Significant Predictor Of Bone Mineral Density Research Articles

Determinants of bone mineral density in various regions of the skeleton among smokers and non-smokers: the role of physical activity.

The adult human skeleton is composed of cortical and cancellous bone. The proportions of these two types of bone tissue differ in various parts of the skeleton. The aim of this cross-sectional study was to quantify the determinants of bone mineral density (BMD) and bone mineral content in various regions of interest (ROIs) in smokers and never-smokers. In this study, 4,332 bone scans of three regions of interest (ROIs) were analyzed: the forearm (distal and proximal), femur, and lumbar spine. Body composition and bone parameters were measured using dual-energy X-ray absorptiometry. Smoking was measured using the Global Adult Tobacco Survey questionnaire. Body mass index (BMI) was calculated, and physical activity (PA) was characterized by the metabolic equivalent of task (MET). Among women, the interaction between PA (positive β coefficient) and smoking (negative β coefficient) was a significant predictor of BMD in the distal and proximal forearm (adj. R2 = 0.40 and R2 = 0.58; p < 0.001). The interaction of three variables-age, smoking (negative β), and MET (positive β)-was significant for total hip BMD (adj. R2 = 0.54; p < 0.001). The interaction between BMI and MET (positive β) and smoking (negative β) was significant for BMD in the lumbar spine (adj. R2 = 0.62; p < 0.001). In men, the interaction between MET (positive β) and smoking (negative β) was significant for BMD in the forearm and lumbar spine (adj. R2 = 0.44, R2 = 0.46, and R2 = 0.49; p < 0.01). Smoking alone was a significant negative predictor of total hip BMD (adj. R2 = 0.34; p < 0.001). Among both women and men, never-smokers had significantly better bone parameters than smokers. Smoking was a significant negative predictor for BMD in the various ROIs in both women and men. Physical activity was a significant positive predictor of BMD, with a strong association with bone parameters.

Evaluation of bone metabolism in children with cystic fibrosis.

Cystic fibrosis (CF) bone disease (CFBD) has attracted considerable recent interest from researchers, although several aspects of CFBD pathophysiology remain poorly understood. The objective of this research was to investigate CFBD in children with CF and its relation to clinical and bone metabolism markers. In a prospective observational study of 68 patients with CF and 63 healthy controls, we studied bone turnover biomarkers and bone mineral density (BMD). The biomarkers included osteocalcin, total-alkaline phosphatase, bone-alkaline phosphatase, N-terminal propeptide of type-1-procollagen, osteoprotegerin (OPG), interleukine-6, tumor necrosis factor alpha (TNF-α), type-1-collagen cross-linked C-telopeptide (CTX), parathormone (PTH), 25-vitamin D, 1,25-vitamin D, calcium and phosphorus. BMD was examined in lumbar spine, comparing two healthy Spanish populations. Two regression analyses were applied to any significant associations to evaluate predictors of BMD and of CF, expressed as odds ratios (OR) with 95% confidence intervals. After adjusting for age, sex, and height Z-score, gains in BMD LS in children and adolescents (6-16years) with CF were not less than in healthy reference population. Patients with CF showed significant associations with different bone turnover biomarkers. Age, gender, body mass index, PTH, CTX and OPG were significant predictors of BMD (R2=0.866, p<0,001). Moreover, we found that PTH (OR=1.070; 95% CI 1.019-1.123), and TNFα (OR=2.173; 95% CI 1.514-3.118) were significantly linked to CF, and calcium (OR=0.115; 95% CI 0.025-0.524), 1,25-vitamin D (OR=0.979; 95% CI 0.962 0.996) and OPG (OR=0.189; 95% CI 0.073-0.489) were significant reduced. A normal bone mineral density along with altered remodeling was found in CF patients with a normal nutritional status and without acute lung disease.

Pectoralis muscle area is associated with bone mineral density and lung function in lung transplant candidates

Sarcopenia and osteoporosis are associated with aging and chronic illnesses and may be linked in patients with advanced lung disease. Pectoralis muscle index (PMI) quantitated on computed tomography (CT) of the chest can be used to measure skeletal muscle mass. This study aimed to determine the relationship of PMI to clinical parameters including bone mineral density (BMD) in candidates for lung transplantation. A retrospective review of transplant candidates at a single center was performed. Demographic, anthropomorphic, and clinical data were recorded. Pectoralis muscle area (PMA) was determined on an axial slice from a chest CT. PMI was calculated as the PMA divided by height squared. BMD was obtained from routine dual-energy X-ray absorptiometry (DXA) scan. In 226 included patients, mean PMI was 8.2 ± 3.0cm2/m2 in males and 6.1 ± 2.1cm2/m2 in females. Osteopenia was present in 44.4%, and 23.2% of patients had osteoporosis. Patients with obstructive lung disease had lower body mass index (22.0 ± 4.9 versus 27.9 ± 4.9kg/m2, p < 0.001), PMI (6.0 ± 2.3 versus 8.2 ± 2.8cm2/m2, p < 0.001), and BMD (- 2.3 ± 1.1 versus - 1.3 ± 1.1, p < 0.001) compared with patients with restrictive lung disease. PMI was a significant predictor of BMD (β = 0.16, p < 0.001). The association between muscle area and BMD in lung transplant candidates suggests that similar mechanisms may underlie the development of both. Differences in PMI and BMD in patients with obstructive versus restrictive lung disease may result from differences in respiratory physiology or disease processes.

Statistical analysis of fat and muscle mass in osteoporosis in elderly population using total body DXA scans.

The magnitude of effects of lean mass and fat mass on bone health is controversial, and this study is a contribution to understand its effects on skeletal composition. We explored the relationship of body fat and muscle parameters with bone mineral density (BMD) and age and observed if it changed when matched with body mass index (BMI) of the same study subjects. One-hundred sixty-four community dwelling, ambulatory elderly attending the osteoporosis services of a Dublin hospital was recruited. Out of these, 158 female patients had a total body DXA scan, and their body composition outcomes were included in this analysis. The relationship between body fat and muscle composition and BMD at all sites was determined and also matched by BMI. Total-Body BMD had a strong positive correlation with lean mass(r= 0.492, p 0.00) and fat mass(r= 0.414, p 0.00), though lean mass remained the strongest predictor of BMD at all sites. Increasing BMI categorically had a positive effect on both lean mass and fat mass. Increasing age was significantly associated with an increase in fat mass(r= 2.40, p 0.00) and a decrease in muscle mass(r= 0.478, p 0.01). Both lean mass and fat mass are significant predictors of BMD. To preserve BMD maintenance or increase of lean mass is more effective than fat mass. BMI correlates well with body composition; however, we recommend the use of direct measures of body fat and muscle to make this relation more interpretable. Total Body DXA is a readily available diagnostic tool which provides high-valued information about body composition.

Clinical and body composition predictors of bone turnover and mineral content in obese postmenopausal women.

The purpose of this study was to determine the predictors of bone mineral density (BMD), bone mineral content (BMC), and bone turnover markers in obese postmenopausal women. In this cross-sectional study, 81 postmenopausal women aged 58.40 ± 6.08years were analyzed. Anthropometric parameters were recorded. Serum glucose parameters, serum lipid profiles, adipokines, renal, hepatic parameters, and bone markers concentrations were determined by well-validated laboratory routine methods. BMD, BMC, and body composition were measured by Dual X-ray Absorptiometry. We found a significant correlation of BMD with age, years since menopause, anthropometric parameters, glycemia, alkaline phosphatase, fat mass, and lean mass. Multiple regression analysis demonstrated that years since menopause, waist circumference, alkaline phosphatase, trunk fat, and lean mass were independently associated to BMD. Also, age, years since menopause, anthropometric parameters, total cholesterol, alkaline phosphatase, fat mass, and lean mass were correlated to BMC. However, only waist circumference and trunk fat were independently related to BMC. Bone turnover markers were significantly correlated to the age, glycemia, HbA1c, adipokines, hepatic parameters, and lean mass. Nevertheless, only adipokines, gamma glutamyl transferase (GGT), and alkaline phosphatase were independently associated to bone turnover markers. These observations suggest that number of years since menopause, waist circumference, alkaline phosphatase, trunk fat, and lean mass were the only significant predictors of BMD. However, waist circumference seems to be a stronger predictor than trunk fat for BMC. Moreover, adiponectin, resistin, GGT, and alkaline phosphatase were significant predictors of the bone resorption (CTX-I) and the bone formation (P1NP) markers.

Relative Contributions of Lean and Fat Mass to Bone Mineral Density: Insight From Prader-Willi Syndrome.

Context: Low bone mineral density (BMD) is the most important risk factor for fragility fracture. Body weight is a simple screening predictor of difference in BMD between individuals. However, it is not clear which component of body weight, lean (LM), or fat mass (FM), is associated with BMD. People with the genetic disorder of Prader-Willi syndrome (PWS) uniquely have a reduced LM despite increased FM.Objective: We sought to define the individual impact of LM and FM on BMD by investigating subjects with and without PWS.Design, Setting and Participants: This cross-sectional study was conducted at the Clinical Research Facility of the Garvan Institute of Medical Research, with PWS and control participants recruited from a specialized PWS clinic and from the general public by advertisement, respectively. The study involved 11 adults with PWS, who were age- and sex-matched with 12 obese individuals (Obese group) and 10 lean individuals (Lean group).Main Outcome Measures: Whole body BMD was measured by dual-energy X-ray absorptiometry. Total body FM and LM were derived from the whole body scan. Differences in BMD between groups were assessed by the analysis of covariance model, taking into account the effects of LM and FM.Results: The PWS group had significantly shorter height than the lean and obese groups. As expected, there was no significant difference in FM between the Obese and PWS group, and no significant difference in LM between the Lean and PWS group. However, obese individuals had greater LM than lean individuals. BMD in lean individuals was significantly lower than in PWS individuals (1.13 g/cm2 vs. 1.21 g/cm2, p < 0.05) and obese individuals (1.13 g/cm2 vs. 1.25 g/cm2, p < 0.05). After adjusting for both LM and FM, there was no significant difference in BMD between groups, and the only significant predictor of BMD was LM.Conclusions: These data from the human genetic model Prader-Willi syndrome suggest that LM is a stronger determinant of BMD than fat mass.

Bone Mineral Density In Patients With Addison Disease On Replacement Therapy With Prednisolone

In primary adrenal insufficiency (PAI), replacement with prednisolone may result in lower bone mineral density (BMD) compared with hydrocortisone therapy. However, the number of patients studied on prednisolone is small and the results are conflicting. We conducted a cross-sectional study to determine BMD and its relation with therapy in patients on physiologic doses of prednisolone replacement. Forty-one consecutive patients (31 males, age [mean ± SD] 50.9 ± 13.0 years), receiving prednisolone (hydrocortisone equivalent [HCE] 13.0 ± 3.0 mg/m(2)) for 104 ± 95 months were studied. BMD was evaluated by dual-energy X-ray absorptiometry and compared with an age- and sex-matched reference group of healthy Indian subjects (n = 677). Among males, BMD Z-scores (mean [95% confidence interval {CI}]) at lumbar spine (-0.42 [-0.80, -0.04]), femoral neck (-0.50 [-0.95, -0.06]) and total hip (-0.58 [-0.90, -0.26]) were significantly lower than the reference population. Z-scores in female patients did not differ from controls. Among postmenopausal females and males >50 years, 43% had osteoporosis (T-score ≤-2.5), as compared with 25% in the reference group (P = .04). There was no correlation between BMD Z-scores and HCE dose or duration of therapy. On multivariate regression analysis, body mass index was the only significant predictor of BMD. A high proportion of males (45%) had low serum testosterone (<300 ng/dL), but there was no correlation between testosterone and BMD. Male patients with PAI receiving physiologic prednisolone replacement had a small but significant diminution in BMD at all sites.

Non-linear pattern of age-specific bone mineral density and related factors in women: data from the 5th Korea National Health and Nutrition Examination Survey.

Age-specific bone mineral density (BMD) of Korean women showed a nonlinear pattern. According to our study, this pattern could be mainly attributed to the nonlinear effects of body composition. Interventions targeting these factors in premenopausal women could be critical for achieving peak BMD. The patterns of age-specific bone mineral density (BMD) of femur and spine in women showed a non-unidirectional decrease, with ups and downs around the point of achieving peak BMD, that are not evident in men. We investigated the factors associated with these age-specific BMD in women using linear and nonlinear models. A total of 4681 women recruited during the 5th Korean National Health and Nutrition Examination Survey 2010-2011 (KNHANES V) were included. A range of related factors were considered including body compositional, reproductive, and socio-behavioral factors. Age-specific BMD was demonstrated using a generalized additive model (GAM) with smoothing spline transformation. Age, lean body mass, fat mass, and age at menarche were significant predictors of BMD in premenopausal women. The GAM plot of BMD according to age revealed two peaks for total femur, femoral neck, and lumbar spine. After adjustment for body compositional factors, the peaks flattened. In the full model, the pattern for lumbar spine showed a single peak around the mid-40s. The GAM showed a generally better performance than the linear model for BMD at all three sites. Reduced models that included only lean body mass and fat mass best explained the variance of BMD in GAMs. The BMD of Korean women in reproductive period could be largely attributed to the nonlinear effects of age and body compositional factors. Intervention targeting these factors could be critical for maintaining peak BMD.

Relationship of calf circumference with bone mineral density and hip geometry: a hospital-based cross-sectional study.

Calf circumference has significant predictive value for bone mineral density (BMD) at hip and spine and for fracture at spine in both genders and hence may be used as a clinical risk factor for fracture when BMD is not available. Lean muscle mass and higher regular physical ability has been shown to correlate with BMD and hip geometry. Calf circumference is an indicator of muscle mass. We examined the association of calf circumference (CC), thigh circumference (TC), and physical performances with BMD and hip geometry. Females above 45 years (at least 5 years postmenopausal) and males above 55 years were enrolled. Bilateral CC and TC were measured, and BMD was assessed at neck of femur (NF), trochanter (TR), inter-trochanter (IT), spine, and forearm. Dual energy X-ray absorptiometry scan-based hip geometry parameters were analyzed. One hundred sixteen subjects (29 males and 87 females) were enrolled. CC correlated significantly with BMD at NF, IT, TR, and spine in male and female, respectively, and at forearm in female. Multivariate regression analysis showed CC as a significant predictor of BMD (at TR, IT, NF, and spine in both genders) and fracture (at spine in both genders). CC had significant positive correlation with hip parameters-cross-sectional area; cortical thickness; and section modulus at NF, IT, and TR in both genders and negative correlation with buckling ratio at NF and IT in females. CC is a significant predictor of BMD at hip and spine and fracture at spine in both genders.

Higher Serum Insulin Concentrations Positively Influence the Bone Mineral Density in African American Adolescents.

Puberty is a developmental stage of increased insulin resistance that also is a critical period for bone mass accrual. Historically, African Americans (AA) have lesser risk for osteoporotic fractures compared to European Americans (EA). AA also have higher incidence of insulin resistance. The possibility that bone health and insulin secretion or concentrations are linked has not been investigated. We aimed to examine the associations of bone mineral density (BMD) and bone mineral apparent density (BMAD) with insulin sensitivity and secretion in healthy adolescent girls and healthy female adults and to evaluate ethnic differences in these associations. Observational cohort design. University of Alabama at Birmingham, between January 2010 and September 2011. Healthy, female, non-smoking adolescents and young adults (14-55 years) were enrolled in this observational cohort study. Adolescents had significantly higher fasting insulin (P=0.0002), insulin area under the curve [AUC] (P= 0.0004) and lower insulin sensitivity (P=0.0005) compared to adults. Among adolescents, AA race was significantly associated with BMD (β=0.086, P=0.01) and BMAD (β=0.0075, P=0.002); however, adjusting for insulin AUC explained this difference. Insulin AUC (β=0.0006, P=0.029) and fasting insulin (β=0.0005, P=0.01) were positively associated with BMAD only in AA adolescents. Insulin AUC and fasting insulin were not significant predictors of BMD for adults. The higher insulin concentration among AA adolescents is associated with increased BMD and higher BMAD.

Predictors of bone mineral density in a convenience sample of young Caucasian adults living in southern Ontario

Osteoporosis is a major public health concern in Canada and worldwide. Although much is known about bone health in older adults, little is known about bone health in young, healthy Canadian men and women. The objectives of this research were to describe bone mineral density (BMD) of young, healthy adults living in southern Ontario, Canada, and to identify predictors of BMD in this population. Two-hundred and fifty-eight Caucasian men and women aged 18-33 years completed health and physical activity questionnaires along with a calcium and vitamin D specific food frequency questionnaire. Height and mass were measured. BMD of the total hip, femoral neck, spine, and total body was measured using dual energy X-ray absorptiometry. Among men, body mass, weight-bearing physical activity, and calcium intake were significant predictors of BMD. Among women, body mass, calcium intake, and family history of osteoporosis significantly predicted log BMD. The predictors of BMD in young Canadian men and women identified in this study may inform the development of longitudinal studies designed to examine the influence of lifestyle factors on BMD in young adults.

Estradiol levels predict bone mineral density in male collegiate athletes: a pilot study

Strenuous training commonly results in amenorrhoea, which contributes to bone loss in some female collegiate athletes. However, the impact of athletic training on endocrine function and bone mineral density (BMD) in male collegiate athletes is less well understood. The objective of the study was to investigate the specific endocrine determinants of BMD in male collegiate runners and wrestlers, including the potential impact of gonadal steroid levels. Cross-sectional study. Twenty-six division I collegiate male athletes (wrestlers, runners and golfers). Main outcome measures included (i) BMD endpoints measured by dual energy x-ray absorptiometry (DXA); (ii) endocrine end-points: total and free oestradiol, total and free testosterone; (iii) body composition end-points: lean and fat mass, measured by DXA; and (iv) exercise end-points: maximal oxygen uptake (VO(2) max), number of miles run weekly and grip strength. Free and total oestradiol levels were important positive determinants of BMD. In contrast, total and free testosterone levels were not significant predictors of BMD at any skeletal site (except for free testosterone at the radius). In addition, lean body mass, % ideal body weight, total body weight, body mass index (BMI) and hours per week of resistance training were positive predictors of BMD. VO(2) max was a negative predictor of BMD. Mean BMD was higher at all skeletal sites in the wrestlers compared with the runners and a comparison group (golfers). Our data suggest that oestradiol levels, BMI, and resistance training are more important determinants of BMD in male collegiate athletes than testosterone.

Bone mineral density is not associated with homocysteine level, folate and vitamin B12 status

The relationship of homocysteine (Hcy), folate and vitamin B(12) with bone mineral density (BMD) has been studied in various populations but still remains inconsistent. The aim of this study was to test whether the levels of plasma Hcy, serum and red blood cell folate, and vitamin B(12) are related to BMD in the group of adult Croatian women regardless of menopausal status. Some other lifestyle and dietary habits like smoking, physical activity and alcohol consumption were also observed in relation to BMD. One-hundred and thirty-one women, aged 45-65 years participated in the study. BMD was measured using dual-energy X-ray absorptiometry. Measurements were made at the lumbar spine (L1-L4), left femoral neck, total femur and distal third of the radius. Plasma total Hcy, serum folate, red blood cell folate and serum vitamin B(12) were also determined. No significant correlations were found between Hcy, folate and/or vitamin B(12) and BMD of measured skeletal sites. Body mass index (BMI), age, as well as alcohol consumption were significantly correlated with BMD at the lumbar spine. Positive significant correlation was found between BMI and BMD at the femoral neck and total femur while BMI and age were significant predictors of BMD at the radius (multiple regression analysis). When only postmenopausal women were included, significant predictors of BMD at the lumbar spine were age, BMI, alcohol consumption and intake of hormone replacement therapy. Results of this study suggest that Hcy, folate or vitamin B(12) levels were not related to BMD in population of healthy Croatian women aged 45-65. In the group of postmenopausal Croatian women, beside BMI and age, alcohol consumption was significant positive predictor of BMD at the lumbar spine.

Contributions of lean mass and fat mass to bone mineral density: a study in postmenopausal women

BackgroundThe relative contribution of lean and fat to the determination of bone mineral density (BMD) in postmenopausal women is a contentious issue. The present study was undertaken to test the hypothesis that lean mass is a better determinant of BMD than fat mass.MethodsThis cross-sectional study involved 210 postmenopausal women of Vietnamese background, aged between 50 and 85 years, who were randomly sampled from various districts in Ho Chi Minh City (Vietnam). Whole body scans, femoral neck, and lumbar spine BMD were measured by DXA (QDR 4500, Hologic Inc., Waltham, MA). Lean mass (LM) and fat mass (FM) were derived from the whole body scan. Furthermore, lean mass index (LMi) and fat mass index (FMi) were calculated as ratio of LM or FM to body height in metre squared (m2).ResultsIn multiple linear regression analysis, both LM and FM were independent and significant predictors of BMD at the spine and femoral neck. Age, lean mass and fat mass collectively explained 33% variance of lumbar spine and 38% variance of femoral neck BMD. Replacing LM and FM by LMi and LMi did not alter the result. In both analyses, the influence of LM or LMi was greater than FM and FMi. Simulation analysis suggested that a study with 1000 individuals has a 78% chance of finding the significant effects of both LM and FM, and a 22% chance of finding LM alone significant, and zero chance of finding the effect of fat mass alone.ConclusionsThese data suggest that both lean mass and fat mass are important determinants of BMD. For a given body size -- measured either by lean mass or height --women with greater fat mass have greater BMD.

Reduced amylin levels are associated with low bone mineral density in women with anorexia nervosa

ContextAnorexia nervosa, characterized by extreme low body weight due to reduced nutrient intake, is associated with severe bone loss. Peptide hormones, including amylin, GIP, and GLP2, are released immediately after nutrient intake and may be involved in the regulation of bone turnover. ObjectiveTo investigate fasting levels of amylin, GIP, and GLP2 and their relationships with bone mineral density (BMD) in women with anorexia nervosa compared to healthy controls. DesignCross-sectional. SettingClinical Research Center. Study participants15 women with anorexia nervosa and 16 healthy controls. InterventionNone. Main outcome measuresFasting serum amylin, GIP, and GLP2, and BMD. ResultsWomen with anorexia nervosa had significantly lower fasting serum amylin and GIP levels than healthy controls. Fasting serum GLP2 levels were not significantly different between groups. Fasting amylin levels were positively associated with BMD and Z-score at the PA spine, total hip, and femoral neck. Fasting amylin levels were also positively associated with weight and percent fat; after controlling for these variables, amylin was still a significant predictor of BMD and Z-score at the femoral neck and of Z-score at the total hip. In the anorexia nervosa group, there was a trend toward an inverse association between amylin and C-terminal telopeptide (CTX) levels (R=−0.47, p=0.08). GIP and GLP2 levels did not predict BMD at any site. ConclusionDecreased secretion of amylin may be a mechanism through which reduced nutrient intake adversely affects BMD in anorexia nervosa.

Participation in High-Impact Sports Predicts Bone Mineral Density in Senior Olympic Athletes

Background:Loss of bone mineral density (BMD) and resultant fractures increase with age in both sexes. Participation in resistance or high-impact sports is a known contributor to bone health in young athletes; however, little is known about the effect of participation in impact sports on bone density as people age.Hypothesis:To test the hypothesis that high-impact sport participation will predict BMD in senior athletes, this study evaluated 560 athletes during the 2005 National Senior Games (the Senior Olympics).Study Design:Cross-sectional methods. The athletes completed a detailed health history questionnaire and underwent calcaneal quantitative ultrasound to measure BMD. Athletes were classified as participating in high impact sports (basketball, road race [running], track and field, triathalon, and volleyball) or non-high-impact sports. Stepwise linear regression was used to determine the influence of high-impact sports on BMD.Results:On average, participants were 65.9 years old (range, 50 to 93). There were 298 women (53.2%) and 289 men (51.6%) who participated in high-impact sports. Average body mass index was 25.6 ± 3.9. The quantitative ultrasound-generated T scores, a quantitative measure of BMD, averaged 0.4 ± 1.3 and −0.1 ± 1.4 for the high-impact and non-high-impact groups, respectively. After age, sex, obesity, and use of osteoporosis medication were controlled, participation in high-impact sports was a significant predictor of BMD (R2 change 3.2%, P < .001).Conclusions:This study represents the largest sample of BMD data in senior athletes to date. Senior participation in high-impact sports positively influenced bone health, even in the oldest athletes.Clinical Relevance:These data imply that high-impact exercise is a vital tool to maintain healthy BMD with active aging.

Lean Body Mass and Weight-Bearing Activity in the Prediction of Bone Mineral Density in Physically Active Men

Weight-bearing endurance activity and resistance exercise are recommended to help preserve bone health during adulthood. However, the effects of resistance training relative to those of weight-bearing endurance activity often are confounded by body weight and composition. The purpose of this study was to determine the effects of long-term running, cycling, and resistance training on whole-body and regional bone mineral density (BMD), adjusting for body weight and composition. Cyclists (CYCLE; n = 19), runners (RUN; n = 10), and resistance trained men (RT; n = 13) ages 19-45 years participated in this cross-sectional study. Current and lifetime bone loading was calculated using ground-reaction force values of the reported physical activities. Whole-body and regional BMD and body composition were assessed using dual X-ray absorptiometry. Bone turnover markers and hormones were measured in fasting serum samples. The RT athletes had significantly greater body weight, lean body mass (LBM), and fat mass than CYCLE and RUN athletes; percent body fat did not differ among groups. Unadjusted BMD at all sites was significantly greater in the RT compared with CYCLE and RUN. After adjusting for LBM, RUN had significantly greater spine BMD than CYCLE. Subjects' LBM was a significant predictor of BMD in RT and CYCLE but not in RUN, suggesting that high-impact activity may override the benefits of LBM on BMD. Current bone loading was positively associated with serum osteocalcin concentrations (r = 0.480, p = 0.002). In conclusion, the results of the present study demonstrate that long-term running and resistance training increase BMD compared with cycling. However, it seems that high-impact activities, such as running, have a greater positive effect on BMD than resistance training.

Abstract 4605: Increased Body Mass Index is Protective against Low Bone Mineral Density in Patients with Heart Failure

Patients with heart failure (HF) may be at greater risk for decreased bone mineral density (BMD) than similarly-aged healthy adults due to limited activity and medications. Being overweight or obese may protect against decreased BMD due to greater weight bearing and hormonal differences. However, these assumptions have never been tested. The purposes were to compare BMD between patients with HF and similarly-aged healthy adults, compare BMD among normal weight, overweight, and obese patients with HF, and determine whether body mass index (BMI) is a predictor of BMD in patients with HF. A total of 119 patients with HF (preserved or non-preserved systolic function, age = 61 ± 12 yrs, 61% NYHA Class III/IV) and 58 community-dwelling older adults free of cardiovascular disease (age = 70 ± 7 yrs) underwent total body dual-energy x-ray absorptiometry scans. Bone mineral density Z-scores (matched for sex, age, weight, and ethnicity) were compared between patients with HF and healthy elders. Patients with HF were divided into four BMI categories to compare differences in total body BMD by BMI. Multiple linear regression was used to test whether BMI predicted BMD in patients with HF after controlling for age, sex, and NYHA class. Patients with HF had lower total body area BMD Z-scores (0.32 ± 1.20) than the healthy elders (0.88 ± 1.30, p = 0.005). Within the HF group, those with a BMI &lt;25 kg/m 2 had lower total body BMD (1.13 ± 0.13 g/cm 2 ) compared to those with BMIs of 25–29.9 kg/m 2+ (1.24 ± 0.13 g/cm 2 , p = 0.002), 30 –34 kg/m 2+ (1.23 ± 0.12 g/cm 2 , p = 0.019), and &gt;34 kg/m 2 (1.26 ± 0.13 g/cm 2 , p &lt; 0.001). In the multiple linear regression, BMI was a significant predictor of BMD in patients with HF (β= 0.337, p &lt; 0.001), explaining an additional 11% of the variance beyond age, sex, and NYHA class (R 2 = 0.40, p &lt;0.001). These results suggest that while HF is associated with decreased BMD, being overweight or obese may be protective against low BMD. This may be another example of better outcomes in overweight and obese patients with HF. This research has received full or partial funding support from the American Heart Association, AHA Great Rivers Affiliate (Delaware, Kentucky, Ohio, Pennsylvania &amp; West Virginia).

Non-weight-bearing effect of trunk and peripheral fat mass on bone mineral density in pre- and post-menopausal women

Objective To investigate the non-weight-bearing effect of trunk fat mass (composed of visceral and subcutaneous fat mass) and peripheral fat mass (subcutaneous fat mass alone) on bone mineral density (BMD) in pre- and post-menopausal women. Methods The subjects were 412 pre-menopausal women, 20–50 years of age and 228 post-menopausal women, 50–75 years of age. Age, years since menopause (YSM), height, body weight, and body mass index were recorded. Trunk, peripheral (extremities), left arm (non-weight-bearing site), lean mass, and BMD were measured by dual-energy X-ray absorptiometry. Results In pre-menopausal women, the amount of trunk fat mass was 6.8 ± 4.1 kg, which was significantly lower than the amount of peripheral fat mass (11.6 ± 3.8 kg, p < 0.001). Although trunk fat mass was positively correlated with arm BMD on Pearson's correlation test, arm lean mass was the only significant predictor of BMD on multiple regression analysis. In post-menopausal women, the amount of trunk fat mass (8.7 ± 3.6 kg) was also significantly lower than the peripheral fat mass (10.3 ± 3.4 kg, p < 0.001). On multiple regression analysis, however, trunk fat mass, but not arm lean mass, was the significant predictor of BMD. In both groups, peripheral fat mass was not correlated with left arm BMD. Conclusion The effect of adipocyte-derived biochemical factors on BMD may differ with menopausal status and the sites of adipocyte deposition.

The Association Between Cysteine, Bone Turnover, and Low Bone Mass

With the identification of hyperhomocysteinemia as a risk factor for developing osteoporosis, the contribution of thiols metabolically linked with homocysteine (tHcy) may be of importance. Cysteine (Cys) is formed from tHcy and is involved in bone metabolism via incorporation into collagen and cysteine protease enzymes. We investigated the association of plasma Cys and related thiols, the bone turnover markers C-telopeptide (CTX) and procollagen type 1 N propeptide (P1NP) and folate and vitamin B(6) with calcaneal bone mineral density (BMD) in 328 postmenopausal British women grouped according to their BMD measurement. Subjects with low BMD had a significantly lower plasma Cys concentration (146.3 vs. 177.7 micromol/l, p < 0.0001), a significantly higher recent fracture rate (30.9% vs. 16.4%, p = 0.017), and a significantly higher percentage of current smokers (26.4% vs. 7.3%. p = 0.003) than those with normal BMD. Additionally, they had a significantly lower plasma Cys, and higher plasma tHcy and CTX, than those with osteopenia. In the whole population, Cys was significantly associated with BMD, weight, height, smoking habit, log creatinine, Cys-Gly, log tHcy, and log folate, but the significant positive association of Cys with BMD was maintained after correction for all other variables (r = 0.197, p = 0.003). After weight, Cys was the next most significant predictor of BMD in a stepwise multiple linear regression model. Our study suggests a significant association between plasma Cys and BMD. A reduced Cys concentration, possibly modulated by smoking, or reduced flux from tHcy, may lead to reduced availability for collagen formation. Increased osteoclast activation, possibly as a result of relative hyperhomocysteinemia, may lead to increased Cys utilization in cysteine proteases.