Relationship of skeletal age to limb composition during pubescence

The relationships between skeletal age (SA) and limb composition (arms, legs, and all four limbs) in terms of fat mass (FM), fat-free mass (FFM), muscle mass (MM) and bone mineral content (BMC) were investigated in 55 males and 53 females aged 9–15 years. The Fels method was used to assess hand-wrist SAs which were expressed as SA/chronological age (SA/CA). The limb composition data were obtained from a Lunar dual-energy x-ray absorptiometer using 3.6z software. The means for the limb composition variables increased gradually with age except in males for whom FM decreased from 12 to 13 years, and FFM and MM increased markedly from 13 to 14 years. There were similar findings when the limb composition data were expressed as percentages of body weight. All of the regressions of SA/CA on limb composition variables had positive slopes. Each of the slopes was significant for males, but nonsignificant for females. © 1996 Wiley-Liss, Inc.     

Validation of body composition by dual energy X-ray absorptiometry (DEXA)

The present study validates the use of dual energy X-ray absorptiometry (DEXA) for measurement of body composition. The precision error was expressed as the SD (CV%) for fat mass, FAT%, lean tissue mass, and total body bone mineral: 1.1 kg (6.4%), 1.6% (5.7%), 1.4 kg (3.1%), and 0.03 kg (1.2%), respectively. The accuracy study in vitro used (1) mixtures of water and alcohol, (2) mixtures of ox muscle and lard, and (3) dried bones. In the clinically relevant range of values there were only small influences on DEXA measurements of variations in amount and composition of the soft tissue equivalents. The accuracy study in vivo compared the components of body composition measured recently by DEXA and earlier by dual photon absorptiometry, counting of naturally occurring total body 40K, and body density by underwater weighing in 25 healthy adult subjects. We found agreement between fat percentage (and lean body mass) by DEXA and the three established measurements modalities; mean differences were (-5.3 to -0.4%) and (-0.7 to 2.5 kg) for fat percentage and lean body mass, respectively. We conclude that DEXA provides a new method of measuring body composition with precision and accuracy errors, which are compatible with the application of DEXA in group research studies and probably also in clinical measurements of the single subject.     

Assessment of total and segmental body composition in spinal cord-injured athletes in Okayama prefecture of Japan

This study assessed total and segmental distribution of fat mass (FM) in athletes with spinal cord injury (SCI) and examined the relationships between segmental distribution of fat mass and age, injury level, athletic history, and training load in order to provide useful information for improvements in their physical strength and training. Twenty-five male athletes with SCI participated in the study. The whole bone composition was measured by a dual-energy X-ray absorptiometry (DXA) method for the calculation of bone minerals, FM, and fat-free mass. The percent fat of the trunk, arms, and legs was also calculated. The percent fat in the legs was highest in comparison with that in the trunk and arms (p < 0.001), and the percent fat in the trunk was higher than that in the arms (p < 0.001). The body fat (p < 0.01), waist circumference (p < 0.01), and waist-to-hip ratio (p < 0.0001) were higher in the group aged 40 or older in comparison with that aged 39 or younger. Path analysis revealed that training load was a factor decreasing the percent fat on the arms and trunk (p < 0.01), and athletic history was a factor reducing the percent fat on the arms (p < 0.05). Our study suggests that exercise is effective in reducing the waist circumference, waist-to-hip ratio, and percent body fat of SCI individuals, and that such effects can help to enhance athletic performance and likely to protect against development of metabolic syndromes resulting from a sedentary lifestyle.     

Body fluid distribution in elderly subjects with congestive heart failure

The aims of this study were to investigate body fluid changes in elderly patients suffering from congestive heart failure (CHF) and to identify the fluid measurement that best characterizes fluid overload states in CHF patients by comparison with normal hydration in the elderly. In a case-controlled experimental design, 72 elderly subjects (65-98 yr), 38 healthy and 34 with CHF, were studied. Total body water (TBW) and extracellular water (ECW) were determined by dilution methods; fat-free mass (FFM) and fat mass (FM) were determined by dual-energy X-ray absorptiometry (DEXA). In healthy subjects, the FFM hydration expressed as TBW% FFM (males 72.0 +/- 4.3 vs females 72.4 +/- 5.0%) and ECW% TBW (males 47.3 +/- 3.4 vs females 47.8 +/- 5.1) were similar in both genders. ECW in liters for FFM and for TBW (ECW% TBW), corrected for body weight, was greater in the group with CHF than in the control group, in both sexes. Among the relative fluid measures, only ECW% TBW [odds ratio (OR) 1.5] independently predicted fluid retention. Having an ECW% TBW greater than 50% corresponded to an OR of about 10. In conclusion, elderly patients suffering from CHF have a characteristic increase in body fluid levels, mainly affecting the extracellular compartment, and ECW% TBW is a useful indicator of fluid retention.     

Cross-calibration of eight-polar bioelectrical impedance analysis versus dual-energy X-ray absorptiometry for the assessment of total and appendicular body composition in healthy subjects aged 21-82 years

AIM: To calibrate eight-polar bioelectrical impedance analysis (BIA) against dual-energy X-ray absorptiometry (DXA) for the assessment of total and appendicular body composition in healthy adults. RESEARCH DESIGN: A cross-sectional study was carried out. SUBJECTS: Sixty-eight females and 42 males aged 21-82 years participated in the study. METHODS: Whole-body fat-free mass (FFM) and appendicular lean tissue mass (LTM) were measured by DXA; resistance (R) of arms, trunk and legs was measured by eight-polar BIA at frequencies of 5, 50, 250 and 500 kHz; whole-body resistance was calculated as the sum R of arms, trunk and legs. RESULTS: The resistance index (RI), i.e. the height(2)/resistance ratio, was the best predictor of FFM and appendicular LTM. As compared with weight (Wt), RI at 500 kHz explained 35% more variance of FFM (vs 0.57), 45% more variance of LTM(arm) (vs 0.48) and 36% more variance of LTM(leg) (vs 0.50) (p < 0.0001 for all). The contribution of age to the unexplained variance of FFM and appendicular LTM was nil or negligible and the RI x sex interactions were either not significant or not important on practical grounds. The percent root mean square error of the estimate was 6% for FFM and 8% for LTM(arm) and LTM(leg). CONCLUSION: Eight-polar BIA offers accurate estimates of total and appendicular body composition. The attractive hypothesis that eight-polar BIA is influenced minimally by age and sex should be tested on larger samples including younger individuals.     

Relative contribution of aging and menopause to changes in lean and fat mass in segmental regions

Objective: The aim of the study was to investigate the relative contribution of aging and menopause to the changes in lean and fat mass in segmental regions. Materials and methods: Subjects were 365 pre- and 201 postmenopausal Japanese women aged between 20 and 70 years old. Age, height, weight, body mass index (BMI, Wt/Ht²), age at menopause, years since menopause (YSM), and menopausal status were recorded. Lean and fat mass of the arms, trunk, legs, total body, and the ratio of trunk fat mass to leg fat mass amount (trunk–leg fat ratio) were measured by dual-energy X-ray absorptiometry (DEXA). Regional (arms, lumbar spine, pelvis, legs, and total body) bone mineral density (BMD) were measured by DEXA. Results: Total body lean mass and regional BMD decreased (P<0.001), while percentage of body fat, trunk fat mass, and trunk–leg fat ratio increased (P<0.001) with aging and after menopause. On multiple regression analyses, trunk and total body lean mass were inversely correlated with menopausal status (P<0.001 and 0.05, respectively) but not with age. Trunk fat mass, trunk–leg fat ratio, and percentage of body fat were positively correlated with age (P<0.01) but not with menopausal status. Regional BMD were more inversely correlated with menopausal status (P<0.001) than age. Conclusion: Decrease in lean mass and BMD are more menopause-related, while the shift toward upper body fat distribution and overall adiposity are more age-related. Lean tissue is similar to bone tissue from the viewpoint of more undergoing menopausal effect.     

Cross-calibration of eight-polar bioelectrical impedance analysis versus dual-energy X-ray absorptiometry for the assessment of total and appendicular body composition in healthy subjects aged 21-82 years

Aim: To calibrate eight-polar bioelectrical impedance analysis (BIA) against dual-energy X-ray absorptiometry (DXA) for the assessment of total and appendicular body composition in healthy adults. Research design: A cross-sectional study was carried out. Subjects: Sixty-eight females and 42 males aged 21-82 years participated in the study. Methods: Whole-body fat-free mass (FFM) and appendicular lean tissue mass (LTM) were measured by DXA; resistance ( R ) of arms, trunk and legs was measured by eight-polar BIA at frequencies of 5, 50, 250 and 500 kHz; whole-body resistance was calculated as the sum R of arms, trunk and legs. Results: The resistance index (RI), i.e. the height 2 /resistance ratio, was the best predictor of FFM and appendicular LTM. As compared with weight (Wt), RI at 500 kHz explained 35% more variance of FFM ( vs 0.57), 45% more variance of LTM arm ( vs 0.48) and 36% more variance of LTM leg ( vs 0.50) ( p < 0.0001 for all). The contribution of age to the unexplained variance of FFM and appendicular LTM was nil or negligible and the RI &#50 sex interactions were either not significant or not important on practical grounds. The percent root mean square error of the estimate was 6% for FFM and 8% for LTM arm and LTM leg. Conclusion: Eight-polar BIA offers accurate estimates of total and appendicular body composition. The attractive hypothesis that eight-polar BIA is influenced minimally by age and sex should be tested on larger samples including younger individuals.     

Heterogeneity of growth of bone in children at the spine, radius and total skeleton.

Bone mineral content (BMC), density (BMD), and size were measured in 202 subjects ranging from 3 to 25 years of age (106 males and 96 females), half of which were children and half young adults. BMC and BMD were measured using single photon absorptiometry at the proximal and distal radius and dual photon absorptiometry at the lumbar spine and the total body. In the pre-pubertal age group (3-9 yrs), no differences were found in BMC nor BMD between males and females at any site. Growth of bone during puberty was characterized by an increase in BMC, bone size and BMD. The percent increase in BMC was greater at the lumbar spine and the total body (+200 to +390 %) than at the radius (+90 to +270 %). The increase in BMC was higher than the increase in BMD (+50 to +90 %). Overall bone growth in the total body was not reflected by changes in BMC of the appendicular skeleton. The increase in BMD was heterogeneous and was higher in the legs than in the arms. In males, the increase in BMC and size during growth was greater than in females resulting in a higher peak bone mass and size in males. The increase in BMD was similar between males and females at the distal radius, the lumbar spine and the total body, but higher at the proximal radius, the arms and the legs in males.(ABSTRACT TRUNCATED AT 250 WORDS)     

甘肃裕固族成人骨强度和体成分变化特点及相关性分析

目的分析甘肃裕固族成人骨强度和体成分随年龄变化特征并探讨骨强度与体成分的相关性。方法2015年7月至2016年8月选取甘肃省肃南裕固族自治县成人725例(男性354例,女性371例),年龄20~86岁,采用超声骨密度仪和生物电阻抗分析仪,分别测量跟骨骨强度及体成分指标。结果甘肃裕固族成年男性骨强度在20~29岁低于女性(P0.05),50岁后高于女性(P0.01);男性各年龄段的肌肉量均高于女性(P0.01);各年龄段的总脂肪量、皮下脂肪含量均低于女性(P0.01);内脏脂肪含量仅在20~29岁及70岁后低于女性(P0.01)。男女骨强度分别在30~39岁和20~29岁达峰值、50~59岁和40~49岁开始较前出现差异(P0.05),男性在70岁后和女性在50岁后骨强度低于之前各年龄组(P0.01)。男性躯干及四肢肌肉量均在40~49岁及60~69岁呈现双峰,女性躯干及四肢肌肉量均在40~49岁达峰值。甘肃裕固族成年身体各部位的脂肪含量变化同步,男女性分别在60~69岁和50~59岁达峰值。多元线性逐步回归分析显示,骨强度与四肢肌肉量和皮下脂肪量正相关(P0.01),与内脏脂肪量负相关(P0.01)。结论随年龄增长,甘肃裕固族成人身体各部位的同种体成分呈同步变化,女性骨强度较男性下降时间早且速度快。裕固族成人骨强度由肌肉和脂肪共同决定且与其分布部位有关。裕固族70岁以上男性及50岁以上女性是骨质疏松性防治的重点人群;男女性应分别从50岁后和40岁后应加强肢体锻炼、增加四肢肌肉量、控制内脏脂肪,预防骨质疏松。     

Interleukin-6 release is higher across arm than leg muscles during whole-body exercise

Exercising muscle releases interleukin-6 (IL-6), but the mechanisms controlling this process are poorly understood. This study was performed to test the hypothesis that the IL-6 release differs in arm and leg muscle during whole-body exercise, owing to differences in muscle metabolism. Sixteen subjects (10 men and six women, with body mass index 24 ± 1 kg m(-2) and peak oxygen uptake 3.4 ± 0.6 l min(-1)) performed a 90 min combined arm and leg cycle exercise at 60% of maximal oxygen uptake. The subjects arrived at the laboratory having fasted overnight, and catheters were placed in the femoral artery and vein and in the subclavian vein. During exercise, arterial and venous limb blood was sampled and arm and leg blood flow were measured by thermodilution. Lean limb mass was measured by dual-energy X-ray absorbtiometry scanning. Before and after exercise, biopsies were obtained from vastus lateralis and deltoideus. During exercise, IL-6 release was similar between men and women and higher (P < 0.05) from arms than legs (1.01 ± 0.42 and 0.33 ± 0.12 ng min(-1) (kg lean limb mass)(-1), respectively). Blood flow (425 ± 36 and 554 ± 35 ml min(-1) (kg lean limb mass)(-1)) and fatty acid uptake (26 ± 7 and 47 ± 7 μmol min(-1) (kg lean limb mass)(-1)) were lower, glucose uptake similar (51 ± 12 and 41 ± 8 mmol min(-1) (kg lean limb mass)(-1)) and lactate release higher (82 ± 32 and -2 ± 12 μmol min(-1) (kg lean limb mass)(-1)) in arms than legs, respectively, during exercise (P < 0.05). No correlations were present between IL-6 release and exogenous substrate uptakes. Muscle glycogen was similar in arms and legs before exercise (388 ± 22 and 428 ± 25 mmol (kg dry weight)(-1)), but after exercise it was only significantly lower in the leg (219 ± 29 mmol (kg dry weight)(-1)). The novel finding of a markedly higher IL-6 release from the exercising arm compared with the leg during whole-body exercise was not directly correlated to release or uptake of exogenous substrate, nor to muscle glycogen utilization.     

内蒙古蒙古族察哈尔部人体组成成分分析

目的 探讨内蒙古蒙古族察哈尔部的人体组成成分的现状及特点.方法 采用生物电阻抗分析法,对内蒙古蒙古族察哈尔部403(男161,女242)例成人进行人体组成成分的测量.结果 男性躯干脂肪率最高,总体脂率和下肢脂肪率接近,上肢脂肪率最低;女性躯干脂肪率、总体脂率、下肢脂肪率相近,高于上肢脂肪率;男、女性左、右上肢及左、右下...     

Difference in the effects of body composition on bone mineral density between pre- and postmenopausal women

Objective: This study was to investigate whether the effect of lean and fat mass component on bone mineral density (BMD) differs between pre- and postmenopausal women. Materials and methods: Subjects were 360 pre- and 193 postmenopausal Japanese women with right side dominance. Age, height, and years since menopause (YSM, in postmenopausal women) were recorded. Body fat and lean body mass were measured by whole body scanning with dual-energy X-ray absorptiometry (DEXA). BMD of the vertical axis (L2-4 of the lumbar spine, pelvis, bilateral legs, and total body) and horizontal axis (arms) were also measured by DEXA. Results: In premenopausal women, lean body mass was independently correlated with BMD of the left arm (partial correlation COEFFICIENT=0.417), right arm (0.430), L2-4 (0.285), pelvis (0.276), left leg (0.403), right leg (0.412), and total body (0.377) (P<0.001). However, body fat mass was not correlated with several BMD sites except for pelvis BMD (0.187, P<0.01). In postmenopausal women, body fat mass was independently correlated with BMD of the left arm (0.248, P<0.01), L2-4 (0.188, P<0.05), pelvis (0.263, P<0.01), left leg (0.228, P<0.01), right leg (0.319, P<0.001), and total body (0.188, P<0.01)). However, lean body mass was correlated with BMD in only three segmental regions including left arm (0.175), right arm (0.217), and left leg (0.210; P<0.05). Conclusion: Lean body mass is a significant determinant of BMD in premenopausal women, while body fat mass is a significant determinant in postmenopausal women.     

Gender difference in the relationship of performance in the handgrip and standing long jump tests to lean limb volume in young adults

Summary Groups of young, adult males and females performed the handgrip and standing long jump tests. Their total forearm and leg volumes were calculated from a series of circumference and length measurements, and the lean volumes (bone + muscle) calculated by taking the skinfold thickness into consideration. In the handgrip, the mean female performance was 298 N compared with 496 N for the males. In the standing long jump, mean performance expressed as distance x body mass was 87.3 kg · m for females compared with 137.7 kg · m for males. These superior performances of males could simply reflect their greater muscle mass, as the mean lean volumes of female and male limbs respectively were 0.54 l and 0.89 l for forearms, and 11.82 l and 14.82 l for the two legs. However, when the performances of males and females were grouped by lean limb volume, it was found that while in both tests there were linear relationships, males and females did not share a common line. In both tests the male relationship was at a higher level than the female; therefore, for a given lean volume, the male performance was significantly superior to that of the female. The gender difference found in this study has not been seen in other studies in which the performance of skeletal muscle has been related to the cross-sectional area of the active muscles and the possible reasons for the differences are considered.     

Muscle strength and soft tissue composition as measured by dual energy x-ray absorptiometry in women aged 18–87 years

Dual energy x-ray absorptiometry (DEXA) offers the possibility of assessing regional soft tissue composition, i.e. lean mass (LM) and fat mass : LM may be considered a measure of muscle mass. We examined age-related differences in LM, percentage fat (%fat) and muscle strength in 100 healthy non-athletic women aged 18–87 years. Relationships between muscle strength and leg LM in 20 elite female weight lifters and in 18 inactive women with previous hip fractures were also studied. The LM and %fat of the whole body, trunk, arms and legs were derived from a whole body DEXA scan. Isokinetic knee extensor strength (KES) and flexor strength (KFS) at 30°?·?s^–1 were assessed using an isokinetic dynamometer. The women aged 71–87 years had 35% lower KES and KFS than the women aged 18–40 years (P P r _partial?=??0.74, P r _partial?=?0.65, P r?=??0.70, P P P 相似文献   

Independent associations of body-size adjusted fat mass and fat-free mass with the metabolic syndrome in Chinese

Background: Excess fat leads to adverse health outcomes. Most previous studies investigating body fatness using BMI or fat percentage, which contain both fat mass and fat-free mass, were not able to differentiate the exposure.

Aim: The present study assessed the independent association of fat and fat-free mass with metabolic syndrome (MetS) in Chinese.

Subjects and methods: A population-based study of 1144 subjects aged 50–70 from urban and rural areas of Shanghai in 2005–2006 was employed. Body composition was measured with DEXA. Fat mass index (FMI) and fat-free mass index (FFMI) were calculated. MetS was defined using the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria without waist circumference for its high correlation with body composition.

Results: Both FMI and FFMI were significantly related with higher odds of MetS (OR 3.97, 95% CI 2.58–6.09 for FMI; OR 2.67, 95% CI 1.70–4.18 for FFMI, the highest quartile vs the lowest group) after adjusting for age, residence, sex, smoking, drinking, physical activity, medication, family history of chronic diseases, and fat-free mass (for FMI) or fat mass (for FFMI).

Conclusion: Both FMI and FFMI are independently associated with increased MetS risks. Proper expression of body composition is essential in assessing body composition and disease risk association.     

Prospective evaluation of body weight and body fat distribution in early postmenopausal women with and without hormonal replacement therapy

AIMS: In order to assess the effects of menopause and hormonal replacement therapy (HRT) on body weight and body fat distribution (determined by dual energy X-ray), early postmenopausal women were given either oral calcium (500 mg/day, control group, n=13) or HRT, a combination of estradiol valerate (EV, 2 mg/day for 21 days) with cyproterone acetate (CPA, 1 mg/day in the last 10 days of the treatment cycle, n=18; Climen, Schering). RESULTS: There were no differences in basal body weight and body fat distribution in the two groups before the study. In control group, a significant (P<0.05) increase in body weight (from 63.5+/-2.0 to 68.7+/-2.0 kg after 36 months) paralleled a shift to a prevalent central, android fat distribution with a slight but significant (P<0.05) increase in total body fat mass (from 23.4+/-2.1 to 29.1+/-2.1 kg), an increase in trunk (from 10.1+/-0.4 to 12.7+/-0.4 kg, P<0.05), arms (from 2.4+/-0.2 to 2.9+/-0.2 kg, P<0.05) and legs (from 6.5+/-0.4 to 7.8+/-0.4 kg, P<0.05) fat. In the HRT group total body bone mineral showed a significant increase (from 1086+/-21 to 1128+/-19 mg/cm(2), P<0.05) increase after 36 months, with no significant increase in body weight (from 62.6+/-1.8 to 65.0+/-1.9 kg), and no modifications in trunk (from 10.0+/-0.2 to 10.1+/-0.2 kg) and arms (from 2.4+/-0.1 to 2.6+/-0.1 kg) fat, but a significant increase in legs fat (from 6.9+/-0.3 to 9.9+/-0.4 kg, P<0.05). CONCLUSION: Present results demonstrate that menopause is associated with an accelerated increase in body weight and body fat, with a prevalent central, android fat distribution, that can be counteracted at least in part by oral HRT.     

Estimation of body fat from skinfold thicknesses in middle-aged and older men and women: A multiple component approach

The relationship of skinfold thicknesses and body density to body fatness was assessed, and skinfold prediction equations were developed for the estimation of body fatness determined from measures of body density, total body water, and bone mineral in a sample of 91 males and 116 females aged 34–84 years. For a given skinfold thickness, adjustment for individual deviations in the water and bone mineral fractions of the fat-free body assumed constant by traditional body composition models resulted in absolute reductions in overstimates of body fatness from 4.5 to 1.9% in females and from 2.8 to 1.7% in males for every 15 year increase in age. Percentage fat from density, water, and bone was estimated from skinfold thicknesses with SEEs of 2.9% in males and 3.8% in females. When compared to percentage fat from our multicomponent-derived criterion, percentage fat from body density and a two-component model resulted in individual errors ranging from underestimates of 5.6% fat to overestimates of 14.0% fat. The multicomponent prediction equations presented herein should produce more valid estimates of body composition in middle-aged and older men and women than equations based on two-component models. © 1992 Wiley-Liss, Inc.     

广西毛南族群体体成分与血脂和血尿酸的相关性

目的 了解毛南族成年人的体成分与血脂、血尿酸的相关关系,探讨体成分变化对血脂、血尿酸的影响.方法 广西毛南族自治县毛南族村寨毛南族成人584人(男237,女347),年龄20～80岁.用人体测高仪测量身高;用ANITA MC-180仪测量体成分;用日立7600仪测量血脂和血尿酸.所得数据用SPSS 20.0统计学软件进...     

Adiponectin and leptin levels in HIV-infected subjects with insulin resistance and body fat redistribution

In this study, we sought to determine the relationship between serum levels of leptin and adiponectin (Acrp30) in patients with HIV-associated lipodystrophy (HIV-LD). Three groups of subjects were studied; HIV-positive subjects with lipodystrophy (HIV-LD; n = 22), HIV-positive subjects without lipodystrophy (HIV; n = 17), and ethnicity- and body mass index-matched healthy control subjects (n = 20). Although total body fat from dual energy x-ray absorptiometry was similar in all three groups, the HIV-LD group had a significantly lower mean proportion of body fat in the limbs +/- SEM (37.2% +/- 2.2%) than either controls (49.8% +/- 1.5%) or HIV subjects (45.7% +/- 2.0%). The HIV-LD group also had the lowest mean insulin sensitivity +/- SEM (5.11 +/- 0.59 mg of glucose/[kg of lean body mass. min] vs. 10.2 +/- 0.72 mg of glucose/[kg of lean body mass. min] in controls and 8.64 +/- 0.69 mg of glucose/[kg of lean body mass. min] in the HIV group). Leptin levels were similar in all three groups and were significantly correlated to total body fat (r = 0.86; p <.001), but these levels did not correlate with either insulin sensitivity or limb fat. Mean Acrp30 levels +/- SEM were lowest in the HIV-LD group (5.43 +/- 0.44 microg/mL vs. 11.2 +/- 1.4 microg/mL in the HIV group and 14.9 +/- 1.8 microg/mL in control subjects). Further, Acrp30 levels were positively correlated with insulin sensitivity (r = 0.610; p <.001) and limb fat (r = 0.483; p <.001). However, the correlation between limb fat and insulin sensitivity disappeared when Acrp30 level and other potential mediators were removed from the association, suggesting that a deficiency in Acrp30 in subjects with HIV-LD may be part of the mechanism for the reduced insulin sensitivity.     

Forearm composition and muscle function in trained and untrained limbs

The influence of a period of training, which lasts for several years, on the proportions of muscle, fat and bone present in the human forearm has been investigated by comparing trained and untrained limbs of nine experienced male tennis players. Ten healthy but untrained males of similar age served as a control group. Computed tomography (CT) scans of the forearm were made at intervals along its length to identify fat, muscle and bone and to calculate the volumes occupied by each of these components. Total forearm volume was greater in the dominant limb compared with the contralateral side in both trained (by 135 +/- 59 cm3, mean +/- SD, P less than 0.001) and untrained subjects (by 41 +/- 45 cm3, P less than 0.02). Forearm muscle volume was also greater in dominant limbs of trained (by 117 +/- 52 cm3, P less than 0.001) and untrained by 35 +/- 41 cm3, P less than 0.025) subjects. Muscle accounted for 75.4 +/- 2.7% of the total volume in the dominant arm of trained subjects compared with 71.4 +/- 4.2% in the control group (P less than 0.05). There was a greater proportion of muscle (P less than 0.05) and a smaller proportion of fat (P less than 0.001) in the trained limb compared with the contralateral limb of the same subjects. No differences in proportions of fat, muscle and bone were observed in dominant and non-dominant limbs of the control subjects. Trained subjects were able to exert a greater isometric force with the dominant limb (549 +/- 76N) than with the non-dominant limb (496 +/- 48N; P less than 0.005). There was no difference in grip strength between the arms of the untrained group (dominant: 516 +/- 107N; non-dominant: 491 +/- 91N). The ratio of strength to muscle volume was, however, the same in dominant and non-dominant arms of both groups of subjects.