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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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Ann L. Gibson, Vivian H. Heyward and Christine M. Mermier

This study assessed the predictive accuracy of a new hand-held, segmental, bioimpedance (BI) analyzer in estimating the relative body fat (%BF) of a sample of 25 men and 23 women (18–55 years, 7.0 to 42.8%BFHW). The reference method was hydrostatic weighing (HW) at residual lung volume. The %BF estimates obtained from manufacturer’s (Omron) gender-specific equations were cross-validated. There were high validity coefficients (ry,y=.91 and .83, for men and women, respectively), moderate prediction errors (SEE = 3.46%, E = 3.64%BF for men; SEE = 4.04%, E = 3.87%BF for women), and no significant difference (p >.05) between the average %BFHW and %BFOmron for women (21.8% vs. 2I.6%BF, respectively). For men, there was a small but significant (p < .05) difference in %BFHW (18.7%) and %BFOmron (20.1 %). For both men and women, the line of identity did not differ significantly (p > .05) from the line of best fit. The Omron® BI equations accurately estimated the %BF of 72% of the men and 65% of the women in this sample within ±3.5%BF. Therefore, use of the Omron® BI analyzer is suitable for assessing the %BF of adults having demographic characteristics similar to those of this sample.

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Kerri L. Vasold, Andrew C. Parks, Deanna M.L. Phelan, Matthew B. Pontifex and James M. Pivarnik

Body composition is a key component of health-related fitness and often used as a tool for risk assessment or as a measure of change in physical activity or diet. A variety of situations require the use of accurate body composition measurement techniques. There are various methods used to assess

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Gregory Severino, Marcos Sanchez-Gonzalez, Michelle Walters-Edwards, Michael Nordvall, Oksana Chernykh, Jason Adames and Alexei Wong

that traditional exercise, such as aerobic and resistance training, improves HRV and body composition in several populations. However, due to perceived or actual barriers associated with traditional exercise (e.g., musculoskeletal discomfort, lack of motivation, reduced physical activity) many obese

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Grant M. Tinsley and Brett S. Nickerson

When estimating body composition, a pervasive recommendation is to perform assessments after a period of rest and fasting. This recommendation seeks to minimize biological error induced by daily activities, such as food and fluid ingestion or exercise. Overnight fasts are implemented for a variety

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Donna W. Lockner, Vivian H. Heyward, Sharon E. Griffin, Martim B. Marques, Lisa M. Stolarczyk and Dale R. Wagner

The Segal fatness-specific bioelectrical impedance (BIA) equations are useful for predicting fat-free mass (FFM). Stolarczyk et al, proposed a modified method of averaging the two equations for individuals who are neither lean nor obese, thus eliminating the need to know % BF a priori. To cross-validate this modification, we compared FFM determined using the averaging method versus hydrostatic weighing for 76 adults. Per the averaging method, accuracy for males was excellent (r = .91, SEE = 2.7kg, E = 2.7kg), with 78% of individuals within ± 3.5% BF predicted by hydrostatic weighing. Accuracy for females was lower (r = .88, SEE = 3.0kg, E = 3.1 kg), with %BF of 51% within ±3.5% of the reference method. The relative ease and practicality of the averaging method and the results of this study indicate this method may be useful with a diverse group.

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Chia-Lin Li, Feng-Hsuan Liu and Jen-Der Lin

The purpose of this prospective study was to examine the effect of physical activity independent of obesity on metabolic risk factors. A total of 358 participants were recruited from the Department of Health Management of Chang Gung Medical Center. Physical activity was assessed using a 3-d activity record. Body-mass index (BMI) and metabolic risk factors were also assessed. Our findings demonstrate that an effect of obesity that was statistically independent of the levels of physical activity is associated with metabolic risk factors. Moreover, physical activity displayed inverse associations with triglycerides, and fasting plasma glucose and a positive association with HDL cholesterol. Those participants with time spent in moderate activity more than 0.5 h each day had significantly less risk of high fasting glucose. Significantly, these associations were independent of BMI.

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Pedro Curi Hallal, Felipe Fossati Reichert, Fernando Vinholes Siqueira, Samuel Carvalho Dumith, Juliano Peixoto Bastos, Marcelo Cozzensa da Silva, Marlos Rodrigues Domingues, Mario Renato Azevedo and Ulf Ekelund

Objectives:

The objective of this study was to evaluate physical activity (PA) levels in adults and their association with sex, age, and education level across categories of body mass index (BMI).

Methods:

We conducted a population-based, cross-sectional study including 3100 individuals age ≥20 years living in Pelotas, Brazil. PA was assessed using the leisure-time section of the long International Physical Activity Questionnaire. “No PA” was defined as zero minutes of activity/week; “insuffcient PA” was defined as <150 minutes of activity/week; “high PA” was defined as ≥500 minutes of activity/week. BMI was categorized into normal (<25 kg/m2), overweight (25–29.9 kg/m2), and obesity (≥30 kg/m2).

Results:

The prevalence of insufficient PA was 71.6% among normal BMI subjects, 71.3% among overweight individuals, and 73.7% among obese ones (P = .67). No PA and high PA were also not associated with BMI. The associations between sex, age, and education level and PA levels tended to be stronger among normal-weight individuals compared with overweight and obese individuals. Among the obese, most associations were not significant. Among normal-weight individuals, higher PA levels were observed in men, young adults, and those with higher education.

Conclusions:

Variables associated with leisure-time PA differed between normal-weight, overweight, and obese individuals. Studies on PA correlates might benefit from stratifying by BMI.

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David P. MacKinnon, Linn Goldberg, JeeWon Cheong, Diane Elliot, Greg Clarke and Esther Moe

This research examined the relationships among body attributes (i.e., body fat percent and bench press performance) and psychological esteem (i.e., perceived athletic competence, body image, and general self-esteem) in high school football players. Structural equation modeling was used to model the relationships among the constructs. Body fat was negatively related to athletic competence and body image, which in turn were positively related to general self-esteem. The role of bench press performance in predicting psychological esteem was inconsistent, however, suggesting that leanness may be more important than body strength for adolescent psychological esteem among high school football players.

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Alison Schinkel-Ivy, Timothy A. Burkhart and David M. Andrews

To date, there has not been a direct examination of the effect that tissue composition (lean mass/muscle, fat mass, bone mineral content) differences between males and females has on how the tibia responds to impacts similar to those seen during running. To evaluate this, controlled heel impacts were imparted to 36 participants (6 M and 6 F in each of low, medium and high percent body fat [BF] groups) using a human pendulum. A skin-mounted accelerometer medial to the tibial tuberosity was used to determine the tibial response parameters (peak acceleration, acceleration slope and time to peak acceleration). There were no consistent effects of BF or specific tissue masses on the un-normalized tibial response parameters. However, females experienced 25% greater peak acceleration than males. When normalized to lean mass, wobbling mass, and bone mineral content, females experienced 50%, 62% and 70% greater peak acceleration, respectively, per gram of tissue than males. Higher magnitudes of lean mass and bone mass significantly contributed to decreased acceleration responses in general.