The prediction of total body water using bioelectrical impedance in children and adolescents

Total body water was measured in 26 children and adolescents using the stable isotope H2O18. Body resistance was measured using a tetrapolar technique with a constant 50Khz, 800 microA alternating current. Total body water was highly correlated (r = 0.97; P less than 0.001) with height2/body resistance. Measurements of body resistance are non-invasive, rapid and readily acceptable to children. For these reasons the measurement of body resistance requires further investigation, including cross validation studies and is a potentially valuable technique for assessing body composition in the paediatric population.     

Creatine Supplementation Increases Total Body Water Without Altering Fluid Distribution

OBJECTIVE: To examine the effects of oral creatine (Cr) monohydrate supplementation on muscle Cr concentration, body mass, and total body water (TBW), extracellular water (ECW), and intracellular water (ICW) volumes. DESIGN AND SETTING: After an overnight fast, urinary Cr and creatinine concentrations, muscle Cr concentration, body mass, TBW, ECW, and ICW were measured, and subjects were randomly assigned to either a Cr or a placebo (P) group. The Cr group ingested 25 g/d of Cr for 7 days (loading phase) and 5 g/d for the remaining 21 days (maintenance phase), whereas the P group ingested a sucrose P using the same protocol. All the measures were reassessed immediately after the loading and maintenance phases. SUBJECTS: Sixteen men (age = 22.8 +/- 3.01 years, height = 179.8 +/- 7.1 cm, body mass = 84.8 +/- 11.2 kg) and 16 women (age = 21.8 +/- 2.51 years, height = 163.4 +/- 5.9 cm, body mass = 63.6 +/- 14.0 kg) involved in resistance training volunteered to participate in this study. MEASUREMENTS: Muscle Cr concentration was determined from the vastus lateralis muscle using a percutaneous needle-biopsy technique. Total body water, ECW, and ICW volumes were assessed using deuterium oxide and sodium bromide dilution analyses. RESULTS: The Cr group experienced a significant increase in muscle Cr concentration, body mass, and TBW. The P group experienced a small but significant increase in TBW only. CONCLUSIONS: The Cr supplementation protocol was effective for increasing muscle Cr concentrations, body mass, and TBW; however, fluid distribution was not changed.     

Methodological agreement between two-compartment body-composition methods in children.

Increases in childhood obesity have emphasized the importance of accurate and accessible body composition assessment, especially in monitoring prevention and treatment efforts. Previous pediatric studies, comparing measures from air-displacement plethysmography (ADP) to dual-energy X-ray absorptiometry (DXA) and anthropometry (ANTH, skinfold measures), were performed in small numbers of children or in children across large age and body-size ranges. The objectives of this study were: 1) to compare body fat percentage (%BF), fat mass (FM), and fat-free mass (FFM) from ADP with DXA and ANTH, to determine the agreement between techniques; 2) to identify factors that influence agreement or lack of agreement; and 3) to determine if the agreement is constant over a range of body fatness. Healthy children (n = 125), 7-10 years old, participating in a longitudinal pediatric bone health study, were evaluated. Body composition was assessed by ADP, DXA, and ANTH to determine %BF, FM, and FFM. ADP underestimated %BF compared to DXA and ANTH by 5.0% and 1.4%, respectively. Agreement between techniques was influenced by body fatness, height, age, and gender (all P < 0.05). Relatively good agreement was observed between ADP and both DXA and ANTH for FM and FFM. In conclusion, the underestimation of %BF by ADP compared to DXA may be of a magnitude that is clinically significant, especially when using %BF in children to confirm a diagnosis of obesity. Further development of body-composition techniques for young children need to account for variability in age, gender, and level of fatness.     

Association of Peripheral Total and Differential Leukocyte Counts with Obesity-Related Complications in Young Adults

ObjectiveObesity has been demonstrated to be associated with elevated leukocytes in adults and children. This study assessed the associations between peripheral total and differential leukocyte counts and obesity-related complications in young adults.Methods12 obese (median age 21.5 (range 19-28) years, median BMI 35.7 (range 32.0-44.9) kg/m²) and 11 normal (median age 23 (range 18-27) years, median BMI 19.5 (range 18.1-21.7) kg/m²) adults were enrolled. Complete blood count and serum levels of liver enzymes, fasting blood glucose, insulin and lipids were measured, and the homeostasis model assessment of insulin resistance was calculated. Fat mass was calculated using a bioimpedance analysis device, and ultrasonography was performed to measure fat thickness and to detect fatty change of the liver.ResultsTotal leukocyte and monocyte counts were significantly increased in obese young adults. Total leukocyte count was associated with liver enzyme levels, insulin resistance as well as visceral and subcutaneous fat thickness. Neutrophil count was associated with insulin resistance. Lymphocyte count was associated with serum liver enzymes, insulin resistance, and dyslipidemia. Monocyte count was associated with serum liver enzyme, insulin resistance, visceral and subcutaneous fat thickness, body fat mass, and percentage body fat.ConclusionThe results of this study suggest that chronic low-grade systemic inflammation is associated with obesity-related complications such as nonalcoholic fatty liver disease, insulin resistance, and dyslipidemia in young adults.Key Words: Inflammation, Obesity, Insulin resistance, Dyslipidemia, Body fat     

The effects of physical exercise on body fat distribution and bone mineral density in postmenopausal women

OBJECTIVE: The present cross-sectional study investigated the effects of physical exercise on body fat distribution and bone mineral density (BMD). METHODS: Subjects were 57 postmenopausal women (mean age, 60.5+/-6.4 years) who had exercised regularly for at least 2 years. Controls were 130 age-matched sedentary women. Age, years since menopause (YSM), height, weight, and body mass index (BMI, wt./ht.(2)) were recorded. Total fat mass, percentage of body fat, trunk fat mass, leg fat mass, the ratio of trunk fat mass to leg fat mass (trunk-leg fat ratio), total body lean mass, percentage of body lean, and lumbar spine BMD (L2-L4) were measured by dual-energy X-ray absorptiometry. RESULTS: Baseline characteristics and leg fat mass did not differ between the two groups. Total fat mass, percentage of body fat, trunk fat mass, and trunk-leg fat ratio were lower (P<0.05, P<0.01, P<0.01 and P<0.001, respectively), while total body lean mass, percentage of body lean mass, and lumbar spine BMD were higher in exercising women (P<0.05, P<0.05 and P<0.01, respectively). Performing physical exercise was inversely correlated with trunk-leg fat ratio (standardized regression coefficient=-0.178, P<0.01), but positively correlated with BMD (0. 203, P<0.01) irrespective of age, height, YSM, and total fat mass. CONCLUSION: Physical exercise has beneficial effects on body fat distribution and BMD in postmenopausal women. Reduction of upper body fat distribution with physical exercise may be more attributable to the decrease in trunk fat mass.     

Relationship between soft tissue body composition and bone mass in perimenopausal women

OBJECTIVES: Perimenopause, the transition into menopause, marks the beginning of accelerated bone loss, contributing to the development of osteoporosis, a major public health problem. This perimenopausal transition has also been associated with a decrease in body lean mass, an increase in fat mass, and an increase in body weight. How these changes in fat mass and lean mass may influence bone mineral density (BMD) is currently unknown. The purpose of this study is to determine the independent effect and relative contribution of lean mass and fat mass to BMD in perimenopausal women. MATERIAL AND METHODS: The sample consisted of 43 sedentary perimenopausal women (age: mean = 49.6; S.D. = 3.2) with an intact uterus and ovaries, participating in a study of exercise and perimenopausal symptoms. Total body BMD, regional BMD, and soft tissue body composition were measured by dual-energy X-ray absorptiometry. Other measures including age, height, weight, and serum FSH and E2 were also obtained. RESULTS: Findings revealed that 14% of these perimenopausal women had low bone mass (osteopenia) in the lumbar spine and/or the femoral neck. Overall body fat mass and lean mass had positive relationships with BMD of lumber spine and the femur. However, using multiple regression analyses, only lean mass and ethnicity remained significant predictors for BMD of the femoral neck (r2 = 45%) with lean mass explaining more variance than ethnicity. Lean mass was the sole predictor of total proximal femur BMD explaining 38% of the variance. Fat mass was not a significant predictor of BMD at any skeleton site. CONCLUSIONS: These findings suggest that body lean mass, not fat mass, is a significant contributor to femoral BMD in perimenopausal women.     

The distribution of subcutaneous and internal fat in man

Total body fat mass was estimated in 25 women and 21 men from densitometry. All subjects were apparently healthy. Subcutaneous fat mass was calculated by measuring subcutaneous fat thickness at 12 sites using A-mode ultrasound. The proportion of fat situated subcutaneously (PFSS) was found to vary considerably between individuals (range 0.50-0.97 in the women, 0.40-0.97 in the men). Moreover, there was no relationship between subcutaneous and internal fat masses. More information is required on the variability of the PFSS, and the technique described may have a role to play in this field.     

Relationship between total body water and surface area in normal and obese subjects

Total body water was measured using tritium in 30 males and 30 females. It was found that total body water could be predicted from height and weight, and formulae for both males and females have been produced with multiple correlation coefficients (r) of 0.95 and 0.96 respectively. The predicted total body water was found to be very closely related to the predicted surface area giving correlation coefficients (r) for males and females of 0.997 and 0.985 respectively.     

The use of body mass index to predict body composition in children

BACKGROUND: Simple anthropometric indices of body composition have particular appeal for use in children, and as such body mass index (BMI) has been used to predict percentage body fat in a number of studies. AIM: To evaluate the relationship between BMI and percentage body fat (%body fat) and a proposed, more appropriate relationship between BMI and fat mass/height(2) in a cohort of young children. SUBJECTS AND METHODS: Cross-sectional study of 109 children aged between 6 and 10 years residing in either Sydney or Brisbane, Australia. Weight and height were measured using standard methods. Body composition was measured using a stable isotope method to firstly determine total body water and subsequently fat free mass. RESULTS: The correlation between BMI and fat mass/height(2) was markedly greater than that between BMI and percentage body fat. In the entire group of children the R(2) (x100%) value for the relationship between BMI and fat mass/height(2) was 73.3% compared with 46.5% for the relationship between BMI and percentage body fat. CONCLUSIONS: We have shown that the use of BMI to predict fat mass/height(2), and consequently percentage body fat, is superior to the use of BMI to predict percentage body fat based directly upon the R(2) values of the above analysis.     

The effects of creatine supplementation on muscular performance and body composition responses to short-term resistance training overreaching

To determine the effects of creatine supplementation during short-term resistance training overreaching on performance, body composition, and resting hormone concentrations, 17 men were randomly assigned to supplement with 0.3 g/kg per day of creatine monohydrate (CrM: n=9) or placebo (P: n=8) while performing resistance exercise (5 days/week for 4 weeks) followed by a 2-week taper phase. Maximal squat and bench press and explosive power in the bench press were reduced during the initial weeks of training in P but not CrM. Explosive power in the bench press, body mass, and lean body mass (LBM) in the legs were augmented to a greater extent in CrM (P0.05) by the end of the 6-week period. A tendency for greater 1-RM squat improvement (P=0.09) was also observed in CrM. Total testosterone (TT) and the free androgen index (TT/SHBG) decreased in CrM and P, reaching a nadir at week 3, whereas sex hormone binding globulin (SHBG) responded in an opposite direction. Cortisol significantly increased after week 1 in CrM (+29%), and returned to baseline at week 2. Insulin was significantly depressed at week 1 (–24%) and drifted back toward baseline during weeks 2–4. Growth hormone and IGF-I levels were not affected. Therefore, some measures of muscular performance and body composition are enhanced to a greater extent following the rebound phase of short-term resistance training overreaching with creatine supplementation and these changes are not related to changes in circulating hormone concentrations obtained in the resting, postabsorptive state. In addition, creatine supplementation appears to be effective for maintaining muscular performance during the initial phase of high-volume resistance training overreaching that otherwise results in small performance decrements.     

The use of body mass index to predict body composition in children

Background : Simple anthropometric indices of body composition have particular appeal for use in children, and as such body mass index (BMI) has been used to predict percentage body fat in a number of studies. Aim : To evaluate the relationship between BMI and percentage body fat (%body fat) and a proposed, more appropriate relationship between BMI and fat mass/height 2 in a cohort of young children. Subjects and methods : Cross-sectional study of 109 children aged between 6 and 10 years residing in either Sydney or Brisbane, Australia. Weight and height were measured using standard methods. Body composition was measured using a stable isotope method to firstly determine total body water and subsequently fat free mass. Results : The correlation between BMI and fat mass/height 2 was markedly greater than that between BMI and percentage body fat. In the entire group of children the R 2 ( &#50 100%) value for the relationship between BMI and fat mass/height 2 was 73.3% compared with 46.5% for the relationship between BMI and percentage body fat. Conclusions : We have shown that the use of BMI to predict fat mass/height 2, and consequently percentage body fat, is superior to the use of BMI to predict percentage body fat based directly upon the R 2 values of the above analysis.     

Water turnover in children and young adults

Water homeostasis is essential for life and optimal function and considerable interest surrounds the issue of recommendations for water consumption in healthy individuals. Objective data on water turnover in free-living individuals are limited, however. The aim of the present work was to measure water turnover in children and young adults using isotopically labeled water to provide objective data on magnitude and variability in relation to body weight, fat-free mass and physical activity level. Water turnover was measured by deuterated water dilution in 91 healthy children (40 boys, 51 girls; age 5–14 years) and 109 healthy young adults (80 women, 29 men; age 18–27 years) with a wide range of body mass index (13.3–51.8 kg/m²) and percent body fat (6.1–59.3%). Total energy expenditure (TEE) and resting metabolic rate were measured by the doubly labeled water technique and indirect calorimetry, respectively. Water turnover was 1.77 ± 0.57 (SD), 1.79 ± 0.44, 2.85 ± 0.82, and 3.90 ± 0.81 L/day in girls, boys, women, and men, respectively. Water turnover indexed to body surface area did not differ significantly between girls and women but was higher in men than boys. Water turnover indexed to TEE was 0.8 mL/kcal in girls and boys and 1.0 mL/kcal in women and men. This study provides objective data on water turnover for children and young adults in a temperate climate and shows that anthropometric parameters can account for the variation between girls, boys and women but not between these groups and the more active men.     

Nutritional status assessment and body composition analysis in pre-end stage renal disease patients

Malnutrition is a known risk factor for survival in renal failure patients. Of concern, a significant degree of malnutrition may develop in the predialysis period due to dietary restrictions and uremia. To further define this issue, we evaluated 25 predialysis patients using serum chemistries, body mass index (BMI), fat free mass (FFM), body cell mass (BCM), and protein appearance rate (PAR) as surrogates of nutritional status and compared their results to those obtained in established hemodialysis patients and recipients of living donor renal allografts during a nine-month observation period. Pre- dialysis patients had significantly (p<0.0001) higher body weight (28%), body mass index (26%), body cell mass (17%) and fat free mass (15%) than hemodialysis and transplant patients. Intracellular water content was similar in all groups. As many patients do not start dialysis until clearance values fall below 10 ml/min, it is possible that greater tissue mass losses occur in the weeks preceding initiation of dialytic therapy. Why renal transplant recipients fail to increase tissue mass may relate to the catabolic effects of immunosuppression. We conclude that the early stages of pre-end stage renal disease are associated with relatively good preservation of body cell mass.     

Physical activity level measured by doubly labeled water and accelerometry in children

The present study investigated the use of a tri-axial accelerometer, Tracmor2, for the measurement of physical activity in children. Eleven children [age 6.9 (2.2) years, body mass 19.5 (5.3) kg and height 112.3 (14.4) cm] were studied. Total daily energy expenditure (TDEE) was measured using the doubly labeled water method over a 2-week period. In addition, basal metabolic rate (BMR) was determined by the ventilated hood system. Physical activity level (PAL) was defined as TDEE/BMR. Tracmor2 was worn during the same 2-week period throughout waking hours after which average counts per day were calculated. The average counts per day were shown to be highly correlated to PAL values measured by doubly labeled water: PAL = 1.156×10^–5×Tracmor2 average counts day^–1 + 0.978 (r=0.79, P<0.01). In conclusion, Tracmor2 is a valid instrument to measure physical activity in children under free-living conditions.     

Maximal oxygen consumption,pulmonary function,body composition,and anthropometry of adolescent female athletes

Three groups of girl athletes — 10 gymnasts and 8 middle-distance swimmers averaging 14 years of age, and 8 middle-distance runners averaging almost 19 — were the subjects of this study. The maximal oxygen intake was determined by graded work load on a bicycle ergometer, certain pulmonary functions by spirometry, and total body potassium by wholebody counting of naturally radioactive⁴⁰K. The total body water was obtained from measurements of deuterium oxide and application of the dilution principle, and creatinine excretion was determined from urine collections. Fat-free mass was calculated from total body water, and the amount of body fat was obtained by subtracting fat-free mass from body weight. Cell mass was calculated from total body potassium. Supporting evidence of leanness or fatness was provided by anthropometric measurements.The runners and swimmers achieved significantly higher maximal oxygen consumption per kg of body weight, fat-free mass, and cell mass; and the runners excelled the gymnasts in certain other pulmonary functions. Total body potassium in milliequivalents per kg of body weight, total body water expressed in percentage of body weight, and creatinine coefficients were similar in all three groups of subjects. These results indicated no differences in body composition. Calculations of body fat, fat-free mass, and cellular mass verified that conclusion; and supporting evidence was obtained from subcutaneous fat folds and from appraisal of leanness by corrected limb diameters or volumes, which also were similar in all three groups.     

Effects of age on ventilatory threshold and peak oxygen uptake normalised for regional skeletal muscle mass in Japanese men and women aged 20–80 years

Ventilatory threshold (VT) is an important predictor of cardiorespiratory fitness, such as peak oxygen uptake (VO2peak) and is a valuable index of aerobic exercise intensity. However, little is known about the role of skeletal muscle (SM) mass in the age-associated decline of VT. Therefore, the present study was performed to investigate the effects of age on cardiopulmonary fitness normalised for regional SM mass in 1,463 Japanese men and women, and to determine the relevance of VT normalised to SM mass based on age and gender. Total, trunk and thigh SM mass were measured using an ultrasound method, while VO2peak and VT were determined during treadmill walking. VO2peak was estimated using the predicted maximum heart rate (HR) and the HR-VO2 relationship for sub-maximal treadmill walking. There were significant negative correlations between VT normalised for body mass and age in men and women (P < 0.001). Age-associated declines were also observed in VT normalised for body mass in both men and women; however, VT normalised for SM mass was not significantly different with age. Significant correlations were also observed between thigh SM mass and VT in both men and women. These results suggest that thigh SM mass is closely associated with VO2peak and/or VT in both men and women, and the decrease in VT with age is predominantly due to an age-related decline of SM mass. Moreover, this study provides normative cardiorespiratory fitness data regarding VT normalised SM mass in healthy men and women aged 20-80 years.     

A rat resistance exercise regimen attenuates losses of musculoskeletal mass during hindlimb suspension

Exposure to microgravity and/or spaceflight causes dramatic losses in both muscle and bone mass. In normal gravity, resistance exercise has been effectively used to increase muscle and bone mass. We tested a novel form of resistance exercise training using flywheel technology as a countermeasure to offset the loss of musculoskeletal mass during 4 weeks of adult rat hindlimb suspension (HS), an unloading model of microgravity. Male, Sprague-Dawley rats (6-month old) were operantly conditioned to perform resistance exercise, and then randomly assigned to groups of sedentary control (CON), HS, and HS with resistance exercise training (HSRT; 2 sets of approximately 21 repetitions, 3 days week(-1) for 4 weeks during suspension). In soleus, HS resulted in lower (P < 0.05) muscle mass to body mass ratio (approximately 50% of controls) and rates of protein synthesis. HSRT significantly attenuated the loss of muscle mass in soleus muscle, and rates of protein synthesis for soleus were similar for HSRT and controls. There were no differences among groups for mass or rates of protein synthesis in extensor digitorum longus. In cancellous regions of the distal femur, HS resulted in significant reductions of bone mineral density (BMD), but this was restored to control levels with HSRT. Cortical regions of the femur were not different among HS, HSRT or control groups. Together, these data suggest that resistance training using flywheel technology may be a promising tool to attenuate losses of the musculoskeletal system during periods of hindlimb unloading.     

Determination of body composition in conscious adult female Wistar utilising total body electrical conductivity.

Total body electrical conductivity (TOBEC) is a noninvasive method for estimating fat free mass (FFM) in live animals. In this study, we have evaluated the use of the Em-Scan SA-3000, which is claimed by the manufacturers to perform better than earlier analysers. Previous studies in rats using these earlier versions of the TOBEC analyser have always used anaesthesia to minimise movement artefacts. As repeated anaesthesia also has the potential to induce artefacts by disrupting food intake, for example, we have also attempted to determine if this TOBEC analyser can be used to predict body composition in conscious adult weight-stable female Wistar rats. A simplified cafeteria diet was used to produce large variations in body composition (40-350 g fat/carcass) and a full chemical body composition analysis was performed to generate a TOBEC calibration equation. The TOBEC parameter was more strongly correlated to FFM (r(2)=.785) than it was to body weight (r(2)=.669) or other body composition parameters. Using the TOBEC calibration equation to predict fat mass on these data, there was an excellent correlation with the value obtained by chemical analyses (r(2)=.952, slope=0.958). To determine if the TOBEC calibration equation derived from this calibration study would then be useful for the routine estimation of body composition an additional, validation study was performed. This validation study was performed 6 months later, used an independent group of obese female Wistar rats and was undertaken by different TOBEC operators. This validation study, again, showed a good correlation between the TOBEC- and chemical-derived fat mass (r(2)=.918, slope=1.003) indicating stability of the calibration equation with time and independence from operator. We therefore conclude that it is possible to meaningfully estimate body fat changes in conscious rats using this TOBEC analysis system.     

Leptin production in pre- and postmenopausal women

OBJECTIVES: To investigate the differences in leptin production between pre- and postmenopausal women. METHODS: Subjects were 75 pre- and 75 postmenopausal women. Age, height, weight, and body mass index (BMI, wt/ht(2)) were recorded. Serum leptin levels were measured by RIA. Total body fat mass and percentage of body fat mass were measured by whole-body scanning with dual-energy X-ray absorptiometry. Serum leptin levels, the ratio of serum leptin levels to total body fat mass (leptin-fat mass ratio), baseline characteristics, and anthropometric variables were compared between the two groups. In all subjects (n=150), relationship of serum leptin levels with menopausal status (pre- and postmenopause) was investigated by univariate and multiple regression analysis. RESULTS: Serum leptin levels in premenopausal women 8.4+/-4.8 ng/ml, which did not differ from that in postmenopausal women (9.2+/-7.1 ng/ml). Total body fat mass, percentage of body fat mass, and BMI did not differ between the two groups. Leptin-fat mass ratio in premenopausal women was 0.43+/-0.17 ng/ml/kg, which did not differ from that in postmenopausal women (0.44+/-0.24 ng/ml/kg). On both univariate and multiple regression analysis, serum leptin levels were not correlated with menopausal status. CONCLUSIONS: Menopausal status does not have a significant impact on leptin production.     

Distal versus proximal electrode placement in the prediction of total body water and extracellular water from multifrequency bioelectrical impedance

In 48 normal weight subjects, 25 females and 23 males, body impedance was measured at multiple frequencies. Two different electrode placements were used, one the commonly used distal electrode placement, in which the source electrodes are on the dorsal sides of the hand and foot and the sensor electrodes are on ankle and wrist, and a second placement, in which the sensor electrodes are placed more proximally, at the knee and elbow. Theoretically a proximal electrode placement could result in more precise estimates of body water compartments. Total body water (TBW) and extracellular water (ECW) were determined using deuterium oxide dilution and bromide dilution, respectively. The aim of the study was to investigate whether proximal electrode placement results in a more precise estimation of TBW and ECW using multifrequency impedance analysis. Correlation coefficients of impedance and the impedance index stature²/impedance) with TBW and ECW were not or were only slightly higher using proximal impedance values, resulting in slight improvement of the estimation error for TBW (0.13 kg) and ECW (0.04 kg). The differences between measured and predicted values (residuals) of TBW and ECW were not correlated with TBW and ECW, but they were correlated with body fat and body water distribution (ECW/TBW). These correlations did not differ between distal and proximal impedance measurements. It is concluded that proximal impedance measurements do not substantially improve the prediction of body water compartments. © 1995 Wiley-Liss, Inc.