In peripubertal girls, artistic gymnastics improves areal bone mineral density and femoral bone geometry without affecting serum OPG/RANKL levels

RANKL/RANK/OPG Pathway: A Mechanism Involved in Exercise-Induced Bone Remodeling

Bones as an alive organ consist of about 70% mineral and 30% organic component. About 200 million people are suffering from osteopenia and osteoporosis around the world. There are multiple ways of protecting bone from endogenous and exogenous risk factors. Planned physical activity is another useful way for protecting bone health. It has been investigated that arranged exercise would effectively regulate bone metabolism. Until now, a number of systems have discovered how exercise could help bone health. Previous studies reported different mechanisms of the effect of exercise on bone health by modulation of bone remodeling. However, the regulation of RANKL/RANK/OPG pathway in exercise and physical performance as one of the most important remodeling systems is not considered comprehensive in previous evidence. Therefore, the aim of this review is to clarify exercise influence on bone modeling and remodeling, with a concentration on its role in regulating RANKL/RANK/OPG pathway.

Systematic review and meta-analysis of the association between childhood physical activity and age at menarche

AIM

To systematically appraise and summarise published evidence on the association between childhood physical activity (PA) and subsequent age at menarche (AAM).

METHODS

We searched PubMed (1990-2018) for studies that reported the relationship between childhood PA and AAM. We performed tabular synthesis of population-based studies and a random-effects meta-analysis of results of athlete/nonathlete studies.

RESULTS

One randomised controlled trial was identified, in which an intervention to prevent obesity reduced the likelihood of menarche during the two-year study period (relative risk: 0.75, 95% CI: 0.66-0.87; n = 422 girls). One of five prospective cohort studies (total n = 4492) reported a significant association between self-reported PA duration and subsequent menarche timing. Four of five historical cohort studies (total n = 89 470) reported significant associations between recalled premenarcheal PA and later AAM. Meta-analysis across 12 athlete/nonathlete studies showed that menarche occurred 1.13 years later (95% CI: 0.80-1.47) in athletes compared to nonathletes.

CONCLUSION

These findings suggest that AAM is a behaviourally modifiable trait. However, the quality of reported population-based study evidence is low and estimation of the true relationship between childhood PA and AAM is likely confounded by concomitant changes in diet and lifestyle behaviours.

Genetic variation in Wnt/β-catenin and ER signalling pathways in female and male elite dancers and its associations with low bone mineral density: a cross-section and longitudinal study

The association of genetic polymorphisms with low bone mineral density in elite athletes have not been considered previously. The present study found that bone mass phenotypes in elite and pre-elite dancers are related to genetic variants at the Wnt/β-catenin and ER pathways.

INTRODUCTION

Some athletes (e.g. gymnasts, dancers, swimmers) are at increased risk for low bone mineral density (BMD) which, if untreated, can lead to osteoporosis. To investigate the association of genetic polymorphisms in the oestrogen receptor (ER) and the Wnt/β-catenin signalling pathways with low BMD in elite and pre-elite dancers (impact sport athletes).

METHODS

The study included three phases: (1) 151 elite and pre-elite dancers were screened for the presence of low BMD and traditional osteoporosis risk factors (low body weight, menstrual disturbances, low energy availability); (2) a genetic association study was conducted in 151 elite and pre-elite dancers and age- and sex- controls; (3) serum sclerostin was measured in 101 pre-elite dancers and age- and sex-matched controls within a 3-year period.

RESULTS

Eighty dancers revealed low BMD: 56.3% had at least one traditional osteoporosis risk factor, whereas 28.6% did not display any risk factor (37.2% revealed traditional osteoporosis risk factors, but had normal BMD). Body weight, menstrual disturbances and energy availability did not fully predict bone mass acquisition. Instead, genetic polymorphisms in the ER and Wnt/β-catenin pathways were found to be risk factors for low BMD in elite dancers. Sclerostin was significantly increased in dancers compared to controls during the 3-year follow-up (p < 0.05).

CONCLUSIONS

Elite and pre-elite dancers demonstrate high prevalence of low BMD, which is likely related to genetic variants at the Wnt/β-catenin and ER pathways and not to factors usually associated with BMD in athletes (body weight, menstrual disturbances, energy deficiency).

BONE GEOMETRY AND PHYSICAL ACTIVITY IN CHILDREN AND ADOLESCENTS: SYSTEMATIC REVIEW

OBJECTIVE

To perform a systematic review on the practice of physical activity and/or sports in health and its influence on bone geometry of healthy children and adolescents.

DATA SOURCE

The method used as reference was the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Databases searched for articles published from 2006 to 2016, with "Bone geometry" AND (Sport* OR Exercise* OR "Physical Activity") as descriptors, were PubMed, BIREME/LILACS and SciELO.

DATA SYNTHESES

After the selection, 21 articles were included. Most studies stated that practice of physical activity and/or sports was beneficial for bone geometry and bone mineral density. Only two studies presented values of bone parameters for control individuals better than those of swimmers. Physical activities and sports studied were: gymnastics (n=7), rhythmic gymnastics (n=2), tennis (n=1), soccer (n=3), capoeira (n=1), swimming (n=4), cycling (n=0), jumping activities (n=2), studies relating physical activity with isokinetic peak torque (n=1), physical activity measured by questionnaire (n=4), and additional physical education classes (n=2).

CONCLUSIONS

Among the sports and physical activities found, gymnastics, soccer, and more intense physical activity assessed by questionnaires were mentioned along with better results in bone geometry compared to the absence of physical activity, whereas swimming and jumping exercises did not influence it. Therefore, sports activities with weight bearing and those practiced more frequently and intensively are beneficial for bone geometry.

Physical activity may be a potent regulator of bone turnover biomarkers in healthy girls during preadolescence

This study investigated the effects of different levels of habitual physical activity (PA) assessed by pedometry on bone turnover markers of preadolescent girls according to a cross-sectional experimental design. Sixty prepubertal girls of similar chronological age, bone age, maturity level, and nutritional status were assigned to a low PA (LPA; n = 25), a moderate PA (MPA; n = 17), or a high PA (HPA; n = 18) group. Dual-energy X-ray absorptiometry was used to measure areal bone mineral density (BMD) and bone mineral content (BMC) of the lumbar spine (L2-L4) and dominant hip (femoral neck and trochanter). Blood was collected for the measurement of alkaline phosphatase (ALP), bone-specific ALP (BSAP), procollagen type I N-terminal propeptide (PINP), C-terminal telopeptide of collagen I (CTX), parathyroid hormone (PTH), osteocalcin, thyroid-stimulating hormone, estradiol, testosterone, luteinizing hormone, and follicle-stimulating hormone concentrations. ANOVA revealed that the HPA group (18,695 ± 1244 steps per day) had a lower daily energy intake and body mass than the MPA group (10,774 ± 521 steps per day) and the LPA group (7633 ± 1099 steps per day). The HPA group had higher (P < 0.05) lumbar and hip BMD and hip BMC than the LPA group and higher (P < 0.05) lumbar BMD than the MPA group. The MPA group had higher (P < 0.05) hip BMC than the LPA group. The HPA group had greater (P < 0.05) values of BSAP, PINP, and ALP and lower (P < 0.05) values of PTH and CTX than the LPA group but not the MPA group. A partial correlation analysis (adjusted for body mass index) revealed a positive correlation of steps per day with BMD and BSAP concentration and a negative correlation with PTH and CTX concentration. In conclusion, PA increases BMD and BMC of premenarcheal girls by favoring bone formation over bone resorption.

Relationship between total and segmental bone mineral density and different domains of physical activity among children and adolescents: cross-sectional study

BACKGROUND

This study aimed to investigate the relationship between total and segmental bone mineral density (BDM) and physical activity (PA) in different domains (school, leisure and sports) among adolescents and children.

DESIGN AND SETTING

Cross-sectional study in the Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP).

METHODS

The study sample consisted of 173 children and adolescents (10.31 ± 1.87 years). The BMDs for the whole body (WB) and the regions of the trunk and legs were measured using dual energy X-ray absorptiometry (DXA). PA was measured using the Baecke questionnaire. A regression model was used to analyze the relationship between all the BMDs and the different domains of PA.

RESULTS

41.5% of the adolescents had high percentages of body fat. Regarding the comparison between physically active and insufficiently active adolescents, there were no statistically significant differences in any BMD variables (P > 0.05). The BMD of the legs showed positive relationships with the total PA (β = 0.009; P = 0.013) and sports PA (β = 0.010; P = 0.049) after insertion of the confounders. Similarly, the WB BMD showed the same relationships (total PA: β = 0.005; P = 0.045; and sports PA: β = 0.008; P = 0.049). No relationship was found between leisure and school PA and any of the BMDs (P > 0.05).

CONCLUSION

The results indicated that practice of sport was related to higher BMD values, independent of sex, age and body fatness.

[Intensive training and menstrual disorders in young female: Impact on bone mass]

Participation in recreational physical activity is widely acknowledged to provide significant health benefits. Conversely, intense training imposes several constraints, such as intermittent or chronic metabolic and psychogenic training stressors and maintenance of very low body fat to maximize performance. Adolescent and adult athletic women are therefore at risk of overtraining and/or poor dietary intake, which may have several consequences for endocrine function particularly on hypothalamic-pituitary-gonadal axis. Female athletes, particularly those participating in sports needing leanness or low body weight, present a high prevalence of menstrual disorders with clinical manifestations ranging from delayed menarche, oligomenorrhea to primary and secondary amenorrhea. A high degree of variability according to the type of sport and the intensity of the practice is however observed. Exercise-related reproductive dysfunction may have some consequences for growth velocity and peak bone mass acquisition during adolescence and bone pathologies in adults. Recent findings highlight the endocrine role of adipose tissue and energy balance in the regulation of homeostasis and reproductive function. A better understanding of the mechanisms whereby intense training affects the endocrine systems may orient research to develop innovative strategies probably based on individualized nutritional approach to improve the medical care of these female athletes and protect their reproductive function.

Site-specific, adult bone benefits attributed to loading during youth: A preliminary longitudinal analysis

We examined site-specific bone development in relation to childhood and adolescent artistic gymnastics exposure, comparing up to 10years of prospectively acquired longitudinal data in 44 subjects, including 31 non-gymnasts (NON) and 13 gymnasts (GYM) who participated in gymnastics from pre-menarche to ≥1.9years post-menarche. Subjects underwent annual regional and whole-body DXA scans; indices of bone geometry and strength were calculated. Anthropometrics, physical activity, and maturity were assessed annually, coincident with DXA scans. Non-linear mixed effect models centered growth in bone outcomes at menarche and adjusted for menarcheal age, height, and non-bone fat-free mass to evaluate GYM-NON differences. A POST-QUIT variable assessed the withdrawal effect of quitting gymnastics. Curves for bone area, mass (BMC), and strength indices were higher in GYM than NON at both distal radius metaphysis and diaphysis (p<0.0001). At the femoral neck, greater GYM BMC (p<0.01), narrower GYM endosteal diameter (p<0.02), and similar periosteal width (p=0.09) yielded GYM advantages in narrow neck cortical thickness and buckling ratio (both p<0.001; lower BR indicates lower fracture risk). Lumbar spine and sub-head BMC were greater in GYM than NON (p<0.036). Following gymnastics cessation, GYM slopes increased for distal radius diaphysis parameters (p≤0.01) and for narrow neck BR (p=0.02). At the distal radius metaphysis, GYM BMC and compressive strength slopes decreased, as did slopes for lumbar spine BMC, femoral neck BMC, and narrow neck cortical thickness (p<0.02). In conclusion, advantages in bone mass, geometry, and strength at multiple skeletal sites were noted across growth and into young adulthood in girls who participated in gymnastics loading to at least 1.9years post-menarche. Following gymnastics cessation, advantages at cortical bone sites improved or stabilized, while advantages at corticocancellous sites stabilized or diminished. Additional longitudinal observation is necessary to determine whether residual loading benefits enhance lifelong skeletal strength.

Number of years of participation in some, but not all, types of physical activity during adolescence predicts level of physical activity in adulthood: Results from a 13-year study

Background

Adolescent physical activity (PA) levels track into adulthood. However it is not known if type of PA participated in during adolescence is associated with PA levels later in life. We aimed to identify natural groupings of types of PA and to assess whether number of years participating in these different groupings during adolescence is related to PA level in early adulthood.

Methods

673 adolescents in Montreal, Canada, age 12–13 years at baseline (54 % female), reported participation in 29 physical activities every 3 months over 5 years (1999–2005). They also reported their PA level at age 24 years (2011–12). PA groupings among the 29 physical activities were identified using factor analysis. The association between number of years participating in each grouping during adolescence and PA level at age 24 was estimated using linear regression within a general estimating equation framework.

Results

Three PA groupings were identified: “sports”, “fitness and dance”, and “running”. There was a positive linear relationship between number of years participating in sports and running in adolescence and PA level at age 24 years (β (95 % confidence interval) = 0.09 (0.04-0.15); 0.08 (0.01-0.15), respectively). There was no relationship between fitness and dance in adolescence and PA level at age 24.

Conclusions

The association between PA participation in adolescence and PA levels in young adulthood may be specific to certain PA types and to consistency of participation during adolescence. Results suggest that efforts to establish the habit of participation in sports and running in adolescence may promote higher PA levels in adulthood.

Soccer increases bone mass in prepubescent boys during growth: a 3-yr longitudinal study

The aim of this study was to examine the effect of 3-yr soccer practice on bone acquisition in prepubescent boys. We investigated 65 boys (aged 10-13 yr, Tanner stage I) at baseline, among which only 40 boys (Tanner stages II and III) have continued the 3-yr follow-up: 23 soccer players (F) completed 2-5 h of training plus 1 competition game per week and 17 controls (C). Bone mineral density (BMD, g/cm(2)) and bone mineral content (BMC, g) were measured by dual-energy X-ray absorptiometry at different sites. At baseline, BMD was higher in soccer players than in controls in the whole body and legs. In contrast, there was nonsignificant difference BMD in head, femoral neck, arms, and BMC in all measured sites between groups. At 3-yr follow-up, soccer players were found to have higher BMD and BMC at all sites than controls, except for head BMD and BMC and arms BMC in which the difference was nonsignificant between groups. During the 3-yr follow-up, the soccer players were found to gain significantly more in lumbar spine (31.2% ± 2.9% vs 23.9% ± 2.1%; p < 0.05), femoral neck (24.1% ± 1.8% vs 11.4% ± 1.9%; p < 0.001), whole body (16.5% ± 1.4% vs 11.8% ± 1.5%; p < 0.05), and nondominant arm BMD (18.2% ± 1.4% vs 13.6% ± 1.7%; p < 0.05) as well as lumbar spine (62.5% ± 20.1% vs 39.5% ± 20.1%; p < 0.001), femoral neck, (37.7% ± 14.2% vs 28.9% ± 12.8%; p < 0.05) and nondominant arm BMC (68.6% ± 22.9% vs 50.1% ± 22.4%; p < 0.05) than controls. In contrast, soccer players have less %BMD and %BMC changes in the head than controls. A nonsignificant difference was found in legs, dominant arm, head %BMD and %BMC changes, and whole-body %BMC changes between groups. In summary, we suggest that soccer has an osteogenic effect BMD and BMC in loaded sites in pubertal soccer players. The increased bone mass induced by soccer training in the stressed sites was associated to a decreased skull bone mass after 3 yr of follow-up.

Endocrine disorders in adolescent and young female athletes: impact on growth, menstrual cycles, and bone mass acquisition

CONTEXT

Puberty is a crucial period of dramatic hormonal changes, accelerated growth, attainment of reproductive capacity, and acquisition of peak bone mass. Participation in recreational physical activity is widely acknowledged to provide significant health benefits in this period. Conversely, intense training imposes several constraints, such as training stress and maintenance of very low body fat to maximize performance. Adolescent female athletes are therefore at risk of overtraining and/or poor dietary intake, which may have several consequences for endocrine function. The "adaptive" changes in the hypothalamic-pituitary-gonadal, -adrenal, and somatotropic axes and the secretory role of the adipose tissue are reviewed, as are their effects on growth, menstrual cycles, and bone mass acquisition.

DESIGN

A systematic search on Medline between 1990 and 2013 was conducted using the following terms: "intense training," "physical activity," or "exercise" combined with "hormone," "endocrine," and "girls," "women," or "elite female athletes." All articles reporting on the endocrine changes related to intense training and their potential implications for growth, menstrual cycles, and bone mass acquisition were considered.

RESULTS AND CONCLUSION

Young female athletes present a high prevalence of menstrual disorders, including delayed menarche, oligomenorrhea, and amenorrhea, characterized by a high degree of variability according to the type of sport. Exercise-related reproductive dysfunction may have consequences for growth velocity and peak bone mass acquisition. Recent findings highlight the endocrine role of adipose tissue and energy balance in the regulation of homeostasis and reproductive function. A better understanding of the mechanisms whereby intense training affects the endocrine system may orient research to develop innovative strategies (ie, based on nutritional or pharmacological approaches and individualized modalities of training and competition) to improve the medical care of these adolescents and protect their reproductive function.

Physical activity is associated with bone geometry of premenarcheal girls in a dose-dependent manner

OBJECTIVE

To determine the relationship between habitual physical activity (PA) level and peripheral qualitative computed tomography-determined quantitative tibia characteristics of premenarcheal girls.

METHODS

Premenarcheal girls matched for age (10-13 years), bone age and maturity level were assigned into: a) low PA group (LPA, n=25), b) moderate PA group (MPA, n=17), and c) high PA group (HPA, n=18). Participants' daily dietary intake, tibia's geometry and serum levels of calcium and vitamin D were assessed.

RESULTS

Premenarcheal girls demonstrating HPA exhibited greater pericortical thickness, cross-sectional area (CSA) and bone mineral content (BMC) (p<.001) in cortical bone, greater BMC, volumetric bone density (vBMD) and polar stress strength index (SSIp) in trabecular bone (p<0.001-0.05) and greater total BMC (p<.05) and vBMD (p<.01) when compared to their physically inactive or moderately active counterparts. MPA exhibited greater values of cortical BMC (p<.01) and SSIp (p<.05) than LPA. Partial correlation analysis (adjusted for BMI) revealed modest associations between PA score and bone geometry parameters (r=0.36-0.49, p<.05) at 38% of tibia length.

CONCLUSIONS

Habitual PA affects geometry of both cortical and trabecular areas of a long bone of premenarcheal girls in a dose-dependent manner. Specifically, PA increases both the density and size of cortical bone but only the density of trabecular bone during preadolescence. Given the importance of peak bone mass for future fracture risk, high levels of PA during childhood could be a major target for public health interventions aimed at optimising bone health in prepubertal children when the greatest bone gains occur.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Body composition and reproductive function exert unique influences on indices of bone health in exercising women

Reproductive function, metabolic hormones, and lean mass have been observed to influence bone metabolism and bone mass. It is unclear, however, if reproductive, metabolic and body composition factors play unique roles in the clinical measures of areal bone mineral density (aBMD) and bone geometry in exercising women. This study compares lumbar spine bone mineral apparent density (BMAD) and estimates of femoral neck cross-sectional moment of inertia (CSMI) and cross-sectional area (CSA) between exercising ovulatory (Ov) and amenorrheic (Amen) women. It also explores the respective roles of reproductive function, metabolic status, and body composition on aBMD, lumbar spine BMAD and femoral neck CSMI and CSA, which are surrogate measures of bone strength. Among exercising women aged 18-30 years, body composition, aBMD, and estimates of femoral neck CSMI and CSA were assessed by dual-energy x-ray absorptiometry. Lumbar spine BMAD was calculated from bone mineral content and area. Estrone-1-glucuronide (E1G) and pregnanediol glucuronide were measured in daily urine samples collected for one cycle or monitoring period. Fasting blood samples were collected for measurement of leptin and total triiodothyronine. Ov (n = 37) and Amen (n = 45) women aged 22.3 ± 0.5 years did not differ in body mass, body mass index, and lean mass; however, Ov women had significantly higher percent body fat than Amen women. Lumbar spine aBMD and BMAD were significantly lower in Amen women compared to Ov women (p < 0.001); however, femoral neck CSA and CSMI were not different between groups. E1G cycle mean and age of menarche were the strongest predictors of lumbar spine aBMD and BMAD, together explaining 25.5% and 22.7% of the variance, respectively. Lean mass was the strongest predictor of total hip and femoral neck aBMD as well as femoral neck CSMI and CSA, explaining 8.5-34.8% of the variance. Upon consideration of several potential osteogenic stimuli, reproductive function appears to play a key role in bone mass at a site composed of primarily trabecular bone. However, lean mass is one of the most influential predictors of bone mass and bone geometry at weight-bearing sites, such as the hip.

Peripubertal female athletes in high-impact sports show improved bone mass acquisition and bone geometry

OBJECTIVE

Intensive physical training may have a sport-dependent effect on bone mass acquisition. This cross-sectional study evaluated bone mass acquisition in girls practicing sports that put different mechanical loads on bone.

MATERIALS/METHODS

Eighty girls from 10.7 to 18.0 years old (mean 13.83 ± 1.97) were recruited: 20 artistic gymnasts (AG; high-impact activity), 20 rhythmic gymnasts (RG; medium-impact activity), 20 swimmers (SW, no-impact activity), and 20 age-matched controls (CON; leisure physical activity <3h/wk). Areal bone mineral density (aBMD) was determined using DEXA. Hip structural analysis applied at the femur evaluated cross-sectional area (CSA, cm(2)), section modulus (Z, cm(3)), and buckling ratio. Bone turnover markers and OPG/RANKL levels were analyzed.

RESULTS

AG had higher aBMD than SW and CON at all bone sites and higher values than RG in the lumbar spine and radius. RG had higher aBMD than SW and CON only in the femoral region. CSA and mean cortical thickness were significantly higher and the buckling ratio was significantly lower in both gymnast groups compared with SW and CON. In RG only, endocortical diameter and width were reduced, while Z was only increased in AG compared with SW and CON. Reduced bone remodeling was observed in RG compared with AG only when groups were subdivided according to menarcheal status. All groups showed similar OPG concentrations, while RANKL concentrations increased with age and were decreased in SW.

CONCLUSION

High-impact activity clearly had a favorable effect on aBMD and bone geometry during the growth period, although the bone health benefits seem to be more marked after menarche.

Specific bone mass acquisition in elite female athletes

CONTEXT

Cross-sectional studies have demonstrated that physical activity can improve bone mass acquisition. However, this design is not adequate to describe the specific kinetics of bone mass gain during pubertal development.

OBJECTIVE

To compare the kinetics of bone mass acquisition in female adolescent athletes of sports that impose different mechanical loads and untrained controls throughout puberty.

STUDY PARTICIPANTS

A total of 72 girls with ages ranging from 10.8 to 18.0 years were recruited: 24 rhythmic gymnasts (RG, impact activity group), 24 swimmers (SW, no-impact activity), and 24 age-matched controls (CON).

MAIN OUTCOME MEASURES

Areal bone mineral density (aBMD) was determined using dual-energy x-ray absorptiometry and bone turnover markers were analyzed. All the investigations were performed at baseline and after 1 year.

RESULTS

At baseline and after 1 year of follow-up, RG presented significantly greater aBMD adjusted for age, fat-free soft tissue, and fat mass compared with CON and SW, only at the femoral region. When aBMD variation throughout the pubertal period was modeled for each group from individual values, the aBMD at the femoral region was significantly higher in RG compared with the other 2 groups from 12.5 to 14 years, and this difference lasted up to 18 years. Moreover, the mean annual aBMD gain tended to be higher in RG compared with SW and CON only at the femoral region and this gain lasted longer in RG. Bone remodeling markers decreased similarly with age in the 3 groups.

CONCLUSIONS

This study, which was based on linear mixed models for longitudinal data, demonstrated that the osteogenic effect of gymnastics is characterized by greater bone mass gain localized at mechanically loaded bone (ie, the proximal femur) principally around the menarcheal period. Moreover, the bone mass gain lasts longer in gymnasts, which may be explained by the delay in sexual maturation.

Análise comparativa do equilíbrio unipodal de atletas de ginástica rítmica

INTRODUÇÃO: A ginástica rítmica (GR) requer alto nível de qualidade física; assim, o bom desempenho é dependente da força e resistência muscular, coordenação motora e equilíbrio postural. OBJETIVO: Desenvolver uma análise comparativa do equilíbrio unipodal de atletas de GR. MÉTODOS: Foram avaliadas dez atletas de GR, do sexo feminino, por meio de uma plataforma de força em apoio unipodal e testes funcionais de equilíbrio (Side Hop Test e Figure of Eight Hop Teste). Para a plataforma, os parâmetros do Centro de Pressão (COP) nas direções anteroposterior e mediolateral foram utilizados para análise, enquanto para os testes funcionais, o tempo-segundos de performance. RESULTADOS: Diferença significativa (p = 0,01) foi encontrada entre os membros inferiores no parâmetro de frequência média na direção mediolateral, no qual o membro inferior não dominante apresentou maior estabilidade postural do que o dominante. Para os testes funcionais não houve diferença significativa entre os membros. CONCLUSÃO: A diferença encontrada no controle do equilíbrio na direção mediolateral pode estar relacionada às diferenças nas ações musculares da região do quadril, na qual durante a prática do esporte para estabilização, manutenção do tronco e execução de manobras com os membros inferiores estão presentes. Estes resultados indicam a necessidade de um programa de reequilíbrio e estabilização pélvica para as atletas analisadas no intuito de preservar a simetria muscular dos membros para o bom desempenho esportivo.

Testosterone secretion in elite adolescent swimmers does not modify bone mass acquisition: a 1-year follow-up study

OBJECTIVE

To investigate whether high plasma testosterone (T) levels affect areal bone mineral density (aBMD), bone geometry, and bone remodeling in young elite female swimmers (SW).

DESIGN

Cross-sectional and 1-year follow-up study.

SETTING

Pediatric endocrinology and gynecology units.

PARTICIPANT(S)

Twenty-five SW and 21 control subjects (CON) with breast stages IV or V (mean age 15.3 ± 1.3 y).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Clinical and biologic parameters, aBMD, and bone geometry.

RESULT(S)

Two groups of SW were constituted on the basis of total T level. High T level SW (HSW; n = 15) presented higher T than SW with normal T (NSW; n = 10) and CON (0.63 ± 0.17; 0.36 ± 0.07, and 0.38 ± 0.14 ng/mL, respectively). The SHBG level (62.1 ± 18.7 vs. 43.3 ± 19.8 nmol/L) and the LH/FSH ratio (1.7 ± 1.1 vs. 0.9 ± 0.5) were higher, and menstrual disorders (60% vs. 23.8%) were more frequent in HSW than CON, and no difference was observed between the three groups for other sex hormones and insulin-like growth factor (IGF) 1 or IGF-binding protein 3. SW presented lower fat mass in the whole body and higher lean mass in the upper limbs only. aBMD was only modestly increased in the upper limbs in the SW groups, but no other bone-specific differences (aBMD, bone geometry, bone turnover markers) were demonstrated between SW and CON at baseline or for aBMD after 1 year in a subgroup of participants.

CONCLUSION(S)

High plasma T levels have no detectable effect on bone mass and bone geometry in SW during the period of peak bone mass acquisition.

Lean mass predicts hip geometry and bone mineral density in chinese men and women and age comparisons of body composition

Previous studies have suggested that changes in hip geometry increase the risk of hip fracture. The aim of this study was to identify whether body composition were associated with hip geometry or bone mineral density (BMD) in a large sample of Chinese people. A total of 2072 subjects aged 20-79 yr (including 700 males and 1372 females) were selected. The following measurements were taken: lumbar spine (L1-4); proximal femur BMD; lean mass (LM); fat mass (FM); and hip geometric parameters, including hip axis length (HAL), cross-sectional moment of inertia (CSMI), cross-sectional area (CSA), neck-shaft angle, and femur strength index (SI) by dual-energy X-ray absorptiometry. FM and LM were positively correlated with HAL, CSMI, and CSA, and negatively correlated with SI in both men and women. Multiple regression analysis showed that leg LM contributions to HAL, CSMI, and CSA variance were 12.6-37.6%. Compared with FM, LM was generally more strongly related to hip geometry and BMD in young and old men and women. Body composition was a good predictor for hip geometry parameter variation and BMD variation.

Skeletal effects of long-term caloric restriction in rhesus monkeys

Age-related bone loss is well established in humans and is known to occur in nonhuman primates. There is little information, however, on the effect of dietary interventions, such as caloric restriction (CR), on age-related bone loss. This study examined the effects of long-term, moderate CR on skeletal parameters in rhesus monkeys. Thirty adult male rhesus monkeys were subjected to either a restricted (R, n = 15) or control (C, n = 15) diet for 20 years and examined throughout for body composition and biochemical markers of bone turnover. Total body, spine, and radius bone mass and density were assessed by dual-energy X-ray absorptiometry. Assessment of biochemical markers of bone turnover included circulating serum levels of osteocalcin, carboxyterminal telopeptide of type I collagen, cross-linked aminoterminal telopeptide of type I collagen, parathyroid hormone, and 25(OH)vitamin D. Overall, we found that bone mass and density declined over time with generally higher levels in C compared to R animals. Circulating serum markers of bone turnover were not different between C and R with nonsignficant diet-by-time interactions. We believe the lower bone mass in R animals reflects the smaller body size and not pathological osteopenia.

Skeletal adaptations associated with pre-pubertal gymnastics participation as determined by DXA and pQCT: a systematic review and meta-analysis

Participation in gymnastics prior to puberty offers an intriguing and unique model, particularly in girls. The individuality comes from both upper and lower limbs being exposed to high mechanical loading through year long intensive training programs, initiated at a young age. Studying this unique model and the associated changes in musculoskeletal health during growth is an area of specific interest. Previous reviews on gymnastics participation and bone health have been broad; and not limited to a particular maturation period, such as pre-puberty.

OBJECTIVES

To determine the difference in skeletal health between pre-pubertal girls participating in gymnastics compared with non-gymnasts.

DESIGN

Meta-analysis.

METHODS

Following a systematic search, 17 studies were included in this meta-analysis. All studies used dual-energy X-ray absorptiometry to assess bone mineral density and bone mineral content. In addition, two studies included peripheral quantitative computed tomography.

RESULTS

Following the implementation of a random effects model, gymnasts were found to have greater bone properties than non-gymnasts. The largest difference in bone health between gymnasts and non-gymnasts was observed in peripheral quantitative computed tomography-derived volumetric bone mineral density at the distal radius (d=1.06).

CONCLUSIONS

Participation in gymnastics during pre-pubertal growth was associated with skeletal health benefits, particularly to the upper body.

Site-specific advantages in skeletal geometry and strength at the proximal femur and forearm in young female gymnasts

PURPOSE

We evaluated site-specific skeletal adaptation to loading during growth, comparing radius (RAD) and femoral neck (FN) DXA scans in young female gymnasts (GYM) and non-gymnasts (NON).

METHODS

Subjects from an ongoing longitudinal study (8-26yr old) underwent annual DXA scans (proximal femur, forearm, total body) and anthropometry, completing maturity and physical activity questionnaires. This cross-sectional analysis used the most recent data meeting the following criteria: gynecological age ≤2.5yr post-menarche; and GYM annual mean gymnastic exposure ≥5.0h/wk in the prior year. Bone geometric and strength indices were derived from scans for 173 subjects (8-17yr old) via hip structural analysis (femoral narrow neck, NN) and similar radius formulae (1/3 and Ultradistal (UD)). Maturity was coded as M1 (Tanner I breast), M2 (pre-menarche, ≥Tanner II breast) or M3 (post-menarche). ANOVA and chi square compared descriptive data. Two factor ANCOVA adjusted for age, height, total body non-bone lean mass and percent body fat; significance was tested for main effects and interactions between gymnastic exposure and maturity.

RESULTS

At the distal radius, GYM means were significantly greater than NON means for all variables (p<0.05). At the proximal femur, GYM exhibited narrower periosteal and endosteal dimensions, but greater indices of cortical thickness, BMC, aBMD and section modulus, with lower buckling ratio (p<0.05). However, significant interactions between maturity and loading were detected for the following: 1) FN bone mineral content (BMC) and NN buckling ratio (GYM BMC advantages only in M1 and M3; for BMC and buckling ratio, M1 advantages were greatest); 2) 1/3 radius BMC, width, endosteal diameter, cortical cross-sectional area, and section modulus (GYM advantages primarily post-menarche); and 3) UD radius BMC and axial compressive strength (GYM advantages were larger with greater maturity, greatest post-menarche).

CONCLUSIONS

Maturity-specific comparisons suggested site-specific skeletal adaptation to loading during growth, with greater advantages at the radius versus the proximal femur. At the radius, GYM advantages included greater bone width, cortical cross-sectional area and cortical thickness; in contrast, at the femoral neck, GYM bone tissue cross-sectional area and cortical thickness were greater, but bone width was narrower than in NON. Future longitudinal analyses will evaluate putative maturity-specific differences.