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Patricia W. Bauer, James M. Pivarnik, Willa C. Fornetti, Jennifer J. Jallo and Lawrence Nassar

The purpose of this investigation was to evaluate three bioelectrical impedance analysis (BIA) prediction models for fat-free mass (FFM) using the U.S. National Women’s Gymnastics team (N = 48; age = 15.8 ± 1.8 years). One model had been developed recently using dual-energy x-ray absorptiometry (DEXA) as the criterion measure, whereas the other two used hydrodensitometry. In this investigation, FFM predictions were compared with measures obtained via DEXA. FFM measured by DEXA averaged 40.5 ± 7.4 kg (± SD), whereas values generated using the three BIA models were within 0.8 kg of this actual measure. Validity coefficients for all models were high (Rxy = .95-98). FFM prediction error was lowest with the model using DEXA as the criterion measure (1.3 kg) compared with the other two (1.9 and 2.4 kg). All BIA models underpredicted FFM in the heaviest girls, and the Lohman and Van Loan et al. models overpredicted FFM in the lightest girls. Whereas prediction error was significantly correlated to the girls’ bone mineral density in all BIA models, this relationship was strongest in the two that were developed using hydrodensitometry.

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April J. Chambers, Alison L. Sukits, Jean L. McCrory and Rakié Cham

Age, obesity, and gender can have a significant impact on the anthropometrics of adults aged 65 and older. The aim of this study was to investigate differences in body segment parameters derived using two methods: (1) a dual-energy x-ray absorptiometry (DXA) subject-specific method (Chambers et al., 2010) and (2) traditional regression models (de Leva, 1996). The impact of aging, gender, and obesity on the potential differences between these methods was examined. Eighty-three healthy older adults were recruited for participation. Participants underwent a whole-body DXA scan (Hologic QDR 1000/W). Mass, length, center of mass, and radius of gyration were determined for each segment. In addition, traditional regressions were used to estimate these parameters (de Leva, 1996). A mixed linear regression model was performed (α = 0.05). Method type was significant in every variable of interest except forearm segment mass. The obesity and gender differences that we observed translate into differences associated with using traditional regressions to predict anthropometric variables in an aging population. Our data point to a need to consider age, obesity, and gender when utilizing anthropometric data sets and to develop regression models that accurately predict body segment parameters in the geriatric population, considering gender and obesity.

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Michael J. Davies, Gail P. Dalsky and Paul M. Vanderburgh

This study employed allometry to scale maximal oxygen uptake (V̇O2 max) by body mass (BM) and lean body mass (LBM) in healthy older men. Ratio standards (ml · kg−1 · min−1) derived by dividing absolute V̇O2 max (L · min−1) by BM or LBM often fail to control for the body size variable. The subjects were 73 older men (mean ± SD: age = 69.7 ± 4.3 yrs, BM = 80.2 ± 9.6 kg, height = 174.1 ± 6.9 cm). V̇O2 max was assessed on a treadmill with the modified Balke protocol (V̇O2 max = 2.2 ± 0.4 L · min−1). Body fat (27.7 ± 6.4%) was assessed with dual energy x-ray absorptiometry. Allometry applied to BM and V̇O2 max determined the BM exponent to be 0.43, suggesting that heavier older men are being penalized when ratio standards are used. Allometric scaling applied to LBM revealed the LBM exponent to be 1.05 (not different from the ratio standard exponent of 1.0). These data suggest that the use of ratio standards to evaluate aerobic fitness in older men penalized fatter older men but not those with higher LBM.

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Amy E. Mark and Ian Janssen

Background:

Despite the plethora of research examining the physical activity-adiposity relation in youth, questions remain regarding the ideal intensity. Therefore, the purpose of this study was to explore the independent effects of physical activity intensity and incidental movement on total and trunk adiposity.

Methods:

The sample consisted of 1165 youth aged 8 to 17 years from the 2003−04 U.S. National Health and Nutrition Examination Survey. Physical activity (low, moderate, vigorous intensity) and incidental movement (activity level when not physically active) were measured using Actigraph accelerometers over 7 days. Total body and trunk fat were measured using dual-energy X-ray absorptiometry; age- and sex-specific percentile scores were calculated.

Results:

Bivariate analyses revealed an inverse relation between total, low, moderate and vigorous intensity physical activity with total body and trunk fat. After consideration of the total volume of physical activity in the multivariate analyses, moderate-to-vigorous intensity physical activity remained significantly related to total and trunk fat. Participants with the highest (top 12.5%) moderate-to-vigorous intensity activity values had total fat percentile scores that were 34 points lower than participants with the lowest (bottom 25%) values.

Conclusion:

These results are consistent with public health guidelines which recommend that children and youth participate in moderate-to-vigorous intensity physical activity.

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Hawley Chase Almstedt and Zakkoyya H. Lewis

Context:

Intermittent pneumatic compression (IPC) is a common therapeutic modality used to reduce swelling after trauma and prevent thrombosis due to postsurgical immobilization. Limited evidence suggests that IPC may decrease the time needed to rehabilitate skeletal fractures and increase bone remodeling.

Objective:

To establish feasibility and explore the novel use of a common therapeutic modality, IPC, on bone mineral density (BMD) at the hip of noninjured volunteers.

Design:

Within-subjects intervention.

Setting:

University research laboratory.

Participants:

Noninjured participants (3 male, 6 female) completed IPC treatment on 1 leg 1 h/d, 5 d/wk for 10 wk. Pressure was set to 60 mm Hg when using the PresSsion and Flowtron Hydroven compression units.

Main Outcome Measures:

Dual-energy X-ray absorptiometry was used to assess BMD of the hip in treated and nontreated legs before and after the intervention. Anthropometrics, regular physical activity, and nutrient intake were also assessed.

Results:

The average number of completed intervention sessions was 43.4 (± 3.8) at an average duration of 9.6 (± 0.8) wk. Repeated-measures analysis of variance indicated a significant time-by-treatment effect at the femoral neck (P = .023), trochanter (P = .027), and total hip (P = .008). On average, the treated hip increased 0.5–1.0%, while the nontreated hip displayed a 0.7–1.9% decrease, depending on the bone site.

Conclusion:

Results of this exploratory investigation suggest that IPC is a therapeutic modality that is safe and feasible for further investigation on its novel use in optimizing bone health.

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Sakiho Miyauchi, Satomi Oshima, Meiko Asaka, Hiroshi Kawano, Suguru Torii and Mitsuru Higuchi

The purpose of this study was to determine whether overfeeding and high-intensity physical training increase organ mass. We examined this question using cross-sectional and longitudinal studies in which we measured collegiate male American football players. Freshman (n = 10) and senior players in their second and third years of college (n = 17) participated in the cross-sectional study. The same measurements of the same freshman players (n = 10) were assessed after the one-year weight gain period in the longitudinal study. Fat-free mass (FFM), skeletal muscle, and adipose tissue mass were obtained using dual-energy X-ray absorptiometry. Liver, kidney, brain, and heart volumes were calculated using magnetic resonance imaging or echocardiography. Compared with the freshman players, the senior players had 10.8 kg more FFM, and 0.29 kg, 0.08 kg, and 0.09 kg greater liver, heart, and kidney mass, respectively. In the longitudinal study, FFM, liver, heart, and kidney mass of the freshman players increased by 5.2 kg, 0.2 kg, 0.04 kg, and 0.04 kg, respectively, after one year of overfeeding and physical training. On the other hand, the organ-tissue mass to FFM ratio did not change, except for the brain, in either the cross-sectional or longitudinal studies. Our results indicated that the organtissue masses increased with overfeeding and physical training in male collegiate American football players.

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Ann L. Gibson, Vivian H. Heyward, Christine M. Mermier, Jeffrey M. Janot and M. Virginia Wilmerding

The authors used 3-component (3C) Db-mineral-model (Lohman, 1986) reference measures to cross-validate Siri’s (1961) 2-component (2C) conversion formula and dual-energy X-ray absorptiometry (DXA) estimates of relative body fat (%BF) for physically active adults. Participants varied in age (18 to 59 y), body fatness, ethnicity (black, Hispanic, white), and physical activity level. The 3C Db-mineral model was used to obtain reference measures of %BF (%BF3C) for comparison with body-composition measures from DXA and hydrodensitometry. For men (n = 110) and women (n = 110), %BF3C (14.0% BF and 24.4% BF, respectively) was more accurately estimated by Siri’s 2C formula (%BFSiri; men, r = 0.97, SEE = 1.77% BF; women, r = 0.98, SEE = 1.56% BF) than by DXA (%BFDXA; men, r = 0.86, SEE = 3.54% BF; women, r = 0.88, SEE = 3.73% BF). The average %BFSiri (men, 15.8% BF; women, 24.7% BF) and %BFDXA (men, 16.2% BF; women, 26.0% BF) differed significantly (P < 0.001) from %BF3C. Siri’s 2C model estimated the average %BF3C in this sample more accurately than DXA did.

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Ann M. Swartz, Sergey Tarima, Nora E. Miller, Teresa L. Hart, Elizabeth K. Grimm, Aubrianne E. Rote and Scott J. Strath

The purpose of the study was to determine the relationship between sedentary behavior (SB), physical activity (PA), and body fat (total, abdominal) or body size (body-mass index [BMI], waist circumference [WC]) in community-dwelling adults 50 yr old and over. This study included 232 ambulatory adults (50–87 yr, 37.4% ± 9.6% body fat [BF]). Average daily time spent in SB (<100 counts/min) and light (100–759 counts/min), lifestyle-moderate (760–1,951 counts/min), walking-moderate (1,952–5,724cts/min), and vigorous-intensity (≥5,725 counts/min) PA were determined by accelerometer and corrected for wear time. BF was measured with dual-energy X-ray absorptiometry. SB was positively related to measures of BF. Measures of SB, PA, and gender accounted for 55.6% of the variance in total BF, 32.4% of the variance in abdominal fat, and 28.0% of the variance in WC. SB, PA, and age accounted for 27.1% of the variance in BMI. Time spent in SB should be considered when designing obesity interventions for adults 50 yr old and over.

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Melissa Hodge, Mary Hovinga, Kelley Gabriel, Linda Snetselaar, John Shepherd, Linda Van Horn, Victor Stevens, Brian Egleston, Alan Robson, Seungyoun Jung and Joanne Dorgan

This study prospectively investigates associations between youth moderate-to-vigorous-intensity physical activity (MVPA) and body composition in young adult women using data from the Dietary Intervention Study in Children (DISC) and the DISC06 Follow-Up Study. MVPA was assessed by questionnaire on 5 occasions between the ages 8 and 18 years and at age 25-29 years in 215 DISC female participants. Using whole body dual-energy x-ray absorptiometry (DXA), overall adiposity and body fat distribution were assessed at age 25-29 years by percent body fat (%fat) and android-to-gynoid (A:G) fat ratio, respectively. Linear mixed effects models and generalized linear latent and mixed models were used to assess associations of youth MVPA with both outcomes. Young adult MVPA, adjusted for other young adult characteristics, was significantly inversely associated with young adult %fat (%fat decreased from 37.4% in the lowest MVPA quartile to 32.8% in the highest (p-trend = 0.02)). Adjusted for youth and young adult characteristics including young adult MVPA, youth MVPA also was significantly inversely associated with young adult %fat (β=-0.40 per 10 MET-hrs/wk, p = .02) . No significant associations between MVPA and A:G fat ratio were observed. Results suggest that youth and young adult MVPA are important independent predictors of adiposity in young women.

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Katherine A. Beals and Amanda K. Hill

The purpose of this study was to examine the prevalence of disordered eating (DE), menstrual dysfunction (MD), and low bone mineral density (BMD) among US collegiate athletes (n = 112) representing 7 different sports (diving, swimming, x-country, track, tennis, field hockey, and softball) and determine differences in prevalence existed between athletes participating in lean-build (LB) and non-lean build (NLB) sports. DE and MD were assessed by a health, weight, dieting, and menstrual history questionnaire. Spinal BMD was determined via dual energy x-ray absorptiometry. Twenty-eight athletes met the criteria for DE, twenty-nine for MD, and two athletes had low BMDs (using a Z score below −2.0). Ten athletes met the criteria for two disorders (one with disordered eating and low BMD and nine with disordered eating and menstrual dysfunction), while only one athlete met the criteria for all three disorders. Using a Z score below −1.0, two additional athletes met the criteria for all three disorders and three more athletes met the criteria for a combination of two disorders. With the exception of MD, which was significantly more prevalent among LB vs. NLB sports (P = 0.053), there were no differences between the groups in the prevalence of individual disorders or combinations of disorders. These data indicate that the combined prevalence of DE, MD, and low BMD among collegiate athletes is small; however, a significant number suffer from individual disorders of the Triad.