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Herculina S. Kruger, Lize Havemann-Nel, Chrisna Ravyse, Sarah J. Moss and Michael Tieland

Background:

Black women are believed to be genetically less predisposed to age-related sarcopenia. The objective of this study was to investigate lifestyle factors associated with sarcopenia in black South African (SA) urban women.

Methods:

In a cross-sectional study, 247 women (mean age 57 y) were randomly selected. Anthropometric and sociodemographic variables, dietary intakes, and physical activity were measured. Activity was also measured by combined accelerometery/heart rate monitoring (ActiHeart), and HIV status was tested. Dual energy x-ray absorptiometry was used to measure appendicular skeletal mass (ASM). Sarcopenia was defined according to a recently derived SA cutpoint of ASM index (ASM/height squared) < 4.94 kg/m2.

Results:

In total, 8.9% of the women were sarcopenic, decreasing to 8.1% after exclusion of participants who were HIV positive. In multiple regressions with ASM index, grip strength, and gait speed, respectively, as dependent variables, only activity energy expenditure (β = .27) was significantly associated with ASM index. Age (β = –.50) and activity energy expenditure (β = .17) were significantly associated with gait speed. Age (β = –.11) and lean mass (β = .21) were significantly associated with handgrip strength.

Conclusions:

Sarcopenia was prevalent among these SA women and was associated with low physical activity energy expenditure.

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Peter N. Wiebe, Cameron J.R. Blimkie, Nathalie Farpour-Lambert, Julie Briody, Helen Woodhead, Chris Cowell and Robert Howman-Giles

The correlates and determinants of total body (TB), femoral neck (FN), greater trochanter (GT) and leg areal bone mineral density (aBMD), and FN volumetric (vol) BMD were investigated in 42 healthy 6–10-year-old girls. Predictor variables included age, height, weight, lean tissue mass (LTM), fat mass, percent body fat, physical activity level, calcium intake, isokinetic knee flexion and extension strength and endocrine (E2) status. Bone density and body composition were determined by dual energy-x-ray absorptiometry (DEXA), and pubertal status was self-determined. LTM, weight, age, knee extensor strength and fat mass were significantly correlated (Pearson correlation coefficients; 0.36 £ r ‡ 0.62) with TBaBMD. These same variables with the addition of height and knee flexor strength were significantly correlated (0.33 £ r ‡ 0.77) with leg aBMD. Only LTM correlated significantly with FNaBMD and none of the independent variables correlated with FNvolBMD or GTaBMD. Only LTM entered as a significant predictor in multiple linear regression analysis (R 2 = 46.7%) for TBaBMD. In conclusion, estradiol status, dietary calcium intake and physical activity level appeared not to be important predictors of BMD in this population, whereas LTM was consistently correlated with most BMD measures and was the single significant determinant of TBaBMD in this study.

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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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Michael R. Esco, Brett S. Nickerson, Sara C. Bicard, Angela R. Russell and Phillip A. Bishop

The purpose of this investigation was to evaluate measurements of body-fat percentage (BF%) in 4 body-mass-index- (BMI) -based equations and dual-energy X-ray absorptiometry (DXA) in individuals with Down syndrome (DS). Ten male and 10 female adults with DS volunteered for this study. Four regression equations for estimating BF% based on BMI previously developed by Deurenberg et al. (DEBMI-BF%), Gallagher et al. (GABMI-BF%), Womersley & Durnin (WOBMI-BF%), and Jackson et al. (JABMI-BF%) were compared with DXA. There was no significant difference (p = .659) in mean BF% values between JABMI-BF% (BF% = 40.80% ± 6.3%) and DXA (39.90% ± 11.1%), while DEBMI-BF% (34.40% ± 9.0%), WOBMI-BF% (35.10% ± 9.4%), and GABMI-BF% (35.10% ± 9.4%) were significantly (p < .001) lower. The limits of agreement (1.96 SD of the constant error) varied from 9.80% to 16.20%. Therefore, BMI-based BF% equations should not be used in individuals with DS.

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Alessandra Madia Mantovani, Scott Duncan, Jamile Sanches Codogno, Manoel Carlos Spiguel Lima and Rômulo Araújo Fernandes

Background:

Physical activity level is an important tool to identify individuals predisposed to developing chronic diseases, which represent a major concern worldwide.

Objective:

To identify correlates of daily step counts measured using pedometers, as well as analyze the associations between health outcomes and 3 different amounts of daily physical activity.

Methods:

The sample comprised 278 participants (126 men and 153 women) with a mean age of 46.51 ± 9.02 years. Physical activity was assessed using pedometers for 7 consecutive days, and 3 amounts of daily physical activity were considered: ≥10,000 steps/day, ≥7500 steps/day, and <5000 steps/day. Sleep quality was assessed through a questionnaire, and dual-energy x-ray absorptiometry was used to measure body fat. Sociodemographic and anthropometric data were also collected.

Results:

The percentages of adults achieving at least 10,000 and 7500 steps/day on a minimum of 5 days of the evaluated week were 12.9% and 30.9%, respectively. Adults who reached ≥7500 steps/day had a lower likelihood of being obese (odds ratio [OR] = 0.38, 95% confidence interval [CI], 0.17–0.85) and reporting worse sleep quality (OR = 0.58, 95% CI, 0.34–0.99). Adults who reached <5000 steps/day had a higher likelihood of reporting worse sleep quality (OR = 2.11, 95% CI, 1.17–3.82).

Conclusion:

Physical activity in adulthood, as measured by pedometer, constituted a behavior related to lower adiposity and better sleep quality.

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Nai-Hsin Meng, Chia-Ing Li, Chiu-Shong Liu, Wen-Yuan Lin, Chih-Hsueh Lin, Chin-Kai Chang, Tsai-Chung Li and Cheng-Chieh Lin

Objectives:

To compare muscle strength and physical performance among subjects with and without sarcopenia of different definitions.

Design:

A population-based cross-sectional study.

Participants:

857 community residents aged 65 years or older.

Methods:

Sarcopenia was defined according to the European Working Group of Sarcopenia in Older People consensus criteria. Dual-energy X-ray absorptiometry measured lean soft tissue mass. Sarcopenic participants with low height-adjusted or weight-adjusted skeletal muscle index (SMI) were classified as having h-sarcopenia or w-sarcopenia, respectively. Combined sarcopenia (c-sarcopenia) was defined as having either h- or w-sarcopenia. The participants underwent six physical performance tests: walking speed, timed up-and-go, six-minute walk, single-leg stance, timed chair stands, and flexibility test. The strength of five muscle groups was measured.

Results:

Participants with h-sarcopenia had lower weight, body mass index (BMI), fat mass, and absolute muscle strength (p ≤ .001); those with w-sarcopenia had higher weight, BMI, fat mass (p < .001), and low relative muscle strength (p ≤ .003). Participants with c-sarcopenia had poorer performance in all physical performance tests, whereas h-sarcopenia and w-sarcopenia were associated with poor performance in four tests.

Conclusion:

Subjects with h- and w-sarcopenia differ significantly in terms of obesity indicators. Combining height- and weight-adjusted SMIs can be a feasible method to define sarcopenia.

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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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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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Ana Anton-Solanas, Barry V. O’Neill, Tessa E. Morris and Joe Dunbar

Purpose:

To assess changes in body composition and monitor cognitive function, subjective well-being, and physiological stress, as measured by salivary hormones and markers of mucosal immunity, during an Antarctic expedition.

Methods:

A 36-y-old man (188.2 cm height, 94.5 kg body mass) took part in a world-record attempt. A total-body dual-energy X-ray absorptiometry scan and measurement of 8 skinfolds and 5 girths were performed before and after the expedition. In addition, daily subjective data were recorded (sleep quality, total hours of sleep, energy levels, perceived exertion, mood, muscle soreness, and muscle/joint pain) along with distance covered and hours of physical activity per day. As a measure of cognitive function, the athlete completed a computerized battery of tasks (Axon Sports Cognitive Priming Application) every third morning. Saliva samples were collected before, during, and after the expedition to determine salivary cortisol (sCort), testosterone (sT), alpha amylase (sAA), and secretory immunoglobulin A (sIgA).

Results:

The athlete lost 5.3 kg body mass and sum of 8 skinfolds decreased from 73 mm to 59 mm from preexpedition to postexpedition. Psychomotor speed declined over the course of the expedition. sT increased and sCort decreased throughout, and sAA and sIgA peaked toward the end of the expedition.

Conclusions:

This case study provides novel data about the physiological and cognitive impact of an Antarctic expedition. The findings may inform strategies for future expeditions, allowing individuals undertaking expeditions of this nature to better prepare for success.