The relative body fat and anthropometric prediction of body density of South Australian females aged 17-35 years

One hundred and thirty-five females were tested in order to: produce some normative percentage body fat (% BF) data on an Australian sample which represented a cross-section of physical activity patterns, cross-validate existing multiple regression equations which predict body density (BD) from anthropometric measurements, and if necessary develop population specific equations. Measurements were taken of 10 girths, 3 widths and 7 skinfolds. Body density was measured by underwater weighing with the residual volume (RV) being determined by helium dilution. The Siri equation was then used to convert BD to % BF. The % BF scores had an overall mean of 23.4 (range 10.8-49.2). The very active group (n = 45) had a significantly lower (p less than 0.05) relative body fat (X = 20.6% BF) than either the active (n = 45; 23.5% BF) or sedentary groups (n = 45; 26.2% BF). Previously published equations were found to have limited applicability to Australian subjects. A stepwise multiple regression was therefore used to develop the following equation (R = 0.893): BD(g X cm-3) = 1.16957-0.06447 (log10 sigma triceps, subscapular, supraspinale, front thigh, abdominal and calf skinfolds in mm)-0.00081 (gluteal girth in cm) + 0.0017 (forearm girth in cm) + 0.00606 (biepicondylar humerus breadth in cm). Only those predictors which resulted in a statistically significant increase in r (p less than or equal to 0.05) were included. The standard error of estimate of 0.00568 g X cm-3 was equivalent to 2.6% BF at the mean.     

Plasma leptin in female athletes: relationship with body fat, reproductive, nutritional, and endocrine factors.

The relationship of leptin to thyroid and sex hormones, insulin, energy intake, exercise energy expenditure, and reproductive function was assessed in 39 female athletes. They comprised elite athletes who were either amenorrheic (EAA; n = 5) or cyclic (ECA; n = 8) and recreationally active women who were either cyclic (RCA; n = 13) or taking oral contraceptives (ROC; n = 13). Leptin was significantly lower in EAA (1.7 +/- 0.2 ng/ml) than in ECA (2.9 +/- 0.3 ng/ml), RCA (5.8 +/- 0.9 ng/ml), and ROC (7.4 +/- 1.3 ng/ml). Hypoleptinemia in EAA was paralleled by reductions (P < 0.05) in caloric intake, insulin, estradiol, and thyroid hormones. Leptin increased by 40-46% (P < 0.05) in the luteal phase of the menstrual cycle in RCA and ECA. Plasma leptin was similar in the placebo and active pill phases in ROC despite a significant increase in ethinylestradiol. Leptin correlated (P < 0.05) with triiodothyronine and insulin but not with estrogen, energy intake, or exercise energy expenditure. These data suggest that in female athletes 1) leptin may be a metabolic signal that provides a link between adipose tissue, energy availability, and the reproductive axis and 2) sex hormones do not directly regulate leptin secretion.     

Reliability and validity of body composition measures in female athletes.

The purpose of this investigation was to determine the reliability and validity of bioelectrical impedance (BIA) and near-infrared interactance (NIR) for estimating body composition in female athletes. Dual-energy X-ray absorptiometry was used as the criterion measure for fat-free mass (FFM). Studies were performed in 132 athletes [age = 20.4 +/- 1.5 (SD) yr]. Intraclass reliabilities (repeat and single trial) were 0.987-0.997 for BIA (resistance and reactance) and 0.957-0.980 for NIR (optical densities). Validity of BIA and NIR was assessed by double cross-validation. Because correlations were high (r = 0.969-0.983) and prediction errors low, a single equation was developed by using all 132 subjects for both BIA and NIR. Also, an equation was developed for all subjects by using height and weight only. Results from dual-energy X-ray absorptiometry analysis showed FFM = 49.5 +/- 6.0 kg, which corresponded to %body fat (%BF) of 20.4 +/- 3.1%. BIA predicted FFM at 49.4 +/- 5.9 kg (r = 0.981, SEE = 1.1), and NIR prediction was 49. 5 +/- 5.8 kg (r = 0.975, SEE = 1.2). Height and weight alone predicted FFM at 49.4 +/- 5.7 kg (r = 0.961, SEE = 1.6). When converted to %BF, prediction errors were approximately 1.8% for BIA and NIR and 2.9% for height and weight. Results showed BIA and NIR to be extremely reliable and valid techniques for estimating body composition in college-age female athletes.     

The role of body fat in female attractiveness

The purpose of the present study was to investigate the role of body fat percentage (BF%) on female attractiveness. To this end, a series of female body images were selected from a collection of dual-energy X-ray absorptiometry scans. Images were stratified by three levels (low, mid, and high) of waist-to-hip ratio (WHR) and seven levels (15%–50%) of BF%. These 21 images were presented in a random order and rated for attractiveness. Results indicate that WHR, BMI, and BF% are all significant predictors of female attractiveness when regressed separately (R²= 0.19, 0.70, and 0.76, respectively). When regressed simultaneously, all three variables accounted for 87% of the variance in image attractiveness, with only BF% and WHR being significant predictors. Further analysis revealed that body fat might disrupt the negative linear relationship between WHR and attractiveness. Men and women differed significantly in most categories of WHR and BF%, with men generally rating images as less attractive than women. These data indicate that BF% appears to be a strong cue for attractiveness and that the impact of WHR and BMI on attractiveness is dependent, in part, on BF%. The appearance of body fat may provide disruption in the visual cues of both shape and size of the female body, potentially impacting behavior.     

Estimation of body fat in female rhesus monkeys

Measurement of height (crown–rump length), body weight, and abdominal subcutaneous fat depth, based on skinfold thickness taken from 13 female rhesus monkeys comprising two age groups were correlated with body fat values derived from tritiated water determinations of total body water. The manner with which each measure was related to percent body fat differed as a function of age of the animal. In the young, nulliparous females, crown–rump length was the single best predictor of body fat, whereas in the older, multiparous females, skinfold thickness correlated most highly with body fat. When all measurements, including the Quetelet index [(wt/ht)² × 1,000], were combined statistically and regressed against percent body fat, a significant increase in predictive ability was obtained. When each age group was considered separately, the resulting equations again reflected the agegroup biases. In addition, as an internal check on the validity of the regression equations, an additional regression analysis was performed using morphometric data from selected animals in each age group. These equations yielded accurate estimates of body fat when compared to determinations made from total body water. These analyses indicate that the predictive accuracy of morphometric data is greatly enhanced by using these measurements in concert. Furthermore, the utility of such predictions is influenced by the specific physical characteristics of the subject population.     

Relative reliability of circumferences and skinfolds as measures of body fat distribution

The question has arisen whether patterns of body fat distribution can be identified by body circumferences, a method which is said to be more reliable and simpler than skinfold thickness or like measures of subcutaneous fat (Ashwell et al., Int. J. Obes. 6: 143-152, 1982). Here we address the question of whether body circumferences are inherently more reliable than skinfold thicknesses in 77 intra- and 224 interexaminer replicates from the Health Examination Survey of 12 to 17-year-olds in the U.S.A. Reliability of six body circumferences (0.96) was significantly (P less than .01) higher than that of skinfold thicknesses at five sites (0.91), suggesting that circumferences are a more reliable method. However, the reliability of skinfolds is still high, and skinfolds may be used in studies which focus on preadults or other groups in which the validity of circumferences as measures of body fat distribution is unknown.     

Evaluation of the BOD POD for estimating percent body fat in collegiate track and field female athletes: a comparison of four methods

This investigation examined the accuracy of the BOD POD on a group of Division I collegiate track and field female athletes (N = 30). Hydrostatic weighing (HW) was used as the gold standard method. Body density (Db) values obtained from the BOD POD (Db BP) were compared with those determined by HW (Db HW). Both Db values were converted to percent body fat (%BF) using the Siri equation for comparison. Percent body fat values obtained from the BOD POD (BF BP) were also compared with those obtained from dual-energy X-ray absorptiometry (DXA, BF DXA) and skinfold (SF, BF SF). The validity of the BOD POD was assessed using repeated-measures analysis of variance (ANOVA), and the relationship between the methods was examined through Pearson correlation. Average Db BP was 0.00890 g x cm(-3) lower (p < 0.05) than Db HW, resulting in a significant overestimation of %BF (p < 0.05) by the BOD POD. Values for BFDXA and BFBP also differed significantly (p < 0.05). On the other hand, BFSF and BF BP were not significantly different. The correlation between percent body fat values obtained from HW (BFHW) and BF BP was good (r = 0.88, SEE = 2.30) as well as between BF SF and BF BP (r = 0.85, SEE = 2.05). Conversely, the correlation between BFDXA and BF BP was poor (r = 0.25, SEE = 5.73). The strong correlation between BF BP and BF HW presented here suggests that the BOD POD has the potential to be used as a body composition analysis tool for female athletes. The advantages of the BOD POD over HW encourage further investigation of this instrument. However, the fact that the BOD POD and SF results did not differ significantly might suggest that the SF could be used in its place until a better rate of accuracy for this instrument is established.     

Evaluation of the BOD POD for estimating percent fat in female college athletes

The purpose of this investigation was to examine the accuracy of percent body fat (%BF) estimates obtained by air displacement plethysmography (ADP) using the BOD POD Body Composition System compared with hydrostatic weighing (HW) in a group of female college athletes (n = 80). In addition, %BF estimates by skinfold measures (SF) were also obtained for comparison. A lean subset (n = 39) of the sample was also examined. Mean %BF estimated for the entire sample by ADP (21.2 +/- 5.9%) was significantly greater than that determined by HW (19.4 +/- 6.4%) and SF (18.8 +/- 5.5%). Results from the lean subset also revealed that %BF determined by ADP (17.1 +/- 3.7%) was significantly higher than %BF estimates by HW (14.3 +/- 2.8%) and SF (15.2 +/- 3.2%). The regression equation for the entire sample (%BF HW = 0.937%BF ADP - 0.452, r(2) = 0.73, standard error of estimates (SEE) = 3.34) did not differ from the line of identity. In contrast, the line of identity differed significantly from the regression equation for the lean subset of female athletes (%BF HW = 0.48%BF ADP + 6.115, r(2) = 0.41, SEE = 2.18). The results of this investigation indicate that ADP significantly overestimated %BF by 8% in female athletes and by 16% for a leaner subset of the sample compared with HW. It appears that %BF estimates by SF may be more accurate than those obtained by ADP for female college athletes, regardless of body composition. Coaches and trainers evaluating body composition should consider the use of SF before ADP when measuring %BF in female college athletes. Sports scientists should continue to examine the possible gender and body composition bias for ADP.     

New percentage body fat prediction equations for Japanese males

Anthropometry is simple, cheap, portable and non-invasive method for the assessment of body composition. While the Nagamine and Suzuki body density prediction equation has been frequently used to estimate %BF of Japanese, the equation was developed more than 40 years ago and its applicability to the current Japanese population has not been studied. This study aimed to compare %BF results estimated from anthropometry and dual energy X-ray absorptiometry (DXA) in order to examine applicability of the Nagamine and Suzuki equation. Body composition of 45 Japanese males (age: 24.3+/-5.5 years, stature: 171.6+/-5.8 cm, body mass: 62.6+/-7.1 kg, %BF: 15.7+/-5.6%) were assessed using whole-body DXA (Hologic QDR-2000) scan and anthropometry using the protocol of the International Society for the Advancement of Kinanthropometry (ISAK). From anthropometric measurements %BF was calculated using the Nagamine and Suzuki equation. The results showed that the Nagamine and Suzuki equation significantly (p<0.05) underestimated %BF of Japanese males compared to the DXA results. There was a trend towards greater underestimation as the estimated %BF values using DXA increased. New %BF prediction equations were proposed from the DXA and anthropometry results. Application of the proposed equations may assist in more accurate assessment of body fatness in Japanese males living today.     

New percentage body fat prediction equations for Japanese females

Anthropometry is a simple and cost-efficient method for the assessment of body composition. However prediction equations to estimate body composition using anthropometry should be 'population-specific'. Most popular body composition prediction equations for Japanese females were proposed more than 40 years ago and there is some concern regarding their usefulness in Japanese females living today. The aim of this study was to compare percentage body fat (%BF) estimated from anthropometry and dual energy x-ray absorptiometry (DXA) to examine the applicability of commonly used prediction equations in young Japanese females. Body composition of 139 Japanese females aged between 18 and 27 years of age (BMI range: 15.1-29.1 kg/m(2)) was measured using whole-body DXA (Lunar DPX-LIQ) scans. From anthropometric measurements %BF was estimated using four equations developed from Japanese females. The results showed that the traditionally employed prediction equations for anthropometry significantly (p<0.01) underestimate %BF of young Japanese females and therefore are not valid for the precise estimation of body composition. New %BF prediction equations were proposed from the DXA and anthropometry results. Application of the proposed equations may assist in more accurate assessment of body fatness in Japanese females living today.     

Standard anthropometric, body composition, and strength variables as predictors of jumping performance in elite junior athletes

The aim of the study was to investigate whether variables routinely assessed while testing athletes can also predict movement performance. The relation between jumping performance and standard strength, anthropometric, and body composition variables was examined in elite junior basketball players. The 33 males were tested for maximal vertical jump, as well as for maximal isometric voluntary force and rate of force development of hip and knee extensors. Standard anthropometric and body composition measures (body height, lean body mass, as well as the percentage of fat and muscle tissue) were also taken. Except for maximal isometric forces (0.38 and 0.52 N.kg(-1) for hip and knee extensors, respectively), all correlation coefficients between the selected variables and jump height were insignificant. As a consequence, the corresponding multiple correlation coefficient, R = 0.71, also suggested a moderate predictability of jumping performance by the standard strength tests and anthropometric and body composition variables. The results obtained dispute the use of the examined tests in sport performance assessment, and also question applying the tests for other purposes such as evaluation of training procedures or selection of young athletes. Therefore, the results are in line with the concept that a reliable performance assessment in homogeneous groups of athletes requires predominantly movement-specific testing.     

Menstrual state and exercise as determinants of spinal trabecular bone density in female athletes.

OBJECTIVE--To study the effects of amenorrhoea and intensive back exercise on the bone mineral density of the lumbar spine in female athletes. DESIGN--Cross sectional study comparing amenorrhoeic with eumenorrhoeic athletes and rowers with non-rowers. SETTING--The British Olympic Medical Centre, Northwick Park Hospital. PATIENTS--46 Elite female athletes comprising 19 rowers, 18 runners, and nine dancers, of whom 25 were amenorrhoeic and 21 eumenorrhoeic. MAIN OUTCOME MEASURE--Trabecular bone mineral density of the lumbar spine measured by computed tomography. RESULTS--Mean trabecular bone mineral density was 42 mg/cm3 (95% confidence interval 22 to 62 mg/cm3) lower in the amenorrhoeic than the eumenorrhoeic athletes; this difference was highly significant (p = 0.0002). Mean trabecular bone mineral density was 21 mg/cm3 (1 to 41 mg/cm3) lower in the non-rowers than the rowers; this was also significant (p = 0.05). There was no interaction between these two effects (p = 0.28). CONCLUSION--The effect of intensive exercise on the lumbar spine partially compensates for the adverse effect of amenorrhoea on spinal trabecular bone density.     

Patterns of eye movements when male and female observers judge female attractiveness, body fat and waist-to-hip ratio

Behavioural studies of the perceptual cues for female physical attractiveness have suggested two potentially important features: body fat distribution [the waist-to-hip ratio (WHR)] and overall body fat [often estimated by the body mass index (BMI)]. However, none of these studies tell us directly which regions of the stimulus images inform observers' judgments. Therefore, we recorded the eye movements of three groups of 10 male observers and three groups of 10 female observers, when they rated a set of 46 photographs of female bodies. The first sets of observers rated the images for attractiveness, the second sets rated for body fat and the third sets for WHR. If either WHR and/or body fat is used to judge attractiveness, then observers rating attractiveness should look at those areas of the body which allow assessment of these features, and they should look in the same areas when they are directly asked to estimate WHR and body fat. So we are able to compare the fixation patterns for the explicit judgments with those for attractiveness judgments and infer which features were used for attractiveness. Prior to group analysis of the eye-movement data, the locations of individual eye fixations were transformed into a common reference space to permit comparisons of fixation density at high resolution across all stimuli. This manipulation allowed us to use spatial statistical analysis techniques to show the following: (1) Observers' fixations for attractiveness and body fat clustered in the central and upper abdomen and chest, but not the pelvic or hip areas, consistent with the finding that WHR had little influence over attractiveness judgments. (2) The pattern of fixations for attractiveness ratings was very similar to the fixation patterns for body fat judgments. (3) The fixations for WHR ratings were significantly different from those for attractiveness and body fat.