Percent Lean Body Mass Research Articles

An evaluation of the biting force, the body composition and the amount of masticatory action in young females

The purposes of this study were to investigate factors related to maximum biting force and to understand the characteristics of physical properties of daily ingested foods in young females. One hundred and forty subjects aged 18-23, with Angle 1 class occlusion, had not suffered from periodontitis, and had not been treated for preparation of tooth crown of first molars. Body height and weight were measured, and percentage of body fat, fat mass (FM) and lean body mass (LBM) were estimated, using the impedance analyzer. The maximum biting force was measured by the press sensation method. According to the formula on the basis of our new version of Yanagisawa's food classification, the mean value of the amount of masticatory action for one day was calculated. Subjects were divided into the normal biting force and the low biting force groups with -1SD of the maximum biting force, in order to compare body composition and backgrounds in sports activities between these two groups. Multiple linear regression analysis was carried out, employing maximum biting force (kg.f) as a dependent variable, and having a background in sports activities, FM, LBM, the number of missing teeth, the number of dental caries and the amount of masticatory action for one day as independent variables. Results were as in the following: 1) The proportion of subjects who had a background in sports activities in the low biting force group were less than that in the normal biting force group (p < 0.01). 2) Having a background in sports activities and LBM were positively correlated to maximum biting force (p < 0.01), while the amount of masticatory action for one day was not. 3) All subjects, especially those in the low biting force group seldom had food requiring the highest amount of masticatory action. Having a background in sports activities and LBM are positively correlated with the maximum biting force, while the amount of masticatory action for one day was not correlated positively nor negatively in young females.

Effect of estrogen deficiency on cancellous and cortical bone structure and strength of the femoral neck in rats.

Eighty mature Sprague-Dawley rats were weight matched before ovariectomy (Ovx) or Sham surgery (Sham). Sham rats had free access to food and water throughout the experiment, whereas Ovx rats were kept on the pair-fed diet. Rats were euthanized at 4, 8, and 12 weeks after surgery, and had received fluorochrome bone markers at 9 and 2 days prior to euthanasia. In addition 10 rats were euthanized at the time of surgery serving as baseline controls. All rats were also scanned for body composition and bone mineral parameters by DEXA before surgery and euthanasia. Left proximal femurs (femoral necks) were used for bone histomorphometry, whereas right femurs were used for in vitro DEXA measurements and mechanical testing. Despite pair-feeding, ovariectomized rats had increased body weights and fat body mass, whereas the percent lean body mass steadily declined throughout the experiment. Mineral density of the whole femur and femoral neck was significantly higher in the Sham rats relative to Ovx animals. Ovariectomy reduced trabecular number and thickness, and increased trabecular separation and bone marrow space at the femoral midneck location. The structure of the remaining trabeculae was dramatically changed toward simpler struts as revealed by nodal analyses. Cortical thickness in Ovx rats was reduced because of the high endocortical resorption, which, in addition to cancellous bone resorption, resulted in fewer endocortico-trabecular connections. Femoral necks obtained from ovariectomized rats had reduced strength and were less stiff relative to controls. Because of the enormous clinical significance of the proximal femur for osteoporosis in humans, and the opportunity for studying bone BMD, mass, structure, and strength at the same skeletal location, the femoral neck appears superior to other skeletal sites routinely used for bone histomorphometry or mechanical testing in the Ovx rat model.

Comparative Evaluation of Body Composition in Medically Stable Elderly

Objective Accurate assessment is needed to identify the nutritional status of elderly persons. Anthropometric data were collected to describe body composition of the sample, including blacks and whites aged 55 to 89 years, and to explore the usefulness of several methods of body composition measurement. Design Baseline measurements were made as part of a longitudinal study. Body composition variables, particularly lean and lean-to-height measures, were used. Subjects/setting One hundred twenty-nine free-living medically stable elderly at senior community centers were self-selected into the study. Statistical analysis Descriptive statistics were generated for all variable by gender, race, and age (<65, 65 to 74, and ≥75 years). Actual height was correlated with estimated height using published equations. Analysis of variance revealed the effect of gender, race, or age on outcome variables. Results White women, black women, and white men made up 54%, 23%, and 23% of the sample, respectively. Most gender differences were expected. Black women had greater weight, body mass index, arm muscle circumference, and ratio of lean to height but lower percent lean body mass than white women. Subjects over 75 years old were shorter, lighter, and had lower ratio of lean to height. Gender and age had the greatest effect on ratio of lean to height. Conclusions/applications A lean-to-height index appears to be a useful tool for tracking the status of lean mass in the elderly. Knee height may be especially useful because it, unlike stature, does not decrease with age. Furthermore, some published equations for estimating stature from knee height need adjustment, specifically for elderly black women. J Am Diet Assoc. 1997;97:1105–1109.

Whole body lean mass is altered by dexamethasone treatment through reductions in protein and energy utilization in piglets.

The objective of this study was to assess the effect of dexamethasone on growth, body composition and protein metabolism using the piglet as a model for rapidly growing premature infants. Seven-day-old male pigs (n = 18) were randomized to 0.5 mg/kg/day oral dexamethasone or placebo for 15 consecutive days. Weight and length gains and weight gained per energy or protein consumed were significantly lower in the dexamethasone group. Serum urea nitrogen was significantly higher in the dexamethasone group by day 15 of the study. No differences were observed between groups for urinary creatinine. The whole body percent lean mass was significantly lower and percent fat mass was significantly higher in the dexamethasone piglets, as measured by dual energy X-ray absorptiometry. In young piglets, dexamethasone, at doses similar to those in premature infants, induces protein catabolism, impairs growth and alters its composition.

Resting metabolic rate and body composition in stunted and nonstunted children

The resting metabolic rate (RMR) and body composition of 34 stunted children (height-for-age < or = 1.5 SD) aged 7-8 y were compared with that of two groups of nonstunted control subjects (height-for-age > or = -1.0 SD) matched for either age and sex or height and sex. No significant group differences were found in percentage lean body mass (LBM). The RMR of the stunted children (4702 +/- 570 kJ/d) was significantly lower than that of both the age-matched (5802 +/- 616 kJ/d) and height-matched (5269 +/- 663 kJ/d) groups (ANOVA, P < 0.001). However, in a multiple-regression model including sex and LBM, the RMRs of the stunted and age-matched groups were not significantly different, suggesting that the stunted children's smaller LBM accounted for their lower RMR. This suggests that the composition and metabolic activity of the LBM is unaffected by stunting. The younger, height-matched control subjects had significantly higher RMRs than the stunted children after adjustment for LBM (P < 0.001). This may have been due to age-related changes in the composition of LBM.

Recent Food Intake did not Influence Precision of Body Composition Estimates by Bioelectrical Impedance Analysis in Men with HIV Infection

Bioelectrical impedance analysis (BIA), the measurement of the resistance to an electrical current in a living organism, is a common method of assessing body composition. It has been found to be a reliable method for estimating the percentage of lean body mass, fat mass, and water in people infected with the human immunodeficiency virus (HIV) and people with acquired immunodeficiency syndrome without opportunistic infection (1,2).

Adequacy of dialysis and nutrition in continuous peritoneal dialysis: association with clinical outcomes. Canada-USA (CANUSA) Peritoneal Dialysis Study Group.

The objective of the study presented here was to evaluate the relationship of adequacy of dialysis and nutritional status to mortality, technique failure, and morbidity. This was a prospective cohort study of consecutive patients commencing continuous peritoneal dialysis in 14 centers in Canada and the United States. Between September 1, 1990 and December 31, 1992, 680 patients were enrolled. Follow-up was terminated December 31, 1993. There were 90 deaths, 137 transplants, and 118 technique failures. Fifteen withdrew from dialysis. Analysis of the patient and technique survival used the Cox proportional hazards model with adequacy of dialysis and nutritional status as time-dependent covariates. The relative risk (RR) of death increased with increased age, insulin-dependent diabetes mellitus, cardiovascular disease, decreased serum albumin concentration and worsened nutritional status (subjective global assessment and percentage lean body mass). A decrease of 0.1 unit Kt/V per week was associated with a 5% increase in the RR of death; a decrease of 5 L/1.73 m2 creatinine clearance (CCr) per week was associated with a 7% increase in the RR of death. The RR of technique failure was increased with decreased albumin concentration and decreased CCr. Hospitalization was increased with decreased serum albumin concentration, worsened nutrition according to subjective global assessment and decreased CCr. A weekly Kt/V of 2.1 and a weekly CCr of 70 L/1.73 m2 were each associated with an expected 2-yr survival of 78%.

Significance of type II fiber atrophy in chronic alcoholic myopathy

To determine the significance of type II fiber atrophy in alcoholic myopathy and its relationship with ethanol-related diseases a prospective study was carried out in 100 chronic alcoholics who showed clinical suspicion of skeletal myopathy. Measurement of muscle strength, laboratory analysis, nutritional assessment and open biopsy of deltoid muscle were performed in each case, as well as electrophysiological testing for peripheral neuropathy. Hepatic ultrasonography and liver biopsy, echocardiography and radionuclide cardiac scanning were carried out in selected subjects. According to histomorphometric analysis, type II fiber atrophy was found in 33 cases (33%), being selective for type II B fiber in 23 (70%). Skeletal myopathy was diagnosed in 61 cases, alcoholic cardiomyopathy in 26, peripheral neuropathy in 23 and cirrhosis in 12. Patients with type II fiber atrophy had a significantly higher total lifetime dose of ethanol, presented a greater incidence of skeletal myopathy and peripheral neuropathy, and exhibited significantly lower values of percentage of ideal body weight and lean body mass than their counterparts. However, the only independent factors for developing type II fiber atrophy were the coexistence of caloric malnutrition ( p = 0.004) and the presence of skeletal myopathy ( p = 0.043). Selective type II fiber atrophy is a non-specific finding in alcohol-induced muscle damage appearing, overall, in the patients with caloric malnutrition as well as in those with histologic evidence of myopathy.

Body mass index: a measure of fatness or leanness?

The relationship between body fat and stature-adjusted weight indices was explored. Assuming the term height2 is a valid indicator of a subject's lean body mass, height2/weight was shown to be an accurate measure of percentage lean body mass and, as such, a better predictor of percentage body fat than the traditional body mass index (BMI; weight/height2). The name, lean body mass index (LBMI), is proposed for the index height2/weight. These assumptions were confirmed empirically using the results from the Allied Dunbar National Fitness Survey (ADNFS). Using simple allometric modelling, the term heightp explained 74% of the variance in lean body mass compared with less than 40% in body weight. For the majority of ADNFS subjects the fitted exponent from both analyses was approximately p = 2, the only exception being the female subjects aged 55 years and over, where the exponent was found to be significantly less than 2. Using estimates of percentage body fat as the dependent variable, regression analysis was able to confirm that LBMI was empirically, as well as theoretically, superior to the traditional BMI. Finally, when the distributional properties of the two indices were compared, BMI was positively skewed and hence deviated considerably from a normal distribution. In contrast, LBMI was found to be both symmetric and normally distributed. When height and weight are recorded in centimetres and kilograms respectively, the suggested working normal range for LBMI is 300-500 with the median at 400.

Body composition assessed by bioelectrical impedance analysis (BIA) in patients with Graves' disease before and after treatment.

Body composition was assessed by bioelectrical impedance analysis (BIA) in 11 female patients with Graves' disease and in 49 age-matched healthy Japanese women. Patients with Graves' disease were examined in the hyperthyroid state before treatment and in the stable euthyroid state after treatment with antihyroid drugs for 6 to 18 months. Body weight (BW), percent body fat (BF/BW), percent lean body mass (LBM/BW) and percent total body water (TBW/BW) were not statistically different between hyperthyroid Graves' patients and healthy subjects. Percent body cell mass (BCM/BW) was much lower in hyperthyroid Graves' patients than in healthy subjects (mean +/- SEM; 33.9 +/- 2.4% vs. 41.5 +/- 0.5%, P < 0.001). Percent ratio of extracellular water to total body water (ECW/TBW) was much greater in hyperthyroid Graves' patients than in healthy subjects (53.9 +/- 3.0% vs. 41.8 +/- 0.5%, P < 0.001). These abnormal ratios, BCM/BW and ECW/TBW, were normalized after treatment. Serum free T4 levels showed a positive correlation with ECW/TBW (r = 0.779) and a reverse correlation with BCM/BW (r = -0.760) in all of the patients with Graves' disease examined. These findings indicate that body composition is affected by thyroid hormones and that body composition in hyperthyroid Graves' disease is characterized by decreased BCM associated with increased ECW.

Relationship of upper arm anthropometry to body composition in female athletes

Arm muscle area (AMA) and triceps skinfold (TSF) are simple techniques which are widely used in nutritional assessment. The value of AMA as a measure of lean mass and TSF as a measure of fat mass in female athletes was examined in this study. Subjects were 12 female NCAA Division III soccer and cross country athletes. Body fat percentage was determined by hydrostatic weighing (with residual volume estimated from age, height, and weight). Dietary intake (by six day diet record), hemoglobin and menstruation status were also assessed. The athletes were apparently in good nutritional status, although their intake of iron, calcium, folate and dietary fiber was somewhat low. TSF was significantly correlated with fat mass (r=.60, p=.04) and body fat percentage (r=.59, p=.04); but not with body weight (r=.33, p=.29). AMA was not significantly correlated with lean mass (r=.47, p=.12) or percent lean body mass (r=−.12, p=.72); but was more closely related to body weight (r=.56, p=.06). Both TSF (r=.58, p=.05) and AMA (r=.67, p=.02) were significantly correlated with body mass index. The results suggest that TSF may be useful for assessing fat mass in female athletes; while AMA tends to be more closely related to body weight than to lean mass.

RAPID CHANGES IN BODY COMPOSITION AFTER GH TREATMENT IN PATIENTS WITH GH DEFICIENCY

This study was designed to assess the changes in the body composition in patients with GH deficiency after 3 months of human growth hormone (hGH) treatment. Nine prepubertal patients (1 female and 8 males, aged 8 - 14 yr old) with GH deficiency were studied. The changes were measured on a monthly basis. The body composition measurements were made by the bioelectrical impedance analysis (BIA) method (BIA 101, RJL Systems, USA). The mean percentage (% FAT) and kilograms (kg FAT) of body fat significantly decreased at 2 months of hGH therapy from 15.3 +/−3.7 to 13.0 +/− 3.8% (P<0.005) and from 4.1 +/− 1.5 to 3.7 +/− 1.6 kg (P<0.05), respectively. The mean percentage (% LBM) and kg (kg LBM) of lean body mass increased from 84.7 +/− 3.7 to 86.6 +/− 3.9% (P<0.05) and from 22.7 +/− 5.5 to 24.1 +/− 5.9 kg (P<0.01), respectively. Subsequently, the mean LBM/FAT ratio (L/F) increased from 6.03 +/− 1.82 to 7.42 +/− 2.23 (P<0.05) in terms of the percentage of FAT and LBM. and from 5.82 +/− 1.38 to 7.30 +/− 2.25 (P<0.05) in terms of the kilograms of FAT and LBM. There were no significant changes in FAT and L/F between 2 and 3 months of hGH therapy. These results indicate that the body composition changes rapidly by 2 months of hGH treatment, and then settles into a stabilized state.

Bromocriptine redirects metabolism and prevents seasonal onset of obese hyperinsulinemic state in Syrian hamsters

Bromocriptine redirects metabolism and prevents seasonal onset of the obese hyperinsulinemic state in Syrian hamsters. Metabolic and hormonal effects of bromocriptine were studied in seasonally obese female Syrian hamsters, Mesocricetus auratus. Daily injections of bromocriptine and vehicle (controls) were made at light onset (10:14-h light-dark cycle) for 10 wk. After 9 wk of treatment blood samples were taken every 4 h during a day for assays of hormones, glucose, triglyceride, and fatty acids, and after 10 wk of treatment, tests were carried out to measure insulin-stimulated glucose disposal during a hyperinsulinemic clamp, lipid mobilization (rate of glycerol appearance), protein turnover (lysine flux and deamination), and body composition (deuterium dilution). Bromocriptine reduced percent body fat by 53% and increased percent lean body mass by 8%. It also decreased triglyceride levels by 52% and plasma free fatty acid concentration during the dark-near light onset by 49% and glycerol appearance by 25%. Protein synthesis and catabolism were increased by 62 and 56%, respectively, and deamination of amino acid was decreased by 53% by bromocriptine. Bromocriptine reduced plasma concentration of insulin throughout the day, especially at light onset, by 78% without change in baseline glucose level and markedly decreased steady state plasma glucose (by 40%) during a continuous infusion of insulin and glucose. It also reduced the nocturnal plasma concentration of prolactin by 90%, cortisol by 70%, and thyroid hormones (thyroxine and triiodothyronine) by 50% and dramatically altered the circadian profiles of these hormones and insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Body composition of patients with Alzheimer's disease

Low body weight is frequently reported in patients with Alzheimer's disease. We sought to discover why by comparing the body composition of 28 cognitively normal elders and 23 institutionalized individuals with Alzheimer's disease. Body mass index was calculated from standing height and weight. Percentages of lean body mass, body fat, and body water were derived from bioimpedance measurements of resistance and reactance. Skinfold thickness was measured at seven body sites to estimate regional fat distribution. Variables were analyzed by analysis of variance with subjects grouped by cognitive status within gender. Activity level and age were not significant covariates. Both women and men with Alzheimer's disease weighed less than control subjects. Differences in body composition were more pronounced in women with Alzheimer's disease, who had lower body mass index (22.0 ± 3.0 vs 26.1 ± 5.1), higher percentage of lean body mass (73.8 ± 5.1 vs 66.9 ± 6.5), lower percentage of body fat (26.1 ± 5.1 vs 33.1 ± 6.5), and higher percentage of body water (55.8 ± 5.0 vs 49.3 ± 6.5) compared with control women. Except for lower body weight, the body composition of men with Alzheimer's disease was not significantly different from that of control men. Patients of both sexes with Alzheimer's disease had less truncal body fat compared with controls, which gave them a youthful body habitus. These differences were not accounted for by age, diet, or activity. Our findings indicate that patients with Alzheimer's disease have lower body weight and may require higher energy intake than cognitively normal elders.

Total Body Water and Body Composition in Phalaropes and Other Birds

Contrary to some reviews, total body water (TBW) may fall below the expected value of about 65% in birds if measured as a percentage of total body mass. However, water constitutes a relatively stable proportion (659%-70%) of body composition when measured as a percentage of lean body mass (LBM). We demonstrate this by using data from two migratory phalaropes (Phalaropus tricolor and Phalaropus lobatus), which exhibit inverse relationships between TBW and body mass and between TBW and fat content. As the phalaropes fatten before migration, lipids increase but not at the expense of water, which also increases with gains in lean tissue. The gain in lean dry mass with body size is also correlated with migration. Because absolute water increases with body mass, TBW is a poor measure of hydration; however, because of the inverse relationship between TBW and fat, TBW can predict body fat accurately if a calibration curve is first generated. We provide equations that predict fat content in both species of phalaro...

Maximum Fat Deposition Rates in Migrating Birds

The rate at which birds can deposit fat (before migration starts, and at stopover sites), is a major factor determining the overall speed of migration. The existence of an upper limit to daily metabolisable energy intake (DMEmax, Kirkwood 1983), implies that there also is an upper limit of fat deposition rate (FDRmax, the daily gain in fat mass as a percentage of lean body mass). FDRmax in birds of different sizes is on theoretical grounds predicted to be proportional to M-0.27, where M = lean body mass. An examination of literature data on rapid body mass increases in migrating birds, reveals that the highest values for individuals and populations are proportional to body mass as M-0-25 and M-0.31, respectively. Studies of foraging ecology at stopover sites indicate that migrants exploiting very abundant food sources may regularly reach the DMEmax (metabolically limited migrants). The fat deposition rates of these birds will mainly depend on their daily energy expenditure. In other species, DMEmax may never be reached and fat deposition rates are determined by foraging efficiency and time available for foraging (foraging-time limited migrants). As far as maximum speed of migration is concerned, larger birds are generally more efficient flyers than smaller birds and can therefore partly compensate for their lower maximum fat deposition rates. Maximum speed of migration is predicted to be proportional to M-014.

Factors affecting anaerobic power output in the Margaria-Kalamen test.

The purpose of this study was to determine the effect of three approach distances and two vertical ascent methods on approach velocity, vertical velocity and power output of the Margaria-Kalamen test. Male (n = 43) and female (n = 53) university students were tested using a traditional and a modified (ramp) Margaria-Kalamen test with approaches of 2, 6 and 10m. The average of five trials for each approach distance was used to calculate anaerobic power. Males averaged 14.0% greater approach velocity, 28.8% greater vertical velocity and 41.1% greater power output than females, regardless of approach distance or vertical ascent method. Anaerobic power output was not significantly different between the sexes for any method when the effects of the percentage of fat and lean body mass were removed by the covariance technique. The 2m approach produced significantly slower approach velocity, vertical velocity and power output than the other approaches. The ramp method resulted in significantly greater approach velocity (11.5%), vertical velocity (9.6%) and anaerobic power output (9.4%) than the stair method. Males averaged 8.4% higher power output using the ramp, while females averaged 11.0% higher than the conventional stair method. Females appeared to benefit more than males from using a ramp in the anaerobic power test. Anaerobic power measurement from the Margaria-Kalamen method can be maximized using a ramp method.

Exercise responses in females with anorexia nervosa

Exercise responses were evaluated in 42 primary anorexic females (Pri-AN; mean age 18.8 years) and 33 bulimic females (Bul-AN; mean age 19.7 years) and compared with 14 healthy unconditioned lean females (Lean Control; mean age 19.6 years). All subjects performed isometric handgrip at 50% of maximum voluntary contraction (MVC) for 90 seconds and treadmill exercise to subjective exhaustion (Balke Protocol). Resting heart rate (HR) and blood pressure (BP) were not different in the three groups. Maximal grip strength and 90 second isometric handgrip systolic blood pressure (SBP) was significantly lower (p <.05) in Pri-AN compared with Bul-AN and Lean Controls. With treadmill exercise, maximal HR and BP were similar for all groups. However, estimated treadmill work capacity (METs) for Pri-AN (10.7 ± 3) and Bul-AN (10 ± 8.3) was significantly lower (p <.05) than lean Control subjects (12.3 ± 3). There was a positive correlation between maximal SBP and body weight (wt), percent body fat (% fat) and lean body mass (LBM). These findings indicate that Pri-AN and Bul-AN are associated with a substantial reduction in aerobic capacity. The attenuated BP response to exercise seen in both anorexia groups appears to be a general function of tissue mass and may be an appropriate adaptation to weight loss.

Suppression of plasma renin activity by cyclosporine

Cyclosporine treatment is associated with hypertension and suppression of plasma renin activity, the causes of which are unclear. To determine whether suppressed plasma renin activity is due to extracellular fluid volume expansion, 10 cyclosporine-treated renal transplant recipients were compared with 10 azathioprine-treated renal transplant recipients and seven patients with renal insufficiency. Glomerular filtration rate and effective renal plasma flow were significantly lower in cyclosporine-treated patients than in azathioprine-treated patients. Upright plasma renin activity was suppressed in cyclosporine-treated patients (cyclosporine 2.9 ± 0.9, azathioprine 4.7 ± 0.9, renal insufficiency 5.2 ± 1.9 ng/ml/hour) but could be stimulated by a four-day period of dietary sodium restriction and diuretic administration (cyclosporine) 15.8 ± 4.4 ng/ml/hour). Extracellular fluid volume tended to be higher in cyclosporine-treated patients (cyclosporine 30.7 ± 2.3, azathioprine 26.7 ± 2.5, renal insufficiency 25.5 ± 1.4 percent lean body mass), although the difference between cyclosporine-treated and azathioprine-treated patients did not attain statistical significance. There were no differences in the urinary excretion of prostaglandin E 2 or 6-keto prostaglandin F 1α between the two groups of renal transplant recipients. It is concluded that suppression of plasma renin activity by cyclosporine is physiologic and may reflect expansion of extracellular fluid volume, which can be reversed by sodium depletion.

Effect of physical fitness and body composition on sleep and sleep-related hormone concentrations.

The study assessed the effect of physical fitness and body composition on sleep and the nighttime secretion of the hormones, human growth hormone (hGH), prolactin, and cortisol. Two groups of 17 subjects, one of fit athletes and the other of unfit nonathletes, were selected so that the groups were matched for weight, height, lean body mass (LBM), and fat levels. Subjects slept in a sleep laboratory for 3 nonconsecutive nights: 1 adaptation night and 2 experimental nights. On 1 experimental night blood samples were collected; on the other, baseline sleep was assessed and the catheter was not inserted. Weight and height were measured and LBM assessed by 24 h urinary creatinine. The effect of physical fitness was tested by a comparison of the two groups; body composition was assessed by correlation analyses. Physical fitness did not have a significant effect on either sleep or hormone levels, although in the latter case the results were marginal. In contrast, body composition was related to both sleep and hGH. Percentage LBM was negatively correlated with slow-wave sleep and positively correlated with hGH levels. These results were significant for all subjects combined and for the fit group, although not the unfit group alone.