Bone Mineral Content Of Radius Research Articles

Per- and polyfluoroalkyl substances and bone mineral content in early adolescence: Modification by diet and physical activity

BackgroundPer- and polyfluoroalkyl substance (PFAS) exposures may negatively impact bone mineral accrual, but little is known about potential mitigators of this relation. We assessed whether associations of PFAS and their mixture with bone mineral content (BMC) in adolescence were modified by diet and physical activity. MethodsWe included 197 adolescents enrolled in a prospective pregnancy and birth cohort in Cincinnati, Ohio (2003–2006). At age 12 years, we collected serum for PFAS measurements and used dual-energy x-ray absorptiometry to measure BMC. We calculated dietary calcium intake and Health Eating Index (HEI) scores from repeated 24-h dietary recalls, physical activity scores using the Physical Activity Questionnaire for Older Children (PAQ-C), and average moderate to vigorous physical activity (MVPA) based on accelerometry. We estimated covariate-adjusted differences in BMC z-scores per interquartile range (IQR) increase of individual PFAS concentrations using linear regression and per simultaneous IQR increase in all four PFAS using g-computation. We evaluated effect measure modification (EMM) using interaction terms between each modifier and PFAS. ResultsHigher serum perfluorooctanoic acid, perfluorooctanesulfonic acid, and perfluorononanoic acid concentrations and the PFAS mixture were associated with lower BMC z-scores. An IQR increase in all PFAS was associated with a 0.27 (−0.54, 0.01) lower distal radius BMC z-score. Associations with lower BMC were generally stronger among adolescents classified as < median for calcium intake, HEI scores, or MVPA compared to those ≥ median. The difference in distal radius BMC z-score per IQR increase in all PFAS was −0.38 (−0.72, −0.04) for those with <median calcium intake versus −0.03 (−0.48, 0.35) for ≥ median (EMM p-value = 0.16); the corresponding differences by MVPA were −0.42 (−0.76, −0.07) for < median and −0.05 (−0.42, 0.32) for ≥ median (EMM p-value = 0.13). ConclusionHealthy, calcium-rich diets and higher intensity physical activity may mitigate the adverse impact of PFAS on adolescent bone health.

Associations of maternal gestational urinary environmental phenols concentrations with bone mineral density among 12-year-old children in the HOME Study.

Early life environmental exposures may affect bone mass accrual in childhood, but only one study has assessed the role of environmental phenols on child bone health. We used data from 223 mother-child dyads enrolled in the Health Outcomes and Measures of the Environment (HOME) Study (Cincinnati, OH; 2003-2006). We quantified benzophenone-3, bisphenol A (BPA), 2,5-dichlorophenol, and triclosan in maternal urine collected at 16- and 26-weeks gestation and calculated the average of creatinine-adjusted concentrations. We performed dual x-ray absorptiometry at age 12 years and calculated Z-scores for whole body (less head), total hip, femoral neck, and 1/3rd distal radius bone mineral content (BMC) and areal bone mineral density (aBMD) as well as ultra-distal radius aBMD and spine BMC and bone mineral apparent density (BMAD). We estimated covariate-adjusted associations per doubling of maternal urinary environmental phenol concentrations in linear regression models. We also examined effect measure modification by child's sex and estimated associations of the environmental phenol mixture with BMC and aBMD using quantile g-computation. We observed generally null associations for all analytes and bone measures. Yet, in adjusted models, higher urinary 2,5-dichlorophenol concentrations were associated with higher 1/3rd distal radius BMC (β: 0.09; 95% CI: 0.02, 0.17) and aBMD (β: 0.09; 95% CI: 0.02, 0.17) Z-scores in the overall sample. In sex-stratified analyses, the magnitude of the BMC association was positive for females (β: 0.16; 95% CI: 0.06, 0.26) and null for males (β: 0.02; 95% CI: 0.08, 0.13). The environmental phenol mixture was associated with greater 1/3rd distal radius BMC and aBMD Z-scores in both sexes, which was mostly driven by benzophenone-3 in males and 2,5-dichlorophenol in females. In this prospective cohort study, we observed generally null associations for environmental phenols with BMC and aBMD at age 12 years. While there was a positive association of 2,5-dichlorophenol concentrations during fetal development with distal radius BMC and aBMD at age 12 years, future studies utilizing methods capable of differentiating cortical and trabecular bone are needed to elucidate potential mechanisms and implications for bone strength and microarchitecture.

Early life organophosphate ester exposures and bone health at age 12 years: The Health Outcomes and Measures of the Environment (HOME) Study

BackgroundNo human studies have evaluated early life organophosphate ester (OPE) exposures with bone health outcomes, despite evidence of osteotoxicity. ObjectivesWe assessed associations of urinary OPE metabolites measured across early life with areal bone mineral density (aBMD) and bone mineral content (BMC) at age 12 years. MethodsAmong 223 mother-child dyads enrolled in the Health Outcomes and Measures of the Environment (HOME) Study, we quantified concentrations of bis-2-chloroethyl phosphate (BCEP), bis-(1,3-dichloro-2-propyl) (BDCIPP), di-n-butyl phosphate (DnBP), and diphenyl phosphate (DPHP) in urine collected from mothers during pregnancy and children at ages 1, 2, 3, 5, and 8 years. At age 12 years, we performed dual energy x-ray absorptiometry and calculated aBMD and BMC z-scores at six skeletal sites. We estimated overall and sex-stratified BMD/BMC z-score differences per interquartile range (IQR) increase in OPE concentrations at multiple exposure timepoints: gestation (average) and 1–3 (average), 5, and 8 years. ResultsIn adjusted models, overall associations of BCEP and BDCIPP with total hip and 1/3rd distal radius aBMD and BMC varied significantly by exposure timepoint, as did BDCIPP with whole body aBMD. For example, differences (95 % CI) in total hip aBMD z-score per IQR increase in BDCIPP were 0.33 (0.01, 0.64), −0.10 (−0.34, 0.14), −0.18 (−0.40, 0.05), and 0.14 (−0.09, 0.38) for concentrations during gestation and at 1–3, 5, and 8 years, respectively. Overall DnBP and DPHP associations were generally null at all timepoints. We observed sex-specific associations for some timepoints and skeletal sites. For example, an IQR increase in 8-year DPHP was associated with a 0.21 (0.05, 0.38) greater total hip aBMD z-score among females but −0.19 (−0.43, 0.05) lower z-score among males. DiscussionEarly life OPE exposures may be associated with sex- and exposure period-dependent alterations in early adolescent bone mineral accrual and strength.

Associations of Maternal Serum Perfluoroalkyl Substances Concentrations with Early Adolescent Bone Mineral Content and Density: The Health Outcomes and Measures of the Environment (HOME) Study.

Background:Per- and polyfluoroalkyl substances (PFAS) may impair bone accrual and strength via endocrine disruption and nuclear receptor agonism, but human studies are primarily of adults or cross-sectional.Objectives:We assessed associations of individual PFAS and their mixture during pregnancy with child bone mineral content (BMC) and areal bone mineral density (aBMD) at age 12 y.Methods:Among 206 mother–child pairs enrolled in a prospective cohort (2003–2006), we quantified perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), and perfluorooctane sulfonic acid (PFOS) in maternal serum collected during gestation or delivery. When children were age 12 y, we performed dual energy X-ray absorptiometry and calculated BMC, aBMD, and bone mineral apparent density (BMAD) -scores for six skeletal sites. We estimated covariate-adjusted -score differences per doubling of individual PFAS using linear regression and assessed the PFAS mixture using quantile g-computation and Bayesian kernel machine regression. We explored whether associations were modified by child’s sex or mediated by whole-body lean mass.Results:In covariate-adjusted models, we found that higher maternal serum concentrations of PFOA, PFNA, and the PFAS mixture were associated with lower total hip and forearm (one-third distal radius) BMC -scores in children. Differences in forearm BMC -scores were [95% confidence interval (CI): , 0.01] and (95% CI: , ) per doubling of PFOA and PFNA, respectively, and (95% CI: , ) per quartile increase in the PFAS mixture. Child’s sex modified PFOA associations for some skeletal sites; for example, differences in spine BMAD -score per doubling were (95% CI: , ) among males and 0.07 (95% CI: , 0.30) among females (modification ). Except for PFNA among females, these associations were not mediated by whole-body lean mass.Discussion:Maternal PFAS concentrations during pregnancy may be associated with lower bone mineral accrual and strength in early adolescence. https://doi.org/10.1289/EHP9424

Effects of backhand stroke styles on bone mineral content and density in postmenopausal recreational tennis players: a cross-sectional pilot investigation

BackgroundOne-handed backhand (OB) and two-handed backhand (TB) styles are commonly used in tennis, but only TB generates loadings on the non-dominant arm and a greater extension torque on the rear leg, leading to a greater axial torque involving rotation of the hip and trunk. The current study investigated whether those effects can further affect bone area (BA), bone mineral content (BMC) and density (BMD) in postmenopausal recreational tennis players.MethodsBA, BMC and BMD of the lumbar spine, hip and distal radius were assessed using dual-energy X-ray absorptiometry in TB, OB, and swimmers’ group as a control (SG) (all participants self-reported for at least 5 years of exercise history, n = 14 per group). Muscular strength was assessed with a hand dynamometer. Among these three groups, the BA, BMC and BMD of distal radius and muscle strength were assessed using one-way ANOVA, and those of the lumbar region and the hip joint were tested by one-way ANCOVA.ResultsTB showed higher BMC and BMD for both lumbar spine and femoral neck than SG (all, p < 0.05). Both OB and TB showed greater BMD inter-trochanter than SG (both, p < 0.05). OB demonstrated greater inter-arm differences in the distal radius, which involved 1/3 distal for BMC and mid-distal radius for BMD compared to the TB and SG (all, p < 0.05). In addition, greater inter-arm asymmetry of grip strength was found in OB compared to TB and SG (both, p < 0.05).ConclusionFor postmenopausal women, performing two-handed backhand strokes, leads to higher BMC and BMD in the non-dominant arm, the lumbar region, and hips, indicating potential benefit to maintain bone health and strength. Whether this result leads to reducing the risk of osteoporosis needs to be investigated in further research.

Pregnancy-Related Change in pQCT and Bone Biochemistry in a Population With a Habitually Low Calcium Intake.

In pregnancy, changes in maternal calcium (Ca) economy occur to satisfy fetal Ca demand. It is unclear whether maternal mineral reserves facilitate these requirements and no data exist from sub-Saharan Africa. The aim was to determine skeletal changes with peripheral quantitative computed tomography (pQCT) and bone biochemistry between early second and third trimesters. Pregnant rural Gambians aged 18 to 45 years (n=467) participating in a trial of antenatal nutritional supplements (ISRCTN49285450) had pQCT scans and blood collections at mean (SD) 14 (3) and 31 (1) weeks' gestation. Outcomes were pQCT: radius/tibia 4% total volumetric bone mineral density (vBMD), trabecular vBMD, total cross-sectional area (CSA), 33%/38% radius/tibia cortical vBMD, bone mineral content (BMC), total CSA; biochemistry: collagen type 1 cross-linked β-C-telopeptide (β-CTX), type 1 procollagen N-terminal (P1NP), parathyroid hormone (PTH), and 1,25(OH)2 D. Independent t tests tested whether pooled or within-group changes differed from 0. Multiple regression was performed adjusting for age. Data for change are expressed as mean (confidence interval [CI] 2.5, 97.5%). Radius trabecular vBMD, cortical vBMD, and BMC increased by 1.15 (0.55, 1.75)%, 0.41 (0.24, 0.58)%, and 0.47 (0.25, 0.69)%. Tibia total and trabecular vBMD increased by 0.34 (0.15, 0.54)% and 0.46 (0.17, 0.74)%, while tibia cortical vBMD, BMC, and cortical CSA increased by 0.35 (0.26, 0.44)%, 0.55 (0.41, 0.68)% and 0.20 (0.09, 0.31)%, respectively. CTX, PTH, and 1,25(OH)2 D increased by 23.0 (15.09, 29.29)%, 13.2 (8.44, 19.34)%, and 21.0 (17.67, 24.29)%, while P1NP decreased by 32.4 (-37.19, -28.17)%. No evidence of mobilization was observed in the peripheral skeleton. Resorption, although higher in late versus early gestation, was lower throughout pregnancy compared with non-pregnant non-lactating (NPNL) in the same community. Formation was lower in late pregnancy than in early, and below NPNL levels. This suggests a shift in the ratio of resorption to formation. Despite some evidence of change in bone metabolism, in this population, with habitually low Ca intakes, the peripheral skeleton was not mobilized as a Ca source for the fetus. © 2021 crown copyright . Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR). The article published with the permission of the Controller of HMSO and the Queen's Printer of Scotland..

Associations of fluoride intake with children's cortical bone mineral and strength measures at age 11.

There is strong affinity between fluoride and calcium, and mineralized tissues. Investigations of fluoride and bone health during childhood and adolescence show inconsistent results. This analysis assessed associations between period-specific and cumulative fluoride intakes from birth to age 11, and age 11 cortical bone measures obtained using peripheral quantitative computed tomography (pQCT) of the radius and tibia (n = 424). Participants were a cohort recruited from eight Iowa hospitals at birth. Fluoride intakes from water, other beverages, selected foods, dietary supplements, and dentifrice were recorded every 1.5-6 months using detailed questionnaires. Correlations between bone measures (cortical bone mineral content, density, area, and strength) and fluoride intake were determined in bivariate and multivariable analyses adjusting for Tanner stage, weight and height. The majority of associations were weak. For boys, only the positive associations between daily fluoride intakes for 0-3 years and radius and tibia bone mineral content were statistically significant. For girls, the negative correlations of recent daily fluoride intake per kg of body weight from 8.5 to 11 years with radius bone mineral content, area, and strength and tibia strength were statistically significant. No associations between cumulative daily fluoride intakes from birth to 11 years and bone measures were statistically significant. In this cohort of 11-year-old children, mostly living in optimally fluoridated areas, life-long fluoride intakes from combined sources were weakly associated with tibia and radius cortical pQCT measures.

Bone Health is Maintained, While Fat Mass is Reduced in Pre-pubertal Children with Obesity Participating in a 1-Year Family-Centered Lifestyle Intervention.

Diet and physical activity (PA) influence bone health in children. This study tested whether increasing milk and milk products and weight-bearing types of PA favorably changed bone outcomes assessed by dual-energy X-ray absorptiometry (DXA) and bone biomarkers in children with obesity participating in a 1-year family-centered lifestyle intervention. Children were randomized to one of three groups: Control (Ctrl; no intervention), Standard treatment (StnTx: two servings milk and milk products/day; meet PA guidelines plus weight-bearing PA three times/week), or Modified treatment (ModTx: four servings milk and milk products/day; meet PA guidelines plus daily weight-bearing PA). Baseline and 12-month measurements included DXA scans for whole body (WB), lumbar spine (LS), lumbar lateral spine (LLS), and ultra-distal (UD) ulna+radius for bone mineral content (BMC), areal bone mineral density (aBMD) and BMD z-scores. Fat mass index (FMI), fat-free mass index (FFMI), and biomarkers of bone metabolism were assessed. Seventy-eight children 6-8years old were recruited (mean body mass index for-age z-score: 3.3±1.2). Compared to baseline, all groups increased BMC of WB, LS, and LLS (p<0.001), whereas only StnTx increased UD ulna+radius BMC at 12 months (p<0.05). At 12 months, WB-BMD z-scores were significantly lower in Ctrl (p<0.05), whereas WB and LLS aBMD increased in StnTx and ModTx (p<0.001) but not in Ctrl. All groups increased FFMI (p<0.001), while only Ctrl increased FMI (p<0.001). Bone biomarkers did not change over time. Participating in a family-centered lifestyle intervention based on Canadian diet and PA guidelines maintained bone health in obese children.

The Influence of Organized Physical Activity (Including Gymnastics) on Young Adult Skeletal Traits: Is Maturity Phase Important?

We prospectively evaluated adolescent organized physical activity (PA) as a factor in adult female bone traits. Annual DXA scans accompanied semiannual records of anthropometry, maturity, and PA for 42 participants in this preliminary analysis (criteria: appropriately timed DXA scans at ~1 year premenarche [predictor] and ~5 years postmenarche [dependent variable]). Regression analysis evaluated total adolescent interscan PA and PA over 3 maturity subphases as predictors of young adult bone outcomes: 1) bone mineral content (BMC), geometry, and strength indices at nondominant distal radius and femoral neck; 2) subhead BMC; 3) lumbar spine BMC. Analyses accounted for baseline gynecological age (years pre- or postmenarche), baseline bone status, adult body size and interscan body size change. Gymnastics training was evaluated as a potentially independent predictor, but did not improve models for any outcomes (p > .07). Premenarcheal bone traits were strong predictors of most adult outcomes (semipartial r2 = .21-0.59, p ≤ .001). Adult 1/3 radius and subhead BMC were predicted by both total PA and PA 1-3 years postmenarche (p < .03). PA 3-5 years postmenarche predicted femoral narrow neck width, endosteal diameter, and buckling ratio (p < .05). Thus, participation in organized physical activity programs throughout middle and high school may reduce lifetime fracture risk in females.

The associations of serum serotonin with bone traits are age- and gender-specific.

ContextSerotonin plays a potential role in bone metabolism, but the nature and extent of this relationship is unclear and human studies directly addressing the skeletal effect of circulating serotonin are rare.ObjectiveThe study aimed to investigate the associations between serum serotonin and bone traits at multiple skeletal sites in women and men.Subjects and MethodsSubjects were part of the CALEX-family study and comprised 235 young women, 121 premenopausal women, 124 postmenopausal women, and 168 men. Body composition was assessed using DXA, as was areal bone mineral density (aBMD) of spine, femur and whole body. In addition, pQCT was used to determine bone properties at tibial midshaft and distal radius. Fasting serum serotonin concentration was assessed using a competitive enzyme-linked immunosorbent assay.ResultsSerum serotonin declined with advancing age both in females and males (all p<0.01). Serotonin was negatively correlated with weight, BMI, lean and fat mass in women (r = −0.22 to −0.39, all p<0.001), but positively with height and lean mass in men (all p<0.01). In the premenopausal women, serotonin was negatively correlated with lumbar spine aBMD (r = −0.23, p<0.05) but the statistical significance disappeared after adjustment for weight. Conversely, in postmenopausal women, serotonin was positively correlated with whole body and femur aBMD, as well as with distal radius bone mineral content and volumetric BMD (r = 0.20 to 0.30, all p<0.05), and these associations remained significant after adjustment for weight. In men, no significant associations were found between serotonin and bone traits.ConclusionSerum serotonin is positively associated with bone traits in postmenopausal women, but not in premenopausal women or men. This partially supports the idea of circulating serotonin playing a role in the regulation of bone metabolism, but also indicates the importance of gender and age specific factors.

Effects of age and starting age upon side asymmetry in the arms of veteran tennis players: a cross-sectional study

While tennis playing results in large bone strength benefits in the racquet arm of young players, the effects of tennis playing in old players have not been investigated. Large side asymmetries in bone strength were found in veteran players, which were more pronounced in men, younger players and childhood starters. Regular tennis results in large racquet arm bone and muscle strength advantages; however, these effects have not been studied in old players. The non-racquet arm can act as an internal control for the exercising racquet arm without confounding factors, e.g. genotype. Therefore, veteran tennis player side asymmetries were examined to investigate age, sex and starting age effects on bone exercise benefits. Peripheral quantitative computed tomography (pQCT) scans were taken at the radius, ulna and humerus mid-shaft and distal radius in both arms of 88 tennis players (51 males, 37 females; mean age 63.8 ± 11.8 years). Thirty-two players began playing in adulthood, thereby termed 'old starters'; players were otherwise termed 'young starters'. Muscle size and bone strength were greater in the racquet arm; notably, distal radius bone mineral content (BMC) was 13 ± 10% higher and humeral bone area 23 ± 12% larger (both P < 0.001). Epiphyseal BMC asymmetry was not affected by age (P = 0.863) or sex (P = 0.954), but diaphyseal asymmetries were less pronounced in older players and women, particularly in the humerus where BMC, area and moment of resistance asymmetries were 28-34 % less in women (P < 0.01). Bone area and periosteal circumference asymmetries were smaller in old starters (all P < 0.01); most notably, no distal radius asymmetry was found in this group (0.4 ± 3.4%). Tennis participation is associated with large side asymmetries in muscle and bone strength in old age. Larger relative side asymmetries in men, younger players and young starters suggest a greater potential for exercise benefits to bone in these groups.

Calcium intake of rural Gambian infants: a quantitative study of the relative contributions of breast milk and complementary foods at 3 and 12 months of age.

BACKGROUND/OBJECTIVES:There is a paucity of information from developing countries on total calcium intake during infancy, and potential consequences for growth and bone development.DESIGN:Observational longitudinal study of rural Gambian infants (13 males and 17 females) at 3 and 12 months of age.SUBJECTS/METHODS:Breast-milk intake and calcium concentration, weighed dietary intake, anthropometry, midshaft radius bone mineral content (BMC) and bone width (BW).RESULTS:At 3 and 12 months (mean±s.d.) calcium intake from breast milk was 179±53 and 117±38, and from other foods 12±38 and 73±105 mg/day. There was no difference in total calcium intake; 94% and 62% of calcium came from breast milk. At 3 and 12 months, weight s.d.-scores were −0.441±1.07 and −1.967±1.06; length s.d.-scores were −0.511±1.04 and −1.469±1.13. Breast-milk calcium intake positively predicted weight (P=0.0002, P⩽0.0001) and length (P=0.056, P=0.001). These relationships were not independent of breast-milk intake, which positively predicted weight (P⩽0.002) and length (P=0.06, P=0.004). At 3, but not 12 months, weight and length correlated with total calcium intake. There were no relationships between total calcium intake and breast-milk intake with BW or BMC.CONCLUSION:The combination of low calcium intake from breast milk and complementary foods resulted in a low total calcium intake close to the estimated biological requirement for bone mineral accretion. Relationships between calcium intake and growth were largely accounted for by breast-milk intake, suggesting that low calcium intake per se was not the limiting factor in the poor growth. These findings have potential implications for deriving calcium requirements in developing countries.

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

PurposeWe 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). MethodsSubjects 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. ResultsAt 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). ConclusionsMaturity-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.

Unilateral Ön Kol Vibrasyonu Uygulanan Olgularda Radius Kemik Yoğunluğunun Kontralateral El Bilek Fleksör İstirahat Kas Elektriksel Aktivitesi Üzerine Etkisi

Objective: To investigate whether bone mineral density or bone mineral content of the ultradistal radius has any effect on the resting muscle activity of contralateral wrist flexor muscles during unilateral forearm vibration. Material and Methods: Ninety healthy adult volunteers (33 women, 57 men) were included in this study. The mean age of participants was 34.2 (20-52) years. The right forearm was exposed to vibration for 1 minute. The frequency of vibration was 46 Hz. The resting myoelectrical activities of the right and left wrist flexor muscles were simultaneously measured by surface electromyography before, during and after vibration. The right ultradistal radius bone mineral density and bone mineral content were measured by dual-energy X-ray absorbtiometry. Results: The resting myoelectrical activity of the left wrist flexor muscles significantly increased during vibration (from 2.0±0.8 microvolts to 4.5±2.2 microvolts, p=0.0001). It decreased to 1.8±0.9 microvolts after vibration (p=0.0001). Multiple linear regression analysis revealed that the right ultradistal radius bone mineral density was an independent predictor of the resting myoelectrical activity of the left wrist flexor muscles measured during vibration. However, age, gender, body mass index, the right ultradistal radius bone mineral content and, the right and left wrist flexor muscles' resting myoelectrical activity measured before vibration were not predictors (R2=0.772, F=301.8, p = 0.0001). Conclusion: It is suggested that the ultradistal radius bone may affect the resting myoelectrical activities in the contralateral wrist flexor muscles, based on its bone mineral density during unilateral forearm vibration.

Whole Body Vibration Increases Hip Bone Mineral Density in Well-Trained Cyclists

Road cycling, a non-weight bearing endurance activity is associated with lower than expected bone mineral density (BMD) in its participants.Whole body vibration (WBV) has been shown to have therapeutic potential in increasing BMD in groups who have an elevated risk of fracture, yet the effects of WBV training have not been examined in road cyclists. PURPOSE: To determine the effects of ten weeks of WBV training, on the bone health in a group of well-trained road cyclists. METHODS: Nineteen road cyclists were randomly assigned to either a WBV training intervention (n=11), three times per week, ten minutes per session, for ten weeks, or a control cycling group (n=8) who did not add WBV to their training. Both groups continued with their normal cycling training during the study period. The cyclists were matched for age, height and weight with 19 sedentary subjects. At baseline, all participants underwent Dual X-ray Absorptiometry scans to measure site specific and regional BMD, bone mineral content (BMC) and lean and fat tissue; calcium intake and training history (for 19 cyclists) were also assessed. All cyclists were reassessed after ten weeks of training. RESULTS: At baseline, cyclists had lower hip (0.76±0.19 vs. 1.00±0.61g.cm-2, p<0.0001), pelvis (1.18±0.16 vs. 1.65±0.57 g.cm-2, p=0.002) and higher head BMD (2.41±0.41 vs. 1.82±0. 60g.cm-2, p=0.001) than sedentary control subjects. After the ten week WBV intervention, hip BMD increased significantly in the vibration cycling group (0.67±0.12 to 0.97±0.11 g.cm-2, p<0.0001) but not in the cycling control group. Ulna BMC (6.87±1.22g to 6.95 ± 1.23g, p=0.04) and radius BMC (10.37±1.70 to 10.52±1.70g, p=0.006) increased significantly in the vibration cycling group, but not in the control cyclists. CONCLUSION: Ten weeks of WBV training offers an intermittent alteration of force, displacement and acceleration and increases hip BMD and forearm BMC in road cyclists who have lower than normal bone mass and an increased fracture risk because of their greater risk of falling consequent to the nature of their sport.

Bone Mass and Bone Size in Pre- or Early Pubertal 10-Year-Old Black and White South African Children and Their Parents

Genetic factors are thought to maintain bone mass in socioeconomically disadvantaged black South Africans. We compared bone mass between environmentally disadvantaged black and advantaged white children and their parents, after determining the most appropriate method by which to correct bone mineral content (BMC) for size. We collected data from 419 healthy black and white children of mean age 10.6 years (range 10.0-10.9), 406 biological mothers, and 100 biological fathers. Whole-body, femoral neck, lumbar spine, and mid- and distal one-third of radius bone area (BA) and BMC were measured by dual-energy X-ray absorptiometry. Power coefficients (PCs) were calculated from the linear-regression analyses of ln(BMC) on ln(BA) and used to correct site-specific BMC for bone size differences. Heritability (½h(2), %) by maternal and paternal descent was estimated by regressing children's Z scores on parents' Z scores. Correcting BMC for height, weight, and BA(PC) accounted for the greatest variance of BMC at all skeletal sites. In so doing, BMC in blacks was up to 2.6 times greater at the femoral neck and lumbar spine. Maternal and paternal heritability was estimated to be ~30% in both black and white subjects. These results may in part explain the lower prevalence of fragility fractures at the hip in black South African children when compared to whites. Heritability was comparable between environmentally disadvantaged black and advantaged white South African children and similar to that reported for Caucasians in other parts of the world.

Sustained skeletal benefit from childhood mechanical loading

Preliminary prospective, longitudinal results suggest that pre-menarcheal exposure to artistic gymnastics is associated with greater radius BMC, aBMD, and projected area throughout growth and into early adulthood, more than 4 years after activity cessation. Any loss of benefit associated with de-training appears to be temporary. Mechanical loading may enhance bone accrual during growth, but prospective evidence of benefit retention is limited. This prospective, longitudinal cohort study tests whether gymnastics is linked to distal radius advantages during growth and four or more years post-training cessation. Semi-annually, female ex/gymnasts and non-gymnasts underwent height and weight measurements; questionnaires assessed calcium intake, physical activity, and maturation. Annual dual energy X-ray absorptiometry scans (Hologic QDR 4500W) measured total body fat-free mass, skull areal density (aBMD), and bone mineral content (BMC); forearm scans measured ultradistal and 1/3 radius area, BMC, and aBMD. Analysis inclusion criteria were: (1) achievement of gynecological age >4 years and (2) for gymnasts, >2 years of pre-menarcheal training (>6 h/week), ceasing between 0.5 year pre-menarche and 1 year post-menarche. Hierarchical linear modeling (HLM v6.0) evaluated outcomes for ex/gymnasts versus non-gymnasts; a slope/intercept discontinuity evaluated de-training effects. Data from 14 non-gymnasts and six ex/gymnasts represented outcomes from 4 years pre-menarche to 9 years post-menarche. All adjusted distal radius parameters were higher in ex/gymnasts than non-gymnasts (p < 0.02). Ultradistal BMC, ultradistal aBMD, and 1/3 aBMD temporarily decreased with gymnastic cessation (p < 0.04); ultradistal area, 1/3 area, and 1/3 BMC did not change significantly. Skull outcomes did not differ between groups or change with activity cessation. Gymnastic exposure during childhood and early puberty is associated with greater radius bone mass, size, and aBMD. Despite brief de-training losses in density and mass, significant skeletal benefits are manifested throughout growth and at least 4 years beyond activity cessation into early adulthood.

The muscle–bone unit of peripheral and central skeletal sites in children and young adults

Changes and gender differences in the muscle bone unit at different skeletal sites were investigated during pubertal development. Females accrued greater BMC in relation to muscle compared to males; these gender differences were greater after adjustment for height and regional fat mass. To describe changes and gender differences in the muscle-bone unit at different skeletal sites during pubertal development. Four hundred forty-two children aged 5-18years were studied. Measurements of bone mineral content (BMC), lean mass (LM) and fat mass of the whole body (WB), legs, arms and lumbar spine were obtained from dual-energy X-ray absorptiometry. Peripheral quantitative computed tomography was used to measure BMC of the radius diaphysis and cross-sectional muscle area (CSMA) of the mid-forearm. These measurements were used to describe differences between, and within, genders at each pubertal stage in BMC accrual relative to muscle, both before and after adjustment for height, regional fat and muscle at central and peripheral skeletal sites. In males, there were significant increases in adjusted WB and leg BMC at the end of pubertal development. Unadjusted and adjusted lumbar spine BMC increased at the onset of, and at the end, of puberty. Radius BMC increased at most pubertal stages. In females, there were increases in unadjusted and adjusted whole body BMC at late puberty, in leg BMC at the onset of puberty and at pubertal stage four. Unadjusted arm BMC increased at most pubertal stages; however, after adjustment, an increase occurred at pubertal stage four. Both adjusted and unadjusted lumbar spine BMC increased at pubertal stage four. Unadjusted radius BMC increased at most pubertal stages. Females had greater BMC at all skeletal sites, compared to males, except at the radius, where adjusted BMC was greater in males at pubertal stage four. Males and females accrue more BMC in relation to lean mass at multiple skeletal sites as puberty proceeds. Females accrue more BMC in relation to lean mass, in comparison to males, at most skeletal sites.

Habitual Site-Specific Upper Extremity Loading is Associated with Increased Bone Mineral of the Ultradistal Radius in Young Women

Osteoporosis and osteopenia are major contributors to the high incidence of fractures in older women. Habitual loading plays a crucial role in the acquisition and maintenance of bone. It may be possible to develop clinical interventions based on targeted modes of physical loading that can improve bone health and reduce fractures in women. If so, an important first step is determining the degree to which common fracture sites, such as the distal radius are responsive to habitual loading. The bone mineral density (BMD) and bone mineral content (BMC) of the ultradistal radius of 15 female gymnasts were compared with those of an age-matched, mass-matched, and height-matched control group. The hypothesis that the ultradistal radius BMD and BMC in gymnasts would be higher than those of the control group was tested using a 2 x 2 (left/right x group) repeated measures analysis of variance (MANOVA). After adjusting for the between-group difference in the influence of body mass, the gymnasts had 24% larger BMD and a 34% larger BMC at the ultradistal radii than the control group (p < 0.001). These results suggest that the ultradistal radius is responsive to the types and magnitudes of load encountered during gymnastics. A responsive distal radius is a necessary prerequisite to the development of loading-based interventions to increase ultradistal radius bone quality. Such interventions have the potential to significantly increase distal radius strength, thereby reducing the incidence of fracture.

Skeletal differences in bone mineral area and content before and after cure of endogenous Cushing’s syndrome

We examined bone densitometric data in a four-year follow-up period before and after the cure of CS. Plasma cortisol concentrations were similar, but the duration of estimated glucocorticoid excess was longer in patients with prevalent bone fractures compared to those without fractures. After therapy of CS, bone area, BMC and BMD increased significantly at the LS and femur during follow-up, but they decreased at the forearm, suggesting redistribution of bone minerals from the peripheral to the axial skeleton. Only a few studies report the changes in bone mineral density (BMD) after the cure of Cushing's syndrome (CS). Forty-one patients with Cushing's disease, 21 patients with adrenal CS and 6 patients with ectopic CS were prospectively enrolled. BMD, bone mineral content (BMC) and bone area were measured by DXA. No significant correlations were found between serum cortisol concentrations and baseline bone densitometric data. After successful therapy of CS, bone area and BMD increased significantly at the lumbar spine (LS) and femur during follow-up, but they decreased at the forearm. The progressive increase in BMC at the LS had a significant negative correlation with the change of the BMC of radius in the first and second follow-up years. The change in the body mass index was an independent predictor for changes in BMC both at the LS and at the forearm at the second year of remission. The regional differences and the time-dependent changes of BMC suggest that the source of marked increase in axial BMC after the cure of CS is, at least partly, due to the redistribution of bone minerals from the peripheral to the axial skeleton.