The relationship between body composition and physical performance in older women

BACKGROUND: The relationship between age-associated change in body composition and physical disability is still unknown. Skeletal muscle mass declines with age in both sexes; however, since women have less muscle mass per unit of weight than men, these changes may be more debilitating in women. OBJECTIVE: To evaluate the relationship between body composition and physical performance. DESIGN: A cross-sectional study. PARTICIPANTS: 144 women aged 68 to 75 were selected randomly from the general population of Verona. MEASUREMENTS: Body composition was evaluated using dual energy X-ray absorptiometry and bioimpedance. Physical performance was evaluated using a modified version of the Activities of Daily Living scale. Distance walked in 6 minutes was calculated, and isometric knee strength was tested. RESULTS: Normal women had a significantly lower body mass index (BMI) and percent body fat. These women also had a higher ratio of body cell mass (BCM) and total fat free mass (FFM) than women with physical impairments. After adjusting for BMI, women in the lowest tertile of muscle strength had significantly lower BCM than those in the highest tertile. CONCLUSIONS: These cross-sectional data show that although muscle strength is related to fat-free mass, disability in older women is associated with heavier BMI and with a higher percentage of body fat.     

体脂分布与血脂代谢的相关性研究

目的:利用双能X线吸收法(dual-energy X-ray absorptiometry,DEXA)测量体脂分布,分析冠心病与对照组男、女两性不同体脂分布及脂代谢特点。方法:将85位受试者分为冠心病组及对照组,逐一测量身高、体质量、腰围(WC)、臀围(WH)、计算体质量指数(BMI)及腰臀比(WHR);利用DEXA法记录不同部位脂肪含量,计算全身脂肪比例(Total Fat%),腰臀部脂肪比(A/G);检测总胆固醇(TC)、三酰甘油(TG)、高密度脂蛋白胆固醇(HDL-C)及低密度脂蛋白胆固醇(LDL-C)各项血脂指标。比较2组间体脂、血脂测量指标差异,并分别比较2组间及冠心病组内男性和女性的体脂分布差异,行体脂与血脂的相关性分析。结果:冠心病组的WC、A/G均高于对照组,差异有统计学意义(P<0.05)。冠心病组男性的BMI、WC、WHR及A/G高于健康人组男性,差异有统计学意义(P<0.05),2组女性间比较各体脂指标之间差异无统计学意义。冠心病组内男性WC、WHR高于女性,差异有统计学意义(P<0.05)。男性HDL-C与A/G、WHR呈显著负相关(P<0.05)。结论:男、女两性体脂分布特点不同,男性更易患腹型肥胖,引起高TG、低HDL为特点的脂代谢紊乱,与冠心病密切相关。     

The relationship between body size and body composition in women of different nutritional status

This study analysed the relationship between weight, size, and body composition in various groups of real and fantasy women. By exploiting natural relationships between the weight and volume of human tissues, comparable data on weight, size, and body composition were obtained for healthy women from western and developing country populations, women with anorexia nervosa (AN), and fantasy figures including popular children's dolls. Women from western and developing country populations have different fatness and size despite having similar weight relative to height. Women with AN have significantly lower fat and lean mass, and thinner size, than healthy women. Fantasy figures have body sizes similar to women with AN, implying similar body composition. In particular, children's dolls have body sizes similar to AN women at the time of death, although these effects are disguised by manipulation of body shape. Our study improves understanding of the body composition implied by manipulation of female shape and size. Copyright © 2001 John Wiley & Sons, Ltd and Eating Disorders Association.     

Association between physical activity (PA) guidelines and body composition variables in middle-aged and older women

The aim of this study was to investigate the association between volume and frequency of moderate-intensity PA and step-based recommendations and individual body composition variables. Our cohort included 167 healthy ambulatory women (mean age 62.8±4.8 years; body mass index [BMI] 27.3±4.2kg/m(2)) who carried out daily activities while wearing the ActiGraph GT1M accelerometer over a seven day period. Measurements of BMI, body fat mass index (BFMI), fat-free mass index (FFMI), waist-hip ratio (WHR) and visceral fat area (VFA) were obtained by the InBody 720 multifrequency bioelectrical impedance analysis (MFBIA) device. The significant relationship (r(s)=0.66; p<0.05) was found between moderate PA and steps per day. Moderate PA (r(2)=0.03-0.06) and steps per day (r(2)=0.05-0.20) were significantly associated with observed body composition parameters. Women spending>300min/week in moderate PA showed significantly lower values of BFMI (p=0.02) than those who spent 150-300min/week. Carrying out moderate PA for 30min 5 days a week was significantly associated with lower BMI (p=0.04; η(2)=0.02), BFMI (p=0.02; η(2)=0.03) and VFA (p=0.03; η(2)=0.03). In addition, higher amounts of daily steps were significantly associated with lower BMI (p=0.00; η(2)=0.16), BFMI (p=0.00; η(2)=0.21), VFA (p=0.00; η(2)=0.20) and WHR (p=0.00; η(2)=0.13). A clear association was found between the generally recommended PA guidelines and body composition variables for the women examined in this study. However, the concept of 10,000steps/day appears to be the strongest predictor of health-related body composition values.     

肥胖男性体成分与骨密度的相关性

目的探讨成年肥胖男性体成分与骨密度（BMD）的关系。方法选取89名20～50岁男性为研究对象,根据体重指数分为体重正常组（25名）、超重组（31名）和肥胖组（33名）。应用双能X线骨密度仪进行BMD及体成分测定。结果肥胖组受试者总体脂肪质量、总体肌肉质量和BMD均高于对照绀（P〈0．05）。BMD与总体脂肪质量（r=0．296）、总体肌肉质量（r=0．392）、上肢脂肪质节（r=0．355）、人腿脂肪质量（r=0．334）和躯干脂肪质量（r=0．256）均呈正相关（P〈0．05）。BMD与躯干／总体脂肪（r=-0．197,P=0．068）呈负相关趋势。以BMD为因变量,行多元线性回归分析结果显爪,总体肌肉质量（B=0．005,P=0．000）和躯干／总体脂肪（β=-0．399,P=0．010）被引入办程。结论成年肥胖男性BMD高于非肥胖男性。肥胖者BMD增加与肌肉质量关系更为密切。建议成年肥胖男性加强体育锻炼,减少脂肪禽硅,增加肌肉含量,以预防骨质疏松症。     

Developmental changes in the relationship between IGF-I and body composition during puberty.

To examine the hypothesis that anthropometric measures and physical fitness influence circulating insulin-like growth factor-I (IGF-I) during puberty, we measured IGF-I, free IGF-I, IGFBP-1, and IGFBP-3 concentrations in 156 healthy girls (9-16 years old) characterized by aerobic capacity (VO2max), fat-free mass (FFM), percent fat mass and pubertal development. IGF-I, free IGF-I and IGFBP-3 increased with pubertal development while IGFBP-1 declined. Percent fat mass correlated inversely with IGFBP-1 (r = -0.57) and directly with insulin (r = 0.50), while VO2max correlated inversely with percent fat mass (r = -0.63), body mass index (BMI, r = -0.57), and FFM (r = -0.40). When subdivided by Tanner stage, IGF-I correlated directly with weight, height, BMI, and FFM in pre-pubertal girls, but these relationships all diminished or disappeared completely by late puberty. Inverse correlations between IGF-I and percent fat mass, and direct correlations between IGF-I and VO2max as observed previously in adults, were not seen until late puberty. These data suggest that in pre-pubertal and early pubertal girls, IGF-I concentrations in blood reflect overall somatic size. This relationship between IGF-I and body size diminishes with sexual maturation, while correlations between IGF-I and both fitness and fatness emerge.     

The relationship between body composition and bone mineral density in postmenopausal Turkish women

In a retrospective cross-sectional study among 202 postmenopausal women aged 46–75 years, we aimed to investigate the relationship between body composition and bone mineral density (BMD) to determine whether fat mass or lean mass is a better determinant of BMD in Turkish postmenopausal women. Lumbar spine (L1–L4) and proximal femur BMD were measured by dual energy X-ray absorbsiometry. Body composition analysis was performed by bioelectric impedance method and fat mass, lean mass, and percent fat were measured. Both fat mass and lean mass were positively correlated with BMD at the lumbar spine and proximal femur, weight and body mass index. Lean mass was also positively correlated with height and negatively correlated with age and years since menopause (P < 0.01). The correlations of fat mass and lean mass with BMD at the lumbar spine and proximal femur remained significant after adjustment for age, years since menopause and height. When the lean mass was adjusted together with age, years since menopause and height, the significant relationship between the fat mass and BMD continued, however the significant correlation between the lean mass and BMD disappeared at all sites after adjustment for fat mass. In multiple regression analyses, fat mass was the significant determinant of all BMD sites. Our data suggest that fat mass is the significant determinant of BMD at the lumbar spine and proximal femur, and lean mass does not have an impact on BMD when fat mass was taken into account in Turkish postmenopausal women.     

The relationship between body composition and knee cartilage volume in healthy, middle-aged subjects

OBJECTIVE: Although obesity is widely accepted as a risk factor for knee osteoarthritis, it is not clear whether individual components of body composition, such as the mass and distribution of muscle and fat, are associated with development of the disease. This study examined the effect of measures of body composition on the longitudinal change in tibial cartilage volume. METHODS: Body composition, assessed via dual x-ray absorptiometry, and tibial cartilage volume, assessed via magnetic resonance imaging, were measured in 86 healthy men and women who were mid-life in age. Change in tibial cartilage volume was assessed by imaging each knee 2 years after the baseline measurement and determining the difference from baseline in tibial cartilage volume. Correlations were determined between the muscle and fat mass of the arm, leg, and total body and the volume of the lateral- and medial-tibial cartilage, as well as the change in tibial cartilage volume over 2 years, after adjusting for confounders. RESULTS: There was a significant association between muscle mass and the medial-tibial cartilage volume, independent of age, sex, body mass index, tibial bone area, and level of physical activity. Although there was a positive association between muscle mass and the lateral-tibial cartilage volume, this did not persist after adjustment for confounders. Loss of muscle mass was associated with an increased loss of medial- and lateral-tibial cartilage over 2 years, after adjusting for confounders. No relationship was apparent between fat mass and either medial- or lateral-tibial cartilage volume, or between fat mass and change in either medial- or lateral-tibial cartilage volume over 2 years, after adjusting for confounders. CONCLUSION: Muscle mass is an independent predictor of medial-tibial cartilage volume in healthy people in mid-life and is associated with a reduction in the rate of loss of tibial cartilage. This suggests that increased muscle mass may be protective against the onset of osteoarthritis.     

The relationship between body composition and muscle power output in men and women with obesity

In order to investigate the effect of gender, age and level of obesity on body composition and anaerobic power output, and to test the hypothesis that variation in body composition affects muscle power output in obesity, a cohort of 377 subjects (112 males and 265 females, aged 18-75 yr) with different levels of obesity [class IIII, body mass index (BMI) range: 30.6-60.3 kg m(-2)] was cross-sectionally investigated. Body composition was assessed with bioelectric impedance analysis (BIA), in standardized conditions and using obesity-specific prediction formulas. Lower limb anaerobic power output (W) was measured with a modification of the Margaria stair climbing test. In males, a similar increase in fat-free mass (FFM) and fat mass (FM) was observed as a function of BMI, while in females, FM increased more than FFM. In both genders, FFM significantly decreased as a function of age (p<0.001), but was higher in men of all ages. Similar patterns of variation were observed in W. A differently significant correlation between BMI and W was observed between men and women, and it was found by multivariate analysis of variance (MANOVA) that W was affected negatively by age (p<0.001) and positively by BMI (p<0.001) in males, while in females only age had a significant effect (p<0.001) but not BMI. A positive correlation (p<0.001) was detected between FFM and W, in both genders. W per unit body mass, the actual muscle power for rapid external work, was higher in men than in women of all groups, and decreased with age in both genders, but only in older women decreased significantly (p<0.01) depending on BMI. It is concluded that the gender-dependent pattern of variation in body composition may be an important determinant of the different motor limitations observed in men and women. Older women (> or =50 yr) with extreme obesity (class III) suffered from the most serious motor dysfunction within this obese cohort. This result may have important clinical relevance in the care of obesity.     

以生物电阻法检测的身体组成成分与女性骨量的关系

目的 探讨体内的体脂和非体脂对绝经前和绝经后妇女骨密度(BMD)的作用。方法 282例绝经前和205例绝经后妇女参加本研究,用双能X线骨密度仪测定腰椎和股骨颈BMD,用生物电阻法测定体脂和非体脂,同时测量身高、体重、腰围、臀围,并计算体重指数(BMI)和腰臀围比(WHR)。结果 体脂和非体脂与绝经前、绝经后妇女腰椎和股骨颈BMD均呈显著正相关(P＜0．01),多元逐步回归分析显示,在绝经前妇女中,非体脂和年龄是腰椎BMD的独立影响因素(R^2=0．077,P=0．000),非体脂、年龄和BMI是影响股骨颈BMD的决定因素(R^2=0．130,P=0．000),在绝经后妇女中,体脂和年龄是影响腰椎和股骨颈BMD的决定因素(R^2分别为0．153和0．184,P=0．000)。结论 体脂和非体脂对绝经前和绝经后妇女BMD的作用不同,非体脂是决定绝经前妇女骨量的重要因素,而体脂是影响绝经后妇女骨量的重要因素。     

Effect of puberty on the relationship between circulating leptin and body composition

Circulating concentrations of leptin are better correlated with absolute amounts of adipose tissue [fat mass (FM)] than with relative body fatness (body mass index or percent body fat). There is a clear sexual dimorphism in circulating concentrations of leptin (females > males) at birth and in adulthood. However, whether such dimorphism is present in the interval between these periods of development remains controversial. We examined body composition and clinical (Tanner stage) and endocrine (pituitary-gonadal axis hormones) aspects of sexual maturation in relationship to circulating concentrations of leptin in 102 children (53 males and 49 females, 6-19 yr of age) to evaluate the relationship between circulating leptin concentrations and body composition before and during puberty. Pubertal stage was assigned by physical examination (Tanner staging) and also assessed by measurement of plasma estradiol, testosterone, and pituitary gonadotropins. Body composition was determined by dual-energy x-ray absorptiometry and by anthropometry. Circulating concentrations of leptin in the postabsorptive state were determined by a solid-phase sandwich enzyme immunoassay. The effect of gender on the relationship between circulating leptin concentrations and FM was determined by ANOVA at each Tanner stage. Stepwise multiple linear regression analyses, including circulating concentrations of pituitary-gonadal axis hormones, and FM were performed, by gender, to determine whether the relationship between circulating concentrations of leptin and FM changes during puberty. Plasma leptin concentrations were significantly correlated with FM at all Tanner stages in males and females. Plasma leptin concentrations, normalized to FM, were significantly higher in females than males at Tanner stages IV and V but not at earlier stages of pubertal development. Plasma leptin concentrations, normalized to FM, were significantly greater in females at Tanner stage V compared with females at Tanner stage I and significantly lower in males at Tanner stage IV and V compared with males at Tanner stage I. These significant gender and maturational differences were confirmed by demonstrating that the regression equation relating circulating leptin concentrations to FM in females and males at Tanner stages IV and V were significantly different (predicted lower leptin concentrations in males than females with identical body composition) and that the regression equations relating circulating concentrations of leptin to FM in each gender before puberty (Tanner stage I) were significantly different (predicted higher plasma concentrations of leptin in prepubertal males and lower leptin concentrations in prepubertal females) than the same regression equations in later puberty. Circulating concentrations of testosterone were significant negative correlates of circulating concentrations of leptin normalized to FM in males when considered as a group over all pubertal stages. The inclusion in multivariate regression analyses of circulating concentrations of testosterone and estradiol, FM, fat-free mass, and gender did not eliminate a significant gender-effect (P < 0.05) on circulating concentrations of leptin at Tanner stages IV and V. The circulating concentration of leptin, normalized to FM, declines significantly in males and rises significantly in females late in puberty to produce a late-pubertal/adult sexual dimorphism. These studies confirm a potent role for gonadal steroids as mediators of this sexual dimorphism in circulating concentrations of leptin. (ABSTRACT TRUNCATED)     

The relationship between inflammatory bowel disease and socioeconomic variables

OBJECTIVES: Inflammatory bowel diseases (IBD) are chronic diseases associated with considerable morbidity. This morbidity may have an impact on the ability of patients to remain employed, on their marital status, and on their ability to complete a course of higher education. It has long been held that IBD patients are of a higher socioeconomic status and more educated than the general population. Our aim was to determine the relationship between IBD and employment, income, disability, education, and marital status in two population-based data sets based in the province of Manitoba, Canada. METHODS: Two studies are reported here. In study A, we surveyed persons with IBD, using the population-based University of Manitoba IBD Database, created in 1995-1996. We compared these IBD patients to the general population with respect to employment, education, and marital status using data from the 1996 National Population Health Survey. IBD patients were queried as to their socioeconomic status as of the time of diagnosis and also at the time of the survey (1995-1996). In study B, we used a database that linked health care and census variables to determine differences in employment, income, occupation, and marital status among individuals who met the administrative definition of IBD (created in forming the University of Manitoba IBD Database, based on ICD-9-CM codes 555 for Crohn's disease and 556 for ulcerative colitis) compared with the rest of working-age population. RESULTS: In study A we found that, compared with the general population, patients with IBD were more likely to be unemployed. Crohn's disease appeared to affect employment more than ulcerative colitis. IBD patients, however, had a low rate of reporting themselves as disabled (1.3%). Among those married when diagnosed with IBD, approximately 10% of men and up to 20% of women were no longer married 5 yr later. More patients with IBD were married in 1995 compared with the general population; however, more were also divorced. Fewer patients with IBD achieved postsecondary education. In study B, we found that individuals with IBD were twice as likely to be out of the labor force as were controls. Sedentary occupations were twice as likely to be associated with IBD. The income, education level, and marital status of IBD patients were not significantly different from those of controls. CONCLUSIONS: Individuals with IBD at some time in the course of their illness are more likely not to be working than are those in the general population. Based on employment status and job classification, as well as income and education, IBD patients are not of a higher socioeconomic status as previously reported. IBD patients are at least as likely as the general population to be married.     

The relationship between accelerometer-determined physical activity (PA) and body composition and bone mineral density (BMD) in postmenopausal women

Studies of the relationships between BMD, PA and body composition have shown variable results. Therefore, the aim of this cross-sectional study was to determine the relationships between accelerometer-determined PA and selected body composition parameters to total and regional BMD of the proximal femur in postmenopausal women. BMD and body composition were measured using dual energy X-ray absorptiometry in 97 women with a mean age 63.63±5.23 years. PA was monitored using an ActiGraph GT1M accelerometer. Correlation analysis did not show significant relationships between PA variables and BMD, but increases in body composition variables were associated with increases in BMD. Lean body mass was the strongest predictor of proximal femur BMD (r=0.18-0.37), explaining 10% of the variance for total femur, and 3-14% of the variance for regional femurs. Correlations increased when the analysis was controlled for age (r(p)=0.20-0.39). A significant relationship was also found between body fat mass and BMD (r=0.16-0.30; r(p)=0.25-0.37). Analysis of differences between women with normal BMD and osteopenic women showed statistically significant differences in age (p=0.003; η(2)=0.09) and lean body mass (p=0.048; η(2)=0.04). In conclusion, body composition is a stronger predictor of proximal femur BMD than PA variables. However, other studies are necessary to clarify the influence of long-term PA and exercise type on proximal femur BMD.     

高血压病血压动态变化与胰岛素变化相关性的研究

目的 调查高血压病血压动态变化与胰岛素变化的相关关系.方法 对30例Ⅰ、Ⅱ期高血压(EH)患者,排除饮食因素对血清胰岛素浓度的影响,在24小时动态血压监测(ABPM)的同时,进行血清胰岛素浓度动态变化监测,每隔4小时观测一次血清胰岛素浓度,证明所测24小时血清胰岛素浓度值存在动态变化(P<0.001).同时对每名患者所测得的各胰岛素浓度值分别与其动态血压进行秩相关分析.结果 所测各点血清胰岛素浓度分别与收缩压、舒张压的均值呈正相关关系(0.429相似文献   

绝经后2型糖尿病患者体成分与骨密度关系初步探讨

目的探讨绝经后2型糖尿病患者骨密度与体成分的关系。方法选择绝经后2型糖尿病患者(DM组)68例,绝经后血糖正常女性(NC组)73例。详细记录全部受试者年龄、身高、体重、体重指数、绝经年限,双能X线吸收测定仪检测正位腰椎(L_(2-4))、股骨(股骨颈、大转子、粗隆间)骨密度(BMD)与全身各部位的脂肪和肌肉含量,并进行临床指标测定,分析骨密度与对应的肌肉和脂肪含量的相关关系。结果 2组受试者的年龄、BMI、绝经年限差异无统计学意义(P0.05);DM组空腹血糖(FBG)、餐后2 h血糖(PBG)、糖化血红蛋白(HbAlc)均明显高于NC组,差异有统计学意义(P0.05);DM组L_(2-4)、股骨颈、大转子BMD较NC组显著下降,差异有统计学意义(P0.05);DM组躯干、腿部、总肌肉含量均较NC组显著下降,差异有统计学意义(P0.05);DM组躯干、总脂肪含量较NC组明显增加,(P0.05)。根据骨密度测定结果将糖尿病组进一步分为糖尿病骨质疏松组(DM-OP组)和糖尿病非骨质疏松组(DM-NP组):2组受试者年龄、BMI、绝经年限的差异无统计学意义(P0.05);DM-OP组DM病程、FBG、PBG、HbAlc明显高于DM-NP组(P0.05),DM-OP组躯干、腿部、总肌肉含量均明显低于DM-NP组(P0.05);总脂肪含量DM-OP组明显高于DM-NP组(P0.05),其他部位脂肪含量2组间的差异无统计学意义(P0.05)。多元线性回归分析显示,糖尿病患者L_(2-4)、股骨均值BMD与年龄、绝经年限、糖尿病病程、BMI、TLM、TKLM关系最为密切。结论绝经后2型糖尿病患者较血糖正常女性容易发生骨质疏松,绝经后2型糖尿病患者肌肉含量、脂肪含量均与骨密度密切相关,肌肉含量较脂肪含量对骨密度影响更为显著。     

The impact of body build on the relationship between body mass index and percent body fat.

OBJECTIVE: The objective of the study was to test the hypothesis that differences in the relationship between percent body fat (%BF) and body mass index (BMI) between populations can be explained (in part) by differences in body build. DESIGN: Cross-sectional, comparative study. SUBJECTS: 120 age, gender and BMI matched Singapore Chinese, Beijing Chinese and Dutch (Wageningen) Caucasians. MEASUREMENTS: From body weight and body height, BMI was calculated. Relative sitting height (sitting height/height) was used as a measure of relative leg length. Body fat was determined using densitometry (underwater weighing) in Beijing and Wageningen and using a three-compartment model based on densitometry and hydrometry in Singapore. Wrist and knee widths were measured as indicators for frame size and skeletal mass was calculated based on height, wrist and knee width. In addition, a slenderness index (height/sum of wrist and knee width) was calculated. RESULTS: For the same BMI, Singapore Chinese had the highest %BF followed by Beijing Chinese and the Dutch Caucasians. Singaporean Chinese had a more slender frame than Beijing Chinese and Dutch Caucasians. Predicted %BF from BMI, using a Caucasian prediction formula, was not different from measured %BF in Wageningen and in Beijing, but in Singapore the formula underpredicted %BF by 4.0 +/- 0.8% (mean +/- s.e.m.) compared to Wageningen. The difference between measured and predicted %BF (bias) was related to the level of %BF and with measures of body build, especially slenderness. Correction for differences in %BF, slenderness and relative sitting height, decreased the differences between measured and predicted values compared to the Dutch group from 1.4 +/- 0.8 (not statistically significant, NS) to -0.2 +/- 0.5 (NS) in Beijing and from 4.0 +/- 0.8 (P < 0.05) to 0.3 +/- 0.5 (NS) in Singapore (all values mean +/- s.e.m.). CONCLUSIONS: The study results confirm the hypothesis that differences in body build are at least partly responsible for a different relationship between BMI and %BF among different (ethnic) groups.     

The relationship between body weight and blood pressure

In adults of Western societies the positive relationship between blood pressure and body weight has often been demonstrated, both cross-sectionally and longitudinally. This correlation is even stronger in children and early adulthood. In most studies in children, the association between age and blood pressure disappears after controlling for weight. Association must be differentiated from causation. It has however been shown in several intervention studies that treatment of obesity by weight loss decreases blood pressure substantially both in hypertensive and normotensive subjects. Although combining results from several intervention trials is difficult this is the only practical way to get an overall estimate of the hypotensive response to be expected from weight reduction. In the randomised controlled intervention studies, conducted in obese hypertensive patients and reviewed in the present meta-analysis, a decrease in body weight by 1 kg resulted in a reduction of systolic and diastolic pressure by 1.2 and 1.0 mmHg, respectively. Blood pressure generally decreased before normal weight was achieved and remained reduced as long as there was no marked regain in body weight. Although a decrease in salt intake during dieting may contribute to the blood pressure lowering effect of weight reduction, also other mechanisms, such as a reduction in plasma renin activity and a decrease in sympathetic tone may also be involved.     

Standardization of Romanowsky stains. The relationship between stain composition and performance.

A panel of 17 eminent haematologists has assessed the performance of 5 Romanowsky stains prepared from pure component dyes, comparing the suitability and acceptability of these stains for the preparation of routine blood and bone-marrow films. It was found that the results obtained using the stain described by Marshall et al (1975) were comparable to those obtained using a modification of the stain described by Wittekind et al (1976). The performance of the 3 other stains was less acceptable. Variations in stain formulation have been correlated with stain performance.     

The relationship between body composition and knee cartilage volume in healthy,middle‐aged subjects

Objective

Although obesity is widely accepted as a risk factor for knee osteoarthritis, it is not clear whether individual components of body composition, such as the mass and distribution of muscle and fat, are associated with development of the disease. This study examined the effect of measures of body composition on the longitudinal change in tibial cartilage volume.

Methods

Body composition, assessed via dual x‐ray absorptiometry, and tibial cartilage volume, assessed via magnetic resonance imaging, were measured in 86 healthy men and women who were mid‐life in age. Change in tibial cartilage volume was assessed by imaging each knee 2 years after the baseline measurement and determining the difference from baseline in tibial cartilage volume. Correlations were determined between the muscle and fat mass of the arm, leg, and total body and the volume of the lateral‐ and medial‐tibial cartilage, as well as the change in tibial cartilage volume over 2 years, after adjusting for confounders.

Results

There was a significant association between muscle mass and the medial‐tibial cartilage volume, independent of age, sex, body mass index, tibial bone area, and level of physical activity. Although there was a positive association between muscle mass and the lateral‐tibial cartilage volume, this did not persist after adjustment for confounders. Loss of muscle mass was associated with an increased loss of medial‐ and lateral‐tibial cartilage over 2 years, after adjusting for confounders. No relationship was apparent between fat mass and either medial‐ or lateral‐tibial cartilage volume, or between fat mass and change in either medial‐ or lateral‐tibial cartilage volume over 2 years, after adjusting for confounders.

Conclusion

Muscle mass is an independent predictor of medial‐tibial cartilage volume in healthy people in mid‐life and is associated with a reduction in the rate of loss of tibial cartilage. This suggests that increased muscle mass may be protective against the onset of osteoarthritis.