Age‐related pattern of body density and body composition of Japanese men and women 18–59 years of age

Age‐related patterns of body size and composition were studied in a cross‐sectional sample of Japanese adults 18–59 years of age. Height, weight, the body mass index (BMI), body density (BD), percentage body fat (%Fat), fat mass (FM), fat‐free mass (FFM), and the sum of seven skinfold thicknesses (SF) of 288 men and 552 women were considered. Body density was measured by underwater weighing densitometry. Mean values of height, weight, BMI, BD, %Fat, FM, FFM, and SF of males were 169.0 cm, 65.3 kg, 22.8 kg/m², 1.0600 g/ml, 17.0%, 11.4 kg, 53.9 kg, and 95.0 mm, respectively, while corresponding values for females were 157.4 cm, 52.9 kg, 21.4 kg/m², 1.0420 g/ml, 24.4%, 13.1 kg, 39.7 kg, and 128.2 mm, respectively. Height, BD, and FFM correlated negatively with age in both sexes, while weight, BMI, %Fat, FM, and SF correlated positively with age. The highest BD and the lowest %Fat were observed in males ages 20 to <25 years (G20) and in females 25 to <30 years (G25). The lowest BD and highest %Fat were observed in G50 in both sexes. Correlations among parameters of body size and composition were stable with age in each sex. Height correlated negatively with BMI and %Fat in females, but not in males. In males, FM started to increase between G20 and G25 and continued to increase until G50, while SF and BMI remained stable during this period. In females, FM accumulation started around 30 years of age and continued until G50 and was accompanied by increases in SF and BMI. Am. J. Hum. Biol. 14:743–752, 2002. © 2002 Wiley‐Liss, Inc.     

Age‐related pattern of body density and body composition in Japanese males and females, 11 and 18 years of age

The age‐related pattern of body density and body composition in Japanese males (n = 266) and females (n = 318), 11.00 to 18.99 years of age was studied. Body density (BD) as well as height, body weight, and seven skinfold thicknesses were measured. Percentage fat (%Fat) was calculated using the age‐ and sex‐specific equation of Lohman. Fat mass (FM), fat‐free mass (FFM), and the body mass index (BMI) were calculated. The trend for BD in males was lowest at 11 years (1.0530 g/ml) and increased to 1.0695 g/ml at 14 years, and then decreased slightly at 15 to 17 years. In female, BD decreased from 1.0530 g/ml at 13 years to 1.0424 g/ml at 17 years. Mean %Fat was highest in males at 11 years (15.8%), and lowest at 14 years (10.1%). The highest mean %Fat in females occurred at 16 years (22.8%), and the lowest at age 11 years (15.2%). Overall, only 6.8% of males and 3.1% of females were classified as obese. Between 11 and 18 years, FFM of males differed by 20.7 kg or 67.9%, whereas females showed a difference of only 10.8 kg or 34.7%. Consequently, age effects explained approximately 60% of the male variance of FFM but only 26% in females. Body density of each sex and age group in this study did not differ significantly from previous Japanese studies, and the pooled BD data for 1,457 Japanese including the present study are reported as a reference. Am. J. Hum. Biol. 14:327–337, 2002. © 2002 Wiley‐Liss, Inc.     

The utility of generalized girth and skinfold equations to predict body composition in women runners

Although generalized equations to predict body composition exist, the validity of these equations when applied to a homogeneous group of athletic women is uncertain. Sixty-five women runners (age = 28.3 ± 6.4 yrs; ht = 166.8 ± 6.2 cm; wt = 58.9 ± 6.6 kg; body density (D_b) = 1.047 ± 0.009 g · cc^?1; percentage body fat (%BF) = 22.1 ± 3.7%; V?O₂max = 56.0 ± 5.3 ml/kg · min^?1; training volume = 45.8 ± 16.0 km · wk^?1) were used to cross-validate the Jackson, Pollock, and Ward (1980) generalized quadratic skinfold equations (JPW) and the Tran and Weltman (1989) generalized girth equation (TW). Additionally, the average of TW and the JPW quadratic skinfold equations were calculated and compared to hydrostatic weighing (HW). None of the JPW equations nor the TW equation accurately predicted D_b (P <0.05). All JPW equations underpredicted %BF with values ranging from 16.3–19.7%. Correlations ranged from r = 0.73 to r = 0.79. Standard errors (SE = [∑(Y ? Y′)²/N]^1/2) for predicting %BF ranged from 6.6% to 3.9%. The TW equation underestimated body density (1.041 ± 0.008) with a correlation of r = 0.54 and a SE of 4.2%. When the results of the JPW sum of 4 skinfolds (or the sum of 7 skinfolds) was averaged with TW, no significant mean differences in D_b or %BF were observed and the standard errors were 2.7%. Additionally, a population specific equation was derived using skinfolds and girths (n = 40) and was shown to accurately predict body density in a cross-validation sample of women runners (n = 25). This equation yielded a correlation of r = 0.72 and a SE = 2.7%. It was concluded that the combination of skinfold and girth techniques is superior to either method alone when predicting body composition in women runners. © 1993 Wiley-Liss, Inc.     

Skeletal differences between black and white men and their relevance to body composition estimates

Skeletal differences exist between closely matched Black and White women, although it is unknown if similar differences also exist between Black and White men after controlling for age, body weight, and stature. The aim of this study was twofold: to test the hypothesis that Black men have greater bone mass, higher bone mineral density, and longer limbs compared to White men of similar age, weight, and height; and second, to establish if ethnic variation in skeletal characteristics has an impact on the models upon which three widely used methods for estimating total body fat are based. Twenty-four healthy Black men were matched by age (±5 years), height (±3 cm), and weight (±2 kg) to 24 healthy White men. Skeletal characteristics and body composition were studied using anatomical and compartment estimates derived by anthropometry, ³H₂O dilution, hydrodensitometry, whole-body ⁴⁰K counting, and dual photon systems. Black men had greater bone mineral mass (P = 0.007), higher bone density (P = 0.054), longer femurs (P = 0.002), longer anthropometric arm and thigh lengths (P = 0.001 and P = 0.002, respectively), lower spine to femur ratio (P = 0.004), and similar spine length (P = 0.271) compared to White men. Total body fat and fat-free body mass (FFM) were estimated in the men using a four-compartment model. Black and White men had similar total body fat, K (TBK), water (TBW), and FFM. Density of FFM and TBK/FFM were also similar between Black and White men, suggesting that current two-compartment hydrodensitometry and TBK models for estimating fat may not require adjustments for ethnicity. The TBW/FFM ratio, which is the main assumed steady-state relation for the two-compartment TBW method of estimating fat, was modestly increased (P = 0.05) in Black men (x? ± SD, 0.744 ± 0.018) compared to White men (0.732 ± 0.021). These results confirm that Black and White men differ significantly in some skeletal characteristics and these differences have implications in the study of both osteoporosis and human body composition. © 1994 Wiley-Liss, Inc.     

Body composition estimates using different measurement techniques in a sample of highland subsistence farmers in Guatemala

This study aims at assessing the accuracy of estimates of body composition provided by bioimpedance (BIA) equations developed for U.S. populations when applied to a sample of Guatemalan farmers. If these equations were shown to have low validity, the second objective was to develop more accurate estimates of fat-free mass (FFM). One hundred males and females 19 to 45 years of age were randomly selected from four rural communities in the Western Highlands of Guatemala. Bioimpedance equations explained 59 and 33% of the variation in FFM, with a RMSE of 2.7 and 2.8 kg in males and females, respectively. Body fat (BF) predictions had a lower R². Using the “all possible regressions” procedure, the best subset for prediction of FFM used anthropometric and BIA variables as predictors. The best model for men and women included only anthropometric variables: 75% of the variance in FFM for men and 70% of the variance in women was explained by this model. The RMSE was 2.1 and 1.9 kg for both groups, respectively. It is concluded that FFM can be estimated from anthropometric dimensions with a high degree of accuracy and use of BIA does not provide more valid estimates.     

Change in body mass index is a stronger predictor of change in fat mass than lean mass in elderly black and white women

The aim of this study was to determine the relation between change in body mass index (BMI) and changes in fat mass (FM), lean soft tissue (LST), and percentage body fat (%Fat) in elderly (67.6 ± 6.0 years) women varying in race (53 black, 144 white) who underwent measurements of BMI, FM, LST, and %Fat at baseline and after 2 years. The group did not markedly change body composition over 2 years (BMI = ?0.1 ± 1.5 kg/m², P = 0.53; FM = 0.0 ± 2.8 kg, P = 0.95; LST = ?0.4 ± 1.7 kg, P < 0.001; %Fat = 0.3 ± 2.0%, P = 0.06). Change in BMI predicted change in FM (r = 0.90, SEE = 1.19 kg FM, P < 0.001) but was less predictive of change in %Fat (r = 0.64, SEE = 1.54%Fat, P < 0.001). Change in BMI was curvilinearly related to change in LST adjusted for change in height (R = 0.76, SEE = 1.10 kg LST, P < 0.001). Change in BMI more strongly predicts change in FM than LST and could be used to monitor change in FM in community‐dwelling women. Am. J. Hum. Biol., 2009. © 2008 Wiley‐Liss, Inc.     

Multicompartment model of body composition assessment in Chinese-American adults

Using hydrodensitometry, dual energy x-ray absorptiometry, and deuterium dilution techniques, multiple compartment body composition assessment was performed on 29 adult Chinese-American men (n = 11) and women (n = 18). The purpose of the investigation was to determine if significant differences exist in the estimation of percentage of body fat (%BF) and fat-free mass (FFM), based on 2-, 3-, and 4-compartment models of body composition. Height, weight, and the body mass index (BMI) for the men were 170 cm, 63 kg, and 22 kg/m²; for the women, values were 161 cm, 59 kg, and 23 kg/m², respectively. Estimated values for %BF from density alone and density adjusted for TBW were not significantly different for either the men or women (20.5% vs. 18.8%) and (28.2% vs. 27.4%). However, %BF estimated from the 4-compartment model of density, TBW and BMC resulted in significantly lower values for both groups, 17.5% for men and 26.8% for women. The lack of a significant difference in %BF between density only and density adjusted for TBW indicates that TBW was within the accepted constancy value associated with hydrodensitometry. When density was adjusted for variation in both TBW and BMC, a significant decline occurred in the estimate of %BF for men, but not for women. The average TBW to FFM ratio was 0.75., 0.74, and 0.73 when using FFM values from 2-, 3-, and 4-compartment models, respectively. The average BMC to FFM ratio from two-, three-, and four-compartment estimates of FFM were 0.054, 0.053, and 0.052 for the men and 0.060, 0.059, and 0.059 for the women. The results suggest that Chinese-American men and women have similar TBW/FFM ratios, but the BMC/FFM ratio is higher in women than men. Am. J. Hum. Biol. 9:21–27 © 1997 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Body composition measures from underwater weighing and dual energy X-ray absorptiometry in black and white girls: A comparative study

The purpose of this study was to compare estimates of body composition in two ethnic groups, 31 black and 38 white girls 10 through 16 years of age, to establish accurate and precise laboratory standards for field measures of body composition in the NHLBI Growth and Health Study HC 55025. The dual energy X-ray absorptiometry (DXA) measures of fat free mass (FFM) and % body fat (%BF) were made using Hologic QDR-1000/W. Corresponding values of FFM and %BF from underwater weighing (UWW) were determined using the two-component model of Siri, and these were corrected using the model of Lohman for white girls only. In the comparison of the different models and methods, the two-component model overestimated FFM compared to estimates from DXA for black girls, as did the corrected Lohman model for white girls. The two-component model significantly overestimated %BF in both white and black girls compared to corresponding estimates from DXA. The ratio of bone mineral content (BMC)/FFM affected the degree of %BF differences in black girls but not in white girls. Also, as the density of FFM increased or approached adult status in black girls (BMC/FFM increased), differences between the two-component model and estimates from DXA decreased. In both groups of girls, the relationship of %BF from UWW and DXA are a function of the level of body fatness. DXA values of %BF are greater than those from UWW under about 24% body fat, but the converse occurs above 25% body fat. The inability of UWW using the two-component model to account for the body composition in these girls can be corrected in part by measuring the variables for a multicomponent model or more easily by using DXA estimates of body composition. © 1994 Wiley-Liss, Inc.     

Influence of training,sex, age and body mass on the energy cost of running

Summary To highlight the influences of age, sex, body mass (m _b) and running training on the energy cost of running (C _r) young basketball players [38 boys (BB) and 14 girls (BG), aged 14.2 (SD 0.3) and 12.2 (SD 1.9) years, respectively] were selected to be compared to middle-distance runners [27 men (MR) and 14 women (FR) aged 23.7 (SD 3.4) and 23.9 (SD 4.1) years, respectively]. TheC _r was measured during a maximal treadmill test. In each groupC _r and body mass (m _b) and body height were negatively and significantly correlated. A stepwise regression showed that among both the body dimensions measured,m _b was the most important factor in determining the variations ofC _r For the whole group (n=93) the correlation coefficient was 0.72 (P<0.0001). For a givenm _b, there was no significant difference between theC _r of BG, BB and MR: this result would support the hypothesis that the differences inC _r currently attributed to age, running training or sex differences are mainly related tom _b. On the other hand, for a givenm _b, FR showed a significantly lower Cr than the basketball players (P<0.01 for BG and BB) and than MR (P<0.05), thus suggesting that women decrease theirC _r as a response to running training more efficiently than do men.     

Allometric scaling of isokinetic peak torque: the Nebraska Wrestling Study

Allometric scaling has been used increasingly in the exercise sciences to control statistically for body size differences in physical performance variables. The purpose of this study was to use multivariate allometric scaling to examine the influence of fat-free mass (FFM) on age-related differences in strength in young club (8–13 years) and high-school (14–18 years) wrestlers. The dependent variables were log-transformed values of isokinetic peak torque for leg extension and flexion at 0.52, 3.14, and 5.24 rad?·?s^?1 (30, 180, and 300?·?s^?1). The independent variables used in the multiple regression analyses were log-transformed values for FFM, age, and the FFM versus age interaction. The resulting regression equations were of the form: log?Y?=?log?a?+?b ₁ log?X ₁?+?b ₂?log?X ₂ ?+?b _n?log?X _n. The initial multiple regression analyses showed significant interaction effects (P??1. For the high-school wrestlers, both FFM and age were significant for the extension data, but only FFM was significant for the flexion data. All FFM exponents included 1.0 in the 95% confidence interval. These results indicate that the relationship between FFM and peak torque differed across age. In addition, with the exception of the flexion data for the high-school wrestlers, within each group increases in isokinetic peak torque occurred across age, independent of increases in FFM. The causes of the age effect for strength are speculative, but it may be due to developmental changes in neuromuscular function, alterations in the distribution of muscle mass as a percentage of FFM and/or the distribution of FFM across body segments.     

Assessment of exercise-induced alterations in body composition of patients with coronary heart disease

Summary The porpose of this study was to determine the effects of exercise habituation on body composition and anthropometric characteristics in cardiac patients. The subjects, comprising 20 patients with coronary heart disease, aged 43–69, participated in our supervised exercise programme for 38.0 (SD 12.5) weeks while in hospital. The intensity of most exercise was set at the lactate threshold. Analyses of the data indicated that small but significant reductions were observed in body mass (m _b) [–1.4 (SD 1.8) kg], abdominal girth [–1.4 (SD 2.6) cm], chest girth [–1.3 (SD 1.8) cm], body mass index [–0.6 (SD 0.7)], and skinfold thicknesses at all the sites measured. As expected, fat-free mass, derived from either bio-electrical impedance (BI) or a skinfold technique with commonly used regression equations, remained essentially unchanged, while there were significant decreases in body fat (BF) and %BF. The absolute amount of change in m _b (i.e. m _b) was significantly associated with abdominal girth (r=0.506), BF estimated by the BI technique (r=0.476), and BF estimated by the skinfold technique (r=0.451). Although the period of the exercise programme [38.0 (SD 12.5) weeks] varied greatly among subjects, it was found not to be associated with m _b and alterations in body composition. We concluded that aerobic exercise induced significant decreases in BF and many anthropometric variables, independent of the duration of exercise, and that a combination of abdominal girth, BI and/or skinfold measurements would be advantageous in estimating primarily exercise-induced alterations in BF in cardiac patients.Data were collected at the Cardiac Rehabilitation Laboratory, Higashi Toride Hospital     

Gender differences in body fat of low- and high-body-mass children: relationship with body mass index

The primary objective of this study was to determine gender differences in total body fat mass (TBFM) and body fat distribution (subcutaneous fat mass, SFM; and internal fat mass, IFM) in a cross-sectional sample of 280 children. Measurements of the body composition of 141 boys and 139 girls, all apparently healthy and aged 3–6 years were made using bioelectrical impedance. Determinations of impedance were made using a four-terminal impedance analyzer (TP-95K; Toyo Physical, Fukuoka, Japan). Lean body mass (LBM) was calculated using a previously published equation [Goran MI, Kaskoun MC, Carpenter WH, Poehlman ET, Ravussin E, Fontvieikke A-M (1993) Estimating body composition of young children by using bioelectrical resistance. J Appl Physiol 75: 1776–1780]. SFM was calculated using a modification of the equation derived by Skerjl [Skerjl B, Brozek J, Hunt EE (1953) Subcutaneous fat and age changes in body build and body form in women. Am J Phys Anthrop 11: 577–580] and Davies [Davies PSW, Jones PRM, Norgan NG (1986) The distribution of subcutaneous and internal fat in man. Ann Hum Biol 13: 189–192]. The main modifications of the equation in the present study were the introduction of: (1) mean thickness of adipose tissue over body surface/2, and (2) skin mass. IFM was calculated as the difference between TBFM and SFM. The body mass index (BMI; kg/m²) was calculated from the formula: body mass/height². For each gender, the subjects in the lowest and highest 25th percentiles were designated as “low body mass” and “high body mass”, respectively. In the present study, no gender differences in absolute TBFM, SFM and IFM were observed in either of these groups. In contrast, gender differences in relative TBFM (%Fat) and SFM (SFM/mass) were evident in girls. However, the four subgroups were similar in terms of relative IFM (IFM/mass). The TBFM was independently related to SFM, IFM and %Fat in both genders after adjustment for BMI; however, there was no significant association of SFM with IFM after adjustment for BMI in any group. Even after adjustment for BMI, IFM was independently related to %Fat in both genders, although SFM was not independently related to %Fat in any group except low-body-mass boys. This study shows that relative TBFM and SFM are higher in high-body-mass groups and tend to be higher in girls than in boys, and that the higher %Fat in high-body-mass girls than in high-body-mass boys appears to be associated with internal adipose tissue deposits. External adipose tissue mass does not appear to be related to the higher %Fat levels in high-body-mass girls. In addition, subcutaneous fat mass appears to be higher in low-body-mass girls than in low-body-mass boys, although this observation needs confirmation using more valid measures of subcutaneous fat such as computerized tomography and magnetic resonance imaging. Accepted: 18 February 2000     

Estimates of body fatness in infancy and childhood

Body composition estimates in infants and children are difficult largely due to ethical and practical reasons. However, the use of H₂¹⁸O as a tracer for the calulation of total body water allows the noninvasive estimation of fat-free mass (FFM) and fat mass (FM) in the pediatric population. Body fatness was estimated on 244 occasions in infants and children 0.1 to 3.99 years of age. The mean percentage body fatness in the first year of life is similar to previously published theoretical reference data. During childhood, however, the reference data were considerably below current estimates of body fatness. This may be evidence to support the hypothesis that there has been a secular trend in levels of body fatness in children in recent years. © 1992 Wiley-Liss, Inc.     

Validity of single-site and multi-site models for estimating body composition of women using near-infrared interactance

The purpose of this study was to develop a multi-site near-infrared (NIR) model (Model I) and compare its predictive accuracy to single-site models (IIA and IIB). In Model I, the sum of two optical density (OD) measures (Σ2OD), age, body weight, height, and physical activity level were used as potential predictors of body density (D_b). In Model IIA, the variables used in the manufacturer's NIR equation (biceps OD₁ and OD₂, body weight, height, gender, and physical activity level) were the potential predictors. This model was modified by including age as an additional potential predictor in Model IIB. We also examined the test-retest reliability and interrelationships of OD measures taken at 10 anatomical sites, as well as the validity of the manufacturer's NIR equation, for estimating body composition of women. The subjects, 148 women between 20 and 72 years, were hydrostatically weighed to determine criterion D_b. The Futrex-5000 was used to measure OD₁ and OD₂ at 10 anatomical sites. Only two sites (pectoral OD₂ and biceps OD₂) contributed significantly to the variance in D_b. Thus, the sum of these two ODs (Σ2OD), was used as a potential predictor in the multi-site model. Test-retest reliability was high, with intraclass correlation coefficients ≥0.85 for many of the OD measurements. Intercorrelations of ODs ranged from 0.22 to 0.91. In the multi-site model (I), ΣOD, body weight, age, and height were significant predictors, accounting for 85.7% of the variance in D_b. The SEE was 0.0076 g/ml or 3.3% BF. In the manufacturer's model (IIA), biceps OD₂, body weight, and height accounted for 76.3% of the variance in D_b, and the SEE was 0.0094 g/ml (4.1% BF). When age was included as a predictor (Model IIB), the R² increased (86.0%) and the SEE (0.0073 g/ml or 3.1% BF) decreased substantially. Cross-validation of the three equations yielded r²s ranging between 0.688 (Model IIA) and 0.748 (Model I) and slightly larger SEEs (0.0094–0.001048 g/ml). There were no significant differences between average criterion D_b and predicted D_b for each equation. The manufacturer's equation programmed in the Futrex-5000 yielded a lower r² (0.55), higher SEE (5.61% BF), and significantly underestimated criterion % BF by an average of 3% BF. Either the multi-site (model I) or single-site (Model IIB) equations is recommended to estimate body composition of this population. © 1992 Wiley-Liss, Inc.     

Fat mass and fat-free mass as indicators of body composition among Bengalee Muslim children

Background: The composition of fat mass (FM) and fat-free mass (FFM) are now considered to be important indicators of body composition.

Aim: This cross-sectional study determines the body composition using FM and FFM among children.

Subjects and methods: The study was conducted among 1248 children (619 boys; 629 girls) aged 5–12 years and belonging to the Bengalee Muslim population of West Bengal, India. Anthropometric measurements of height, weight, triceps and sub-scapular skin-folds were recorded and body mass index (BMI) calculated. Body composition was assessed using FM and FFM.

Results: The age-specific mean values of FM and FFM ranged from 1.93–3.07 kg (boys) and 1.91–3.62 kg (girls) and from 14.69–23.44 kg (boys) and 14.18–22.87 kg (girls), respectively. Statistically significant sex differences were observed in FM and FFM (p < 0.05). Age- and sex-specific smooth percentile curves were derived for BMI, FM and FFM using the L, M and S modelling approach for further evaluation of body composition.

Conclusion: These findings are important for future investigations in the field and in epidemiological and clinical settings so as to accurately identify risk of lower or higher adiposity and body composition using FM and FFM.     

Body mass scaling of projected frontal area in competitive cyclists

The primary purpose of this study was to evaluate the scaling relationship between body mass (m _b) and projected frontal area (A _P) of competitive male cyclists whilst allowing statistically for the influence of bicycle geometry. A group of 21 cyclists [mean m _b 74.4 (SD 7.2) kg, mean height 1.82 (SD 0.06) m, mean age 23.6 (SD 5.1) years] volunteered to have A _p determined from photographs at three trunk angles (TA: 5°, 15°, 25°) for each of three seat-tube angles (STA: 70°, 75°, 80°) using a modified cycle ergometer. Using multiple log-linear regression analysis procedures, the following equation was developed: Body A _p (meters squared)=0.00433×(STA^0.172)×(TA^0.0965)×(m _b ^0.762) (r²=0.73, SEE=0.017 m²) (n=183 images total). This equation indicates that after allowing for the independent influence of STA and TA on A _p, A _p was proportional to m _b raised to the +0.762 power (i.e. A _p∝m _b ^0.762). The 95% confidence interval for this exponent (0.670–0.854) barely included the theoretical two-thirds value but not the +0.55 value for A _p or the +0.32 value for submaximal metabolic power ( ) of outdoor cycling reported in the literature. Further analysis of wind tunnel data reported in the literature suggests that the coefficient of drag (C _D) is proportional to m _b raised to the –0.45 power. When combined with the present study findings, it is suggested that the drag area (C _D×A _P), which should be proportional to at submaximal cycling velocities, is proportional to m _b to the +0.312 power (i.e. C _D×A _p∝(m _b ^–0.45)×(m _b ^+0.762)=m _b ^+0.312), which is consistent with the +0.32 exponent for in the literature. Electronic Publication     

Association of body composition and muscle function with hip geometry and BMD in premenopausal women

Abstract

Background: Muscle mass and function are related to bone mineral density (BMD) but associations with bone geometry and BMD at differently loaded hip regions are less well-known.

Aim: To examine associations of muscle strength, maximal impact forces and body composition with hip bone density and geometry.

Subjects and methods: In 88 sedentary, premenopausal women (32.6 ± 8.5 years), fat-free mass (FFM), isometric knee extension strength (IKES), and peak landing ground reaction force (GRF) were measured. BMD at the proximal femur and sub-regions, section modulus (Z), and cross-sectional area (CSA) were estimated using dual X-ray absorptiometry.

Results: BMD at hip sites was significantly associated with body mass, IKES, GRF and FFM (r = 0.31–0.50) whilst Z and CSA were correlated with FFM (r = 0.67 and 0.62, respectively). In multivariate models, variables explaining most variance were body mass for lower neck and shaft BMD (25% and 17%, respectively), IKES for upper neck BMD (21%), GRF for trochanter (19%) and total hip BMD (18%) and FFM for femoral neck Z, CSA and BMD (54%, 38% and 20%, respectively).

Conclusion: BMD at superolateral hip sites was most strongly related to muscle function and maximal impact forces, BMD at inferiomedial hip sites to body mass, and hip geometry to FFM.     

Body composition and body hydration in old age estimated by means of skinfold thickness and deuterium dilution.

In this study a group of 30 women and 30 men aged 60-90 years was examined. Body density was predicted from the sum of four skinfold thickness (SFT) as described by Durnin and Womersley (1974). Body composition, expressed as a percentage of total body weight as fat mass (FM) and fat free mass (FFM) was calculated by means of Siri's formula (Siri 1961). Total body water (TBW) was measured from the dilution of an oral deuterium dose and FFM calculated assuming a hydration of 73.2%. The FM% predicted from SFT showed a slight but not significant decreasing age trend from 28.3% to 25.4% in men, and from 40.3% to 37.8% in women. Body hydration (about 50% of body weight in men and 44% in women) remained constant throughout the age range. FFM obtained from TBW assuming a constant hydration of FFM, was found to be unchanged with age. FM% predicted from SFT was correlated with values obtained from TBW on an individual basis (R2 = 0.38; p less than 0.0001 in men and R2 = 0.31; p less than 0.002 in women), but the scatter was large. The Bland and Altman statistical analysis (Bland and Altman 1986) suggests that the discrepancy between the two estimates tends to be significantly more positive with increasing fatness of the subject. The assumption of a constant hydration of FFM between individuals and with advancing age was tested. The hydration of FFM was calculated as the ratio between TBW (from deuterium dilution) and FFM (estimated from SFT). The wide range of values (50% to 90%) suggests large inter-individual differences. The mean values were lower than commonly reported, and differed with age and sex. In men, FFM hydration steadily decreases with age from the 7th decade (70.2 +/- 7.7%) to the 10th decade (65.9 +/- 8.2%). Women showed higher average figures than those of men and a lower age-associated decline (72.5% and 68.5% respectively). Our results suggest that FFM hydration decreases with age, and this indicates the need to develop age-related correction factors in order to derive FFM from TBW in an elderly population.     

Nutrition concepts for elite distance runners based on macronutrient and energy expenditure

CONTEXT: Elite distance runners (EDR) must optimize their nutrition to maintain their demanding training schedules. OBJECTIVE: To develop a nutrition concept for EDR based on energy and macronutrient expenditures. DESIGN: This theoretical study provides calculations for macronutrient and energy expenditures of EDR. Anthropometric and metabolic characteristics of EDR were assumed based on average real EDR. SETTING: University of Kiel. PATIENTS OR OTHER PARTICIPANTS: Three prototypic types of male EDR described in the literature as type I (TI; body mass = 72 kg, respiratory quotient = 0.9 at rest, fast-twitch muscle fibers = 60% to 70%), type II (TII; body mass = 67 kg, respiratory quotient = 0.82 at rest, fast-twitch muscle fibers = 50%), and type III (TIII; body mass = 60 kg, respiratory quotient = 0.75 at rest, fast-twitch muscle fibers = 30% to 40%). MAIN OUTCOME MEASURE(S): We calculated the macronutrient and energy expenditures of the 3 types of EDR according to body mass, respiratory quotient, and percentage of fast-twitch muscle fibers. RESULTS: We found that the average energy expenditure was 3750 kcal . d(-1) for TI runners, 3463 kcal . d(-1) for TII runners, and 3079 kcal . d(-1) for TIII runners. The carbohydrate (CHO) expenditure reached an average value of 10.0 g . kg(-1) . d(-1) for TI runners, 8.0 g . kg(-1) . d(-1) for TII runners, and 4.7 g . kg(-1) . d(-1) for TIII runners. When the EDR accomplished running sessions at a pace >or=100% of maximum oxygen consumption, all types of runners had a CHO demand of about 10 g . kg(-1) . d(-1). The TI and TII runners need a CHO intake of 8 to 10 g . kg(-1) . d(-1). For the TIII runners, a CHO intake >6 g . kg(-1) . d(-1) is necessary during anaerobic training sessions. CONCLUSIONS: Nutrition concepts must be differentiated for EDR according to metabolic and anthropometric characteristics of the runners and their special training emphases.     

Resting energy expenditure and body composition in rural Sarawaki adults

The resting energy expenditure (REE) of 43 men and 41 nonpregnant women aged 18–42, of the Iban tribe in rural Sarawak, was measured using the Oxylog and analyzed in relation to fat mass (FM) and fat-free mass (FFM) derived from measurements of skinfold thickness, to estimates of the specific energy expenditure of the FFM, and to microclimatic variables. Measured REEs exceeded values predicted from FFM by 9–22%, but were consistent with the metabolic rates expected of Western adolescents of comparable body size and composition. In both sexes, body fat content significantly influenced REE after accounting for nonlinear effects of variation in FFM. This is consistent with reported high adipocyte metabolic rates in obese Westerners, and with the hypothesis that Iban may possess a relatively large capacity for fat mobilization and storage. Therefore, in some populations, terms representing both FM and FFM should be included in equations describing REE. These findings are consistent with postulated evolutionary advantages of efficiency in regulation of energy turnover. © 1993 Wiley-Liss, Inc.