Objective: This study was conducted to investigate the relationship between hip bone mineral density (BMD), fat free mass (FFM), fat mass (FM), and total body mass (TBM) and the extent to which these relationships were modified by various confounding factors. The cross-sectional analysis included 262 healthy females (mean age 41.6±3.0 years). Methods: BMD of the hip and body composition were assessed by the Hologic 4500W dual energy x-ray absorptiometry (DXA) system. Total and intensity of physical activity (PA) were objectively measured using an Actigraph accelerometer. Dietary calcium and vitamin D from food and beverages, as well as from supplements, were measured separately using the Block food frequency questionnaire. Menopause status and prescription bone drug use were measured by a questionnaire. Results: The relationship between FFM and hip BMD was strong and robust (F=24.5, P<0.0001). Using the pooled standard deviation revealed a large effect size of 1.2 when comparing hip BMD of women with low FFM and high FFM. Potentially confounding variables, considered individually and collectively, did not change this relationship. The association between FM and hip BMD was also substantial (F=9.9, P<0.0001) and remained significant when controlling for all potentially confounding variables, except differences in FFM. The relationship between TBM and hip BMD was also strong and dose-response (F=21.5, P<0.0001) and remained significant, except when differences in FFM were controlled. Conclusion: The relationships between body mass (total, fat, and fat free) and BMD of the hip in middle-age women are strong and significant. The associations are not influenced by differences in age, height, menopause status, calcium or vitamin D intake, volume or intensity of PA, or the use of bone enhancing prescription drugs. The findings suggest that women with low body mass, particularly low FFM, tend to have low hip BMD and there is little that can be done to change this association.

The objectives of this study were to 1) calculate participant-specific segment inertial parameters using dual energy X-ray absorptiometry (DXA) data (referred to as full DXA-driven parameters) and compare the pitching arm kinetic predictions using full DXA-driven inverse dynamics vs scaled, DXA mass-driven (using DXA masses but scaled centers of mass and radii of gyration), and DXA scaled inverse dynamics(ID) (using the full DXA-driven inertial parameters averaged across all participants), 2) examine associations between full DXA-driven kinetics and body mass index (BMI) and 3) examine associations between full DXA-driven kinetics and segment mass index (SMI). Eighteen 10- to 11- year-olds pitched 10 fastballs. DXA scans were conducted and examined to obtain 3D inertial parameters of the upper arm, forearm, and hand. Full DXA-driven and scaled inertial parameters were compared using paired t-tests. Pitching arm kinetic predictions calculated with the four methods (i.e. scaled ID, DXA mass-driven ID, full DXA-driven ID, and DXA scaled ID) were compared using a repeated measures ANOVA with Tukey post-hoc tests. The major results were that 1) full DXA-driven participant specific inertial parameters differed from scaled inertial parameters 2) kinetic predictions significantly varied by method and 3) full DXA-driven ID predictions for shoulder compression force and shoulder internal rotation torque were significantly associated with BMI and/or SMI.

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<p>Background: Increased physical activity has a modest effect on the spatial distribution of bone mineral. The risks and benefits of exercise for women with osteoporosis at high risk to fracture are not known. The decompression of aquatic exercise is an option to increase exercise compliance. The dual energy absorptiometry (DXA) vertebral fracture assessment (VFA) images 2D bone geometry however measurement properties have not been established for this outcome.</p> <p>Purpose: To determine relative and absolute intra-rater reliability of DXA-based vertebral height (VH) measures and to assess the feasibility of investigating bone outcomes in women with established osteoporosis before and after a 6 month aquatic exercise program.</p> <p>Methods: DXA VFA scans of 32 women over 60 years old were analyzed on 2 occasions, 4 weeks apart. Relative reliability, intraclass correlation coefficient (95% CI) and absolute reliability, standard error of measurement (95% CI) were estimated for visible anterior, middle and posterior VHs from T4 to L4. Women with osteoporosis at high risk to fracture (clinical practice guidelines used) were recruited from two osteoporosis clinics. Feasibility of recruitment, adherence to the exercise, adherence to the assessment protocols (DXA, pQCT, physical performance measures), safety and retention were assessed.</p> <p>Results: Intra-rater reliability ICC >0.87 (0.74, 0.94) and SEM <1.17 from T10 to L4. Recruitment of 9 women in 10 weeks; average adherence 68%; pQCT data loss 46%; 1 fracture after class; retention 89% at 12 months.</p> <p>Conclusion: Further study of measurement properties of VH and protocols for recruitment, data management and safety are required.</p> / Master of Science Rehabilitation Science (MSc)

<p>Leptin, an adipose derived hormone, has emerged as a regulator of bone metabolism. Recent findings support a role of leptin in the process of fetal bone remodeling during pregnancy; however, the link between maternal leptin during pregnancy and offspring bone status is undocumented. Evidence exists that the intrauterine environment plays a role in programming peak bone mass that is achieved in late adolescence and thus osteoporosis risk later in life. We investigated the association between maternal leptin during the third trimester and offspring bone mass at 3 years of age.</p> <p><strong>Method:</strong> Based on a sub-sample of a prospective birth cohort study, we conducted analysis on 425 mothers from whom maternal blood samples in pregnancy were analyzed for leptin and 25- hydroxyvitamin D, and whole body bone mass by dual energy x-ray absorptiometry were available for both mother and child at 3 years. Data were collected for maternal prepregnancy body mass index (BMI), lifestyle, and nutrition during pregnancy, as well as the child’s nutrition and physical activity at 3 years.</p> <p><strong>Results:</strong> Women obese on entering pregnancy have a two-fold greater circulating leptin during pregnancy than women with normal weight BMIs. Maternal age and skinfold thickness were positively associated with maternal leptin status. However, maternal leptin status was not a significant predictor of offspring BMC z-score at 3 years of age, when adjusted for relevant maternal and child variables. Maternal vitamin D status was also not a predictor of offspring bone status. Rather the key predictors of child BMC z-score were maternal bone mineral density z-score and child’s weight and vitamin D intake at 3 years.</p> <p><strong>Conclusion:</strong> While maternal leptin status during pregnancy is highly variable among women of different BMI categories, in utero exposure to leptin is not a significant factor that influences child bone status at 3 years of age when adjusted for other relevant variables.</p> / Master of Science (MSc)

Testosterone is a steroid and anabolic hormone found in all mammals. Previous research indicates that testosterone levels correlates with physical capacities related to physical performance. However, these studies refers only to men and boys. The aim of present study was therefore to investigate the potential relationship between body composition, strength, power and endurance capabilities in relation to blood levels of testosterone and DHEAS in young female football players. Seventeen female elite football (age: 15,4 ± 0,6, body mass: 57,2 ± 7,4kg, height 1,65 ±0,04m) players volunteered for the study. Morning levels of testosterone were plotted against results of Dual-energy X-ray absorptiometry, Biodex isokinetic dynamometer, maximal counter movement jump, drop jump, 10 and 20 meters sprints and aerobic fitness (Yo-Yo intermittent endurance test). Testosterone levels were significant correlated with DHEAS as well as bone density (BMD) in L1-L4 (p &lt;0,01) and whole body (WB) BMD (p &lt;0,05). DHEAS also correlated with BMD in L1-L4 and WB (p &lt;0,05). No correlations were found between testosterone, DHEAS and performance capacities. These results suggest that DHEAS predict the level of testosterone and BMD in young women. However, more research is needed to clarify the relationship between testosterone, DHEAS and physical capacities in a larger group of women.

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Não disponível / Background: Visceral adiposity is a risk factor for cardiometabolic diseases and dual-energy x-ray absorptiometry (DXA) represents precise method for measuring visceral adipose tissue (VAT), muscle and bone compartments. The musculoskeletal system deteriorates with aging and may result in osteosarcopenia. Since known risk factors do not fully explain the occurrence of osteosarcopenia, the search for new causal factors, as birth weight (BW) is promising. Objectives: To evaluate whether BW was associated with DXA-determined body composition, bone densitometry and cardiometabolic risk markers in young women from the NutriHS. Paper 1 objective: to propose reference values for DXA-determined VAT, and to test their ability to identify the cardiometabolic risk profile. Paper 2: to examine whether BW was associated with muscle and bone DXA-determined parameters. Paper 3: to investigate whether parameters of muscle and bone compartments were associated and possible predictive factors of these compartments throughout life. Methods: NutriHS is a cohort study conducted in undergraduates and Nutrition graduates and here cross-sectional analyses were performed in 201 healthy women (20-45 years). They answered questionnaires and had anthropometry, muscle strength and performance, DXA-determined body composition and bone densitometry obtained. A random sample of 148 participants had also laboratory tests collected. Multiple regression models, using the directed acyclic graphs-recommended adjustments, were employed. Results: Median age was 23 years and mean BMI was 22.9±2.9 kg/m2. Paper 1: Mean VAT mass and volume were 221.0±306.1 g and 231.8±323.8 cm3, respectively. The third tertiles of VAT were significantly associated with increased frequencies of abnormal anthropometry, HOMA-IR and TyG indexes. Paper 2: Mean BW was 3,199±424 g; BW in quartiles was significantly associated with several muscle and bone parameters. Paper 3: Direct, strong and independent associations between bone and muscle variables were detected. Discussion: Cutoffs for DXA-derived VAT mass (221.0 g) and volume (231.8 cm3) are being suggested for Brazilian young women; these seem able to disclose a mild visceral fat accumulation, prior the deterioration of glucose and lipid metabolism. The role of BW as an early marker for muscle and bone states in young adulthood was shown. In addition, a musculoskeletal profile for a healthy stratus of the Brazilian women was firstly described. Our findings indicated a muscle-bone crosstalk even in young adults and suggested predictive factors (such as BW, physical activity, smoking) of muscle and bone compartments.

Osteoporosis is a disease characterized by low bone mineral density (BMD), which compromises bone tissue increasing fragility and susceptibility to fracture. It affects nearly 50% of women and 20% of men over the age of 50, and fractures resulting from osteoporosis cause significant morbidity and mortality. Therefore, patients with or at risk for osteoporosis should be identified before rather than after a fracture occurs. The gold standard in diagnosing patients with osteoporosis is dual X-ray absorptiomerty (DXA). The purpose of this study is to evaluate the usefulness of assessing BMD at various parts of the distal radius (ultra-distal, mid-point, one third, and total) compared to the conventional sites (lumbar vertebrae and proximal femur) using DXA to diagnose osteoporosis. This was a retrospective study on 1,641 male patients over the age of 50 who had undergone bone densitometry (DXA scans) of at least one hip, lumbar vertebrae and distal radius. Ordinary regression and correlation analysis was used to assess the association between the lowest of the bone density scores of the hip or lumbar vertebrae and scans at the various sites on the radius. Comparing standardized scores from the radius method with the lowest standardized scores from the hip or lumbar vertebrae, a highly significant correlation was found, R = 0.59, p < 0.001 for the left UD radius, R =0.59, p < 0.001 for left MD radius, R =0.54, p < 0.001 for the left 1/3 radius, and R =0.60, p < 0.001 for the total left radius. The results indicate that the left radius total is the most accurate in diagnosing osteoporosis in our study population. The results of this study can have far-reaching psychosocio-economic implications showing that DXA scans of the distal radius can be used to effectively diagnose osteoporosis by using inexpensive, low-technology, portable scanners. These findings are particularly relevant to the needs of the undeserved rural populations of Central Appalachia.