.872, p = 0.001) and HiExVi groups (49.317 m/s, 42.737~55.897, p < 0.001) compared with ShEx group (20.049 m/s, 13.751~26.346). Six-month exercise training generated a reduction of percent of body fat (PBF) and waist-hip ratio (WHR) (p < 0.05). The decrease of PBF was greater in HiExVi (-1.222%, -1.820~-0.624, p = 0.012) and HiInEx groups (-1.395%, -1.809~-0.982, p = 0.003), whereas the reduction of WHR was larger in HiEx (-0.026, -0.039~-0.014, p = 0.009), HiExVi (-0.024, -0.036~-0.012, p = 0.021), and HiInEx groups (-0.035, -0.046~-0.024, p < 0.001) compared with ShEx group. Balance function (BLF), vital capacity (VC), standing long jump (SLJ), and sit up (SU) increased in all intervention groups (p < 0.05). The BLF increased in HiEx (6.332 s, 4.136~8.528, p = 0.001), HiExVi (10.489 s, 8.934~12.045, p < 0.001), and HiInEx groups (9.103 s, 7.430~10.776, p < 0.001) showed a greater change than that of ShEx group (1.727 s, 0.684~2.770). The increment of VC (273.049 mL, 199.510~346.587, p < 0.001) and SU (2.537 times/min, 0.639~4.435, p = 0.017) was higher in HiInEx group, whereas the accrual in SLJ was larger in HiExVi (7.488 cm, 4.936~10.040, p = 0.007) compared with ShEx group (58.902 mL, 7.990~109.814; -0.463 times/min, -2.003~1.077; 1.488 cm, -0.654~3.630).

CONCLUSION

The brief school-based exercises were effective in improving schoolchildren's health, but they showed different effects, with HiEx mostly improving bone health, HiInEx largely benefiting physical fitness function, and HiExVi enhancing both bone and physical fitness.

Risk Factors, Diagnosis and Management of Bone Stress Injuries in Adolescent Athletes: A Narrative Review

Physical activity is known to be beneficial for bone; however, some athletes who train intensely are at risk of bone stress injury (BSI). Incidence in adolescent athlete populations is between 3.9 and 19% with recurrence rates as high as 21%. Participation in physical training can be highly skeletally demanding, particularly during periods of rapid growth in adolescence, and when competition and training demands are heaviest. Sports involving running and jumping are associated with a higher incidence of BSI and some athletes appear to be more susceptible than others. Maintaining a very lean physique in aesthetic sports (gymnastics, figure skating and ballet) or a prolonged negative energy balance in extreme endurance events (long distance running and triathlon) may compound the risk of BSI with repetitive mechanical loading of bone, due to the additional negative effects of hormonal disturbances. The following review presents a summary of the epidemiology of BSI in the adolescent athlete, risk factors for BSI (physical and behavioural characteristics, energy balance and hormone disruption, growth velocity, sport-specific risk, training load, etc.), prevention and management strategies.

Factors influencing peak bone mass gain

Bone mass is a key determinant of osteoporosis and fragility fractures. Epidemiologic studies have shown that a 10% increase in peak bone mass (PBM) at the population level reduces the risk of fracture later in life by 50%. Low PBM is possibly due to the bone loss caused by various conditions or processes that occur during adolescence and young adulthood. Race, gender, and family history (genetics) are responsible for the majority of PBM, but other factors, such as physical activity, calcium and vitamin D intake, weight, smoking and alcohol consumption, socioeconomic status, age at menarche, and other secondary causes (diseases and medications), play important roles in PBM gain during childhood and adolescence. Hence, the optimization of lifestyle factors that affect PBM and bone strength is an important strategy to maximize PBM among adolescents and young people, and thus to reduce the low bone mass or osteoporosis risk in later life. This review aims to summarize the available evidence for the common but important factors that influence bone mass gain during growth and development and discuss the advances of developing high PBM.

The "Goldilocks Day" for Children's Skeletal Health: Compositional Data Analysis of 24-Hour Activity Behaviors

Optimization of children's activity behaviors for skeletal health is a key public health priority, yet it is unknown how many hours of moderate to vigorous physical activity (MVPA), light physical activity (LPA), sedentary behavior, or sleep constitute the best day-the "Goldilocks Day"-for children's bone structure and function. To describe the best day for children's skeletal health, we used data from the cross-sectional Child Health CheckPoint. Included participants (n = 804, aged 10.7 to 12.9 years, 50% male) underwent tibial peripheral quantitative CT to assesses cross-sectional area, trabecular and cortical density, periosteal and endosteal circumference, polar moment of inertia, and polar stress-strain index. Average daily time-use composition (MVPA, LPA, sedentary time, and sleep) was assessed through 8-day, 24-hour accelerometry. Skeletal outcomes were regressed against time-use compositions expressed as isometric log-ratios (with quadratic terms where indicated), adjusted for sex, age, pubertal status, and socioeconomic position. The models were used to estimate optimal time-use compositions (associated with best 5% of each skeletal outcome), which were plotted in three-dimensional quaternary figures. The center of the overlapping area was considered the Goldilocks Day for skeletal health. Children's time-use composition was associated with all skeletal measures (all p ≤ 0.001) except cross-sectional area (p = 0.72). Days with more sleep and MVPA, less sedentary time, and moderate LPA were beneficially associated with skeletal measures, except cortical density, which was adversely associated. The Goldilocks daily time-use composition for overall skeletal health was center (range): 10.9 (10.5 to 11.5) hours sleep; 8.2 (7.8 to 8.8) hours sedentary time; 3.4 (2.8 to 4.2) hours LPA, and 1.5 (1.3 to 1.5) hours MVPA. Estimated optimal sleep duration is consistent with current international guidelines (9 to 11 hours), while estimated optimal MVPA exceeds recommendations of at least 60 min/d. This first study to describe optimal durations of daily activities for children's skeletal health provides evidence to underpin guidelines. © 2020 American Society for Bone and Mineral Research (ASBMR).

The effect of an online exercise programme on bone health in paediatric cancer survivors (iBoneFIT): study protocol of a multi-centre randomized controlled trial

BACKGROUND

New approaches on paediatric cancer treatment aim to maintain long-term health. As a result of radiotherapy, chemotherapy or surgery, paediatric cancer survivors tend to suffer from any chronic health condition. Endocrine dysfunction represents one of the most common issues and affects bone health. Exercise is key for bone mass accrual during growth, specifically plyometric jump training. The iBoneFIT study will investigate the effect of a 9-month online exercise programme on bone health in paediatric cancer survivors. This study will also examine the effect of the intervention on body composition, physical fitness, physical activity, calcium intake, vitamin D, blood samples quality of life and mental health.

METHODS

A minimum of 116 participants aged 6 to 18 years will be randomized into an intervention (n = 58) or control group (n = 58). The intervention group will receive an online exercise programme and diet counselling on calcium and vitamin D. In addition, five behaviour change techniques and a gamification design will be implemented in order to increase the interest of this non-game programme. The control group will only receive diet counselling. Participants will be assessed on 3 occasions: 1) at baseline; 2) after the 9 months of the intervention; 3) 4 months following the intervention. The primary outcome will be determined by dual energy X-ray absorptiometry (DXA) and the hip structural analysis, trabecular bone score and 3D-DXA softwares. Secondary outcomes will include anthropometry, body composition, physical fitness, physical activity, calcium and vitamin D intake, blood samples, quality of life and mental health.

DISCUSSION

Whether a simple, feasible and short in duration exercise programme can improve bone health has not been examined in paediatric cancer survivors. This article describes the design, rationale and methods of a study intended to test the effect of a rigorous online exercise programme on bone health in paediatric cancer survivors. If successful, the iBoneFIT study will contribute to decrease chronic health conditions in this population and will have a positive impact in the society.

TRIAL REGISTRATION

Prospectively registered in isrctn.com: isrctn61195625 . Registered 2 April 2020.

Association of Physical Education With Improvement of Health-Related Physical Fitness Outcomes and Fundamental Motor Skills Among Youths: A Systematic Review and Meta-analysis

IMPORTANCE

Whether quality- or quantity-based physical education (PE) interventions are associated with improvement of health-related physical fitness outcomes and fundamental motor skills (FMSs) in children and adolescents is unknown.

OBJECTIVE

To examine the association of interventions aimed at optimizing PE in terms of quality (teaching strategies or fitness infusion) or quantity (lessons per week) with health-related physical fitness and FMSs in children and adolescents.

DATA SOURCES

For this systematic review and meta-analysis, studies were identified through a systematic search of Ovid MEDLINE, Embase, Cochrane Controlled Trials Registry, and SPORTDiscus databases (from inception to October 10, 2019) with the keywords physical education OR PE OR P.E. AND fitness AND motor ability OR skills. Manual examination of references in selected articles was also performed.

STUDY SELECTION

Studies that assessed the association of quality- or quantity-based PE interventions with improvement in physical fitness and/or FMSs in youths (aged 3-18 years) were included.

DATA EXTRACTION AND SYNTHESIS

Data were processed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. Random-effects models were used to estimate the pooled effect size (Hedges g).

MAIN OUTCOMES AND MEASURES

Health-related physical fitness outcomes and FMSs.

RESULTS

Fifty-six trials composed of 48 185 youths (48% girls) were included in the meta-analysis. Quality-based PE interventions were associated with small increases in health-related physical fitness (cardiorespiratory fitness [Hedges g = 0.24; 95% CI, 0.16-0.32] and muscular strength [Hedges g = 0.19; 95% CI, 0.09-0.29]) and FMSs (Hedges g = 0.38; 95% CI, 0.27-0.49). Subgroup analyses found stronger associations for quality-based PE interventions on body mass index (Hedges g = -0.18; 95% CI, -0.26 to -0.09), body fat (Hedges g = -0.28; 95% CI, -0.37 to -0.18), cardiorespiratory fitness (Hedges g = 0.31; 95% CI, 0.23-0.39), and muscular strength (Hedges g = 0.29; 95% CI, 0.18-0.39). Quantity-based PE interventions were associated with small increases in only cardiorespiratory fitness (Hedges g = 0.42; 95% CI, 0.30-0.55), muscular strength (Hedges g = 0.20; 95% CI, 0.08-0.31), and speed agility (Hedges g = 0.29; 95% CI, 0.07-0.51).

CONCLUSIONS AND RELEVANCE

The findings suggest that quality-based PE interventions are associated with small increases in both student health-related physical fitness components and FMSs regardless of frequency or duration of PE lessons. Because PE aims to improve more than health, high levels of active learning time may need to be balanced with opportunities for instruction, feedback, and reflection.

Study protocol and baseline characteristics of "SCHOOL IN ACTION" program on support to physical activity and healthy lifestyles in adolescents

Physical activity promotes positive effects on people's health, but most adolescents do not engage in sufficient physical activity to receive the benefits. Studies suggest that school-based interventions can be effective in increasing physical activity in adolescents. However, the literature is inconsistent on the effect size and the type of intervention. This paper presents the design of the SCHOOL IN ACTION program to increase physical activity engagement and healthy eating habits. The cluster randomized controlled trial was performed during a period of six months of intervention and 12 months of follow-up in adolescents from four Brazilian public schools. The theoretical model is based on health promoting schools and the social-ecological and self-determination theory. The action strategies were: improvement of exercises intensity during physical education classes and during lunch breaks; vegetable gardening experience; active breaks in non-physical education classes; counselling health to parents and adolescents and changes in the school environment to promote physical activity and healthy eating. Primary variables were physical activity and sedentary behavior (both assessed by accelerometers). Secondary variables were body composition (assessed by dual-energy x-ray absorptiometry) and eating habits (assessed by questionnaire and 3-day food recall). Questionnaires were used to assess other information related to life satisfaction, health behavior and socioeconomic information. Statistical analysis will follow the principles of intention-to-treat and will explore the composition data analysis and mediating factors of lifestyle-related behaviors. We propose that SCHOOL IN ACTION program will be effective to provide evidence to increase physical activity and food healthy habits in adolescents' students.

ClinicalTrials.gov registration: NCT03153176.

TRIAL STATUS: Follow-up and data analysis.

Exercise Degrades Bone in Caloric Restriction, Despite Suppression of Marrow Adipose Tissue (MAT)

Marrow adipose tissue (MAT) and its relevance to skeletal health during caloric restriction (CR) is unknown: It remains unclear whether exercise, which is anabolic to bone in a calorie-replete state, alters bone or MAT in CR. We hypothesized that response of bone and MAT to exercise in CR differs from the calorie-replete state. Ten-week-old female B6 mice fed a regular diet (RD) or 30% CR diet were allocated to sedentary (RD, CR, n = 10/group) or running exercise (RD-E, CR-E, n = 7/group). After 6 weeks, CR mice weighed 20% less than RD, p < 0.001; exercise did not affect weight. Femoral bone volume (BV) via 3D MRI was 20% lower in CR versus RD (p < 0.0001). CR was associated with decreased bone by μCT: Tb.Th was 16% less in CR versus RD, p < 0.003, Ct.Th was 5% less, p < 0.07. In CR-E, Tb.Th was 40% less than RD-E, p < 0.0001. Exercise increased Tb.Th in RD (+23% RD-E versus RD, p < 0.003) but failed to do so in CR. Cortical porosity increased after exercise in CR (+28%, p = 0.04), suggesting exercise during CR is deleterious to bone. In terms of bone fat, metaphyseal MAT/ BV rose 159% in CR versus RD, p = 0.003 via 3D MRI. Exercise decreased MAT/BV by 52% in RD, p < 0.05, and also suppressed MAT in CR (-121%, p = 0.047). Histomorphometric analysis of adipocyte area correlated with MAT by MRI (R2 = 0.6233, p < 0.0001). With respect to bone, TRAP and Sost mRNA were reduced in CR. Intriguingly, the repressed Sost in CR rose with exercise and may underlie the failure of CR-bone quantity to increase in response to exercise. Notably, CD36, a marker of fatty acid uptake, rose 4088% in CR (p < 0.01 versus RD), suggesting that basal increases in MAT during calorie restriction serve to supply local energy needs and are depleted during exercise with a negative impact on bone. © 2019 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Position Statement: Exercise Guidelines to Increase Peak Bone Mass in Adolescents

Background

An increase in bone mineral density during adolescence increases resistance to fractures in older age. The Korean Society for Bone and Mineral Research and the Korean Society of Exercise Physiology developed exercise guidelines to increase the peak bone mass (PBM) in adolescents based on evidence through a systematic review of previous research.

Methods

Articles were selected using the systematic method, and the exercise guidelines were established by selecting key questions (KQs) and defining the effects of exercises based on evidence through a literature review for selecting the final exercise method. There were 9 KQs. An online search was conducted on articles published since 2000, and 93 articles were identified.

Results

An increase in PBM in adolescence was effective for preventing osteoporosis and fractures in older age. Exercise programs as part of vigorous physical activity (VPA) including resistance and impact exercise at least 5 to 6 months were effective for improving PBM in adolescents. It is recommended that resistance exercise is performed 10 to 12 rep·set⁻¹ 1-2 set·region⁻¹ and 3 days·week⁻¹ using the large muscles. For impact exercises such as jumping, it is recommended that the exercise is performed at least 50 jumps·min⁻¹, 10 min·day⁻¹ and 2 days·week⁻¹.

Conclusions

Exercise guidelines were successfully developed, and they recommend at least 5 to 6 months of VPA, which includes both resistance and impact exercises. With the development of exercise guidelines, the incidence of osteoporosis and fractures in the aging society can be reduced in the future, thus contributing to improved public health.

Efficacy and safety of denosumab therapy for low bone mineral density in childhood cancer survivors: A report of preliminary experience

BACKGROUND

In childhood cancer survivors, low bone mineral density (BMD) is a bone-related consequence. Efficacy of denosumab, an effective therapy for adult patients with osteoporosis, remains unclear in children. This study aimed to investigate denosumab therapy efficacy for low BMD in childhood cancer survivors.

PROCEDURE

Between January 2014 and January 2018, we monitored lumbar BMD of children with cancer using dual-energy X-ray absorptiometry after completing chemotherapy with a 6-month interval. For patients with low BMD, defined as height-adjusted Z-scores of BMD < -1.5 in this study, calcium carbonate and vitamin D supplements were initially administered. When low BMD continued for at least 6 months, denosumab therapy was introduced. Calcium and vitamin D supplementation were continued in patients on denosumab. We investigated BMD change and adverse effects during denosumab therapy.

RESULTS

During the study period, 20 patients received denosumab treatment. Mean height-adjusted Z-score of BMD before denosumab treatment was -2.68 but increased to -2, -1.96, and -1.33 at 0.5, 1, and 1.5 years after denosumab treatment, respectively (P = .012). In addition, hypocalcemia occurred in 40% (8/20) of patients; three patients had hypocalcemic symptoms with numbness in all four limbs. All hypocalcemic patients, except one patient who died due to relapsed leukemia, recovered well after continuous calcium supplementation.

CONCLUSIONS

Denosumab is an effective treatment for low BMD in childhood cancer survivors. However, the complication of hypocalcemia might develop posttreatment.

High Impact Exercise Improves Bone Microstructure and Strength in Growing Rats

Physical activity is beneficial for skeletal development. However, impact sports during adolescence, leading to bone growth retardation and/or bone quality improvement, remains unexplained. This study investigated the effects of in vivo low (LI), medium (MI), and high (HI) impact loadings applied during puberty on bone growth, morphometry and biomechanics using a rat model. 4-week old rats (n = 30) were divided into control, sham, LI, MI, and HI groups. The impact was applied on the right tibiae, 5 days/week for 8 weeks mimicking walking (450 µε), uphill running (850 µε) and jumping (1250 µε) conditions. Trabecular and cortical parameters were determined by micro-CT, bone growth rate by calcein labeling and toluidine blue staining followed by histomorphometry. Bio-mechanical properties were evaluated from bending tests. HI group reduced rat body weight and food consumption compared to shams. Bone growth rate also decreased in MI and HI groups despite developing thicker hypertrophic and proliferative zone heights. HI group showed significant increment in bone mineral density, trabecular thickness, cortical and total surface area. Ultimate load and stiffness were also increased in MI and HI groups. We conclude that impact loading during adolescence reduces bone growth moderately but improves bone quality and biomechanics at the end of the growing period.

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

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

A 9-Month Jumping Intervention to Improve Bone Geometry in Adolescent Male Athletes

PURPOSE

Sports have different effects on bone development and effective interventions to improve bone health of adolescent athletes are needed. The purpose of the study was to investigate the effect of a 9-month jumping intervention on bone geometry and metabolism in adolescent male athletes.

METHODS

Ninety-three adolescent (14.1 yr old) male swimmers (SWI), footballers (FOO), and cyclists (CYC) were randomized to intervention and sport (INT-SWI = 19, INT-FOO = 15, and INT-CYC = 14) or sport only (CON-SWI = 18, CON-FOO = 15, and CON-CYC = 12) groups. Cross-sectional area, cross-sectional moment of inertia (CSMI), and section modulus (Z) at the femoral neck were assessed using hip structural analysis and trabecular texture of the lumbar spine using trabecular bone score. Bone mineral content (BMC) at femoral neck and lumbar spine was assessed using dual-energy x-ray absorptiometry. Serum N-terminal propeptide of procollagen type I, isomer of the carboxy-terminal telopeptide of type 1 collagen, total serum calcium, and 25-hydroxyvitamin D were analyzed.

RESULTS

INT-CYC acquired significantly higher lumbar spine BMC (4.6%) and femoral neck BMC (9.8%) than CON-CYC. INT-CYC acquired significantly higher cross-sectional area (11.0%), CSMI (10.1%), and trabecular bone score (4.4%) than CON-CYC. INT-SWI acquired significantly higher femoral neck BMC (6.0%) and CSMI (10.9%) than CON-SWI. There were no significant differences between INT-FOO and CON-FOO in any bone outcomes. N-terminal propeptide of procollagen type I significantly decreased in CON-SWI, INT-FOO, CON-FOO, and CON-CYC. Carboxy-terminal telopeptide of type 1 collagen significantly decreased in CON-SWI and CON-CYC. The 25-hydroxyvitamin D significantly increased in INT-CYC, CON-CYC, INT-FOO, and CON-FOO.

CONCLUSIONS

A 9-month jumping intervention improved bone outcomes in adolescent swimmers and cyclists, but not in footballers. This intervention might be used by sports clubs to improve bone health of adolescent athletes.

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

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

School-based exercise interventions effectively increase bone mineralization in children and adolescents

Osteoporosis and fragility fractures have become major global public health concerns, and they can be prevented by maximizing peak bone mass during childhood and adolescence with weight-bearing physical activity, which can result in stronger and healthier bones that significantly decrease the risk of osteoporosis and fragility fractures in adulthood and the elderly years. From a public health perspective, implementing weight-bearing physical activity for children and adolescents is best achieved with school-based exercise interventions, and a review of school-based exercise interventions was conducted to determine their effectiveness in increasing bone mineral density (BMD) and/or bone mineral content (BMC). Seventeen studies were reviewed, all school-based exercise interventions utilized jumping exercises, and 15 of the 17 studies found at least one significant increase in measures of BMD and/or BMC for the total body, and/or at the hip, vertebrae, and/or wrist. One study that found no significant differences did report significant increases in bone structural strength, and the other study with no significant differences had exercises that measured and reported the lowest ground reaction forces (GRFs) of only 2–3 times body weight (BW), whereas the other studies that showed significant increase(s) in BMD and/or BMC had exercise with measured and reported GRFs ranging from 3.5 × to 8.8 × BW. School-based exercise interventions are time- and cost-efficient and effective in increasing BMD and/or BMC in children and adolescents, but must incorporate high-intensity exercise, such as high-impact jumping of sufficient GRFs, in order to significantly increase bone mineralization for osteoporosis and fragility fracture prevention later in life.

The effect of a high-impact jumping intervention on bone mass, bone stiffness and fitness parameters in adolescent athletes

This study demonstrates that a 9-month jumping intervention can improve bone mass gains and physical fitness performance in adolescent males participating in non-osteogenic sports, such as swimming and cycling.

PURPOSE

To examine the effect of a jumping intervention on bone mass, bone stiffness and fitness parameters in adolescents involved in different sports.

METHODS

Ninety-three adolescent male swimmers (SWI), footballers (FOO) and cyclists (CYC) were randomised to intervention (INT) and sport (INT-SWI = 19, INT-FOO = 15, INT-CYC = 14) or sport only (CON-SWI = 18, CON-FOO = 15, CON-CYC = 12) groups. The 9-month jumping intervention consisted of 3 levels (12 weeks each) of 20 repetitions per set of counter movement jumps (CMJ) using adjustable weight vests (level 1 = 20 CMJ jumps/set, 0 kg, 3 sets/day, 3 times/week; level 2 = 20 CMJ jumps/set, 2 kg, 4 sets/day, 3 times/week; level 3 = 20 CMJ jumps/set, 5 kg, 4 sets/day, 4 times/week). Total body bone mineral content (BMC) at total body less head (TBLH) was measured using dual-energy X-ray absorptiometry and bone stiffness using quantitative ultrasound. Fitness was assessed using the 20-m shuttle run (20mSRT), CMJ and standing long jump (SLJ) tests.

RESULTS

INT-SWI had significantly higher increase in BMC legs and bone stiffness compared to CON-SWI (4.2-12.7%). INT-CYC had significantly higher increase in BMC at TBLH and legs and bone stiffness compared to CON-CYC (5.0-12.3%). There were no significant differences between INT-FOO and CON-FOO in any bone outcomes (0.9-3.9%). The increase in CMJ performance was significantly higher in INT-SWI (3.1 cm) and INT-CYC (3.2 cm) compared to CON-SWI and CON-CYC groups, respectively.

CONCLUSIONS

A 9-month jumping intervention can improve bone mass, bone stiffness and muscular fitness in adolescent males participating in non-osteogenic sports, such as swimming and cycling.

CLINICAL TRIAL REGISTRATION

ISRCTN17982776.

Rope skipping increases bone mineral density at calcanei of pubertal girls in Hong Kong: A quasi-experimental investigation

Bone mineral accrual during puberty is important, especially in girls, because it is related to reduced risks of osteoporosis in adulthood. Previous research has shown that jumping or plyometric exercises may be effective in increasing bone mineral density in adolescents. Rope skipping is a form of activity that involves jumping, thus regular skipping may also increase bone mineral density in pubertal girls. To this end, we conducted a quasi-experimental to examine the effects of rope skipping on girls' bone mineral density and cardiovascular fitness. 176 Hong Kong girls (age = 12.23 ± 1.80 years at baseline) were recruited to take part in the study. Bone density at their forearms and calcanei were measured twice over two academic years (mean time between visits was 10.3 months). Using multilevel modeling analyses and adjusting for participants' height and physical activity, we found that girls who participated in weekly rope skipping activities, compared to those who did not, had higher levels of bone density at the calcanei (B = 0.023, p < .01). However, no differences were found for bone density at forearms or participants' cardiovascular fitness. The rates of change of these variables across time were also not significantly different. Results suggest that regular rope skipping may increase girls' bone density at the lower extremities, irrespective of the amount of self-report physical activity. However, further research is required to examine the potential dose-response relation between skipping behaviors and the measured outcomes.

One-Year Follow-up of the CAPO Kids Trial: Are Physical Benefits Maintained?

PURPOSE

To determine the 12-month maintenance of a 9-month, thrice-weekly, 10-minute high-intensity exercise program, delivered in schools, on bone and other health-related performance variables in prepubertal children.

METHODS

All participants (N = 311) of the CAPO kids trial (testing times T1-T2) were contacted to undergo retesting (T3) of all original measures-including weight, standing and sitting height, calcaneal broadband ultrasound attenuation (Achilles, GE), and stiffness index (Achilles, GE)-waist circumference, resting heart rate, blood pressure, vertical jump, and aerobic capacity. Maturity was determined by estimating age of peak height velocity using sex-specific regression equations.

RESULTS

A total of 240 children [12.3 (0.6) y old] were included in the current study (77% of initial follow-up sample at T2). Between the T2 and T3 time points, both exercise (EX) group and control (CON) group increased broadband ultrasound attenuation (EX: 5.6%, P ≤ .001; CON: 6.5%, P ≤ .001), stiffness index (EX: 7.3%, P ≤ .001; CON: 5.2%, P ≤ .001), vertical jump (EX: 5.9%, P ≤ .001; CON: 6.3%, P ≤ .001), estimated maximal oxygen consumption (EX: 13.3%, P ≤ .001; CON: 12.1%, P ≤ .001), and reduced waist circumference (EX: -5.2%, P ≤ .001; CON: -5.6%, P ≤ .001), with no between-group differences in the magnitude of those changes. No differences were detected in absolute values between groups at T3.

CONCLUSION

Although the statistically significant differences observed between groups following the intervention were no longer significant 1 year after withdrawal of the intervention, the between-group similarities in growth trajectories of those parameters could suggest that some benefit of the intervention for bone health, waist circumference, and physical performance endured.

Exercise for Bone in Childhood-Hitting the Sweet Spot

PURPOSE

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

METHOD

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

RESULTS

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

CONCLUSION

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

Plyometric exercise and bone health in children and adolescents: a systematic review

BACKGROUND

Many jumping interventions have been performed in children and adolescents in order to improve bone-related variables and thus, ensure a healthy bone development during these periods and later in life. This systematic review aims to summarize and update present knowledge regarding the effects that jumping interventions may have on bone mass, structure and metabolism in order to ascertain the efficacy and durability (duration of the effects caused by the intervention) of the interventions.

DATA SOURCES

Identification of studies was performed by searching in the database MEDLINE/PubMed and SportDiscus. Additional studies were identified by contacting clinical experts and searching bibliographies and abstracts. Search terms included "bone and bones", "jump*", "weight-bearing", "resistance training" and "school intervention". The search was conducted up to October 2014. Only studies that had performed a specific jumping intervention in under 18-year olds and had measured bone mass were included. Independent extraction of articles was done by 2 authors using predefined data fields.

RESULTS

A total of 26 studies were included in this review. Twenty-four studies found positive results as subjects included in the intervention groups showed higher bone mineral density, bone mineral content and bone structure improvements than controls. Only two studies found no effects on bone mass after a 10-week and 9-month intervention. Moreover, those studies that evaluated the durability of the effects found that some of the increases in the intervention groups were maintained after several years.

CONCLUSIONS

Jumping interventions during childhood and adolescence improve bone mineral content, density and structural properties without side effects. These type of interventions should be therefore implemented when possible in order to increase bone mass in early stages of life, which may have a direct preventive effect on bone diseases like osteoporosis later in life.

The Case for Vigorous Physical Activity in Youth

Although it is widely recognized that regular physical activity is associated with a variety of health-related benefits in youths, the extent to which vigorous physical activity, as opposed to moderate or light physical activity, may be especially beneficial for youths is not completely understood. This review will examine the evidence for the efficacy of vigorous physical activity for promoting the well-being of youths as indicated by body composition, physical fitness, cardiometabolic biomarkers, and cognitive function. Potential caveats associated with the promotion of vigorous physical activity among youths will also be discussed, as will the inclusion of vigorous physical activity in current recommendations by national organizations for physical activity among youths.

Implications for public health research of models and theories of disability: a scoping study and evidence synthesis

Background

Public health interventions that are effective in the general population are often assumed to apply to people with impairments. However, the evidence to support this is limited and hence there is a need for public health research to take a more explicit account of disability and the perspectives of people with impairments.

Objectives

(1) To examine the literature on theories and models of disability; (2) to assess whether or not, and how, intervention studies of effectiveness could incorporate more inclusive approaches that are consistent with these theories and models; and (3) to use the findings to draw out implications for improving evaluative study designs and evidence-based practice.

Review methods

The project is a scoping review of the literature. The first stage examines theories and models of disability and reflects on possible connections between theories of disability and public health paradigms. This discussion is used to develop an ethical–empirical decision aid/checklist, informed by a human rights approach to disability and ecological approaches to public health. We apply this decision aid in the second stage of the review to evaluate the extent to which the 30 generic public health reviews of interventions and the 30 disability-specific public health interventions include the diverse experiences of disability. Five deliberation panels were also organised to further refine the decision aid: one with health-care professionals and four with politically and socially active disabled people.

Results

The evidence from the review indicated that there has been limited public health engagement with theories and models of disability. Outcome measures were often insensitive to the experiences of disability. Even when disabled people were included, studies rarely engaged with their experiences in any meaningful way. More inclusive research should reflect how people live and ‘flourish’ with disability.

Limitations

The scoping review provides a broad appraisal of a particular field. It generates ideas for future practice rather than a definite framework for action.

Conclusions

Our ethical–empirical decision aid offers a critical framework with which to evaluate current research practice. It also offers a resource for promoting more ethical and evidence-based public health research that is methodologically robust while being sensitive to the experiences of disability.

Future work

Developing more inclusive research and interventions that avoid conceptualising disability as either a ‘burden’ or ‘problem’ is an important starting point. This includes exploring ways of refining and validating current common outcome measures to ensure that they capture a diverse range of disabling experiences, as well as generating evidence on meaningful ways of engaging a broad range of disabled children and adults in the research process.

Funding

The National Institute for Health Research Public Health Research programme.

Adipocytokines and bone metabolism markers in relation to bone mineral values in early pubertal boys with different physical activity

BACKGROUND

We aimed to examine the associations of adipocytokines and circulating bone metabolism markers with bone mineral parameters in early pubertal boys with different physical activity level.

METHODS

Eighty-six early pubertal boys were divided into active and non-active boys according to the accumulated moderate-to-vigorous physical activity (MVPA) level. Body composition and bone mineral parameters were assessed and testosterone, leptin, adiponectin, osteocalcin (OC), and C-terminal telopeptide of type I collagen (CTX) were measured.

RESULTS

Active subjects had significantly lower (p<0.05) body mass, body mass index (BMI), fat mass (FM), leptin, and sedentary time values, while non-active subjects had lower (p<0.05) vigorous physical activity level and femoral neck bone mineral density (FN-BMD). OC contributed to the models in physically active group and explained 6.6% and 9.7% of variance in whole body (WB) [F(5,44)=10.847; p<0.001] and lumbar spine bone mineral content (LS-BMC) [F(5,44)=4.158; p=0.004], respectively. No other biochemical parameters were found to be related to bone mineral parameters in either the active or non-active group.

CONCLUSIONS

Bone metabolism markers were positively correlated with bone mineral values only in active pubertal boys. Leptin and adiponectin were not related to bone mineral parameters in active and non-active pubertal boys.

The National Osteoporosis Foundation's position statement on peak bone mass development and lifestyle factors: a systematic review and implementation recommendations

Lifestyle choices influence 20-40 % of adult peak bone mass. Therefore, optimization of lifestyle factors known to influence peak bone mass and strength is an important strategy aimed at reducing risk of osteoporosis or low bone mass later in life. The National Osteoporosis Foundation has issued this scientific statement to provide evidence-based guidance and a national implementation strategy for the purpose of helping individuals achieve maximal peak bone mass early in life. In this scientific statement, we (1) report the results of an evidence-based review of the literature since 2000 on factors that influence achieving the full genetic potential for skeletal mass; (2) recommend lifestyle choices that promote maximal bone health throughout the lifespan; (3) outline a research agenda to address current gaps; and (4) identify implementation strategies. We conducted a systematic review of the role of individual nutrients, food patterns, special issues, contraceptives, and physical activity on bone mass and strength development in youth. An evidence grading system was applied to describe the strength of available evidence on these individual modifiable lifestyle factors that may (or may not) influence the development of peak bone mass (Table 1). A summary of the grades for each of these factors is given below. We describe the underpinning biology of these relationships as well as other factors for which a systematic review approach was not possible. Articles published since 2000, all of which followed the report by Heaney et al. [1] published in that year, were considered for this scientific statement. This current review is a systematic update of the previous review conducted by the National Osteoporosis Foundation [1]. [Table: see text] Considering the evidence-based literature review, we recommend lifestyle choices that promote maximal bone health from childhood through young to late adolescence and outline a research agenda to address current gaps in knowledge. The best evidence (grade A) is available for positive effects of calcium intake and physical activity, especially during the late childhood and peripubertal years-a critical period for bone accretion. Good evidence is also available for a role of vitamin D and dairy consumption and a detriment of DMPA injections. However, more rigorous trial data on many other lifestyle choices are needed and this need is outlined in our research agenda. Implementation strategies for lifestyle modifications to promote development of peak bone mass and strength within one's genetic potential require a multisectored (i.e., family, schools, healthcare systems) approach.

Physical activity estimated by the bone-specific physical activity questionnaire is also associated with cardiovascular risk

The nature of physical activity that benefits bone is traditionally thought to differ from that benefiting cardiovascular health. Accordingly, exercise recommendations for improving bone health and cardiovascular health are largely incongruent. Our aim was to determine the associations between high-impact physical activity participation and both cardiovascular disease risk factors and bone mass. We recruited 94 men and women (age 34.0 ± 13.3 years) to undergo measures of cardiovascular disease risk (BMI, total cholesterol, fasting blood glucose, waist-to-hip ratio, and mean arterial pressure) and dual-energy X-ray absorptiometry (DXA XR-800, Norland) measures of bone mass (femoral neck, lumbar spine, and whole body BMD) and body composition (whole body lean mass and fat mass). Physical activity participation was estimated using the bone-specific physical activity questionnaire (BPAQ). Those in the upper tertile for current BPAQ score exhibited lower total cholesterol, waist-to-hip ratio, and mean arterial pressure than those in the lower tertiles (P < 0.05) with the relationship being mild-to-moderate (r = -0.49 to 0.29, P < 0.01). Those in the upper tertile for BPAQ score also had greater lumbar spine BMD than those in the lower tertile (P = 0.008), with BPAQ score predicting 6% of the variance in BMD (P = 0.02). We conclude that high-impact physical activity as captured by the BPAQ may be beneficial for both bone health and for attenuating cardiovascular disease risk.

Does Exercise Influence Pediatric Bone? A Systematic Review

BACKGROUND

Periods of growth are thought to be the best time to increase bone mineral content, bone area, and areal bone mineral density (aBMD) through increased loading owing to high rates of bone modeling and remodeling. However, questions remain regarding whether a benefit of exercise is seen at all bone sites, is dependent on pubertal status or sex of the child, or whether other factors such as diet modify the response to exercise.

QUESTIONS/PURPOSES

We asked: (1) Does bone-loading exercise in childhood consistently increase bone mineral content, bone area, or aBMD? (2) Do effects of exercise differ depending on pubertal status or sex? (3) Does calcium intake modify the bone response to exercise?

METHODS

A literature search identified 22 unique trials for inclusion in this meta-analysis of the effect of exercise on bone changes by bone site, pubertal status, and sex. Sample sizes ranged from 16 to 410 subjects 3 to 18 years old with length of intervention ranging from 3 to 36 months. Fifteen of 22 trials were randomized (child randomized in nine, classroom/school randomized in six) and seven were observational trials. Ten trials were Level 2 and 11 were Level 3 based on the Oxford Centre for Evidence-Based Medicine criteria. Random effects models tested the difference (intervention mean effect-control mean effect) in percent change in bone mineral content, bone area, and aBMD. Meta-regression was used to identify sources of heterogeneity and funnel plots were used to assess publication bias.

RESULTS

Children assigned to exercise had greater mean percent changes in bone mineral content and aBMD than children assigned to the control groups. Mean differences (95% CI) in bone mineral content percent change between intervention and control groups at total body (0.8; 95% CI, 0.3-1.3; p = 0.003), femoral neck (1.5; 95% CI, 0.5-2.5; p = 0.003), and spine (1.7; 95% CI, 0.4-3.1; p = 0.01) were significant with no differences in bone area (all p > 0.05). There were greater percent changes in aBMD in intervention than control groups at the femoral neck (0.6; 95% CI, 0.2-1.1; p = 0.006) and spine (1.2; 95% CI, 0.6-1.8; p < 0.001). Benefit of exercise was limited to children who were prepubertal (bone mineral content: total body [0.9; 95% CI, 0.2-1.7; p = 0.01], femoral neck [1.8; 95% CI, 0.0-3.5; p = 0.047], spine [3.7; 95% CI, 0.8-6.6; p = 0.01], and aBMD: femoral neck [0.6; 95% CI, -0.1-1.2; p = 0.07], spine [1.5; 95% CI, 0.7-2.3; p < 0.001]), with no differences among children who were pubertal (all p > 0.05). Changes in aBMD did not differ by sex (all p > 0.05), although the number of studies providing male-specific results was small (six of 22 eligible studies included boys). There was significant heterogeneity in bone mineral content and bone area for which a source could not be identified. Heterogeneity in spine aBMD was reduced by including calcium intake and intervention length as covariates. Three trials designed to determine whether calcium intake modified the bone response to exercise all reported a greater effect of exercise on leg bone mineral content in children randomized to receive supplemental calcium than those receiving placebo.

CONCLUSIONS

Exercise interventions during childhood led to 0.6% to 1.7% greater annual increase in bone accrual, with effects predominantly among children who were prepubertal. If this effect were to persist into adulthood, it would have substantial implications for osteoporosis prevention. It is important to identify sources of heterogeneity among studies to determine factors that might influence the bone response to increased exercise during growth.

LEVEL OF EVIDENCE

Level II, therapeutic study.

The health benefits of muscular fitness for children and adolescents: a systematic review and meta-analysis

BACKGROUND

Physical fitness during childhood and adolescence has been identified as an important determinant of current and future health status. While research has traditionally focused on the association between cardio-respiratory fitness and health outcomes, the association between muscular fitness (MF) and health status has recently received increased attention.

OBJECTIVE

The aim of this systematic review and meta-analysis was to evaluate the potential physiological and psychological benefits associated with MF among children and adolescents.

METHODS

A systematic search of six electronic databases (PubMed, SPORTDiscus, Scopus, EMBASE, PsycINFO and OVID MEDLINE) was performed on the 20th May, 2013. Cross-sectional, longitudinal and experimental studies that quantitatively examined the association between MF and potential health benefits among children and adolescents were included. The search yielded 110 eligible studies, encompassing six health outcomes (i.e., adiposity, bone health, cardiovascular disease [CVD] and metabolic risk factors, musculoskeletal pain, psychological health and cognitive ability). The percentage of studies reporting statistically significant associations between MF and the outcome of interest was used to determine the strength of the evidence for an association and additional coding was conducted to account for risk of bias. Meta-analyses were also performed to determine the pooled effect size if there were at least three studies providing standardised coefficients.

RESULTS

Strong evidence was found for an inverse association between MF and total and central adiposity, and CVD and metabolic risk factors. The pooled effect size for the relationship between MF and adiposity was r = -0.25 (95% CI -0.41 to -0.08). Strong evidence was also found for a positive association between MF and bone health and self-esteem. The pooled effect size for the relationship between MF and perceived sports competence was r = 0.39 (95% CI 0.34-0.45). The evidence for an association between MF and musculoskeletal pain and cognitive ability was inconsistent/uncertain. Where evidence of an association was found, the associations were generally low to moderate.

CONCLUSION

The findings of this review highlight the importance of developing MF in youth for a number of health-related benefits.

Focal enhancement of the skeleton to exercise correlates with responsivity of bone marrow mesenchymal stem cells rather than peak external forces

Force magnitudes have been suggested to drive the structural response of bone to exercise. As importantly, the degree to which any given bone can adapt to functional challenges may be enabled, or constrained, by regional variation in the capacity of marrow progenitors to differentiate into bone-forming cells. Here, we investigate the relationship between bone adaptation and mesenchymal stem cell (MSC) responsivity in growing mice subject to exercise. First, using a force plate, we show that peak external forces generated by forelimbs during quadrupedal locomotion are significantly higher than hindlimb forces. Second, by subjecting mice to treadmill running and then measuring bone structure with μCT, we show that skeletal effects of exercise are site-specific but not defined by load magnitudes. Specifically, in the forelimb, where external forces generated by running were highest, exercise failed to augment diaphyseal structure in either the humerus or radius, nor did it affect humeral trabecular structure. In contrast, in the ulna, femur and tibia, exercise led to significant enhancements of diaphyseal bone areas and moments of area. Trabecular structure was also enhanced by running in the femur and tibia. Finally, using flow cytometry, we show that marrow-derived MSCs in the femur are more responsive to exercise-induced loads than humeral cells, such that running significantly lowered MSC populations only in the femur. Together, these data suggest that the ability of the progenitor population to differentiate toward osteoblastogenesis may correlate better with bone structural adaptation than peak external forces caused by exercise.

Peripheral quantitative computed tomography (pQCT) reveals low bone mineral density in adolescents with motor difficulties

This is the first reported study to describe local bone mineral density, assess parameters of fracture risk and report history of fractures in adolescents with motor difficulties. Motor difficulties evidenced by poor coordination in adolescence should be considered a new risk factor for below-average bone strength and structure and fracture risk.

INTRODUCTION

Adolescents with motor difficulties are characterised by poor coordination and low levels of physical activity and fitness. It is possible these deficits translate into below-average bone strength and structure. The objectives of this study were to describe local bone mineral density (BMD), assess parameters of fracture risk (stress-strain index, SSI) and report history of fractures in this group.

METHODS

Thirty-three adolescents (13 females), mean age of 14.3 (SD = 1.5) years, with motor difficulties underwent peripheral quantitative computed tomography (pQCT) measurements at proximal (66 %) and distal (4 %) sites of the non-dominant radius (R4 and R66) and tibia (T4 and T66). One sample t test was used to compare Z-scores for total BMD, trabecular density, cortical density and stress strain index (SSI) against standardized norms.

RESULTS

Significant differences were present at R4 total density mean Z-score = -0.85 (SD = 0.7, p < 0.001), R66 cortical density mean Z-score = -0.74 (SD = 1.97, p = 0.038), R66 SSI mean Z-score = -1.00 (SD = 1.08, p < 0.001) and T66 SSI mean Z-score = -0.70 (SD = 1.15, p < 0.001). There was a higher incidence of fractures (26.9 %) compared to the normal population (3-9 %).

CONCLUSIONS

Motor difficulties in adolescence should be considered a risk factor for below-average bone strength and structure and fracture risk. Strategies are needed to improve bone health in this high-risk-group.