Concentric and eccentric isokinetic resistance training similarly increases muscular strength, fat-free soft tissue mass, and specific bone mineral measurements in young women

Summary Women participated in 5 months of unilateral concentric (n = 37) or eccentric (n = 33) isokinetic resistance training of the legs and arms. Limb muscular strength increased as did total body, leg, and arm fat-free soft tissue mass, total body BMC, hip BMD, and forearm BMC and BMD. Isokinetic training benefits bone mineral acquisition. Introduction and hypothesis Isokinetic resistance training (IRT) is osteogenic; however, it is not known if concentric or eccentric modalities of IRT produce differential effects on bone. We tested our hypothesis that high-load eccentric versus concentric mode of IRT would produce greater increases in muscular strength, fat-free soft tissue mass (FFSTM), bone mineral density (BMD) and content (BMC) in trained legs and arms. Methods Participants were randomized to 5 months of concentric (n = 37) or eccentric (n = 33) training. The non-dominant leg and arm were used during training; dominant limbs served as controls. Muscular strength was measured with an isokinetic dynamometer; body composition was measured by dual-energy X-ray absorptiometry. Results Muscular strength of the concentrically and eccentrically trained leg (18.6%; 28.9%) and arm (12.5%; 24.6%) significantly increased with training. Gains in total body (TB) BMC (p < 0.05) and, in the trained limbs, total proximal femur BMD (p < 0.05) and total forearm BMD (p < 0.05) and BMC (p < 0.05) occurred in both groups. FFSTM increased for the TB and trained leg and arm (all p < 0.001) in both modes. Conclusion Regardless of the mode, high-intensity, slow-velocity IRT increases muscular strength and FFSTM of trained limbs and imparts benefits to TB BMC and site-specific BMD and BMC in young women.     

Bone density and fragility fractures in patients with developmental disabilities

Summary  We investigated prior fractures, osteoporosis risk factors, and bone mineral density (BMD) in 107 institutionalized adults with developmental disabilities. We found a very high prevalence of BMD in the osteoporotic range and a significant correlation between lower BMD and prior fragility fractures. Introduction  The purpose of this study was to investigate factors contributing to osteoporosis and fragility fractures among developmentally disabled adults. Methods  Adults from a residential center participated in a prospective study in which bone mineral density (BMD) at the forearm and heel were measured with a portable X-ray densitometer. Prior fragility fractures were identified from chart review. Results  Among 107 participants, 84 (78.5%) had a measurement within the osteoporotic range. The heel was more severely abnormal (mean T-score −3.1 ± 1.5) than the forearm (−1.6 ± 1.3, p < .0.0001). Radiographically confirmed prior fragility fractures (17 [16.3%]) were associated with lower heel (p = 0.0155) and forearm (p = 0.0172) T-scores. In multiple regression analysis, there were independent associations between forearm BMD and prior fragility fractures (p = 0.0126) and between heel BMD and prior fragility fractures (p = 0.0291). The odds ratio for prior fracture increased by 2.02 (95% CI 1.12–3.64) for each standard deviation (SD) decrease in heel T-score and by 2.39 (95% CI 1.08–5.32) for each SD decrease in forearm T-score. Conclusions  We found a very high prevalence of osteoporotic BMD measurements in institutionalized adults with developmental disabilities. Lower heel and forearm BMD measurements were significantly and independently associated with prior fragility fractures in this population.     

Olympic fencers: adaptations in cortical and trabecular bone determined by quantitative computed tomography

Summary  We investigated how cortical bone, trabecular bone, and muscle adapt in US Olympic Fencing Team members. These athletes demonstrate femoral cortical bone expansion, greater distal femoral trabecular bone density, and greater muscle mass compared to controls. This is the first study to investigate musculoskeletal adaptations in Olympic fencers. Purpose  Wolff’s law states that bone remodels according to mechanical forces placed upon it. Our goal was to determine how cortical and trabecular bone adapt in Olympic athletes who perform intermittent high-impact activity. Materials and methods  Nine males from the 2004 US Olympic Fencing Team and nine matched controls were evaluated by quantitative computed tomography. Femurs were scanned at 50% and 75% along the shaft. We evaluated cortical thickness (C.Th), cortical (C.Ar), trabecular (Tb.Ar), and total bone areas (Tot.Ar), proportions of C.Ar and Tb.Ar to Tot.Ar, cortical (C.BMD.), trabecular (Tb.MBD), and total bone densities (Tot.BMD), muscle (M.Ar), and thigh areas (Th.Ar). Results  Fencers had greater C.Th (+24.5 to 38.8%), C.Ar (+16.9 to 19.6%), C.Ar/Tot.Ar (+6.3 to 16.3%), and lower Tb.Ar/Tot.Ar (−23.5% to −23.8%; p<0.05). Fencers demonstrated a positive difference in C.Th in the dominant vs. nondominant thigh at 50% (+5.4%, p = 0.040) and at 75% (+13.8%, p = 0.048 by analysis of covariance). Fencers had 54% greater Tb.BMD at 75% (p = 0.025), but not at 50% (p = 0.63). There was no difference between groups for C.BMD (p = .66 at 50%, p = 0.88 at 75%). Fencers had greater M.Ar (+30%) and asymmetrically greater M.Ar (+12.2%) in the dominant thigh (p < 0.004). Conclusion  In world-class athletes who perform intermittent, high-impact activity, cortical bone expands, trabecular bone density is greater, and muscle mass is greater. This is the first study to examine musculoskeletal adaptations in Olympic fencers.     

Genetic influences on bone loss in the San Antonio Family Osteoporosis study

Summary  The genetic contribution to age-related bone loss is not well understood. We estimated that genes accounted for 25–45% of variation in 5-year change in bone mineral density in men and women. An autosome-wide linkage scan yielded no significant evidence for chromosomal regions implicated in bone loss. Introduction  The contribution of genetics to acquisition of peak bone mass is well documented, but little is known about the influence of genes on subsequent bone loss with age. We therefore measured 5-year change in bone mineral density (BMD) in 300 Mexican Americans (>45 years of age) from the San Antonio Family Osteoporosis Study to identify genetic factors influencing bone loss. Methods  Annualized change in BMD was calculated from measurements taken 5.5 years apart. Heritability (h²) of BMD change was estimated using variance components methods and autosome-wide linkage analysis was carried out using 460 microsatellite markers at a mean 7.6 cM interval density. Results  Rate of BMD change was heritable at the forearm (h² = 0.31, p = 0.021), hip (h² = 0.44, p = 0.017), spine (h² = 0.42, p = 0.005), but not whole body (h² = 0.18, p = 0.123). Covariates associated with rapid bone loss (advanced age, baseline BMD, female sex, low baseline weight, postmenopausal status, and interim weight loss) accounted for 10% to 28% of trait variation. No significant evidence of linkage was observed at any skeletal site. Conclusions  This is one of the first studies to report significant heritability of BMD change for weight-bearing and non-weight-bearing bones in an unselected population and the first linkage scan for change in BMD.     

Competitive physical activity early in life is associated with bone mineral density in elderly Swedish men

Summary  In this population-based study of 75-year-old men (n = 498), we investigated the association between physical activity (PA) early in life and present bone mineral density (BMD). We demonstrate that a high frequency of competitive sports early in life is associated with BMD at several bone sites, indicating that increases in BMD following PA are preserved longer than previously believed. Introduction  Physical activity (PA) increases bone mineral density (BMD) during growth. It is unclear if the positive effects remain at old age. In this study, we aimed to determine if PA early in life was associated with BMD in elderly men. Methods  In this population-based study, 498 men, 75.2 ± 3.3 (mean±SD) years old, were included. BMD was assessed using DXA. Data concerning lifetime PA, including both competitive (CS) and recreational sports (RS), and occupational physical load (OPL), were collected at interview. Results  Subjects in the highest frequency group of CS in the early period (10–35 years), had higher BMD at the total body (4.2%, p < 0.01), total hip (7.0%, p < 0.01), trochanter (8.7%, p < 0.01), and lumbar spine (7.9%, p < 0.01), than subjects not involved in CS. A stepwise linear regression model showed that frequency of CS in the early period independently positively predicted present BMD at the total body (β = 0.12, p < 0.01), total hip (β = 0.11, p < 0.01), trochanter (β = 0.12, p < 0.01), and lumbar spine (β = 0.11, p = 0.01). Conclusions  We demonstrate that PA in CS early in life is associated with BMD in 75-year-old Swedish men, indicating that increases in BMD following PA are preserved longer than previously believed. This study was supported by the Swedish Research Council, the ALF/LUA grant from the Sahlgrenska University Hospital, and the Hjalmar Svensson Foundation.     

Bone turnover markers are correlated with quantitative ultrasound of the calcaneus: 5-year longitudinal data

Summary  Associations between bone turnover markers and calcaneal ultrasound (quantitative ultrasound, QUS) were studied in a population-based sample of 810 elderly women. Baseline bone turnover markers correlated with baseline QUS as well as with 5-year prospective changes in QUS. Introduction  Bone turnover markers are associated with areal bone mineral density, but the knowledge on the association with QUS is limited. Methods  Eight hundred ten women, all 75 years old, were investigated at baseline. Five hundred six completed a 5-year follow-up. Bone turnover markers and calcaneal QUS [speed of sound (SoS), broadband ultrasound attenuation (BUA), stiffness] were investigated at baseline. QUS was investigated at follow-up. Results  All bone turnover markers were correlated with baseline QUS [standardized regression (Beta_std) values from −0.07, p < 0.05 to −0.23, p < 0.001], with the exception of bone-specific alkaline phosphatase (S-Bone ALP) which was not correlated with BUA and stiffness index. When the correlations between baseline bone turnover markers and 5-year changes in QUS were analyzed, three serum osteocalcins were correlated with changes of SoS and stiffness index (Beta_std = −0.11, p < 0.05 to −0.17, p < 0.001). Also S-CTX-I correlated with changes of SoS and stiffness index (Beta_std = −0.10 and −0.09, respectively, p < 0.05). S-TRACP5b, urinary deoxypyridinoline/crea, and U-MidOC/crea correlated with changes of SoS (Beta_std = −0.10 and p < 0.05 for all). S-Bone ALP did not correlate with change of QUS. None of the bone turnover markers correlated with changes of BUA. Conclusions  Bone turnover markers correlate with concomitantly assessed QUS as well as with longitudinal change in QUS.     

Relation between fibroblast growth factor-23, body weight and bone mineral density in elderly men

Summary  We evaluated the relation between serum FGF23 and bone mineral density (BMD) in a community-based cohort of elderly men. There was a weak correlation between FGF23 and BMD, which was primarily dependent on body weight. Introduction  FGF23 is a hormonal factor produced in bone and regulates serum levels of phosphate (Pi) and vitamin D. FGF23 over-expression is associated with skeletal abnormalities, including rickets/osteomalacia. The relation between FGF23 and Bone Mineral Density (BMD) in the community remains unexplored. Methods  We employed a large, population-based cohort of 3014 Swedish men aged 69–80 years, without known renal disease. BMD was measured with dual X-ray absorptiometry (DXA) in the hip and lumbar spine. Serum intact FGF23 was analyzed with a two-site monoclonal ELISA. Results  There was a weak but significant correlation between FGF23 and BMD in femoral neck (r = 0.04, p < 0.05), femoral trochanter (r = 0.05, p = 0.004), total hip (r = 0.06, p = 0.0015) and lumbar spine (r = 0.07, p = 0.0004). The correlations remained significant when adjusting for biochemical covariates (Pi, calcium, PTH, 25(OH)D and renal function). However, the association became insignificant in all regions when adjusting for established confounding variables including age, height, weight and smoking. Further analysis confirmed a significant correlation between FGF23 and body weight (r = 0.13, p < 0.0001). Conclusions  The weak correlation between FGF23 and BMD in elderly male subjects is mainly due to an association between FGF23 and body weight. Therefore, FGF23 may not play a significant role in the hormonal regulation of BMD. Richard Marsell and Majd A. I. Mirza contributed equally to this work. Funding source: this study was supported by the Swedish Research Council, the Novo Nordisk Foundation, the Swedish Kidney Foundation and the Swedish Society of Medicine.     

Weight-bearing bones are more sensitive to physical exercise in boys than in girls during pre- and early puberty: a cross-sectional study

Summary  We carried out a cross-section study of the sex-specific relationship between bone mineral content and physical activity at sites with different loading in pre- and early pubertal girls and boys. There was significant sensitivity of bone mineral content of the hip to physical exercise in boys, but not in girls. Background  Since little is known whether there are sex differences in sensitivity of bone to loading, we investigated sex differences in the cross-sectional association between measures of physical activity (PA) and bone mass and size in pre- and early pubertal children of both sexes. Methods  We measured bone mineral content/density (BMC/BMD) and fat-free mass (FFM) in 269 6- to 13-year-old children from randomly selected schools by dual-energy X-ray absorptiometry. Physical activity (PA) was measured by accelerometers and lower extremity strength by a jump-and-reach test. Results  Boys (n = 128) had higher hip and total body BMC and BMD, higher FFM, higher muscle strength and were more physically active than girls (n = 141). Total hip BMC was positively associated with time spent in total and vigorous PA in boys (r = 0.20–0.33, p < 0.01), but not in girls (r = 0.02–0.04, p = ns), even after adjusting for FFM and strength. While boys and girls in the lowest tertile of vigorous PA (22 min/day) did not differ in hip BMC (15.62 vs 15.52 g), boys in the highest tertile (72 min/day) had significantly higher values than the corresponding girls (16.84 vs 15.71 g, p < 0.05). Conclusions  Sex differences in BMC during pre- and early puberty may be related to a different sensitivity of bone to physical loading, irrespective of muscle mass.     

Can geometry-based parameters from pQCT and material parameters from quantitative ultrasound (QUS) improve the prediction of radial bone strength over that by bone mass (DXA)?

The diagnosis of osteoporosis is generally based on the assessment of bone mineral content with dual X-ray absorptiometry (DXA) but does not account for the spatial distribution and inherent material properties of the tissue. Peripheral quantitative computed tomography (pQCT) permits one to measure the compartment-specific density and geometry-based parameters of cortical bone. Quantitative ultrasound (QUS) parameters are associated with material properties of cortical bone. The purpose of this study was to test the hypothesis that pQCT and cortical QUS provide additional information to DXA in predicting structural strength of the distal radius. The intact right arm and the isolated left radius were harvested from 70 formalin-fixed cadavers (age 79±11 years). The bone mineral content (BMC) was assessed with DXA at the radial metaphysis and shaft. pQCT was also used at the metaphysis and the shaft, while QUS was employed only at the shaft. The failure loads of the radius were assessed by use of a 3-point bending test (isolated radius) and a complex fall simulation (intact arm). The BMC (DXA) displayed a correlation of r=0.96 with the failure moments in 3-point bending (P<0.001). The correlation between failure load and geometry-based parameters (pQCT) ranged from r=0.85 to r=0.96 and was r=0.64 for the speed of sound (QUS) (P <0.001). Cortical thickness (pQCT) improved the prediction marginally (r=0.964) in combination with DXA. For the fall simulation, the correlation coefficients were r=0.76 for BMC (DXA) of the shaft, r=0.83 for metaphyseal bone content (pQCT), r=0.55 for QUS, and ranged from r=0.59 to r=0.74 for geometry-based parameters at the shaft (pQCT). pQCT and QUS parameters provided no significant improvement versus DXA alone. Measurement of bone mass by DXA or pQCT thus appears to be sufficient as a surrogate of mechanical strength and fracture risk of the distal radius.M. Hudelmaier and V. Kuhn contributed equally to this study     

Age-related changes in sex steroid levels influence bone mineral density in healthy Indian men

Summary  Age-related changes in sex steroid levels and its contribution to variations in rate of bone loss among men is unclear. Although, Bio-T and Bio-E₂ levels declined with age and depicted an association with BMD in healthy Indian men, Bio-E₂ was found to be an independent predictor of BMD. Introduction  Ethnicity influences sex steroid levels, therefore, their role in pathogenesis of low bone mass needs to be established in various populations. We assessed the extent of changes in sex steroid levels with age and related these to bone mineral density (BMD) in healthy Indian men. Methods  Total testosterone (TT), estradiol (E₂), sex hormone-binding globulin (SHBG), PTH, osteocalcin (OC), and c-terminal telopeptide (CTX) were measured in 330 men aged 20–55 years and correlated with BMD measured by DXA. Results  Both Bio-T (1% per year) and Bio-E₂ (0.8% per year) levels decreased significantly in ageing men, whereas TT (0.4% per year) and E₂ (0.3% per year) levels decreased only marginally with age. In contrast, SHBG (1.4% per year) and PTH (1% per year) levels increased significantly with age. Serum TT (r = 0.19, p = 0.01) and Bio-T (r = 0.2, p = 0.01) levels were associated positively with BMD at spine, whereas E₂ and Bio-E₂ levels were associated with BMD at spine [E ₂ (r = 0.31, p < 0.0001); Bio-E₂ r = 0.37, p < 0.0001] and femur (E₂ r = 0.26, p = 0.001; Bio-E₂ r = 0.27, p = 0.001). Men in the lowest quartile of Bio-E₂ were associated with lower BMD and higher bone turnover. Conclusions  Age-related decrease in bioavailable sex steroid levels is associated with BMD in healthy Indian men. Bio-E₂ was found to be an independent predictor of BMD.     

Influence of creatine supplementation on bone quality in the ovariectomized rat model: an FT-Raman spectroscopy study

The influence of creatine (Cr) supplementation on cortical and trabecular bone from ovariectomized rats was studied using FT-Raman spectroscopy. The intensity of organic-phase Raman bands was compared to mineral phase ones. Twenty-one female Wistar rats aged 3 months were divided into three groups (n = 7 per group): ovariectomized (OVX), ovariectomized treated with creatine (CRE) and sham-operated (SHAM) groups. Creatine supplementation (300 mg kg⁻¹ day⁻¹) was provided for 8 weeks, starting 12 weeks after ovariectomy. FT-Raman spectroscopy was performed on the right medial femoral mid-shaft (cortical bone) and third lumbar vertebral body (trabecular bone). The integrated intensities of mineral phase (phosphate and carbonate bands at 959 and 1,071 cm⁻¹, respectively) and organic phase (amide I band at 1,665 cm⁻¹) Raman bands were analyzed. The mineral-to-matrix (phosphate/amide I), carbonate-to-phosphate, and carbonate-to-amide I ratios were analyzed to assess bone quality. The phosphate content on trabecular bone was higher in the CRE group than the OVX group (p < 0.05). No significant changes in mineral or organic phases on cortical bone were observed. A radiographic assessment of bone density was encouraging as the same findings were showed by Raman intensity of phosphate from cortical (r ²  = 0.8037) and trabecular bones (r ² = 0.915). Severe ovariectomy-induced bone loss was confirmed by FT-Raman spectroscopy. The results suggest that the chemical composition of trabecular bone tissue may be positively influenced by Cr supplementation after ovariectomy.     

Muscle power is related to tibial bone strength in older women

Summary  We enrolled 65 to 75 year-old community-dwelling women and measured muscle power, strength, physical activity using accelerometry and tibial bone strength using peripheral quantitative computed tomography (pQCT). Muscle power contributed 6.6% of the variance in the bone strength–strain index and 8.9% in the section modulus after accounting for age, height, weight, and physical activity; moderate to vigorous physical activity was related to muscle power in the lower extremity. Introduction  Muscle power is associated with DXA measurements of bone mass, but it is not known whether muscle power is associated with bone strength. There are no reports of investigations that have tested the effect of muscle power on bone compartments using advanced imaging. Methods  We enrolled 74 community-dwelling women aged 65–75 years. We measured muscle power and strength of leg extension using Keiser air-pressure resistance equipment. All participants wore a waist-mounted Actigraph accelerometer to record physical activity. We used peripheral quantitative computed tomography (pQCT) to measure tibial mid-shaft (50% of the site) bone strength (strength–strain index, section modulus). We used Pearson correlations and multi-level linear regression to investigate the associations between muscle and bone. Results  Muscle power contributed 6.6% (p = 0.007) of the variance in the bone strength–strain index and 8.9% (p = 0.001) the variance in the section modulus in older women after accounting for age, height, weight, and physical activity. Moderate to vigorous physical activity was significantly related to muscle power in the lower extremity (r = 0.260; p = 0.041). Conclusion  Muscle power significantly contributed to the variance in estimated bone strength. Whether power training will prove to be a more effective stimulus for bone strength than conventional strength training will require further studies.     

Combination of texture analysis and bone mineral density improves the prediction of fracture load in human femurs

Summary  

Twenty-one excised femurs were studied using (1) a high-resolution digital X-ray device to estimate three textural parameters, (2) dual-energy X-ray absorptiometry (DXA) to measure bone mineral density (BMD), and (3) mechanical tests to failure. Textural parameters significantly correlated with BMD (p < 0.05) and bone strength (p < 0.05). Combining texture parameters and BMD significantly improved the fracture load prediction from adjusted r ² = 0.74 to adjusted r ² = 0.82 (p < 0.05).     

Fracture risk in children with a forearm injury is associated with volumetric bone density and cortical area (by peripheral QCT) and areal bone density (by DXA)

Summary

Children who sustain a forearm fracture when injured have lower bone density throughout their skeleton, and have a smaller cortical area and a lower strength index in their radius. Odds ratios per SD decrease in bone characteristics measured by peripheral quantitative computed tomography (pQCT) and dual-energy X-ray absorptiometry (DXA) were similar (1.28 to 1.41).

Introduction

Forearm fractures are common in children. Bone strength is affected by bone mineral density (BMD) and bone geometry, including cross-sectional dimensions and distribution of mineral. Our objective was to identify bone characteristics that differed between children who sustained a forearm fracture compared to those who did not fracture when injured.

Methods

Children (5–16 years) with a forearm fracture (cases, n?=?224) and injured controls without fracture (n?=?200) were enrolled 28?±?8 days following injury. Peripheral QCT scans of the radius (4% and 20% sites) were obtained to measure volumetric BMD (vBMD) of total, trabecular and cortical bone compartments, and bone geometry (area, cortical thickness, and strength strain index [SSI]). DXA scans (forearm, spine, and hip) were obtained to measure areal BMD (aBMD) and bone area. Receiver operating characteristic (ROC) analyses were used to assess screening performance of bone measurements.

Results

At the 4% pQCT site, total vBMD, but not trabecular vBMD or bone area, was lower (?3.4%; p?=?0.02) in cases than controls. At the 20% site, cases had lower cortical vBMD (?0.9%), cortical area (?2.8%), and SSI (?4.6%) (p?<?0.05). aBMD, but not bone area, at the 1/3 radius, spine, and hip were 2.7–3.3% lower for cases (p?<?0.01). Odds ratios per 1 SD decrease in bone measures (1.28–1.41) and areas under the ROC curves (0.56–0.59) were similar for all bone measures.

Conclusions

Low vBMD, aBMD, cortical area, and SSI of the distal radius were associated with an increased fracture risk. Interventions to increase these characteristics are needed to help reduce forearm fracture occurrence.     

The IGF/IGFBP system in relation to macroscopic bone architecture in pediatric renal transplant patients

The post-transplant bone disease of the peripheral skeleton in pediatric renal transplant recipients is characterized by an inadequately thin bone cortex in relation to muscular force. A major hormonal modulator of periosteal growth is the insulin-like growth factor (IGF)/IGF binding protein (IGFBP) system. We therefore hypothesized that the reduced cortical thickness in these patients may be due to functional IGF deficiency. To test this hypothesis, we investigated 55 patients (mean estimated glomerular filtration rate 86.3 ± 30.0 ml/min/1.73 m²) in a cross-sectional study. Parameters of macroscopic bone architecture and forearm muscle size were analyzed by peripheral quantitative computed tomography (pQCT), and serum IGF/IGFBP system components were measured by specific radioimmunoassays. The mean (± standard deviation) standardized serum IGF-I (0.20 ± 1.16 score) level was normal, while the mean IGF-II (1.16 ± 0.11 score) level was significantly elevated. Serum IGFBP-1 and IGFBP-2 levels were not altered, whereas the IGFBP-3 (1.34 ± 0.15 score) level was significantly increased. The serum IGFBP-4 level was slightly elevated (by 11%), the IGFBP-6 level was markedly (2.3-fold) elevated, while the IGFBP-5 level was comparable to that of the control. The respective age-adjusted cortical thickness at both the proximal (r = 0.407, P < 0.005) and distal (r = 0.383, P < 0.01) forearm was positively correlated with the standardized serum IGF-I level. In conclusion, the serum IGF/IGFBP system in pediatric renal transplant recipients is characterized by an increase in the levels of the inhibitory IGFBPs, IGFBP-3, -4 and -6, resulting in a functional IGF deficiency. The positive correlation of IGF-I with cortical thickness underlines the importance of this hormonal system in the modeling of bone, particularly periosteal growth.     

The effect of treatment with a thiazide diuretic for 4 years on bone density in normal postmenopausal women

Summary We performed a 2-year extension of our previous 2-year randomized controlled trial of the effects of hydrochlorothiazide on bone mineral density. The improvements in bone density seen in the first 2 years were sustained throughout the extension study. Thiazides provide a further option in the prevention of postmenopausal bone loss. Introduction Thiazide diuretics reduce urinary calcium excretion and therefore might prevent osteoporosis. Previously we reported a 2-year randomized controlled trial of hydrochlorothiazide treatment in 185 postmenopausal women that showed positive benefits of hydrochlorothiazide on bone density. Here, we report the results of a 2-year extension to that study. Methods Of 185 healthy postmenopausal women, 122 agreed to continue in a double-blinded 2-year extension taking 50 mg hydrochlorothiazide or placebo daily. Measurements of bone density occurred every 6 months and of calcium metabolism at 2 and 4 years. Results The improvements in bone density seen in the first 2 years of the trial were sustained throughout the extension. There were significant between-groups differences in the change in bone density over 4 years at the total body (0.9%, P < 0.001), legs (1.0%, P = 0.002), mid-forearm (1.1%, P = 0.03), and ultradistal forearm (1.4%, P = 0.04). At the lumbar spine (0.9%, P = 0.76) and femoral neck (0.4%, P = 0.53) the between-groups differences did not reach statistical significance. Conclusions Hydrochlorothiazide produces small positive benefits on cortical bone density that are sustained for at least the first 4 years of treatment. They provide a further option in the prevention of postmenopausal bone loss, especially for women with hypertension or a history of kidney stones. This study was funded by the Health Research Council (HRC) of New Zealand.     

Targeted exercises against hip fragility

Summary  Compared to high-impact exercises, moderate-magnitude impacts from odd-loading directions have similar ability to thicken vulnerable cortical regions of the femoral neck. Since odd-impact exercises are mechanically less demanding to the body, this type of exercise can provide a reasonable basis for devising feasible, targeted bone training against hip fragility. Introduction  Regional cortical thinning at the femoral neck is associated with hip fragility. Here, we investigated whether exercises involving high-magnitude impacts, moderate-magnitude impacts from odd directions, high-magnitude muscle forces, low-magnitude impacts at high repetition rate, or non-impact muscle forces at high repetition rate were associated with thicker femoral neck cortex. Methods  Using three-dimensional magnetic resonance imaging, we scanned the proximal femur of 91 female athletes, representing the above-mentioned five exercise-loadings, and 20 referents. Cortical thickness at the inferior, anterior, superior, and posterior regions of the femoral neck was evaluated. Between-group differences were analyzed with ANCOVA. Results  For the inferior cortical thickness, only the high-impact group differed significantly (~60%, p = 0.012) from the reference group, while for the anterior cortex, both the high-impact and odd-impact groups differed (~20%, p = 0.042 and p = 0.044, respectively). Also, the posterior cortex was ~20% thicker (p = 0.014 and p = 0.006, respectively) in these two groups. Conclusions  Odd-impact exercise-loading was associated, similar to high-impact exercise-loading, with ~20% thicker cortex around the femoral neck. Since odd-impact exercises are mechanically less demanding to the body than high-impact exercises, it is argued that this type of bone training would offer a feasible basis for targeted exercise-based prevention of hip fragility.     

Calcium acquisition rates do not support age-appropriate gains in total body bone mineral content in prepuberty and late puberty in girls with cystic fibrosis

Few longitudinal data are available characterizing bone development in adolescents with cystic fibrosis (CF) although this is a critical time for bone mineralization. Dual energy X-ray absorptiometry (DXA) scans were obtained at 1- to 4-year intervals in 18 prepubertal and pubertal girls (age 7–18 years) with CF to determine calcium (Ca) accretion rates and changes (Δ) in total body bone mineral content (TBBMC) and lumbar spine bone mineral density (LS BMD) Z-scores. Daily Ca acquisition rates were calculated assuming TBBMC was composed of 32.2% Ca. Bone Ca accretion averaged 82 mg/day (2.05 mmol/day) [(range:–38 to +197 mg/day (–0.95 to 4.9 mmol/day)] on ∼1,200 mg/day (30 mmol/day) Ca intakes. Estimated mean peak Ca accretion was 160 mg/day (4 mmol/day) at age 13 years; losses of bone Ca occurred in late puberty. Gains in insulin-like growth factor 1 (IGF-1) predicted Ca accretion (p<0.06). Body mass index (BMI) Z-score predicted LS BMD and TBBMC Z-score cross-sectionally but did not predict ΔTBBMC Z-score. Changes in TBBMC Z-score paralleled Ca accretion rates with age. Bone Ca accretion in girls with CF fell below rates in healthy girls during prepuberty and late puberty despite Ca intakes approaching recommendations. IGF-1 and BMI Z-scores may identify children with CF at risk of compromised bone accretion, and more data are required to elucidate roles of lung function and glucocorticoid use in compromised bone health. Supported by the Cystic Fibrosis Foundation and the National Center for Research Resources (NCRR)/General Clinical Research Center, RR00052, Johns Hopkins Hospital     

Effect of antioxidants combined to resistance training on BMD in elderly women: a pilot study

Summary  We determined the effect of antioxidants and resistance training on bone mineral density of postmenopausal women. After 6 months, we observed a significant decrease in the lumbar spine BMD of the placebo group while other groups remained stable. Antioxidants may offer protection against bone loss such as resistance training. Introduction  The purpose of this pilot study was to determine the effects of antioxidant supplements combined to resistance training on bone mineral density (BMD) in healthy elderly women. Methods  Thirty-four postmenopausal women (66.1 ± 3.3 years) were randomized in four groups (placebo, n = 7; antioxidants, n = 8; exercise and placebo, n = 11; and exercise and antioxidants, n = 8). The 6-month intervention consisted in antioxidant supplements (600 mg vitamin E and 1,000 mg vitamin C daily) or resistance exercise (3×/week). Femoral neck and lumbar spine BMD (DXA) and dietary intakes (3-day food record) were measured before and after the intervention. A repeated measure ANOVA and non-parametric Mann–Whitney U tests were used. Results  We observed a significant decrease in the placebo group for lumbar spine BMD (pre, 1.01 ± 0.17 g/cm²; post, 1.00 ± 0.16 g/cm²; P < 0.05 respectively) while it remained stable in all other groups. No changes were observed for femoral neck BMD. Conclusions  Antioxidant vitamins may offer some protection against bone loss in the same extent as resistance exercise although combining both does not seem to produce additional effects. Our results suggest to further investigate the impact of antioxidant supplements on the prevention of osteoporosis.     

Peripheral quantitative computed tomography is useful to monitor response to alendronate therapy in postmenopausal women

A forearm fracture (Colles’ fracture) is often the first sign of osteoporosis and may suggest underlying skeletal fragility. Therefore, establishment of a more accurate and reliable method for the measurement of bone mineral density (BMD) at the distal radius would be beneficial for patients who suffer from osteoporosis. The objective of this study was to evaluate the usefulness of peripheral quantitative computed tomography (pQCT) to monitor the response to alendronate therapy at the distal radius in early postmenopausal Japanese women. Thirty-two early postmenopausal women who were diagnosed with osteoporosis or osteopenia were randomized to either alendronate or control treatment. We analyzed the BMD of the distal radius by pQCT, lumbar spine by dual-energy X-ray absorptiometry (DXA) and the biochemical markers of bone turnover (deoxypyridinoline) at baseline, 3, 6 and 12 months. The control group showed a significant decrease from baseline in the trabecular BMD of the radius at 12 months (3.5 ± 3.7%; p < 0.01), whereas the alendronate group showed a significant increase (4.3 ± 8.1%). The changes in the trabecular BMD of the radius between the alendronate and control groups were statistically different at 6 and 12 months (p < 0.01). However, in the total BMD at the diaphysis of the radius, no significant differences were seen in the changes in bone densities between the alendronate and control groups after 1 year of treatment. pQCT detected significant differences in BMD of the radius in early postmenopausal women after 1 year of treatment with alendronate. Collectively, our preliminary clinical trial showed that pQCT might be useful to monitor response to alendronate therapy, especially at the radius, and it might explain why alendronate prevents Colles’ fracture.