Physiological and biomechanical analysis of treadmill walking up various gradients in men and women

This investigation was undertaken to examine the physiological and biomechanical responses during treadmill walking up various gradients in men and women. Groups of 11 men and 11 women took part in four experiments consisting of 8 min treadmill walks at 1.3 m·s^–1 up gradients of 0%, 5%, 10% and 15%. The subjects also underwent an anthropometric assessment during which their height, body mass (BM), percentage (%) body fat, lean body mass (LBM), and waist-to-hip ratio (WHR) were obtained. During exercise, each subject was videotaped during three walking cycles so that sagittal kinematics including stride length (SL) and frequency (SF) and ranges of motion achieved at the shoulder, hip and knee during a walking cycle could be determined using a motion analysis system. The motion capture was followed by a measurement of steady-state oxygen uptake (VO₂) and heart rate (HR) using indirect calorimetry and a HR monitor. Compared to men, women were higher in % body fat, but lower in height, BM, LBM, and WHR. The VO₂ in millilitres per kilogram per minute and HR were similar between men and women at 0% and 5%, but greater in women than men at 10% and 15%. The SL and SF were greater and smaller, respectively, in men than women up all gradients. Shoulder extension was greater up gradients of 10% and 15% in women than men, whereas no sex difference in shoulder flexion was noted. Hip extension and flexion as well as knee flexion remained the same between men and women up all gradients. An inverse relationship was observed between VO₂ in millilitres per kilogram per minute and BM, LBM, and WHR when men and women were combined. In conclusion, the mass-specific metabolic cost of treadmill walking up high gradients is greater in women than men. Such an increase in relative metabolic cost may be attributable to the fact that women are smaller in size, and/or have relatively more BM distributed peripherally. This sex difference may also be due to a greater movement of the upper limbs in women during walking uphill, although direct evidence is needed to support this contention. Electronic Publication     

Association of FTO gene variants with body composition in UK twins

The association of FTO gene variants with body mass index (BMI) and other obesity characteristics is well established. However, uncertainties remain whether the association is present only in young populations and whether it is attributable to body fat mass specifically. We aimed to clarify these two questions in a large sample (N= 4,523 individuals) of middle-aged and older (range 40-80 years) British female twins. The women were assessed for BMI, waist and hip circumference, total lean (LBM) and fat (FBM) body mass. Since the majority of FTO association signals have been reported in a haploblock bordering 52,355-52,408 kb (on chromosome 16q12.2), we examined five genotyped and 43 imputed SNPs mapped to this block. Canonical correlation and other association analyses showed significant and consistent association between the selected SNP and studied body composition phenotypes, with p-values reaching p= 0.000004. Of particular interest, in addition to the expected significant associations between FTO variants and FBM, we also identified significant associations with LBM. These results suggest that the association between FTO variants and body composition phenotypes is present across a wide range of ages, and that FTO appears primarily to affect the amount of body soft tissue, influencing both fat and lean mass.     

Changes in Body Composition Predict Homocysteine Changes and Hyperhomocysteinemia in Korea

Cardiovascular disease (CVD) is the primary cause of death in Korea. Hyperhomocysteinemia confers an independent risk for CVD comparable to the risk of smoking and hyperlipidemia. The purpose of this study was to assess the effect of cardiovascular risk factors and body composition change on homocysteine (Hcy) levels in Korean men and women. The association between body composition and Hcy levels was investigated in a 2-yr prospective cohort study of 2,590 Koreans (mean age 45.5±9.6 yr). There were 293 cases of hyperhomocysteinemia (>14 µM/L) at follow-up. Increases in total body fat proportion and decreases in lean body mass (LBM) were significantly associated with increases in Hcy concentration after controlling for confounding factors. Further adjustments for behavioral factors showed that decreases in LBM were associated with Hcy increase. Decrease in LBM also predicted hyperhomocysteinemia at follow-up, after controlling for confounding factors. There was no significant association between change in body mass index (BMI) and Hcy concentrations over time. Hcy changes over time were related to change in LBM and body fat content, whereas BMI or weight change did not predict change in Hcy levels. Changes in ratio of LBM to total fat mass may contribute to hyperhomocysteinemia.     

Building your body to survive: the use of anabolic steroids for HIV therapy

The loss of lean body mass (LBM) that is commonly associated with wasting syndrome has been linked to death in HIV disease. Bioelectrical Impedance Analysis (BIA) is a simple, inexpensive and painless technique used to assess body composition. The test gives a good reading of body cell mass, fat mass, and body water, and can be used to detect loss of LBM when it first occurs. BIA is a useful tool in managing and preventing wasting. Other factors that influence LBM include testosterone levels and anabolic steroids. Anabolic steroids, synthetic analogs of testosterone, are a Class III regulated drug. The use of anabolic steroids is controversial, and abuse by athletes led to the drugs being banned for many uses. A list of approved steroids, their actions, and potential problems associated with their use is included. Another table rates the major steroids for their effectiveness in AIDS therapy.     

The effects of treatment with recombinant human growth hormone on body composition and metabolism in adults with growth hormone deficiency

In a double-blind, placebo-controlled trial, we studied the effects of six months of growth hormone replacement in 24 adults with growth hormone deficiency. Most of the patients had acquired growth hormone deficiency during adulthood as a consequence of treatment for pituitary tumors, and all were receiving appropriate thyroid, adrenal, and gonadal hormone replacement. The daily dose of recombinant human growth hormone (rhGH) was 0.07 U per kilogram of body weight, given subcutaneously at bedtime. The mean (+/- SE) plasma concentration of insulin-like growth factor I increased from 0.41 +/- 0.05 to 1.53 +/- 0.16 U per liter during rhGH treatment. Treatment with rhGH had no effect on body weight. The mean lean body mass, however, increased by 5.5 +/- 1.1 kg (P less than 0.0001), and the fat mass decreased by 5.7 +/- 0.9 kg (P less than 0.0001) in the group treated with growth hormone; neither changed significantly in the placebo group. The basal metabolic rate, measured at base line and after one and six months of rhGH administration, increased significantly; the respective values were 32.4 +/- 1.4, 37.2 +/- 2.2, and 34.4 +/- 1.6 kcal per kilogram of lean body mass per day (P less than 0.001 for both comparisons). Fasting plasma cholesterol levels were lower (P less than 0.05) in the rhGH-treated group than in the placebo group, whereas plasma triglyceride values were similar in the two groups throughout the study. We conclude that growth hormone has a role in the regulation of body composition in adults, probably through its anabolic and lipolytic actions.     

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.     

Relationship of body composition to somatotype in college men

This study was designed to determine the relation of somatotype to body composition of college-aged men and to test the assumptions of the Heath and Carter approach to the estimation of second component as lean body mass relative to height. Lean body mass was estimated from whole-body ⁴⁰K spectrometry and from body density. LBM/height accounted for less than one third of the variation in Health and Carter's second component. When lean body mass and height were used together in multiple regression analysis as separate predictors instead of a ratio, 66 per cent of the variation in the second component was accounted for. The muscle circumferences and height, but not skeletal widths, used in the Heath and Carter method were significant predictors in regression analysis, accounting for 84·5 per cent of the variance in LBM. The use of two skinfolds (upper arm and waist) and body weight represents the most accurate approach for predicting LBM with 96·0 per cent of the variance accounted for. While there was a significant relation between the Heath and Carter anthropometric approach to second component as lean body mass relative to height, a more valid approach to the prediction of second component from anthropometry is the use of skinfolds and body weight, rather than body circumferences and widths, to estimate LBM. A new, practical approach to the estimation of second component is proposed using height and estimated LBM in a regression equation derived on the sample investigated.     

Bioelectrical impedance analysis in dialysis patients

Identification of malnutrition is imperative in chronic dialysis patients. Bioelectrical impedance (BIA) is a noninvasive method to measure body composition and estimate total body water (TBW), lean body mass (LBM) and body cell mass (BCM). Studies suggest BIA has good reliability as compared to other accepted methods of body composition analysis. Preliminary data also suggest that BIA-derived parameters (reactance and phase angle) predict clinical outcome in chronic hemodialysis patients. Overall, BIA is a promising nutritional assessment tool to monitor health status, long-term follow-up, tailor nutrition support, and detect early subtle losses of LBM in chronic dialysis patients.     

The impact of equations on calculation of lean body mass by bioelectrical impedance analysis in RDT patients

Several equations are available to derive lean body mass (LBM) from bioelectrical impedance analysis (BIA). The purpose of this study was to investigate in dialysis patients the impact of the equation used on the outcome of LBM assessment. To avoid dyshydration as a confounder, vena cava diameter measurement was used to assess normohydration in the 21 patients studied. Five equations were compared. In a previously published study to assess total body water using antipyrine as a gold standard, Deurenberg's formula was advocated to be used in the estimation of LBM by BIA. Therefore, this formula was used as a basis for comparison with the other four equations. One equation gave results comparable to those obtained by Deurenberg's formula. Despite high correlations and agreement according to Bland and Altman analysis, the other three equations showed a significant difference with Deurenberg-derived LBM. Thus, the equation used has a major impact on the outcome of LBM estimations.     

Body composition changes by DXA, BIA and skinfolds during exercise training in women

Purpose

Few studies have examined responsiveness of bioimpedance (BIA) to detect changes over time in body composition using a longitudinal design. Accuracy of BIA and skinfold thickness in estimating body composition among 39–64 year-old women was investigated using dual-energy X-ray absorptiometry (DXA) as a criterion method both cross-sectionally and during a training intervention.

Methods

97 women had percentage of fat assessed using DXA, skinfolds and eight-polar BIA using multi-frequency current. Fat mass and lean mass were estimated by DXA and BIA. Measurements were performed before and after the 21-week training intervention.

Results

At baseline relative to DXA, BIA under predicted percentage of fat (?6.50 %) and fat mass (?3.42 kg) and overestimated lean mass (3.18 kg) considerably. Also skinfold measurement under predicted percentage of fat compared to DXA, but the difference was smaller (?1.69 % units). Skinfold measurement overestimated percentage of fat at low values and underestimated at high values (r ² = 0.535). A significant bias was detected between DXA and BIA’s estimate of change in percentage of fat, fat mass and lean mass. Compared to DXA, BIA and skinfolds underestimated the training-induced positive changes in body composition.

Conclusions

BIA and skinfold methods compared to DXA are not interchangeable to quantify the percentage of fat, fat mass and lean mass at the cross-sectional design in middle-aged women. Moreover, exercise training-induced small changes in body composition cannot be detected with BIA or skinfold method, even though DXA was able to measure statistically significant within-group changes in body composition after training.     

Body composition characteristics and body fat distribution in lean women with polycystic ovary syndrome

Body composition, fat distribution and bone mineral density were examined in lean women suffering from polycystic ovary syndrome (PCOS) and compared with body composition and fat distribution characteristics of weight-matched lean controls. Ten women with PCOS and a body mass index (BMI) below 25.00 (kg/m(2)) and 10 healthy women with a BMI below 25.00 (kg/m(2)) matched for age and weight and BMI as controls were enrolled in this study. Body composition and bone density were measured by dual-energy- x-ray-absorptiometry and fat distribution patterns were calculated. Although matched for age, weight and BMI, lean PCOS patients showed a significantly higher amount of body fat and lower amount of lean body mass than the controls. The majority of PCOS patients showed an intermediate or android kind of fat distribution. Only 30% of the lean PCOS patients corresponded to the definition of gynoid fat distribution while this was true of all lean controls.     

Loss of fat,water, and protein during very low calorie diets and complete starvation

Summary The magnitude and composition of weight loss obtained in obese women on two forms of very low calorie protein-supplemented diets (Cambridge diet, Dresden drink) as well as by complete starvation has been investigated.With the VLCD, nitrogen equilibrium was reached on the 10th day of fasting, the cumulative nitrogen balance also being compensated. Nearly half of the body weight loss is due to loss of fat. In order to assess the benefit of fasting regimes, we propose to measure at least two parameters which are independent of each other, e.g., nitrogen balance and total body water. Both types of VLCD were equally effective, safe, and acceptable in achieving rapid body weight reduction.Abbreviations BMR basal metabolic rate - ECW extracellular water - ICW intracellular water - LBM lean body mass - TBW total body water - VLCD very low calorie diets     

Increased 2-hydroxylation of estrogen is associated with lower body fat and increased lean body mass in postmenopausal women

Menopause is associated with changes in bone, muscle and fat mass. The importance of postmenopausal estrogen metabolism in bone health has been established. However, its relationship to body composition in postmenopausal women remains undetermined. The objective of this study is to determine the association between estrogen metabolism and body composition in postmenopausal women. This is a cross sectional study of 97 postmenopausal Caucasian women, 49-80 y.o., ≥1 year from the last normal menstrual period or those who have had oophorectomy. Inactive [2-hydroxyestrone (2OHE(1))] and active [16α-hydroxyestrone (16α-OHE(1))] urinary metabolites of estrogen were measured by ELISA. The whole and regional body composition was measured by DXA. We have found that both 2OHE(1), and 2OHE(1)/16α-OHE(1) ratio were negatively correlated with % total fat, and % truncal fat but positively correlated with % total lean mass. Comparing the fat and lean parameters of body composition according to tertiles of 2OHE(1) and 2OHE(1)/16αOHE(1) ratio showed that subjects in the lowest tertiles, had the highest % total fat, and % truncal fat and the lowest % total lean mass. Multiple regression analysis also showed 2OHE(1) and calcium intake as statistically significant predictors of all body composition parameters. In conclusion, in postmenopausal women, an increase in the metabolism of estrogen towards the inactive metabolites is associated with lower body fat and higher lean mass than those with predominance of the metabolism towards the active metabolites.     

Nandrolone decanoate treatment of post-menopausal osteoporosis for 2 years and effects of withdrawal

This study investigated the effects of nandrolone decanoate (ND) therapy (50 mg i.m. every 3 or 4 wk) on bone mass and soft tissue body composition in post-menopausal women. Twenty-two (22) women were followed up over a period of 30 mth, during which they received ND therapy for 12–24 mth and were treatment-free for the other 6–18 mth. While they were receiving treatment forearm bone mineral content (BMC) and lean body mass (LBM) increased, whereas fat mass (FM) decreased. After withdrawal of ND therapy the BMC, LBM and FM values all tended to return to pretreatment levels.

Serum high-density-lipoprotein cholesterol showed a non-significant decrease, while serum lowdensity-lipoprotein cholesterol and serum total cholesterol remained unchanged during therapy. It was concluded that ND therapy can achieve an increase in BMC in post-menopausal women, but this is maintained only for as long as therapy is continued.     

Associations between mammographic density and body composition in Hispanic and non-Hispanic white women by menopause status

OBJECTIVE: To evaluate the associations of body composition, including percentage of lean and fat mass, with the percentage of mammographic density and mammographic dense area among pre- and postmenopausal Hispanic and non-Hispanic white women. DESIGN: In this cross-sectional study, a total of 238 women aged 41 to 50 or 56 to 70 years were recruited from local mammography clinics and community health centers. Postmenopausal status was defined as an absence of any menstrual cycle within the past 12 calendar months or having a follicle-stimulating hormone level between 22 and 138 mIU/mL. The participants' most recent mammograms were used for the mammographic density analysis. Body composition was measured by dual-energy x-ray absorptiometry. The associations between the percentage of mammographic density or mammographic dense area and body composition components were analyzed using logistic regression. RESULTS: Mammographic dense areas were similar in Hispanic and non-Hispanic white women. The percentage of mammographic density varied by ethnicity in premenopausal (P = 0.023), but not in postmenopausal women. Body composition, both higher lean mass and lower fat mass, was associated with a higher percentage of mammographic density (P < 0.05). Interestingly, a higher percentage of total body fat mass and a lower percentage of total body lean mass were correlated with larger breast dense areas in premenopausal women but with lower breast dense areas in postmenopausal women. These relationships between body composition and mammographic density measurements were not significantly affected by factors such as age, ethnicity, and body weight. CONCLUSIONS: Body composition is highly correlated with mammographic density and should be examined as a possible confounding factor in studies involving mammographic density measurements and breast cancer risk.     

Age-related changes in body composition of healthy and osteoporotic women

Objectives: The study was carried out to assess age-related changes of body composition and to evaluate the influence of lean and fat mass in bone mineral density of healthy and osteoporotic women. Methods: 166 healthy women in premenopause (43.2 ± 6.7 years), 591 healthy postmenopausal women (59.9 ± 8.1 years) and 373 women with established involutive osteoporosis (66.2 ± 7.8 years) were evaluated: bone mineral density (BMD) and soft tissue composition (fat mass, lean mass) were measured by a total body Lunar DPX device. Results: no difference in lean mass was appreciated between the groups. Fat mass was significantly lower in premenopausal women (19.5 ± 6.5 kg) and osteoporotic patients (18.8 ± 5.2 kg) than in postmenopausal healthy women (21.8 ± 5.7 kg). In premenopause weight, soft tissue mass and fat mass increased with age (P < 0.05). In postmenopause, lean mass decreased significantly in healthy women (P < 0.05). Fat mass was lower in the osteoporotics than in normals. Total BMD correlated significantly with fat and lean mass in all groups (P < 0.01). BMD/height ratio correlated significantly with fat mass (P < 0.01), not with lean mass. Conclusions: BMD is closely related to fat mass in healthy premenopausal and postmenopausal women, and in osteoporotic patients; osteoporotic patients and healthy premenopausal women are characterized by a lower fat mass than healthy postmenopausal women; fat mass may be considered one of the determinants of bone mass also in involutive osteoporosis.     

Effects of tibolone on body composition in postmenopausal women: a 1-year follow up study

Objective: We investigated the effects of 1-year tibolone treatment on body weight, body composition and indices of android obesity in postmenopausal women.

Methods: Forty-four postmenopausal women participated in this open-label controlled study; mean age was 51.8 ± 2.21 years and all women were menopausal for 3.8 ± 1.40 years. Twenty-two of them started taking 2.5 mg tibolone (TIB) daily for 1 year, whereas the remaining 22 served as age-matched controls. All subjects underwent a structured interview, physical examination, body composition measurements performed by dual-energy X-ray absorptiometry (DXA) — Hologic QDR 4500 A, as well as bioelectrical body impedance analysis (BI) — Tanita TBF-215, Japan.

Results: The TIB group did not significantly increase their weight (+0.4 kg), while the non-treated controls increased their mean weight by 1.4 kg (p = 0.046). In the TIB group, DXA showed a non-significant body fat decrease by a mean of 0.5 kg and a non-significant lean mass increase by 0.8 kg, while in the control group, fat mass increased by 1.7 kg (p = 0.032) and lean mass did not change. BI revealed that the TIB group had lost some fat (≈0.6 kg, n.s.) and put some free-fat mass (≈1.0 kg, p = 0.048) without changes in total body water. The control group put on some fat (≈1.1 kg, p = 0.042) and lost some body water (≈0.4 kg, n.s.).

Conclusion: Results from both methods of measuring body composition show a similar trend: a decrease in fat mass and an increase in lean mass in TIB treated subjects. From the body composition perspective, tibolone may be regarded as a preferential alternative to conventional hormonal therapy (HT) in postmenopausal women.     

Menopause,fat and lean distribution in obese women

Objectives: Whether menopause per se influences fat distribution independently of the effect of aging remains controversial. The lack of consistency in the menopause related changes in body fat distribution may be the result of differences in the methods for measuring fat distribution or in the characteristics of the women studied. The aim of this cross sectional study in obese women was to compare total body composition and regional fat and lean distribution, in premenopausal, perimenopausal and postmenopausal women. Methods: Body composition was assessed by dual energy X-ray absorptiometry (DEXA) in premenopausal (n = 26), perimenopausal (n = 24) and postmenopausal (n = 73) obese women with no intercurrent diseases. Results: It was shown that postmenopausal obese (n = 73) women had a higher proportion of total fat mass in the trunk and a lower proportion of total fat and lean mass in the femoral and leg regions than premenopausal women after adjustment for age and total fat mass. In the same analysis, perimenopausal women had a lower proportion of total fat in the leg and femoral regions and of total lean in the femoral region than premenopausal women; they had a regional body composition similar to that of postmenopausal women. Conclusion: The present data indicate that in obese women, post menopause and perimenopause are associated with differences in fat and lean distribution, independently of age and total fat.     

Anaerobic power output of young obese men: Comparison with non-obese men and the role of excess fat

Summary Anaerobic power output was measured by the staircase climb test in 14 obese, 16 lean, and 21 ordinary men aged from 18–22 years. Fat storage rate (%fat) was estimated by densitometry. The obese group ranked highest with an average power output of 1,012 W. This value was significantly higher than those of the other two groups, 890 W for lean subjects and 855 W for ordinary subjects. The power output per kilogram of lean body mass of the obese group was the highest also. However, the vertical velocity was the lowest although the difference among the three average values was not statistically significant. To investigate the effect of excess fat, eight non-obese subjects engaged in an added-weight experiment. The value obtained was almost the same as for the obese group. The added weights made the vertical velocity decrease but the power output increase. Consequently, it was obvious that the excess fat of an obese man played a role only as an inert mass in the power output measurement. A significantly higher power output of the obese group might be due to more excess fat, and obesity itself was an advantage in the staircase climb test.     

Comparison of DEXA and QMR for assessing fat and lean body mass in adult rats

There are several techniques used to measure body composition in experimental models including dual energy X-ray absorptiometry (DEXA) and quantitative magnetic resonance (QMR). DEXA/QMR data have been compared in mice, but have not been compared previously in rats. The goal of this study was to compare DEXA and QMR data in rats. We used rats that varied by sex, diet, and age, in addition we compared dissected samples containing subcutaneous (pelt) or visceral fat (carcass). The data means were compared by focusing on the differences between DEXA/QMR data using a series of scatter plots without assuming that either method is more accurate as suggested by Bland and Altman. DEXA/QMR data did not agree sufficiently in carcass or pelt FM or in pelt LBM. The variation observed within these groups suggests that DEXA and QMR measurements are not comparable. Carcass LBM in young rats did yield comparable data once the data for middle-aged rats was removed. The variation in our data may be a result of different direct and indirect measures that DEXA and QMR technologies use to quantify FM and LBM. DEXA measures FM and estimates fat-free mass. In contrast, QMR uses separate equations of magnetic resonance to measure FM, LBM, total body water and free water. We found that QMR overestimated body mass in our middle-aged rats, and this increased the variation between methods. Our goal was to evaluate the precision of DEXA/QMR data in rats to determine if they agree sufficiently to allow direct comparison of data between methods. However DEXA and QMR did not yield the same estimates of FM or LBM for the majority of our samples.