Does physical activity in adolescence have site-specific and sex-specific benefits on young adult bone size, content, and estimated strength?

Workup and Management of Premenopausal Osteoporosis

The diagnosis and management of premenopausal low bone mass or osteoporosis is challenging as its relationship to low bone mass and risk of fracture is less defined. Premenopausal or perimenopausal women with low bone density or a history of fragility fractures should undergo a thorough evaluation of causes that predispose them to bone loss. Identification of these underlying risk factors such as estrogen deficiency or malabsorptive disorders offers a treatment strategy to reverse bone loss. This is a review of the diagnostic approach and subsequent management strategies of premenopausal low bone mass or osteoporosis.

Musculoskeletal health in children and adolescents

The purpose of this narrative review was to investigate the key determinants of musculoskeletal health in childhood and adolescence, with particular attention to the role of physical activity. First, we examined the importance of bone modeling and remodeling in maintaining the bone health and the integrity and mechanical characteristic of the skeleton. In addition, we reported the evidence on an appropriate calcium and vitamin D intake, as well as local load variation in achieving proper peak bone mass. Proteomic and transcriptomic studies identified the skeletal muscle "secretoma", consisting of several myokines involved in endocrine and paracrine functions. Among these, we explored the role of irisin, a myokine involved in the muscle-bone crosstalk, and in the regulation of metabolic pathways. It is known that physical activity during growing positively impacts on skeleton and can protect by bone loss in adulthood. However, there are still concerns about the optimal interval duration and exercise intensity, particularly at the pubertal growth spurt which represents a window of opportunity to increase skeletal strength. We reported data from clinical trials performed in the last 5 years analyzing the impact of the type and timing of physical activity during childhood on skeletal development. Finally, we reported recent data on the significance of physical activity in some rare diseases.

Sex differences in bone mineral content and bone geometry accrual: a review of the Paediatric Bone Mineral Accural Study (1991-2017)

CONTEXT

Girls' and boys' growth patterns differ in timing and tempo, and they have different lifestyles with regards to diet and physical activity. These factors have all been linked with bone mineral accrual.

OBJECTIVE

To identify the associations of boys' and girls' growth, maturation, and lifestyle choices relating to parameters of bone geometry and mineral accrual.

METHODS

Between 1991 and 1993, 251 children aged 8-15 years were recruited into a mixed-longitudinal cohort study (The Paediatric Bone Mineral Accrual Study (PBMAS)) and followed repeatedly over 26 years.

RESULTS

It was found that girls matured approximately two years earlier than boys (11.8 vs. 13.4 years) but on average were shorter, had less lean mass and had greater fat mass (p < 0.05). There was a dissociation between the growth of bone and its mineralisation in both sexes. Boys had greater bone mass and bone geometry (p < 0.05). Both a healthy childhood diet and high levels of physical activity were associated with improved bone parameters.

CONCLUSIONS

Most, but not all, of the sex differences observed, were explained by height and lean mass differences. The importance of diet and physical activity on obtaining optimal bone mass during adolescence in both sexes was also paramount.

Dilemmas in the Management of Osteoporosis in Younger Adults

Osteoporosis in premenopausal women and men younger than 50 years is challenging to diagnose and treat. There are many barriers to optimal management of osteoporosis in younger adults, further enhanced by a limited research focus on this cohort. Herein we describe dilemmas commonly encountered in diagnosis, investigation, and management of osteoporosis in younger adults. We also provide a suggested framework, based on the limited available evidence and supported by clinical experience, for the diagnosis, assessment, and management of osteoporosis in this cohort. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Tibial cortical and trabecular variables together can pinpoint the timing of impact loading relative to menarche in premenopausal females

OBJECTIVES

Though relationships between limb bone structure and mechanical loading have provided fantastic opportunities for understanding the lives of prehistoric adults, the lives of children remain poorly understood. Our aim was to determine whether or not adult tibial skeletal variables retain information about childhood/adolescent loading, through assessing relationships between cortical and trabecular bone variables and the timing of impact loading relative to menarche in premenopausal adult females.

METHODS

Peripheral quantitative computed tomography was used to quantify geometric and densitometric variables from the proximal tibial diaphysis (66% location) and distal epiphysis (4% location) among 81 nulliparous young adult female controls and athletes aged 19-33 years grouped according to intensity of impact loading both pre- and post-menarche: (1) Low:Low (Controls); (2) High:Low; (3) High:High; (4) Moderate:Moderate; (5) Low:Moderate. ANCOVA was used to compare properties among the groups adjusted for age, stature, and body mass.

RESULTS

Significant increases in diaphyseal total cross-sectional area and strength-strain index were documented among groups with any pre-menarcheal impact loading relative to groups with none, regardless of post-menarcheal loading history (p < .01). In contrast, significantly elevated distal trabecular volumetric bone mineral density was only documented among groups with recent post-menarcheal loading relative to groups with none, regardless of pre-menarcheal impact loading history (p < .01).

CONCLUSIONS

The consideration of diaphyseal cortical bone geometric and epiphyseal trabecular bone densitometric variables together within the tibia can identify variation in pre-menarcheal and post-menarcheal impact loading histories among premenopausal adult females.

The effect of impact exercise on bone mineral density: A longitudinal study on non-athlete adolescents

PURPOSE

High impact exercise is known to induce osteogenic effects in the skeleton. However, less is known about the systemic effect of exercise practice in a potential adaptive mechanism of the skeletal accrual. This research aimed to assess the effect of impact exercise on bone mineral density (BMD) in the radius throughout adolescence.

METHODS

This study evaluated 1137 adolescents, at 13 and 17 years old, as part of the population-based cohort EPITeen. BMD (g/cm²) was measured at the ultradistal and proximal radius of the non-dominant forearm by dual-energy X-ray absorptiometry (DXA) using a Lunar® Peripheral Instantaneous X-ray Image device. The practice of (extra-curricular) exercise was categorized as: no exercise, exercise with high impact and exercise with low impact. Regression coefficients (β) and respective 95% confidence intervals (CI_95%) were used to estimate the association between exercise practice categories at 13 years old and BMD at 13 and 17 years old and BMD gain between evaluations.

RESULTS

In boys, at 13 years, BMD was similar between the ones not practicing exercise and those practicing exercise with low impact, and the gain of BMD was also similar in both groups. Still in boys, at 13 years, those who practiced exercise with high impact presented higher mean (standard-deviation) of BMD, comparing to the other two groups (no exercise and low impact exercise), and also significantly increased the BMD gain between 13 and 17 years (β = 0.013; CI_95%0.003;0.023). In girls, no statistically significant differences on BMD were found between the categories of exercise at 13 years and BMD at 17 years of age.

CONCLUSION

This research shows that the practice of high impact exercise could help to increase BMD more than low impact exercise even in a nonweight-bearing bone during adolescence.

Activity Level and Sport Type in Adolescents Correlate with the Development of Cam Morphology

The purpose of this study was to evaluate the influence of the volume and type of sport on the development of cam-type femoroacetabular impingement and acetabular dysplasia.

The Association Between Muscle Mass and Strength in Relation to Bone Measures in a Paediatric Population: Sex-Specific Effects

Post-puberty, bone mass displays clear sex-specific patterns. However, research has suggested that a sexual dimorphism in bone mass is evident in younger children and is likely attributable to differences in lean mass. Thus, we aimed to determine whether the association with both overall muscle mass and/or muscle strength was different between the sexes in a paediatric population. Participants were recruited as part of the Vitamin D in Pregnancy Study, Australia. There were 209/402 (52.3%) children at the 11-year follow-up, and 172 had complete data. Children were assessed for bone mineral content (BMC), bone mineral density (BMD) and lean mass by DXA (Lunar). Handgrip strength (kg) was measured using a dynamometer (JAMAR). Linear regression models were adjusted for height, weight, age and pubertal stage. In adjusted models, including both muscle strength and lean mass, the observed association differed between boys and girls. At the spine in boys, BMC and BMD were associated with muscle strength (β 0.34 [95%CI 0.09-0.59] and 0.008 [95%CI 0.003-0.014]; respectively) but not total muscle mass. However, muscle mass was associated with BMC and BMD at the total body (less head). In girls, spine BMC and BMD were associated with total lean mass (β 0.95 [95%CI 0.61-1.3] and β 0.01 [95%CI 0.005-0.02], respectively), with a similar pattern of association with total body (less head) measures. Muscle mass and strength appear to have sexually dimorphic effects on bone mass in school-aged children. These findings should be replicated in longitudinal studies.

Bone Mineral Density of Femur and Lumbar and the Relation between Fat Mass and Lean Mass of Adolescents: Based on Korea National Health and Nutrition Examination Survey (KNHNES) from 2008 to 2011

It is most important to reach the maximum bone density in the childhood period to prevent developing osteoporosis; it is widely known that increased body weight has a positive correlation with bone density and that even though both the fat mass and lean mass have a significant impact on bone density, the latter mass has more importance for adults. Therefore, the study analyzed to identify the relationship between bone density and both fat mass and lean mass of Korean adolescents. Subjects were chosen among 21,303 people from the Korea National Health and Nutrition Examination Survey (KNHNES) between 2008 and 2011 that took a bone density checkup; as a result, 1454 teenagers aged between 12 and 18 were selected. Data analysis was performed in SAS ver. 9.4 (SAS Institute Inc., Cary, NC, USA) following the KNHNES and the weighted complex sample analysis was conducted; body fat mass and lean mass were divided into quintile groups, and to figure out the differences in bone density that were analyzed in six models adjusted by body weight (kg) and walking (yes/no), muscle strengthening exercises (yes/no), nutrition (intake of ca (g), and serum vitamin D (ng/mL)). Then, the generalized linear model (GLM) and trend test were conducted for each gender with a significance level of 0.05. The bone density differences of fat mass and lean mass were analyzed. The result of Model 6 considering all correction variables is as follows; in the case of male adolescents, the total femur and lumbar spine showed a significant difference (F = 13.120, p < 0.001; F = 12.900, p < 0.001) for fat mass, and the trend test showed that the figures significantly decreased (β = −0.030, p < 0.001; −0.035, p < 0.001). Meanwhile, for lean mass, the total femur and lumbar spine had a significant difference (F = 16.740, p < 0.001; F = 20.590, p < 0.001) too, but the trend test showed a significant increase (β = 0.054, p < 0.001; 0.057, p < 0.001). In the case of female adolescents, the lumbar spine (F = 3.600, p < 0.05) for lean mass showed a significant difference, and it also significantly rose in the trend test too (β = 0.020, p < 0.01). To sum up the results, for male adolescents, the bone density differences for fat mass (FM) and lean mass (LM) all had significant differences, but for female adolescents, only the lumbar spine for LM showed such a result. Meanwhile, both genders showed that LM had a more positive impact on bone density than FM.

Bone accrual over 18 months of participation in different loading sports during adolescence

This study investigated the impact and non-impact sports on bone mineral density accrual in adolescents over 18 months. The impact sports were beneficial for bone health (accrual of bone density). In contrast, swimmers had similar or lower bone mineral density compared with the control group depending on the skeletal site.

PURPOSE

To investigate the impact and non-impact sports on bone mineral density (BMD) accrual in adolescents over a period of 18 months METHODS: The sample was composed of 71 adolescents, avarage age of 12.7 (± 1.7) years old at baseline. Bone outcomes were compared according to the loading of the sports practiced (impact sports, n = 33 [basketball, karate, and judo], non-impact sport, n = 18 [swimming], and control group, n = 20). Areal bone mineral density (aBMD) was measured by dual-energy X-ray absorptiometry (DXA) and bone mineral apparent density (BMAD) estimated through equation. The results were compared between the groups using analysis of variance and analysis of covariance.

RESULTS

Adjusted aBMD at lower limbs, whole body less head (WBLH), and adjusted WBLH BMAD were significantly greater in the impact sport group than the non-impact sport group at all time points. Adjusted upper limbs aBMD was significantly higher at the impact sports group compared to the non-impact sport group at 9 months and 18 months, besides compared to the control group at baseline and 18 months. Non-impact sport group presented a significant lower adjusted aBMD compared with control group at lower limbs and WBLH at 9 months, and at 9 months and 18 months in WBLH BMAD. There was a significant interaction (time × sport group) at upper limbs (p = 0.042) and WBLH aBMD (p = 0.006), and WBLH BMAD (p < 0.001).

CONCLUSION

Impact sports were more beneficial on accumulating aBMD and BMAD over a period of 18 months, while non-impact group (swimmers) had similar and lower aBMD and BMAD compared with the control group.

Isolated Cyclic Loading During Adolescence Improves Tibial Bone Microstructure and Strength at Adulthood

Bone is a unique living tissue, which responds to the mechanical stimuli regularly imposed on it. Adolescence facilitates a favorable condition for the skeleton that enables the exercise to positively influence bone architecture and overall strength. However, it is still dubious for how long the skeletal benefits gained in adolescence is preserved at adulthood. The current study aims to use a rat model to investigate the effects of in vivo low- (LI), medium- (MI), and high- (HI) intensity cyclic loadings applied during puberty on longitudinal bone development, morphometry, and biomechanics during adolescence as well as at adulthood. Forty-two young (4-week-old) male rats were randomized into control, sham, LI, MI, and HI groups. After a 5 day/week for 8 weeks cyclic loading regime applied on the right tibia, loaded rats underwent a subsequent 41-week, normal cage activity period. Right tibias were removed at 52 weeks of age, and a comprehensive assessment was performed using μCT, mechanical testing, and finite element analysis. HI and MI groups exhibited reduced body weight and food intake at the end of the loading period compared with shams, but these effects disappeared afterward. HI cyclic loading increased BMD, bone volume fraction, trabecular thickness, trabecular number, and decreased trabecular spacing after loading. All loading-induced benefits, except BMD, persisted until the end of the normal cage activity period. Moreover, HI loading induced enhanced bone area, periosteal perimeter, and moment of inertia, which remained up to the 52nd week. After the normal cage activity at adulthood, the HI group showed increased ultimate force and stress, stiffness, postyield displacement and energy, and toughness compared with the sham group. Overall, our findings suggest that even though both trabecular and cortical bone drifted through age-related changes during aging, HI cyclic loading performed during adolescence can render lifelong benefits in bone microstructure and biomechanics. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

NEUROMUSCULAR FITNESS IN EARLY LIFE AND ITS IMPACT ON BONE HEALTH IN ADULTHOOD: A SYSTEMATIC REVIEW

Objective:

To systematically review the literature to verify the relationship between neuromuscular fitness indicators in childhood/adolescence and bone strength variables in adulthood.

Data sources:

A systematic review was conducted in PUBMED, SCOPUS, SPORTDiscus, Web of Science, PsycINFO, LILACS, and SciELO, covering the entire period until March 2019.

Data synthesis:

The search identified 1149 studies. After duplicity analysis and eligibility criteria, four studies were reported. In one study, baseline was childhood and, in the others, adolescence. In childhood, when adjusting the model for age and body mass index, a statistically significant relation was found for girls: standing long jump with quantitative ultrasound index (β=0.11; p<0.05) and with speed of sound (β=0.14; p<0.01). However, when controlling muscular performance in adulthood, the relationship was no longer significant. In adolescence, coefficients ranged from 0.16 for neuromotor battery and bone mineral density (BMD) in the lumbar region to 0.38 for hanging leg lift test and BMD of arms. The explained variance varied between 2% (bent arm hang for BMD total) and 12% (hanging leg-lift for BMD arms), therefore, a higher performance in neuromuscular fitness in adolescence was associated with better bone strength in adulthood.

Conclusions:

In adults, bone strength variables showed significant correlation from low to moderate magnitude with neuromuscular fitness indicators in adolescence, but not in childhood, after controlling for adult performance in neuromuscular fitness. However, there is limited evidence to support the neuromuscular fitness in early life as a determinant of bone strength in adulthood.

Sex differences in the patterning of age-related bone loss in the human hallucal metatarsal in rural and urban populations

OBJECTIVES

Age-degenerative features of the metatarsals are poorly known despite the importance of metatarsal bone properties for investigating mobility patterns. We assessed the role of habitual activity in shaping the patterning and magnitude of sexual dimorphism in age-related bone loss in the hallucal metatarsal.

MATERIALS AND METHODS

Cross-sections were extracted at midshaft from micro-computed tomography scan models of individuals from medieval rural (Abingdon Vineyard) and early industrial urban (Spitalfields) settings (n = 71). A suite of cross-sectional geometry dimensions and biomechanical properties were compared between populations.

RESULTS

The rural group display generally stronger and larger metatarsals that show a greater capacity to resist torsion and that have comparatively greater bending strength along the medio-lateral plane. Men in both groups show greater values of cortical area than women, but only in the urban group do men show lower magnitudes of age-related decline compared to females. Women in rural and urban populations show different patterns of age-related decline in bone mass, particularly old women in the urban group show a marked decline in cortical area that is absent for women in the rural group.

DISCUSSION

Lifetime exposure to hard, physical activity in an agricultural setting has contributed to the attainment of greater bone mass and stronger bones in young adults. Furthermore, over the life-course, less of this greater amount of bone is lost, such that sustained activity levels may have acted to buffer against age-related decline, and this is most pronounced for women, who are expected to experience greater bone loss later in life than men.

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.

pQCT bone geometry and strength: population epidemiology and concordance in Australian children aged 11-12 years and their parents

OBJECTIVES

To describe the epidemiology and concordance of bone health in a population-based sample of Australian parent-child dyads at child age 11-12 years.

DESIGN

Population-based cross-sectional study (the Child Health CheckPoint) nested between waves 6 and 7 of the Longitudinal Study of Australian Children (LSAC).

SETTING

Assessment centres in seven cities around Australia, February 2015-March 2016.

PARTICIPANTS

of all participating CheckPoint families (n=1874), bone data were available for 1222 dyads (1271 children, 50% girls; 1250 parents, 86% mothers).

OUTCOME MEASURES

Peripheral quantitative CT (pQCT) of the non-dominant leg scanned at the 4% (distal) and 66% (mid-calf) tibial sites. Stratec XCT 2000 software generated estimates of bone density, geometry and polar stress-strain index.Parent-child concordance were assessed using Pearson's correlation coefficients and multivariable linear regression models. Percentiles were determined using survey weights. Survey weights and methods accounted for LSAC's complex sampling, stratification and clustering within postcodes.

RESULTS

Concordances were greater for the geometric pQCT parameters (periosteal circumference 0.38, 95% CI 0.33 to 0.43; endosteal circumference 0.42, 95% CI 0.37 to 0.47; total cross-sectional area 0.37, 95% CI 0.32 to 0.42) than density (cortical density 0.25, 95% CI 0.19 to 0.30). Mother-child and father-child values were similar. Relationships attenuated only slightly on adjustment for age, sex and body mass index. Percentiles and concordance are presented for the whole sample and by sex.

CONCLUSIONS

There is strong parent-child concordance in bone geometry and, to a lesser extent, density even before the period of peak adolescent bone deposition. This geometrical concordance suggests that future intergenerational bone studies could consider using pQCT rather than the more commonly used dual X-ray absorptiometry (DXA).

Physical Activity in Puberty is Associated with Total Body and Femoral Neck Bone Mineral Characteristics in Males at 18 Years of Age

Background and objectives: Studies indicate that genetic and lifestyle factors influence optimal bone development. Adaptations in bone mineral characteristics related to physical activity (PA) are most often observed in pre- and peri-puberty. Longitudinal associations between bone mineral accrual and objectively measured PA in puberty are poorly understood. The present study aims to investigate whether pubertal PA at different intensities is related to bone mineral characteristics in individuals at 18 years of age. Materials and Methods: Anthropometrics, pubertal stage, bone age and PA by accelerometer were measured in 88 boys at the mean age of 12.1 (T1), 13.1 (T2), 14.0 (T3) and 18.0 years (T4). Different bone mineral parameters were measured by dual-energy X-ray at T4. Stepwise multiple regression analysis was performed to determine the effect of bone age, body mass and PA characteristics on measured bone mineral parameters at 18 years of age. Results: Total PA in puberty together with mean pubertal body mass predicted 35.5% of total body (TB) bone mineral density (BMD), 43.0% of TB less head (LH) bone mineral content (BMC) and 48.1% of BMC/height in individuals at 18 years of age. Vigorous PA and body mass in puberty predicted 43.2% of femoral neck (FN) BMD; bone age at T1, vigorous PA and body mass in puberty predicted 47.3% of FN BMC at 18 years of age. No associations between pubertal PA levels and lumbar spine bone mineral characteristics in individuals at 18 years of age were found. Conclusions: Physical activity in puberty has a significant impact on bone mineral characteristics in individuals at 18 years of age, with total PA being a significant predictor of TB BMD and TB LH BMC as well as BMC/height, whereas vigorous PA is a significant predictor of FN BMD and FN BMC.

Bone accrual in oligo-amenorrheic athletes, eumenorrheic athletes and non-athletes

BACKGROUND

Mechanical loading improves bone mineral density (BMD) and strength while decreasing fracture risk. Cross-sectional studies show that exercise advantage is lost in oligo-amenorrheic athletes (OA). Longitudinal studies examining the opposing effects of exercise and hypogonadism on bone are lacking in adolescents/young adults.

OBJECTIVE

Evaluate differences in bone accrual over 12 months in OA, eumenorrheic athletes (EA) and non-athletes (NA). We hypothesized that bone accrual would be lower in OA than EA and NA, with differences most pronounced at non-weight bearing trabecular sites.

METHODS

27 OA, 29 EA, and 22 NA, 14-25 years old, completed 12-months of the prospective study. Athletes were weight-bearing endurance athletes. Subjects were assessed for areal BMD and bone mineral content (BMC) using DXA at the femoral neck, total hip, lumbar spine and whole body (WB). Failure load (a strength estimate) at the distal radius and tibia was assessed using microfinite element analysis of data obtained via high resolution peripheral quantitative computed tomography (HRpQCT). The primary analysis was a comparison of changes in areal BMD, BMC, and failure load across groups over 12-months at the respective sites.

RESULTS

Groups did not differ for baseline age, height or BMI. Percent body fat was lower in both OA and EA compared to NA. OA attained menarche later than EA and NA. Over the follow-up period, OA gained 1.9 ± 2.7 kg of weight compared to 0.5 ± 2.4 kg and 0.8 ± 2.3 kg in EA and NA respectively (p = 0.09); 39% of OA resumed menses. Changes in BMD, BMD Z-scores, and tibial failure load over 12-months did not differ among groups. At follow up, EA had higher femoral neck, hip and WB BMD Z-scores than NA, and higher hip BMD Z-scores than OA (p < 0.05) after adjusting for covariates. At follow-up, radial failure load was lower in OA vs. NA, and tibial failure load lower in OA and NA vs. EA (p ≤ 0.04 for all). Change in weight and fat mass were associated with changes in BMD measures at multiple sites.

CONCLUSION

Despite weight gain and menses recovery in many OA during follow-up, residual deficits persist without catch-up raising concerns for suboptimal peak bone mass acquisition.

Organized Sport Participation From Childhood to Adolescence Is Associated With Bone Mass in Young Adults From the Raine Study

There is a critical need for longitudinal cohort studies to consider the association of the cumulative exposure of physical activity during childhood and adolescence and bone mass. The aim of this study was to investigate the relationship between organized sports trajectories (that capture distinct and potentially meaningful patterns over critical developmental periods) and bone mass at age 20 years. Participation in organized sport was recorded by parental report at ages 5, 8, 10, 14, and 17 years in 984 offspring (48% female) of a pregnancy cohort (Raine Study). Latent class analysis identified three trajectory classes in each sex. In females, these were "consistent sport participators" (48%), "dropouts" (34%), and "non-participators" (18%); in males, "consistent sport participators" (55%), "dropouts" (37%), and "sport joiners" (8%). Whole-body bone mineral content (BMC) at age 20 years was assessed by dual-energy X-ray absorptiometry (DXA). At age 20 years, after adjustment for covariates measured at age 20 years, including height, lean mass, physical activity, calcium intake, serum 25-hydroxyvitamin D, alcohol, and smoking, males who were "consistent sport participators" had significantly greater whole-body and leg BMC than those who dropped out of sport (p < 0.001), whereas males who joined sports had significantly greater leg BMC than those who dropped out of sport (p = 0.002). Females in the "consistent sport participator" trajectory had significantly greater leg BMC than those who dropped out (all p = 0.004). Participation in organized sport during childhood and adolescence is associated with bone mass at age 20 years. Because attainment of optimal peak bone mass in young adulthood is protective against osteoporosis in later life, this may have long-term skeletal benefits. © 2018 American Society for Bone and Mineral Research.

Comparison of Measurements of Bone Mineral Density in Young and Middle-Aged Adult Women in Relation to Dietary, Anthropometric and Reproductive Variables

The objective of this study was to compare current measurements of bone mineral density (BMD) of the lumbar spine (LS), femoral neck (FN), and total femur (TF) regions with initial values recorded 12 years ago in women from Northwest Mexico, and evaluate their correlation with dietary, anthropometric, and reproductive variables. BMD was assessed by Dual-energy X-ray absorptiometry. Participants were grouped as follows: Nulliparous (G1); women who were mothers 12 years ago (G2); and women who were nulliparous 12 years ago, but are now mothers (G3). In all three groups, current LS BMD was higher than initial (p ≤ 0.05) and current TF BMD in G2 was higher than initial values (p ≤ 0.05). When comparing current FN and TF BMD among the three groups, G2 had higher values than G3 (p ≤ 0.05). G2 also showed higher LS BMD than G1 and G3 (p = 0.006). Age at menarche was inversely-correlated with FN and TF BMD in G1 (p < 0.01), while the body mass index (BMI) correlated positively with all three bone regions in G2 (p < 0.05). This study shows that in women without and with children, age at menarche, BMI, and age were factors associated to BMD in healthy subjects in reproductive age.

The application of finite element modelling based on clinical pQCT for classification of fracture status

Fracture risk assessment using dual-energy X-ray absorptiometry (DXA) frequently fails to diagnose osteoporosis amongst individuals who later experience fragility fractures. Hence, more reliable techniques that improve the prediction of fracture risk are needed. In this study, we evaluated a finite element (FE) modelling framework based on clinical peripheral quantitative computed tomography (pQCT) imaging of the tibial epiphysis and diaphysis to predict the stiffness at these locations in compression, shear, torsion and bending. The ability of these properties to identify a group of women who had recently sustained a low-trauma fracture from an age- and weight-matched control group was determined and compared to clinical pQCT and DXA properties and structural properties based on composite beam theory. The predicted stiffnesses derived from the FE models and composite beam theory were significantly different (p < 0.05) between the control and fracture groups, whereas no meaningful differences were observed using DXA and for the stress-strain indices (SSIs) derived using pQCT. The diagnostic performance of each property was assessed by the odds ratio (OR) and the area under the receiver operating curve (AUC), and both were greatest for the FE-predicted shear stiffness (OR 16.09, 95% CI 2.52-102.56, p = 0.003) (AUC: 0.80, 95% CI 0.67-0.93). The clinical pQCT variable total density (ρ_tot) and a number of structural and FE-predicted variables had a similar probability of correct classification between the control and fracture groups (i.e. ORs and AUCs with mean values greater than 5.00 and 0.80, respectively). In general, the diagnostic characteristics were lower for variables derived using DXA and for the SSIs (i.e. ORs and AUCs with mean values of 1.65-2.98 and 0.64-0.71, respectively). For all properties considered, the trabecular-dominant tibial epiphysis exhibited enhanced classification characteristics, as compared to the cortical-dominant tibial diaphysis. The results of this study demonstrate that bone properties may be derived using FE modelling that have the potential to enhance fracture risk assessment using conventional pQCT or DXA instruments in clinical settings.

Role of Inactivity in Chronic Diseases: Evolutionary Insight and Pathophysiological Mechanisms

This review proposes that physical inactivity could be considered a behavior selected by evolution for resting, and also selected to be reinforcing in life-threatening situations in which exercise would be dangerous. Underlying the notion are human twin studies and animal selective breeding studies, both of which provide indirect evidence for the existence of genes for physical inactivity. Approximately 86% of the 325 million in the United States (U.S.) population achieve less than the U.S. Government and World Health Organization guidelines for daily physical activity for health. Although underappreciated, physical inactivity is an actual contributing cause to at least 35 unhealthy conditions, including the majority of the 10 leading causes of death in the U.S. First, we introduce nine physical inactivity-related themes. Next, characteristics and models of physical inactivity are presented. Following next are individual examples of phenotypes, organ systems, and diseases that are impacted by physical inactivity, including behavior, central nervous system, cardiorespiratory fitness, metabolism, adipose tissue, skeletal muscle, bone, immunity, digestion, and cancer. Importantly, physical inactivity, itself, often plays an independent role as a direct cause of speeding the losses of cardiovascular and strength fitness, shortening of healthspan, and lowering of the age for the onset of the first chronic disease, which in turn decreases quality of life, increases health care costs, and accelerates mortality risk.

Committee Opinion No.702: Female Athlete Triad

The female athlete triad is a medical condition observed in physically active females involving three components: 1) low energy availability with or without disordered eating, 2) menstrual dysfunction, and 3) low bone density. An individual does not need to show clinical manifestations of all three components of the female athlete triad simultaneously to be affected by the condition. Consequences of these clinical conditions may not be completely reversible, so prevention, early diagnosis, and intervention are critical. All athletes are at risk of the female athlete triad, regardless of body build or sport. All active females should be assessed for components of the triad and further evaluation should be performed if one or more components are identified. The obstetrician-gynecologist has the opportunity to screen athletes for components of the female athlete triad at comprehensive visits for preventive care. Using the menstrual cycle as a vital sign is a useful tool for identifying athletes at risk of female athlete triad and should be an integral part of the preparticipatory sports physical. The goal of treatment for those diagnosed with female athlete triad is restoration of regular menses as a clinical marker of reestablishment of energy balance and enhancement of bone mineral density. The female athlete triad is a result of energy imbalance; thus, adjusting the energy expenditure and energy availability is the main intervention. Pharmacologic treat-ment may be considered when nonpharmacologic treatment has failed. A team approach involving the patient, obstetrician-gynecologist, sports nutritionist, coaches, parents, and mental health care provider, if indicated, is optimal.

Dietary Calcium Intake and Adherence to the Mediterranean Diet in Spanish Children: The ANIVA Study

The aim of this study was to evaluate the relationship of dietary calcium intake with anthropometric measures, physical activity and adherence to the Mediterranean diet (MedDiet) in 1176 Spanish children aged 6-9 years. Data were obtained from "Antropometría y Nutrición Infantil de Valencia" (ANIVA), a cross-sectional study of a representative sample. Dietary calcium intake assessed from three-day food records was compared to recommended daily intakes in Spain. Anthropometric measures (weight and height) were measured according to international standards and adherence to the MedDiet was evaluated using the Mediterranean Diet Quality Index (KIDMED) test. For the total sample of children, 25.8% had inadequate calcium intake, a significantly higher prevalence in girls (p = 0.006) and inadequate calcium intake was associated with lower height z-score (p = 0.001) for both sexes. In girls, there was an inverse relationship between calcium intake and body mass index (p = 0.001) and waist/hip ratio (p = 0.018). Boys presented a polarization in physical activity, reporting a greater level of both physical and sedentary activity in comparison with girls (p = 0.001). Children with poor adherence to MedDiet, even if they consume two yogurts or cheese (40 g) daily, adjusted by gender, age, total energy intake, physical activity and father's level of education, are at risk of inadequate total calcium intake (odds ratio adjusted [ORa]: 3.36, 95% confidence interval [CI]: 1.13-9.94, p = 0.001). The intake of these dairy products was insufficient to cover calcium intake recommendations in this age group (6-9 years). It is important to prioritize health strategies that promote the MedDiet and to increase calcium intake in this age group.

Functional Hypothalamic Amenorrhea: An Endocrine Society Clinical Practice Guideline

COSPONSORING ASSOCIATIONS

The American Society for Reproductive Medicine, the European Society of Endocrinology, and the Pediatric Endocrine Society. This guideline was funded by the Endocrine Society.

OBJECTIVE

To formulate clinical practice guidelines for the diagnosis and treatment of functional hypothalamic amenorrhea (FHA).

PARTICIPANTS

The participants include an Endocrine Society-appointed task force of eight experts, a methodologist, and a medical writer.

EVIDENCE

This evidence-based guideline was developed using the Grading of Recommendations, Assessment, Development, and Evaluation approach to describe the strength of recommendations and the quality of evidence. The task force commissioned two systematic reviews and used the best available evidence from other published systematic reviews and individual studies.

CONSENSUS PROCESS

One group meeting, several conference calls, and e-mail communications enabled consensus. Endocrine Society committees and members and cosponsoring organizations reviewed and commented on preliminary drafts of this guideline.

CONCLUSIONS

FHA is a form of chronic anovulation, not due to identifiable organic causes, but often associated with stress, weight loss, excessive exercise, or a combination thereof. Investigations should include assessment of systemic and endocrinologic etiologies, as FHA is a diagnosis of exclusion. A multidisciplinary treatment approach is necessary, including medical, dietary, and mental health support. Medical complications include, among others, bone loss and infertility, and appropriate therapies are under debate and investigation.

Current Physical Activity Is Independently Associated With Cortical Bone Size and Bone Strength in Elderly Swedish Women

Physical activity is believed to have the greatest effect on the skeleton if exerted early in life, but whether or not possible benefits of physical activity on bone microstructure or geometry remain at old age has not been investigated in women. The aim of this study was to investigate if physical activity during skeletal growth and young adulthood or at old age was associated with cortical geometry and trabecular microarchitecture in weight-bearing and non-weight-bearing bone, and areal bone mineral density (aBMD) in elderly women. In this population-based cross-sectional study 1013 women, 78.2 ± 1.6 (mean ± SD) years old, were included. Using high-resolution 3D pQCT (XtremeCT), cortical cross-sectional area (Ct.CSA), cortical thickness (Ct.Th), cortical periosteal perimeter (Ct.Pm), volumetric cortical bone density (D.Ct), trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp) were measured at the distal (14% level) and ultra-distal tibia and radius, respectively. aBMD was assessed using DXA (Hologic Discovery A) of the spine and hip. A standardized questionnaire was used to collect information about previous exercise and the Physical Activity Scale for the Elderly (PASE) was used for current physical activity. A linear regression model (including levels of exercise during skeletal growth and young adulthood [10 to 30 years of age], PASE score, and covariates) revealed that level of current physical activity was independently associated with Ct.CSA (β = 0.18, p < 0.001) and Ct.Th (β = 0.15, p < 0.001) at the distal tibia, Tb.Th (β = 0.11, p < 0.001) and BV/TV (β = 0.10, p = 0.001) at the ultra-distal tibia, and total hip aBMD (β = 0.10, p < 0.001). Current physical activity was independently associated with cortical bone size, in terms of thicker cortex but not larger periosteal circumference, and higher bone strength at the distal tibia on elderly women, indicating that physical activity at old age may decrease cortical bone loss in weight-bearing bone in elderly women. © 2016 American Society for Bone and Mineral Research.

Are milk and alternatives and fruit and vegetable intakes during adolescence associated with cortical and trabecular bone structure, density, and strength in adulthood?

We investigated the impact of food group intake during adolescence on bone structure and strength during adulthood. In females, we found a beneficial effect of adolescent milk and alternatives and fruit and vegetable intake on adult radius shaft and distal tibia bone structure, respectively. No association was observed in males.

INTRODUCTION

The purpose of this study was to investigate whether adolescents with high intake of milk and alternatives (M&A) or fruit and vegetables (F&V) had better adult bone structure and strength compared to those with low intake levels.

METHODS

We analyzed data from 47 males and 69 females enrolled in the Pediatric Bone Mineral Accrual Study (PBMAS 1991-2011), who had one peripheral quantitative computed tomography scan at age 29 ± 2 years. We measured radius and tibia shaft total area (ToA), cortical area (CoA), cortical content (CoC), cortical density, bone strength (SSI_p), and muscle area, as well as distal radius and tibia ToA, total density, trabecular area, trabecular content, trabecular density, and bone strength (BSI_c). Sequential 24-h recalls were used to assess M&A and F&V intake; participants were grouped for their mean intake during adolescence (low = bottom quartile, moderate = middle quartiles, high = top quartile) and were compared using multivariate analysis of covariance while adjusting for adult height, muscle area, physical activity, energy and calcium intake and adolescent energy intake, and physical activity.

RESULTS

Females with high M&A intake compared to low M&A intake group (mean 3.8 vs. 1.3 servings/day, respectively) had greater adult ToA (14 %, p < 0.05), CoA (15 %, p < 0.01), and CoC (16 %, p < 0.01) at radius shaft. Females with moderate F&V intake compared to low F&V intake group (mean 3.7 vs. 2.1 servings/day, respectively) had greater adult ToA (8.5 %, p < 0.05) at distal tibia.

CONCLUSION

Higher intake of M&A or F&V during adolescence had a long-term beneficial effect on bone structure in females, an association not observed in males.

Controlled Pilot Study of High-Impact Low-Frequency Exercise on Bone Loss and Vital-Sign Stabilization in Adolescents With Eating Disorders

PURPOSE

Adolescents with anorexia nervosa (AN) face an increased lifetime risk of bone fragility. This randomized controlled study examined the efficacy and safety of a high-impact activity program on markers of bone turnover and stabilization of vital signs (VSS).

METHODS

Forty-one hospitalized adolescents with AN were randomly assigned to routine care or routine care plus 20 jumps twice daily. Bone markers were measured at baseline days 1-3 (T1), days 4-6 (T2), and days 7-9 (T3). The primary outcome was change in bone-specific alkaline phosphatase (BSAP) at T3 adjusted for BSAP and % median body mass index at T1. Secondary outcomes were serum N-telopeptide (NTX) and osteocalcin at T3. Safety was determined by comparing weight gain, time to VSS and length of stay for each group.

RESULTS

BSAP, NTX, or osteocalcin did not differ between groups at baseline or at T3. BSAP and NTX at T3 were not associated with group of enrollment or % median body mass index. VSS was significantly reduced in the intervention group compared with the control group (11.6 ± 5.7 days vs. 17 ± 10.5 days, p = .049). There was no significant difference in weight gain or length of stay between groups.

CONCLUSIONS

Twice-daily jumping activity failed to influence markers of bone turnover in adolescents with AN but was well tolerated, shortened time to vital-sign stabilization and did not slow weight gain.

Peripheral quantitative computed tomography (pQCT) for the assessment of bone strength in most of bone affecting conditions in developmental age: a review

Peripheral quantitative computed tomography provides an automatical scan analysis of trabecular and cortical bone compartments, calculating not only their bone mineral density (BMD), but also bone geometrical parameters, such as marrow and cortical Cross-Sectional Area (CSA), Cortical Thickness (CoTh), both periosteal and endosteal circumference, as well as biomechanical parameters like Cross-Sectional Moment of Inertia (CSMI), a measure of bending, polar moment of inertia, indicating bone strength in torsion, and Strength Strain Index (SSI). Also CSA of muscle and fat can be extracted. Muscles, which are thought to stimulate bones to adapt their geometry and mineral content, are determinant to preserve or increase bone strength; thus, pQCT provides an evaluation of the functional 'muscle-bone unit', defined as BMC/muscle CSA ratio. This functional approach to bone densitometry can establish if bone strength is normally adapted to the muscle force, and if muscle force is adequate for body size, providing more detailed insights to targeted strategies for the prevention and treatment of bone fragility. The present paper offers an extensive review of technical features of pQCT and its possible clinical application in the diagnostic of bone status as well as in the monitoring of the skeleton's health follow-up.

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.

Bone structure of adolescent swimmers; a peripheral quantitative computed tomography (pQCT) study

OBJECTIVES

The aims of the present study were: (1) to characterize vBMD, bone structure and strength with peripheral quantitative computerized tomography (pQCT) in adolescent swimmers and compare it to normo-active controls (CG); and (2) to evaluate the possible interaction that weight-bearing sports might have on swimmers bone.

DESIGN

Cross-sectional.

METHODS

The non-dominant radius and tibia of 79 (32 females) swimmers and 49 (22 females) CG (both 11-18 years old) were evaluated at proximal and distal sites with a pQCT scanner. Values of total, trabecular and cortical volumetric bone mineral density (vBMD) were obtained from each scan. Cortical thickness, endosteal and periosteal circumferences were also measured and bone strength indexes were calculated. Analyses of covariance were used to compare variables between groups adjusting for age, tanner stage and bone length. Three different analyses were performed according to present and past sport participation in addition to swimming in order to determine differences among swimmers who had performed or were performing other sports (OTHER-SP) (10 females/17 males) and swimmers who had not performed other sports (NO-OTHER-SP) (22 females/22 males). Both of these groups were compared to each other and to a CG (22 females/27 males).

RESULTS

No differences were found between swimmers and CG for bone strength indexes, structure or vBMD (independently of the compared sample).

CONCLUSIONS

These results indicate that swimmers present similar bone strength and structure than CG who did not present high physical activity levels.

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

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

Adolescence physical activity is associated with higher tibial pQCT bone values in adulthood after 28-years of follow-up--the Cardiovascular Risk in Young Finns Study

High peak bone mass and strong bone phenotype are known to be partly explained by physical activity during growth but there are few prospective studies on this topic. In this 28-year follow-up of Cardiovascular Risk in Young Finns Study cohort, we assessed whether habitual childhood and adolescence physical activity or inactivity at the age of 3-18 years were associated with adult phenotype of weight-bearing tibia and the risk of low-energy fractures. Baseline physical activity and data on clinical, nutritional and lifestyle factors were assessed separately for females and males aged 3-6-years (N=395-421) and 9-18-years (N=923-965). At the age of 31-46-years, the prevalence of low-energy fractures was assessed with a questionnaire and several tibial traits were measured with pQCT (bone mineral content (BMC; mg), total and cortical cross-sectional areas (mm(2)), trabecular (for the distal site only) and cortical (for the shaft only) bone densities (mg/cm(3)), stress-strain index (SSI; mm(3), for the shaft only), bone strength index (BSI; mg(2)/cm(4), for the distal site only) and the cortical strength index (CSI, for the shaft only)). For the statistical analysis, each bone trait was categorized as below the cohort median or the median and above and the adjusted odds ratios (OR) were determined. In females, frequent physical activity at the age of 9-18-years was associated with higher adulthood values of BSI, total and cortical areas, BMC, CSI and SSI at the tibia independently of many health and lifestyle factors (ORs 0.33-0.53, P≤0.05; P-values for trend 0.002-0.05). Cortical density at the tibial shaft showed the opposite trend (P-value for trend 0.03). Similarly in males, frequent physical activity was associated with higher values of adult total and cortical areas and CSI at the tibia (ORs 0.48-0.53, P≤0.05; P-values for trend 0.01-0.02). However, there was no evidence that childhood or adolescence physical activity was associated with lower risk of low energy fractures during the follow-up. In conclusion, frequent habitual physical activity in adolescence seems to confer benefits on tibial bone size and geometry in adulthood.

Effects of bone-specific physical activity, gender and maturity on tibial cross-sectional bone material distribution: a cross-sectional pQCT comparison of children and young adults aged 5-29 years

Growth is the opportune time to modify bone accrual. While bone adaptation is known to be dependent on local loading and consequent deformations (strain) of bone, little is known about the effects of sex, and bone-specific physical activity on location-specific cross-sectional bone geometry during growth. To provide more insight we examined bone traits at different locations around tibial cross sections, and along the tibia between individuals who vary in terms of physical activity exposure, sex, and pubertal status. Data from 304 individuals aged 5-29 years (172 males, 132 females) were examined. Peripheral quantitative computed tomography (pQCT) was applied at 4%, 14%, 38%, and 66% of tibial length. Maturity was established by estimating age at peak height velocity (APHV). Loading history was quantified with the bone-specific physical activity questionnaire (BPAQ). Comparisons, adjusted for height, weight and age were made between sex, maturity, and BPAQ tertile groups. Few to no differences were observed between sexes or BPAQ tertiles prior to APHV, whereas marked sexual dimorphism and differences between BPAQ tertiles were observed after APHV. Cross-sectional location-specific differences between BPAQ tertiles were not evident prior to APHV, whereas clear location-specificity was observed after APHV. In conclusion, the skeletal benefits of physical activity are location-specific in the tibia. The present results indicate that the peri- or post-pubertal period is likely a more favourable window of opportunity for enhancing cross-sectional bone geometry than pre-puberty. Increased loading during the peri-pubertal period may enhance the bone of both sexes.

Exercise, hormones and skeletal adaptations during childhood and adolescence

Although primarily considered a disorder of the elderly, emerging evidence suggests the antecedents of osteoporosis are established during childhood and adolescence. A complex interplay of genetic, environmental, hormonal and behavioral factors determines skeletal development, and a greater effort is needed to identify the most critical factors that establish peak bone strength. Indeed, knowledge of modifiable factors that determine skeletal development may permit optimization of skeletal health during growth and could potentially offset reductions in bone strength with aging. The peripubertal years represent a unique period when the skeleton is particularly responsive to loading exercises, and there is now overwhelming evidence that exercise can optimize skeletal development. While this is not controversial, the most effective exercise prescription and how much investment in this prescription is needed to significantly impact bone health continues to be debated. Despite considerable progress, these issues are not easy to address, and important questions remain unresolved. This review focuses on the key determinants of skeletal development, whether exercise during childhood and adolescence should be advocated as a safe and effective strategy for optimizing peak bone strength, and whether investment in exercise early in life protects against the development of osteoporosis and fractures later in life.

He had always wanted to ask an andrologist but had never done so

AIM: To understand and analyze what young Italian males attending high school would like to ask andrologists but do not know how to or do not have the courage to do so.

METHODS: As part of our “Androlife” campaign, we invited 1565 students attending the last year of high school to participate in our research. Firstly, they attended a lesson on general and andrological health and then, on a voluntary basis, they responded to a survey and were subjected to a preventive andrological visit.

RESULTS: The data analysis showed that the main topics in which young people are interested are: sexual activity and sexuality, sexually transmitted diseases, andrological health and fertility, and lifestyle.

CONCLUSION: This study highlights that young people are very interested in sexual health issues and that they have specific needs and interests with regard to sexual health information. Public education campaigns such as Androlife should be supported and further improved on the basis of the advice received by young participants. Sexual and reproductive health education targeting adolescents and young adults represent the basis both for wellness and for fertility preservation, and thus benefits of increased support to educational campaigns would be apparent not only in terms of individual health but also in terms of cost reduction in public spending.

Physical Activity-Associated Bone Loading During Adolescence and Young Adulthood Is Positively Associated With Adult Bone Mineral Density in Men

Physical activity during growth increases bone mass and strength; however, it remains unclear whether these benefits persist. The purpose of this study was to determine: (a) if bone loading during adolescence (13-18 years) or young adulthood (19-29 years) in men is associated with greater bone mineral density (BMD) in adulthood; (b) if current participation in high-impact activity (ground reaction force>4×body weight) and/or resistance training is associated with greater BMD; and, (c) if continuous participation in a high-impact activity from adolescence to adulthood is associated with greater BMD. Apparently healthy, physically active men aged 30 to 65 years (n=203) participated in this cross-sectional study. Exercise-associated bone loading was estimated based on ground reaction forces of historical physical activity. Current BMD was measured using dual-energy X-ray absorptiometry. Participants were grouped based on current participation in a high-impact activity (n=18), resistance training (n=57), both (n=14), or neither (n=114); groups were compared by two-way analysis of covariance. Bone loading during adolescence and young adulthood were significant, positive predictors of BMD of the whole body, total hip, and lumbar spine, adjusting for lean body mass and/or age in the regression models. Individuals who currently participate in a high-impact activity had greater lumbar spine BMD than nonparticipants. Men who continuously participated in a high-impact activity had greater hip and lumbar spine BMD than those who did not. In conclusion, physical activity-associated bone loading both during and after skeletal growth is positively associated with adult bone mass.

Underweight, overweight, and pediatric bone fragility: impact and management

Skeletal health is modulated by a variety of factors, including genetic makeup, hormonal axes, and environment. Across all ages, extremes of body weight may exert a deleterious effect on bone accretion and increase fracture risk. The incidence of both anorexia nervosa and obesity, each involving extreme alterations in body composition, is rising among youth, and secondary osteoporosis is increasingly being diagnosed among affected children and adolescents. Compared with the elderly, the definition of osteoporosis that stems from any underlying condition differs for the pediatric population and special precautions are required with regard to treatment of young patients. Early recognition and management of both underweight and overweight youth and the accompanying consequences on bone and mineral metabolism are essential for preservation of skeletal health, although prevention of bone loss and optimization of bone mineral accrual remain the most important protective measures.

Exercise during growth and young adulthood is independently associated with cortical bone size and strength in old Swedish men

Previous studies have reported an association between exercise during youth and increased areal bone mineral density at old age. The primary aim of this study was to investigate if exercise during growth was independently associated with greater cortical bone size and whole bone strength in weight-bearing bone in old men. The tibia and radius were measured using both peripheral quantitative computed tomography (pQCT) (XCT-2000; Stratec) at the diaphysis and high-resolution pQCT (HR-pQCT) (XtremeCT; Scanco) at the metaphysis to obtain cortical bone geometry and finite element-derived bone strength in distal tibia and radius, in 597 men, 79.9 ± 3.4 (mean ± SD) years old. A self-administered questionnaire was used to collect information about previous and current physical activity. In order to determine whether level of exercise during growth and young adulthood or level of current physical activity were independently associated with bone parameters in both tibia and radius, analysis of covariance (ANCOVA) analyses were used. Adjusting for covariates and current physical activity, we found that men in the group with the highest level of exercise early in life (regular exercise at a competitive level) had higher tibial cortical cross-sectional area (CSA; 6.3%, p < 0.001) and periosteal circumference (PC; 1.6%, p = 0.011) at the diaphysis, and higher estimated bone strength (failure load: 7.5%, p < 0.001; and stiffness: 7.8%, p < 0.001) at the metaphysis than men in the subgroup with the lowest level of exercise during growth and young adulthood. Subjects in the group with the highest level of current physical activity had smaller tibial endosteal circumference (EC; 3.6%, p = 0.012) at the diaphysis than subjects with a lower current physical activity, when adjusting for covariates and level of exercise during growth and young adulthood. These findings indicate that exercise during growth can increase the cortical bone size via periosteal expansion, whereas exercise at old age may decrease endosteal bone loss in weight-bearing bone in old men.

Objectively measured physical activity trajectories predict adolescent bone strength: Iowa Bone Development Study

BACKGROUND

Physical activity improves bone strength and reduces the risk for osteoporotic fractures. However, there are substantial gaps in our knowledge as to when, how and how much activity is optimal for bone health.

PURPOSE

In this cohort study, we examined developmental trajectories of objectively measured physical activity from childhood to adolescence to discern if moderate-and-vigorous intensity physical activity (MVPA) predicts bone strength.

METHODS

Starting at age 5 and continuing at 8, 11, 13, 15 and 17 years, Iowa Bone Development Study participants (n=530) wore an accelerometer for 3-5 days. At age 17, we assessed dual X-ray energy absorptiometry outcomes of mass and estimated geometry (femoral neck cross-sectional area and section modulus). We also assessed geometric properties (bone stress index and polar moment of inertia) of the tibia using peripheral computer quantitative tomography. Latent class modelling was used to construct developmental trajectories of MVPA from childhood to late adolescence. General linear models were used to examine the trajectory groups as predictors of age 17 bone outcomes.

RESULTS

Girls and boys who accumulated the most MVPA had greater bone mass and better geometry at 17 years when compared to less active peers. The proportion of participants achieving high levels of MVPA throughout childhood was very low (<6% in girls) and by late adolescence almost all girls were inactive.

CONCLUSIONS

Bone health benefits of physical activity are not being realised due to low levels of activity for most youth, especially in girls.

Physical activity when young provides lifelong benefits to cortical bone size and strength in men

The skeleton shows greatest plasticity to physical activity-related mechanical loads during youth but is more at risk for failure during aging. Do the skeletal benefits of physical activity during youth persist with aging? To address this question, we used a uniquely controlled cross-sectional study design in which we compared the throwing-to-nonthrowing arm differences in humeral diaphysis bone properties in professional baseball players at different stages of their careers (n = 103) with dominant-to-nondominant arm differences in controls (n = 94). Throwing-related physical activity introduced extreme loading to the humeral diaphysis and nearly doubled its strength. Once throwing activities ceased, the cortical bone mass, area, and thickness benefits of physical activity during youth were gradually lost because of greater medullary expansion and cortical trabecularization. However, half of the bone size (total cross-sectional area) and one-third of the bone strength (polar moment of inertia) benefits of throwing-related physical activity during youth were maintained lifelong. In players who continued throwing during aging, some cortical bone mass and more strength benefits of the physical activity during youth were maintained as a result of less medullary expansion and cortical trabecularization. These data indicate that the old adage of "use it or lose it" is not entirely applicable to the skeleton and that physical activity during youth should be encouraged for lifelong bone health, with the focus being optimization of bone size and strength rather than the current paradigm of increasing mass. The data also indicate that physical activity should be encouraged during aging to reduce skeletal structural decay.

Cortical and trabecular bone benefits of mechanical loading are maintained long term in mice independent of ovariectomy

Skeletal loading enhances cortical and trabecular bone properties. How long these benefits last after loading cessation remains an unresolved, clinically relevant question. This study investigated long-term maintenance of loading-induced cortical and trabecular bone benefits in female C57BL/6 mice and the influence of a surgically induced menopause on the maintenance. Sixteen-week-old animals had their right tibia extrinsically loaded 3 days/week for 4 weeks using the mouse tibial axial compression loading model. Left tibias were not loaded and served as internal controls. Animals were subsequently detrained (restricted to cage activities) for 0, 4, 8, 26, or 52 weeks, with ovariectomy (OVX) or sham-OVX surgery being performed at 0 weeks detraining. Loading increased midshaft tibia cortical bone mass, size, and strength, and proximal tibia bone volume fraction. The cortical bone mass, area, and thickness benefits of loading were lost by 26 weeks of detraining because of heightened medullary expansion. However, loading-induced benefits on bone total area and strength were maintained at each detraining time point. Similarly, the benefits of loading on bone volume fraction persisted at all detraining time points. The long-term benefits of loading on both cortical and trabecular bone were not influenced by a surgically induced menopause because there were no interactions between loading and surgery. However, OVX had independent effects on cortical bone properties at early (4 and 8 weeks) detraining time points and trabecular bone properties at all detraining time points. These cumulative data indicate loading has long-term benefits on cortical bone size and strength (but not mass) and trabecular bone morphology, which are not influenced by a surgically induced menopause. This suggests skeletal loading associated with physical activity may provide long-term benefits by preparing the skeleton to offset both the cortical and trabecular bone changes associated with aging and menopause.