Influence of Physical Activity on Ultrasound and Dual-Energy X-ray Absorptiometry Bone Measurements in Peripubertal Girls: A Cross-Sectional Study

The aim of this cross-sectional study was to investigate whether two types of physical exercise affect the growing skeleton differently. We used calcaneal quantitative ultrasound measurements (QUS) and dual-energy X-ray absorptiometry (DXA) for measurement of bone mineral density (BMD), and to test how QUS values reflect the axial DXA values in these various study groups. A total of 184 peripubertal Caucasian girls aged 11–17 years (65 gymnasts, 63 runners, and 56 nonathletic controls) were studied. Weight, height, stage of puberty, years of training, and the amount of leisure-time physical activity were recorded. Broadband ultrasound attenuation (BUA) and sound of speed (SOS) through the calcaneus were measured. The BMD of the femoral neck and the lumbar spine were measured by DXA. The differences in mean values of bone measurements among each exercise group were more evident in pubertal than prepubertal girls. The mean BUA and SOS values of the pubertal gymnasts were 13.7% (77.8 dB/MHz versus 68.4 dB/MHz, P < 0.05) and 2.2% (1607.7 m/s versus 1572.4 m/s, P < 0.001) higher than of the controls, respectively. The mean BMD of the femoral neck in the pubertal gymnasts and runners was 20% (0.989 g/cm² versus 0.824 g/cm², P < 0.001) and 9.0% (0.901 g/cm² versus 0.824 g/cm², P < 0.05) higher than in the controls, respectively. The amount of physical activity correlated weakly but statistically significantly with all measured BMD and ultrasonographic values in the pubertal group (r = 0.19–0.35). The correlation between ultrasonographic parameters and BMD were weak, but significant among pubertal runners (r = 0.47–0.55) and controls (r = 0.39–0.42), whereas the DXA values of the femoral neck and the ultrasonographic parameters of the calcaneus did not correlate among highly physically active gymnasts. By stepwise regression analysis, physical activity accounted for much more of the variation in the DXA values than the ultrasonographic values. We conclude that the beneficial influence of exercise on bone status as measured by ultrasound and DXA was evident in these peripubertal girls. In highly active gymnasts the increase of the calcaneal ultrasonographic values did not reflect statistically significantly the BMD values of the femoral neck. Received: 28 June 1999 / Accepted: 2 November 1999     

Pubertal maturation characteristics and the rate of bone mass development longitudinally toward menarche.

To assess risks for osteoporosis and to compare bone mass in different groups of healthy children or children with diseases, it is important to have knowledge of their sexual maturation status during puberty. The aim of our study was to evaluate bone mass formation longitudinally in relation to pubertal maturation characteristics in healthy white girls. We investigated the bone mineral content (BMC) and the bone mineral density (BMD) at different skeletal sites in 151 girls with increasing pubertal stages in relation with their chronological age and with an early or late onset of puberty or menarche and with a slow or fast maturation. Bone mass was measured at the onset of puberty, during puberty, and at menarche. We conclude the following: (1) from midpuberty to menarche, the increase in bone mass formation is highest at all skeletal sites in white girls; (2) early mature girls at the onset of puberty have slightly but definitely lower bone masses at all skeletal sites and at all pubertal stages than late mature girls, whereas the average bone mass formation from the onset of puberty to menarche is similar in both groups; (3) girls with a slow rate of pubertal maturation have lower bone mass values 2 years after the onset of puberty, but at menarche bone mass is similar compared with fast maturers; and (4) it cannot be confirmed that there is an effect of menarcheal age on bone mass values at menarche.     

Bone mineral accrual in 4‐ to 10‐year‐old precompetitive,recreational gymnasts: A 4‐year longitudinal study

Competitive female gymnasts have greater bone mineral measures than nongymnasts. However, less is known about the effect of recreational and/or precompetitive gymnastics participation on bone development. The purpose of this study was to investigate whether the differences previously reported in the skeleton of competitive female gymnasts are also demonstrated in young children with a current or past participation history in recreational or precompetitive gymnastics. One hundred and sixty‐three children (30 gymnasts, 61 ex‐gymnasts, and 72 nongymnasts) between 4 and 6 years of age were recruited and measured annually for 4 years (not all participants were measured at every occasion). Total‐body (TB), lumbar spine (LS), and femoral neck (FN) bone mineral content (BMC) were measured by dual‐energy X‐ray absorptiometry (DXA). Multilevel random‐effects models were constructed and used to predict differences in TB, LS, and FN BMC between groups while controlling for differences in body size, physical activity, and diet. Gymnasts had 3% more TB and 7% more FN BMC than children participating in other recreational sports at year 4 (p < .05). No differences were found at the LS between groups, and there were no differences between ex‐gymnasts' and nongymnasts' bone parameters (p > .05). These findings suggest that recreational and precompetitive gymnastics participation is associated with greater BMC. This is important because beginner gymnastics skills are attainable by most children and do not require a high level of training. Low‐level gymnastics skills can be implemented easily into school physical education programs, potentially affecting skeletal health. © 2011 American Society for Bone and Mineral Research.     

Childhood fractures are associated with decreased bone mass gain during puberty: an early marker of persistent bone fragility?

Whether peak bone mass is low among children with fractures remains uncertain. In a cohort of 125 girls followed over 8.5 years, 42 subjects reported 58 fractures. Among those, BMC gain at multiple sites and vertebral bone size at pubertal maturity were significantly decreased. Hence, childhood fractures may be markers of low peak bone mass acquisition and persistent skeletal fragility. INTRODUCTION: Fractures in childhood may result from a deficit in bone mass accrual during rapid longitudinal growth. Whether low bone mass persists beyond this period however remains unknown. MATERIALS AND METHODS: BMC at the spine, radius, hip, and femur diaphysis was prospectively measured over 8.5 years in 125 girls using DXA. Differences in bone mass and size between girls with and without fractures were analyzed using nonparametric tests. The contribution of genetic factors was evaluated by mother-daughter correlations and that of calcium intake by Cox proportional hazard models. RESULTS: Fifty-eight fractures occurred in 42 among 125 girls (cumulative incidence, 46.4%), one-half of all fractures affecting the forearm and wrist. Girls with and without fractures had similar age, height, weight. and calcium intake at all time-points. Before and during early puberty, BMC and width of the radius diaphysis was lower in the fracture compared with no-fracture group (p < 0.05), whereas aBMD and BMAD were similar in the two groups. At pubertal maturity (Tanner's stage 5, mean age +/- SD, 16.4 +/- 0.5 years), BMC at the ultradistal radius (UD Rad.), femur trochanter, and lumbar spine (LS), and LS projected bone area were all significantly lower in girls with fractures. Throughout puberty, BMC gain at these sites was also decreased in the fracture group (LS, -8.0%, p = 0.015; UD Rad., -12.0%, p = 0.004; trochanter, -8.4%, p = 0.05 versus no fractures). BMC was highly correlated between prepuberty and pubertal maturity (R = 0.54-0.81) and between mature daughters and their mothers (R = 0.32-0.46). Calcium intake was not related to fracture risk. CONCLUSIONS: Girls with fractures have decreased bone mass gain in the axial and appendicular skeleton and reduced vertebral bone size when reaching pubertal maturity. Taken together with the evidence of tracking and heritability for BMC, these observations indicate that childhood fractures may be markers for low peak bone mass and persistent bone fragility.     

Bone mineral density by age, gender, pubertal stages, and socioeconomic status in healthy Lebanese children and adolescents

Gender, ethnicity, and lifestyle factors affect bone mass acquisition during childhood, thus the need for age- and sex-adjusted Z scores using ethnic-specific data for bone mineral density (BMD) measurement. This study aimed at establishing normative data for BMD in healthy Lebanese children and adolescents. Three hundred sixty-three healthy children aged 10 to 17 years (mean+/-SD: 13.1+/-2.0) were studied. BMD, bone mineral content (BMC), and lean mass were measured by dual-energy X-ray absorptiometry (DXA) using a Hologic 4500A device, and apparent volumetric BMD (BMAD) of the lumbar spine and the femoral neck were calculated. BMD, BMC, and BMAD were expressed by age groups and Tanner stages for boys and girls separately. There was a significant effect of age and puberty on all bone parameters, except at the femoral neck BMAD in boys. BMC and BMD were higher at cortical sites in boys, including subtotal body and hip; whereas, in girls, it was higher at a site more enriched in trabecular bone, namely the lumbar spine. At several skeletal sites, girls had significantly higher BMD adjusted for lean mass than boys. By the end of puberty, adolescents had a mean BMD that was 43-66% higher at the lumbar spine and 25-41% higher at cortical sites than pre-pubertal children, depending on the gender. Mean BMD values in the study group were significantly lower (P<0.01) than Western normative values, with Z scores ranging between -0.2 and -1.1. In both genders, children of lower socioeconomic status tended to have lower BMD than those from a higher socioeconomic background. This study allows additional insight into gender dimorphism in mineral accretion during puberty. It also provides a valuable reference database for the assessment of BMD in children with pubertal or growth disorders who are of Middle Eastern origin.     

Bone densitometry: which skeletal sites are best predicted by bone mass determinants?

Evaluation of bone mineral content/bone mass density (BMC/BMD) is important to determine bone mass development among adolescents in health and disease. It is uncertain at which skeletal site BMC/BMD is best predicted by bone mass determinants. On the other hand, intrapersonal BMC/BMD data can be clustered into a composite index score to facilitate correlation and outcome prediction analysis. This study aimed to identify the skeletal site that was best predicted by bone mass determinants and to develop a composite index score based on multisite BMC/BMD values in healthy adolescent girls. Eleven BMD/BMC variables per subject were evaluated by using dual-energy X-ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) in 236 healthy girls aged 12–15 years. Bone mass determinants, namely, weight, height, puberty, dietary calcium, physical activity, and bone turnover markers, were determined. Factor analysis was used to develop composite index scores that summarized characteristics of multisite BMC/BMD. Results showed that lumbar spinal BMD and BMC (by DXA) and tibial integral BMD (by pQCT) were the BMC/BMD sites better predicted by bone mass determinants (R ², 0.57–0.77) in multiple regression analysis. On the other hand, three composite index scores representing areal BMD, areal BMC, and vBMD were derived to summarize the original BMC/BMD values. The composite index scores had similar predicting power (R ², 0.419–0.749) compared to those of original BMC/BMD, indicating that the composite index scores were representative of the original variables. To conclude, lumbar spinal BMD and BMC and tibial integral BMD were the three BMC/BMD variables better predicted by bone mass determinants. This evaluation would help select appropriate skeletal sites as outcome measures for bone mass evaluation in future studies. Also, the development of composite index scores could help reduce the number of variables for correlation and outcome prediction analyses.     

Dancing for bone health: a 3-year longitudinal study of bone mineral accrual across puberty in female non-elite dancers and controls

Introduction Weight-bearing exercise during growth enhances peak bone mass. However, the window of opportunity for optimizing positive effects of exercise on peak bone mass remains to be fully defined. Ballet dancing provides a model of mechanical loading patterns required to site-specifically modulate bone. Methods We assessed the effects of ballet dancing on bone mineral accrual in female non-elite dancers and normally active controls for 3 years across puberty. We recruited 82 ballet dancers and 61 controls age 8–11 years at baseline. Participants were measured over 3 consecutive years; however, the overlap in ages allowed analysis of the groups across 8–14 years of age. We annually assessed bone mineral content (BMC) at the total body (TB), including upper and lower limb regions, and biannually assessed BMC at the proximal femur and lumbar spine (LS) using dual x-ray absorptiometry (DXA). We derived TB lean mass and fat mass from DXA TB scans. Anthropometry, exercise levels, and calcium intake were also measured biannually. Maturational age was determined by age at peak height velocity (PHV). A multilevel regression model was used to determine the independent effects of body size, body composition, maturation, exercise levels, and calcium intake at each measurement occasion. Results When adjusted for growth and maturation, dancers had significantly greater BMC at the TB, lower limbs, femoral neck (FN), and LS than controls. Excepting the FN region, these differences became apparent at 1 year post-PHV, or the peripubertal years, and by 2 years post-PHV the differences represented a cumulative advantage in dancers of 0.6–1.3% (p<0.05) greater BMC than controls. At the FN, dancers had 4% (p<0.05) greater BMC than controls in prepuberty and maintained this advantage throughout the pubertal years. Conclusions Results from this novel population provide evidence for modest site-specific and maturity-specific effects of mechanical loading on bone.     

Higher premenarcheal bone mass in elite gymnasts is maintained into young adulthood after long‐term retirement from sport: A 14‐year follow‐up

Sports that impact‐load the skeleton during childhood and adolescence increase determinants of bone strength such as bone mineral content and density; however, it is unclear if this benefit is maintained after retirement from the sport. The purpose of this study was to assess whether the previously reported higher bone mass in a group of premenarcheal gymnasts was still apparent 10 years after the cessation of participation and withdrawal of the gymnastics loading stimulus. In 1995, 30 gymnasts 8 to 15 years of age were measured and compared with 30 age‐matched nongymnasts. Twenty‐five former gymnasts and 22 nongymnasts were measured again 14 years later (2009 to 2010). Gymnasts had been retired from gymnastics training and competition for an average of 10 years. Total body (TB), lumbar spine (LS), and femoral neck (FN) bone mineral content (BMC) was assessed at both measurement occasions by dual‐energy X‐ray absorptiometry (DXA). Multivariate analysis of covariance (MANCOVA) was used to compare former gymnasts' and nongymnasts' BMC while controlling for differences in body size and maturation (covariates: age, height, weight, and years from menarche [1995] or age at menarche [2009 to 2010]). Premenarcheal gymnasts (measured in 1995) had significantly greater size‐adjusted TB, LS, and FN BMC (p < 0.05) (15%, 17%, and 12%, respectively) than nongymnasts. Ten years after retirement, gymnasts had maintained similar size‐adjusted TB, LS, and FN BMC differences (p < 0.05) (13%, 19%, and 13%, respectively) when compared with nongymnasts. Bone mass benefits in premenarcheal gymnasts were still apparent even after long‐term (10 years) removal of the gymnastics loading stimulus. © 2012 American Society for Bone and Mineral Research     

The influence of serum ghrelin,IGF axis and testosterone on bone mineral density in boys at different stages of sexual maturity

The aim of our study was to examine the relationship between bone mineral density (BMD) and serum ghrelin, insulin-like growth factor-1 (IGF-1), IGF-binding protein 3 (IGFBP-3), and testosterone levels in boys at different stages of puberty. The study included 60 healthy nonobese Estonian schoolboys at the age of 10–18 years. Subjects were divided in three groups (20 boys in each) based on the results of self-assessment using illustrated questionnaire of pubertal stage (G1, I; G2–G3, II; G3–G4, III). Morning fasting blood samples were collected for analysis of ghrelin, testosterone, IGF-1, and IGFBP-3. Total body BMD, lumbar BMD, lumbar apparent volumetric BMD (BMAD), and bone mineral content (BMC) were measured by DXA. Serum testosterone concentration was the most important biochemical predictor of BMD in the total group, explaining 48.8% of variability in total body BMD, 51.4% in lumbar BMD, and 36.8% in lumbar BMAD. Body mass and height were both related to BMD and BMC throughout puberty. The serum IGF-1/IGFBP-3 ratio was correlated with serum testosterone (r = 0.69) and ghrelin (r = −0.58) levels, but also with total BMD (r = 0.39), lumbar BMD (r = 0.42; P < 0.001 in all cases), BMAD (r = 0.29; P < 0.01), and total BMC (r = 0.48; P < 0.001). We conclude that serum testosterone concentration and serum IGF-1/IGFBP-3 molar ratio are the major determinants of bone mineral density in boys at different pubertal stages. Serum ghrelin concentration did not appear to have a direct independent effect on BMD. If present, the association may be mediated through sex hormones and the GH-IGF-I axis.     

Catch up in bone acquisition in young adult men with late normal puberty

The aim of this study was to investigate the development of bone mineral density (BMD) and bone mineral content (BMC) in relation to peak height velocity (PHV), and to investigate whether late normal puberty was associated with remaining low BMD and BMC in early adulthood in men. In total, 501 men (mean ± SD, 18.9 ± 0.5 years of age at baseline) were included in this 5‐year longitudinal study. Areal BMD (aBMD) and BMC, volumetric BMD (vBMD) and cortical bone size were measured using dual‐energy X‐ray absorptiometry (DXA) and pQCT. Detailed growth and weight charts were used to calculate age at PHV, an objective assessment of pubertal timing. Age at PHV was a strong positive predictor of the increase in aBMD and BMC of the total body (R² aBMD 11.7%; BMC 4.3%), radius (R² aBMD 23.5%; BMC 22.3%), and lumbar spine (R² aBMD 11.9%; BMC 10.5%) between 19 and 24 years (p < 0.001). Subjects were divided into three groups according to age at PHV (early, middle, and late). Men with late puberty gained markedly more in aBMD and BMC at the total body, radius, and lumbar spine, and lost less at the femoral neck (p < 0.001) than men with early puberty. At age 24 years, no significant differences in aBMD or BMC of the lumbar spine, femoral neck, or total body were observed, whereas a deficit of 4.2% in radius aBMD, but not in BMC, was seen for men with late versus early puberty (p < 0.001). pQCT measurements of the radius at follow‐up demonstrated no significant differences in bone size, whereas cortical and trabecular vBMD were 0.7% (p < 0.001) and 4.8% (p < 0.05) lower in men with late versus early puberty. In conclusion, our results demonstrate that late puberty in males was associated with a substantial catch up in aBMD and BMC in young adulthood, leaving no deficits of the lumbar spine, femoral neck, or total body at age 24 years. © 2012 American Society for Bone and Mineral Research.     

Characterization of low bone mass in young patients with thalassemia by DXA, pQCT and markers of bone turnover

Previous reports using dual x-ray absorptiometry (DXA) suggest that up to 70% of adults with thalassemia major (Thal) have low bone mass. However, few studies have controlled for body size and pubertal delay, variables known to affect bone mass in this population. In this study, bone mineral content and areal density (BMC, aBMD) of the spine and whole body were assessed by DXA, and volumetric BMD and cortical geometries of the distal tibia by peripheral quantitative computed tomography (pQCT) in subjects with Thal (n = 25, 11 male, 10 to 30 years) and local controls (n=34, 15 male, 7 to 30 years). Z-scores for bone outcomes were calculated from reference data from a large sample of healthy children and young adults. Fasting blood and urine were collected, pubertal status determined by self-assessment and dietary intake and physical activity assessed by written questionnaires. Subjects with Thal were similar in age, but had lower height, weight and lean mass index Z-scores (all p < 0.001) compared to controls. DXA aBMD was significantly lower in Thal compared to controls at all sites. Adult Thal subjects (> 18 years, n = 11) had lower tibial trabecular vBMD (p = 0.03), cortical area, cortical BMC, cortical thickness, periosteal circumference and section modulus Z-scores (all p < 0.01) compared to controls. Cortical area, cortical BMC, cortical thickness, and periosteal circumference Z-scores (p = 0.02) were significantly lower in young Thal (≤ 18 years, n = 14) compared to controls. In separate multivariate models, tibial cortical area, BMC, and thickness and spine aBMD and whole body BMC Z-scores remained lower in Thal compared to controls after adjustment for gender, lean mass and/or growth deficits (all p < 0.01). Tanner stage was not predictive in these models. Osteocalcin, a marker of bone formation, was significantly reduced in Thal compared to controls after adjusting for age, puberty and whole body BMC (p=0.029). In summary, we have found evidence of skeletal deficits that cannot be dismissed as an artifact of small bone size or delayed maturity alone. Given that reduced bone density and strength are associated with increased risk of fracture, therapies focused on increasing bone formation and bone size in younger patients are worthy of further evaluation.     

Bone response to jumping is site-specific in children: a randomized trial

Skeletal loading during growth may be one way of increasing bone mass early in life. We hypothesized that children randomized to a jumping program (25 jumps/day from a 45-cm box, 5 days/week for 12 weeks) would have greater increases in hip and spine bone mineral content (BMC) and 4% distal tibia volumetric bone density than children randomized to the control group. Our secondary hypothesis was that jumping would not be as beneficial among peripubertal children as compared to prepubertal or pubertal children due to the relatively high growth rate that occurs during the peripubertal period. Fifty-four children (31 girls) ages 3-5, 7-8, 11-12, and 15-18 years were enrolled. We performed bone, anthropometric, and force plate measurements at baseline and 12 weeks. Twenty-four-hour diet recall and Tanner's self-report of pubertal development were completed at baseline. Jumpers had a lower calcium intake than nonjumpers at baseline (965 +/- 403 vs 1295 +/- 465 mg/day, P < 0.01), but the groups were otherwise similar. Overall, jumpers had greater increases in total body BMC (45.0 +/- 4.9 vs 29.4 +/- 5.3 g, P = 0.03) and regional dual energy x-ray absorptiometry leg BMC (19.8 +/- 2.6 vs 11.5 +/- 2.8 g, P = 0.03) than nonjumpers at all pubertal stages. However, the 4% distal tibia bone response to jumping appeared to be modified by pubertal stage, with the greatest bone benefit from jumping observed in pubertal children (interaction of jumping group by pubertal stage, P < 0.05, for both BMC and volumetric BMD). A similar pattern was observed for spine BMC (interaction, P = 0.10). We conclude that skeletal loading increases total body and leg BMC in children, but may not have a positive effect at sites that are predominantly trabecular bone during periods of rapid growth (i.e., peripubertal period).     

Sex differences in bone mass acquisition during growth: the Fels Longitudinal Study.

Risk of osteoporosis in later life may be determined during adolescence and young adulthood. The present study used longitudinal data to examine the accumulation of bone mineral content (BMC) and bone mineral density (BMD) in Caucasian subjects ages 6-36 yr. Growth in BMC and BMD (measured by dual X-ray absorptiometry; Lunar, Madison, WI) of 94 males and 92 females was monitored for a mean period of 4.29 yr. The main findings were that there were no sex differences in BMC or BMD during the prepubertal stage; however, females had significantly higher BMD of the pelvis and BMC and BMD of the spine during puberty, and postpubertal males generally had significantly higher BMC and BMD than their female counterparts. In addition, the longitudinal rate of bone accumulation in both sexes increased rapidly during childhood and adolescence and was nearly complete at the end of puberty. Finally, peak BMC and BMD was achieved between the ages of 20 and 25 and occurred earlier in females than in males. The rates of growth and timing of peak bone mass as reported here define the crucial period during which intervention protocols should be developed for maximizing skeletal mass to prevent the development of osteoporosis.     

Initial years of recreational artistic gymnastics training improves lumbar spine bone mineral accrual in 4- to 8-year-old females.

Gymnasts' bone mineral characteristics are generally not known before starting their sport. Prepubertal females who enrolled in beginning artistic gymnastics (n = 65) had lower bone mineral than controls (n = 78). However, 2 years of gymnastics participation versus no participation led to a significantly greater accrual of forearm bone area and lumbar spine areal BMD. INTRODUCTION: The skeletal response to exercise in children compared with adults is heightened because of the high bone turnover rate and the ability of bone to change its size and shape. Whereas child gymnasts generally have greater rates of bone mineral accrual compared with nongymnasts, it is unknown if some of these skeletal advantages are present before the onset of training or are caused entirely by training. MATERIALS AND METHODS: Changes in bone area (BA; cm2), BMC (g), and areal BMD (aBMD; g/cm2) over 24 months were examined in prepubertal females, 4-8 years of age, who selected to perform recreational gymnastics (GYM; n = 65), nongymnastic activities, or no organized activity (CON; n = 78). Participants had essentially no lifetime history of organized athletic participation (< 12 weeks). Pubertal maturation was assessed annually by a physician. Total body, lumbar spine, total proximal femur, and forearm BA, BMC, and aBMD were measured every 6 months using DXA (Hologic QDR-1000W). Independent samples t-tests determined baseline group differences. Nonlinear mixed effects models were used to model 24-month changes in bone data. In subset analyses, high-level gymnasts advancing to competition (HLG; n = 9) were compared with low-level nonadvancing gymnasts (LLG; n = 56). RESULTS: At baseline, GYM were shorter, lighter, and had lower BA, BMC, and aBMD compared with CON (p < 0.05), whereas HLG did not differ significantly in these measurements compared with LLG (p > 0.05). Controlling for differences in race, baseline measures of body mass, height, and calcium intake, and change in breast development beyond stage II at 24 months, GYM had greater long-term (asymptotic) mean responses for total body aBMD and forearm BMC (p < 0.04) and greater rates of increase in the mean responses of lumbar spine aBMD and forearm BA compared with CON over 24 months. Over time, forearm BA increased to a greater extent in HLG compared with LLG (p < 0.01). CONCLUSIONS: Females participating in recreational gymnastics initiated during childhood have enhanced bone mineral gains at the total body, lumbar spine, and forearm over 24 months. Higher-level training promotes additional gains in forearm BA.     

Differences in bone density, body composition, physical activity, and diet between child gymnasts and untrained children 7-8 years of age.

Strategies that enhance the acquisition of bone mass may be protective against osteoporosis. BMD was compared in 20 artistic gymnasts (10 boys; 10 girls) and 20 untrained children ages 7-8 years. Higher regional values of BMD were observed in female gymnasts than untrained girls. If retained to adulthood, this higher BMD may protect skeletal integrity in later life. Strategies that enhance the acquisition of bone mass in children may assist with the prevention of osteoporosis. This study explored the effects of regular high-impact and weight-bearing activity before the age of 7 years on total and regional bone mineral density (BMD). Twenty artistic gymnasts (10 boys and 10 girls) and 20 untrained children, 7-8 years of age, were recruited. The untrained children were matched to gymnasts by sex, height, weight, and age. Female gymnasts trained 8-10 h per week and had trained regularly for 3-4 years. Male gymnasts trained 4-6 h per week and had trained for 1-2 years. Measurements of bone mineral density were made using DXA for total body BMD (TBBMD); lumbar spine, both areal (aSBMD) and volumetric (vSBMD); total spine; pelvis; arms; and legs. Significant mean differences (8-10%) in aSBMD, vSBMD, arm BMD, and TBBMD were observed between female gymnasts and untrained girls (p < 0.05: aSBMD, vSBMD, and TBBMD body mass (BM); p < 0.01: arm BMD). A nonsignificant trend toward a higher TBBMD/BM and arm BMD was observed in male gymnasts compared with untrained boys. Trends toward a higher BMD within the pelvis, legs, and total spine were also observed in gymnasts. There were no differences in total and regional BMD between untrained boys and untrained girls. The results suggest that gymnastics training before the age of 7 years enhances the acquisition of bone mass at selected skeletal sites. The magnitude of this enhancement seems to be linked to the cumulative volume of such training. If retained during adolescence and young adulthood, a surfeit of bone acquired through high-impact and weight-bearing activity in early childhood may protect skeletal integrity in later life.     

Bone mineral acquisition during adolescence and early adulthood: A study in 574 healthy females 10–24 years of age

Low bone mass is known to be associated with an increased risk of fractures. Osteoporosis prevention by maximizing bone mass will be crucial and requires a better knowledge of bone mass acqusition during adolescence. Bone mass was assessed in 574 healthy volunteer females aged 10–24 years. Spine bone mineral density (BMD) in anteroposterior (AP L2–4) and lateral (LAT L3) views was measured using dual-energy X-ray absorptiometry (DXA) and AP bone mineral content (BMC) was calculated. At the same time, spine AP-BMD (L2–4) was evaluated in 333 normal menstruating women, aged 27–47 years. Bone values, osteocalcin and IGF-1 serum concentrations were correlated with chronological age, skeletal age, pubertal stages and time after menarche. In this cross-sectional study, AP- and LAT-BMD and BMC increased dramatically between skeletal ages 10 and 14 or until the first year after menarche. Between 14 and 17 skeletal years of age, AP-BMD and BMC increased moderately, whereas LAT-BMD remained unchanged. After skeletal age 17, or the fourth year after menarche, there was no significant increase in BMD or BMC, and their values did not differ from those of menstruating women. A serum osteocalcin peak was observed at skeletal ages 11–12 or at stage P3, whereas IGF-1 peaked at 13–14 skeletal years of age or at P4 and the first year after menarche. Eighty-six per cent of the adult bone mass of the spine is acquired before skeletal age 14 or the second year after menarche; therefore osteoporosis prevention programs will be particularly effective before that age.     

The correlation between calcaneus stiffness index calculated by QUS and total body BMD assessed by DXA in Chinese children and adolescents

Few studies have shown comparison data between calcaneus stiffness index (SI) calculated by quantitative ultrasound (QUS) and bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) in the Chinese population. This study was aimed to examine the correlations between calcaneus SI calculated by QUS and total body BMD and bone mineral content (BMC) measured by DXA in Chinese children and adolescents. We measured the total body BMD and BMC using Lunar Prodigy (GE Healthcare), and speed of sound (SOS), broadband ultrasound attenuation (BUA), and a calculated SI of the left os calcis using Lunar Achilles Express (GE Healthcare) in 392 healthy Chinese schoolchildren and adolescents aged 5–19 years. The short-term precision for DXA was 0.5 % for total body BMD. The precision for QUS was 1.8 % for SI, 2.9 % for BUA, and 0.4 % for SOS. Pearson’s correlation coefficients (r) were calculated to assess the possible correlations between the total body BMC by DXA and SI calculated by QUS. There were significantly positive correlations between SI of the left os calcis and total body BMD (r = 0.693, p < 0.001, n = 392) and BMC (r = 0.690, p < 0.001, n = 392). For all the subjects, significant positive correlations were observed between the calcaneal SI and the age, weight, height, BMI, total body BMD, total body BMC, total body lean mass, and total body fat mass, with r ranging from 0.310 (total body fat mass) to 0.693 (total body BMD) (p < 0.001, n = 392). In conclusion, QUS bone densitometry is a useful measuring method showing the physiological bone development in childhood and adolescence.     

Pubertal timing predicts previous fractures and BMD in young adult men: the GOOD study.

The importance of pubertal timing for adult BMD in males was studied through association of pubertal timing with young adult bone phenotype. Pubertal timing was found to predict both cortical and trabecular volumetric BMD and previous fractures in young adult men. Thus, late puberty is a risk factor for low BMD and previous fractures in young adult men. INTRODUCTION: Peak bone mass (PBM), achieved during puberty, is a determinant of the risk for osteoporosis and future fractures. The role of variations within the normal range in pubertal timing for fractures during pubertal development and for adult bone mass in men is unknown. MATERIALS AND METHODS: The aim of this study was to investigate the importance of pubertal timing for adult BMD and for fractures before achievement of PBM in men. The population-based Gothenburg Osteoporosis and Obesity Determinants (GOOD) study is a well-characterized cohort of young adult Swedish males 18-20 years of age. Detailed growth charts from birth to 18-20 years of age were retrieved for 642 men participating in the GOOD study. Age at peak height velocity (PHV) was estimated and used as an assessment of pubertal timing. The skeletal phenotype was analyzed at young adult age using DXA and pQCT and previous fractures were assessed by questionnaires. RESULTS: Age at PHV was a negative independent predictor of both adult cortical and trabecular volumetric BMD and of total body and radius areal BMD. Moreover, age at PHV was associated with previous fractures in a logistic regression analysis. The OR for cortical osteopenia was 2.49 (95% CI, 1.91-3.24; p < 0.001) and for previous upper limb fractures was 1.35 (95% CI, 1.04-1.75; p < 0.05) per year increment in age at PHV. CONCLUSIONS: Age at PHV is a negative independent predictor of BMD and a positive predictor of previous fractures in young adult men. Longitudinal studies to determine if pubertal timing also predicts BMD and fractures in elderly men are required.     

Bone mineral density in girls and boys at different pubertal stages: relation with gonadal steroids, bone formation markers, and growth parameters

Puberty has a key role in bone development. During puberty, several nutritional and hormonal factors play a major role in this process. The aim of this study was to determine the changes in areal bone mineral density (BMD), gonadal steroids, bone formation markers, and growth parameters in healthy Turkish pubertal girls and boys at different pubertal stages. In additional, we aimed to detect the relationship between BMD, sex steroids, and growth parameters, and to reveal the most important determinant of BMD in the pubertal period. BMD of the lumbar spine and total body was performed by dual-energy X-ray absorptiometry (Lunar DPX series) in 174 healthy pubertal children (91 girls, 83 boys), aged 11–15 years. Height and weight were measured. Pubertal stages were assesed. Bone formation markers and gonadal steroids were measured. BMD values significantly increased until stage IV in girls. In boys, BMD values also increased during puberty (P < 0.05), but it was significantly higher in stage IV compared with that in other pubertal stages (P < 0.01). Testosterone levels increased until stage IV in both sexes, particularly in boys. Estrogen levels significantly increased during puberty in girls, whereas it was significantly higher at stage IV in boys (P < 0.001). Bone-specific alkaline phosphatase (BAP) level was higher in early and midpuberty, and decreased in late puberty in girls (P < 0.001). BAP level was higher in stage IV in boys. Osteocalcin level was shown not to change significantly in pubertal stages. There was a modest correlation between BMD values and estrogen and testosterone levels in boys. In girls, there was a correlation between BMD values and estrogen levels only (P < 0.05). Weight was significantly associated with BMD in both sexes (P < 0.05). Estrogen had a significant influence on BMD in boys and girls. In conclusion, bone mass increased throughout puberty in both sexes. Peak bone mass was not achieved in girls, but was obtained at stage IV in boys. Bone formation markers were good predictors of bone mass in girls, but not in boys. Estrogen level made the greatest contribution to bone mineral acquisition in boys and girls. The achievement of peak bone mass was sustained by estrogen in boys. The major independent determinant of BMD in both sexes was weight.     

Effects of pubertal development, height, weight, and grip strength on the bone mineral density of the lumbar spine and hip in peripubertal Japanese children: Kyoto kids increase density in the skeleton study (Kyoto KIDS study)

The effects of growth and pubertal development on the bone mineral density (BMD) of the lumbar spine and hip in peripubertal Japanese children were studied as a basis for evaluating the effects of modifiable factors on bone mass gain. The study comprised bone mass measurements in the lumbar spine (L2–4), femoral neck, and total hip using dual-energy X-ray absorptiometry as well as body size measurements and detailed interviews on medical history and pubertal status. The subjects were 404 first-grade students in three junior high schools (129 boys and 275 girls, mean age 12.8 ± 0.3 years) with no diseases or medication that would affect bone metabolism. BMD at each site showed an increasing trend with physical growth and sexual maturity. Significant positive correlations were observed between BMD at every skeletal site and height, weight, and grip strength in pre- and postpubertal boys and girls. In multiple regression analyses, pubertal development had a significant positive independent effect on BMD at every skeletal site in girls, but not in boys. Physical and pubertal development showed major effects on BMD, but the magnitude of these effects differed in boys and girls, even if they were of the same age. We conclude that confounding factors due to physical and pubertal development should be taken into consideration in different ways for boys and girls in investigations on the effects of environmental or behavioral factors on bone mass acquisition in peripubertal children.