Fat-free Mass Gain Research Articles

Anthropometry and body composition in ethnic Japanese and Caucasian adolescent boys

The effect of environmental conditions on development, including growth, maturation and the fulfillment of genetic potential, can be identified through the study of the variations found among different ethnic groups in the same population. The objectives of the present study were: (i) to compare the various anthropometric and body composition parameters based on ethnicity and maturation stage in 31 Japanese and 99 Caucasian prepubescent boys and 50 Japanese and 98 Caucasian post-pubescent boys; and (ii) to assess body mass index (BMI) and its relationship with other methods of body fat evaluation. The percentage of body fat was measured using bioelectrical impedance, near-infrared interactance and Slaughter cutaneous skinfold equations. Weight and height were statistically lower for the Japanese than the Caucasian subjects. There were no differences in body fat between the ethnic groups, but the Japanese subjects had statistically lower levels of fat-free mass. The gain in fat-free mass and the loss in body fat when attaining maturation were greater in the Caucasian subjects. The agreement of BMI with other methods was good in all of the groups but lower for the Japanese than for the Caucasian subjects. Height and weight differences between the ethnic groups indicated distinct genetic potential ranges. The body fat mass did not differ between the ethnic groups, but the degree of changes when attaining maturation in the Caucasian subjects was greater. If this difference were to be maintained between the groups then years later there would be a greater accumulation of fat in the Japanese subjects.

Resting energy expenditure, adiponectin and changes in body composition of young children (EarlyBird 34)

OBJECTIVE. Serum adiponectin levels are inversely related to adiposity and resting energy expenditure (REE) in adults yet may protect against excess weight gain. Little is known of these associations in children, in whom obesity is rising. The aim of this study was therefore to investigate the relationships between REE, adiponectin and weight gain in young children. METHODS. Adiponectin by ELISA, REE by indirect calorimetry, fat-free mass (FFM) and fat mass (FM) by DEXA were measured at 6.9 years, and repeated one year later in 151 healthy children, aged 7.9±0.3 years. RESULTS. There were no significant correlations between REE and adiponectin at 6.9 years or at 7.9 years (boys r=-0.02, p=0.88 and r=0.05, p=0.69, respectively; girls r=-0.11, p=0.35 and r=0.05, p=0.70, respectively). There was no link between REE at 6.9 years and subsequent weight gain or adverse change in body composition (all r<0.20, all p>0.08). Similarly, there were no correlations between adiponectin and weight change, but there was a significant inverse association between adiponectin at 6.9 years and FFM gain in boys (r=-0.27, p=0.02). CONCLUSIONS. The relationship between adiponectin and REE has yet to appear in young children. REE is not a significant predictor of future weight gain or adverse change in body composition and, although the period of follow-up was limited, adiponectin seems unlikely to confound such a relationship in healthy young children.

A randomized trial on the efficacy of a 2-month tube feeding regimen in anorexia nervosa: A 1-year follow-up study

Despite the high mortality rate in malnourished anorexia nervosa (AN) patients, very few trials have prospectively studied the efficacy of tube feeding. This open prospective study was conducted in malnourished AN patients, who were randomized in tube feeding (n=41) or control (n=40) groups during a 2-month period. Thereafter, body weight, body mass gain, energy intake, eating behavior and relapse rates were compared during a 1-year follow-up, using paired Student t-test and ANOVA. At the end of the 2-months period, weight gain was 39% higher in the tube feeding group than in the control group (194+/-14 vs 126+/-19g/day; P<0.01). The fat-free mass gain was greater in the tube-feeding group: 109+/-14 vs 61+/-17g/day (P<0.01). Energy intake was higher in the tube feeding group than in the control group (P<0.05), as well as the decrease in bingeing episodes (P<0.01). Most patients thought that CEN improved their eating disorder. After discharge, the relapse-free period was longer in the CEN group than in the control one: 34.3+/-8.2 weeks vs 26.8+/-7.5 weeks (P<0.05). CEN is helpful in malnourished AN patients for weight restoration, without hindrance on the eating behavior therapy nor inducing a more rapid relapse.

Impact of malnutrition on gastrointestinal disorders and gross motor abilities in children with cerebral palsy

Children with cerebral palsy (CP) often demonstrate abnormal feeding behaviours, leading to reduced food consumption and malnutrition. Moreover, most of them present with gastrointestinal disorders, such as gastroesophageal reflux disease (GERD) and/or chronic constipation (CC), and poor motor function rehabilitation. The aim of our study was to assess the possible relationship between malnutrition and gastrointestinal problems and to evaluate the role of nutrition on their gross motor abilities in a population of children with CP and mental retardation. Patients: Twenty-one consecutive children (10 boys; mean age: 5.8 ± 4.7 years; range: 1–14 years) with CP and severe mental retardation. Methods: Nutritional assessment included the measurement of body mass index (BMI = W/H 2), fat body mass (FBM) and fat free mass (FFM). Children with symptoms suggesting GERD underwent prolonged 24 h intraesophageal pH monitoring and/or upper GI endoscopy with biopsies before and after a 6 months of pharmaceutical (omeprazole) and nutritional (20% increment of daily caloric intake) treatments. The motor function was evaluated by “The Gross Motor Function Measure” (GMFM) before and after the 6 months on nutritional rehabilitation. Results: BMI for age was ⩽5° percentile in 11 children (52%) and FBM was ⩽80% of ideal value for height in 15 (71%). GERD was present in 14 children (67%), 9 of them were affected by both GERD and CC. Among children with FBM ⩽ 80%, GERD was present in 11 (73%) and CC in 9 (60%). Considering the group of patients with BMI ⩽ 5° percentile, 9 out of 11 children had GERD (82%) and 7 had CC (64%). Fourteen malnourished children (FBM ⩽ 80%) completed the 6 months nutritional trial. Their starting and final means ± SD BMI were 13.56 ± 1.31 and 14.15 ± 1.85 ( p = 0.08), respectively. GMFM values were significantly ( p < 0.05) improved in 9/14 pts (Group A), while it remained unchanged in 5/14 pts (Group B). Nine children with GERD and malnutrition completed the 6 months of pharmaceutical and nutritional treatments. Their initial mean ± SD weight was 10.1 ± 2.9 kg, whereas the final mean ± SD weight was 12.7 ± 4 kg ( p < 0.05). A marked improvement of GERD was noted in four of nine (44.4%) children. Despite successful nutritional rehabilitation with a BMI achievement of ⩾25° percentile, five of nine (55.5%) patients had persistent GERD when they were taken off the medication. Conclusions: Malnutrition and gastrointestinal disorders are very common in children with cerebral palsy. Improved nutritional status, particularly fat free mass gain, appears to have an impact on motor function in children with CP.

Synthesis and Pharmacological Profile of an Orally-Active Growth Hormone Secretagogue, SM-130686

Hypothalamic hormones physiologically regulate pulsatile release of growth hormone (GH) from the anterior pituitary gland. Since the discovery of these hormones in the 1970s, several new chemically synthesized peptidyl and non-peptidyl derivatives have been proved to stimulate and amplify GH secretion, and this series of molecules has been named the growth hormone secretagogues (GHSs). One of these compounds led to the discovery of a GPCR-type receptor for GHSs (GHS-R), and subsequently the endogenous ligand for the receptor has been identified, and is referred to as ghrelin. The identification of GHSs as physiological regulators of GH secretion encouraged us to examine our GHSs pharmacologically. We previously reported that novel oxindole derivatives have been identified as GHS-R agonists from our internal chemical library. Among these derivatives, (+)-6-carbamoyl-3-(2-chlorophenyl)-(2-diethylaminoethyl)-4-trifluoromethyloxindole (SM-130686, 37S) was found to have potent activity in vitro with a good pharmacokinetic profile in rats (bioavailability of 28%). In this article, we review the synthesis and pharmacological evaluation of SM-130686. SM-130686 binds specifically to GHS-R and increases the Ca(2+) concentration in Chinese hamster ovary cells expressing recombinant GHS-R. Maximal enhancement of the intracellular Ca(2+) concentration induced by SM-130686 treatment was approximately 55% that induced by ghrelin, suggesting that SM-130686 may be a partial GHS-R agonist. Also, in in vivo studies, oral administration of SM-130686 increased body length and fat-free mass gain. We compare the pharmacological profile of SM-130686 with other GHSs, including GHRH and ghrelin, and discuss the therapeutic usefulness of GHSs against several disorders, as well as for treatment of GH deficiency.

Simulated high altitude selectively decreases protein intake and lean mass gain in rats

The aim of this study was to find out whether high altitude (HA)-induced hypophagia was macronutrient-specific using a self-selection procedure. Body composition was assessed by dual X-ray absorptiometry before and after exposure and by dissection at the end of the experiment. Energy intake, macronutrient selection, body composition, plasma insulin and leptin concentrations were measured in rats (FHx) exposed 16 h daily for 10 days to hypobaric hypoxia (HH) simulating an altitude of 5500 m. Rats were fasted during the exposure to HH and had access to food only during the 8 h of normoxia in their active period. This group was compared to control group (C) with ad libitum access to food and a group of rats submitted only to the 16-h fast (FNx). Results showed that sustained hypophagia was specific to protein (55 ± 5% of C, P < .05), whereas after a decline, carbohydrate intake reached its basal level on the 5th day. HH dramatically reduced fat-free mass gain ( P < .05 and P < .0001 compared to C and FNx, respectively). Plasma leptin concentrations at the onset of the period of access to food were not significantly different from those of controls. Across groups, leptin was positively correlated with fat mass ( r = .71, P < .001) and negatively with energy intake ( r = − .52, P < .05), more specifically with protein intake ( r = − .57, P < .05). These results suggest that HA leads to a reduced preference for protein impairing fat-free mass gain and that leptin may contribute to this hypophagia.

Effect of equilibrated hydration changes on total body water estimates by bioelectrical impedance analysis.

The present study was performed to determine how equilibrated fluctuations in hydration affected the validity of bioelectrical impedance analysis (BIA) for body composition assessment. Total body water (TBW) expansion was induced by a 4 d endurance trial and the subsequent water loss was obtained over the recovery period. Twelve healthy men exercised on a cycle and treadmill alternately for 5 h/d over 4 d at moderate intensity. TBW, fat mass (FM) and fat-free mass (FFM) were assessed 3 d before the trial (control), and on the first and eighth day of recovery (R1 and R8 respectively). TBW was evaluated by (2)H dilution (TBW2H) as a reference method and by BIA (TBWBIA) at 100 kHz at the same time. TBW2H increased significantly between the control day and R1 by 1.87 (sd 1.11) litres (P=0.005) and TBWBIA by 1.38 (sd 1.56) litres (P=0.009). Both values returned to the control level on R8. For each period, TBW2H and TBWBIA did not differ significantly and were correlated (r(2) 0.85, P=0.0004 for the control day; r(2) 0.63, P=0.03 for R1; r(2) 0.75, P=0.02 for R8). Plasma Na concentration and osmolality did not differ between the control day, R1 and R8. FFM gain (1208 (sd 1983) g) and FM loss (-1168 (sd 906) g) between the control day and R1 were followed by a FFM decrease (-624 (sd 1281) g) and a FM increase (860 (sd 1212) g) between R1 and R8. As expected, these FFM and FM changes were significantly correlated with TBW variations. The present results provide evidence that BIA may be a useful method for estimating TBW when fluid shifts are equilibrated and electrolyte concentrations are unchanged. However, it is not a valid technique for assessing FM and FFM under these conditions.

Short- and long-term effects of growth hormone (GH) replacement on protein metabolism in GH-deficient adults.

Reduced fat-free mass (FFM) in GH-deficient (GHD) adults is improved by GH replacement, but the protein metabolic changes are unclear. Using iv [(2)H(3)]leucine and oral l-[(13)C(1)]leucine infusions and dual emission x-ray absorptiometry, we compared leucine kinetics and body composition in eight GHD adults and eight healthy controls in the fasted and fed states, before and after 2 wk and 6 months of GH replacement. Leucine kinetics were not different between pretreatment GHD subjects and controls. After 2 wk of GH treatment, leucine oxidation decreased in the GHD subjects compared with baseline values [fasted, 41 +/- 6 vs. 30 +/- 5 micromol/kg FFM.h (P < 0.01); fed, 49 +/- 3 vs. 41 +/- 3.6 micromol/kg FFM.h (P < 0.05)], leucine balance improved [fasted, -14 +/- 4 vs. -3.5 +/- 3 micromol/kg FFM.h (P < 0.01); fed, 65 +/- 10 vs. 72 +/- 7 micromol/kg FFM.h (P = 0.07)], and protein synthesis increased [fasted, 116 +/- 5 vs. 131 +/- 6 micromol/kg FFM.h (P < 0.05); fed, 103 +/- 6 vs. 116 +/- 6 micromol/kg FFM.h (P < 0.05)]. After 6 months of GH treatment, these changes were not maintained in the fed state. The five GHD subjects with decreased FFM at baseline showed a significant increase after 6 months of GH treatment (P < 0.05). GH replacement in GHD acutely improves protein balance by stimulating synthesis and inhibiting catabolism. After 6 months, protein kinetics reached a new homeostasis to maintain the net gain in FFM.

Composition of gestational weight gain impacts maternal fat retention and infant birth weight

Objective The purpose of this study was to evaluate how changes in gestational weight and body composition affect infant birth weight and maternal fat retention after delivery in underweight, normal-weight and overweight women. Study design We assessed the body composition of 63 women (low body mass index, 17 women; normal body mass index, 34 women; and high body mass index, 12 women) on the basis of measurements of total body nitrogen by prompt-gamma activation analysis, total body potassium by whole body counting, and a multicomponent model based on total body water by deuterium dilution, body volume by densitometry, and bone mineral content by dual energy x-ray absorptiometry (DXA) before pregnancy, at 9, 22, and 36 weeks of gestation, and at 2, 6, and 27 weeks after delivery. Infant weight and length were recorded at birth; infant anthropometry and body composition by DXA were assessed at 2 and 27 weeks of age. Results Gestational weight gain was correlated significantly with gains in total body water, total body potassium, protein, fat-free mass, and fat mass ( P = .001-.003). Gains in total body water, total body potassium, protein and fat-free mass did not differ among body mass index groups; however, fat mass gain was higher in the high body mass index group ( P = .03). Birth weight was correlated positively with gain in total body water, total body potassium, and fat-free mass ( P<.01), but not fat mass. Postpartum weight and fat retention were correlated positively with gestational weight gain ( P = .001) and fat mass gain ( P = .001) but not with total body water, total body potassium, or fat-free mass gain. Conclusion Appropriate, but not excessive, gestational weight gain is needed to optimize infant birth weight and minimize maternal postpartum fat retention.

Weight-losing HIV-infected patients on recombinant human growth hormone for 12 wk: a national study

OBJECTIVE: In patients with human immunodeficiency virus, body weight (BW) loss, due mainly to loss of fat-free mass, is associated with progression of disease and mortality. Recombinant human growth hormone (rhGH) may promote BW gain by restoring FFM. METHODS: We investigated the results of adding to highly active antiretroviral therapy of routine rhGH treatment in 34 patients with human immunodeficiency virus who had lost 5% to 20% of their usual BWs. They were recruited by their physicians in Switzerland and were instructed to self-administer the drug. Patients were given 6 mg of rhGH each day for 12 wk. BW and body composition, measured by bioelectrical impedance analysis (50 kHz, tetrapolar), were recorded at baseline and at 4, 8, and 12 wk of treatment. RESULTS: At week 12, BW gain averaged 3.0 ± 0.5 kg ( P < 0.001), fat-free mass gain was 4.8 ± 0.5 kg ( P = 0.001), and body fat mass loss was 1.8 ± 0.4 kg ( P = 0.008). BW and fat-free mass increases and FM decrease were evident by week 4 and tended to plateau by week 8. Therapy was well tolerated; one patient developed carpal tunnel syndrome. Five patients abandoned the study for reasons unrelated to the rhGH treatment. CONCLUSION: Our data strongly support the use of rhGH in the treatment of unintentional BW loss associated with human immunodeficiency virus. The low rate of dropouts and the low incidence of side effects make the use of rhGH suitable for primary care management.

Resultado de intervenção nutricional em crianças e adolescentes com fibrose cística

Few studies have verified longitudinally the evolution of the nutritional status of patients with cystic fibrosis. The objective of this study is to follow the evolution of the nutritional status, body composition and energy consumption, macronutrients and micronutrients ingested by children and adolescents by means of nutritional interventions at the Clinic of Cystic Fibrosis/Pediatric Pneumology of the Department of Pediatrics of Universidade Federal de São Paulo. 18 patients were involved in this study, thirteen males and five females with ages ranging from 0.3 to 18.4 years. We performed three evaluations: evaluation 1 (M1--prenutritional intervention), M2 after 6 months, and M3 after 12 months. In these three instances we verified: the z score for weight/age, weight/height and height/age and the calculation of a 3-day diet record. We verified the body composition (anthropometry) in M1 and M3. The nutritional interventions were hypercaloric, hyperproteic, with adequate amount of ingested macronutrients and micronutrients. We observed an increase in the z score for height/age (M1=-1.07; M2=-0.69; M3=-0.50) and fat-free mass after the nutritional interventions, without improvement in the z score for weight/height and fat mass. We verified an increase in the energy intake during M2 (139%) and M3 (132%) compared to M1 (106%). Remarkable increase in the intake of protein, calcium, iron and vitamin C by the patients was found. The occurrence of anemia was found in 44% (8/18) of the patients. The improvement of the z score in height/age and fat-free mass was probably due to the increase in energy consumption after the nutritional intervention. A significant improvement in the z score for weight/height and fat mass was not found, probably due to a gain in height and fat-free mass.

Anorectic, thermogenic and anti-obesity activity of a selective orexin-1 receptor antagonist in ob/ ob mice

A single dose of the orexin-1 (OX 1) receptor antagonist 1-(2-methylbenzoxazol-6-yl)-3-[1,5] naphthyridin-4-yl urea hydrochloride (SB-334867-A) reduces orexin-A-induced feeding and natural feeding in Sprague Dawley rats. In this study, the anti-obesity effects of SB-334867-A were determined in genetically obese ( ob/ ob) mice dosed with SB-334867-A (30 mg/kg, i.p.) once daily for 7 days, and then twice daily for a further 7 days. SB-334867-A reduced cumulative food intake and body weight gain over 14 days. Total fat mass gain, determined by Dual Emission X-ray Absorptiometry, was reduced, while gain in fat-free mass was unchanged. Fasting (5 h) blood glucose was also reduced at the end of the study, with a trend to reduced plasma insulin. Interscapular brown adipose tissue (BAT) weight was reduced, the tissue was noticeably darker in colour and quantitative PCR (TaqMan) analysis of this tissue showed a trend to an increase in uncoupling protein-1 mRNA expression, suggesting that SB-334867-A might stimulate thermogenesis. This was confirmed in a separate study in which a single dose of SB-334867-A (30 mg/kg, i.p.) increased metabolic rate over 4 h in ob/ ob mice. OX 1 receptor mRNA was detected in BAT, and its expression was increased by 58% by treatment with SB-334867-A. This is the first demonstration that OX 1 receptor antagonists have potential as both anti-obesity and anti-diabetic agents.

Body Composition in 70-Year-Old Adults Responds to Dietary β-Hydroxy-β-Methylbutyrate Similarly to That of Young Adults

Studies in young adults have demonstrated that beta-hydroxy-beta-methylbutyrate (HMB) can increase gains in strength and fat-free mass during a progressive resistance-training program. The purpose of this study was to determine whether HMB would similarly benefit 70-y-old adults undergoing a 5 d/wk exercise program. Thirty-one men (n = 15) and women (n = 16) (70 +/- 1 y) were randomly assigned in a double-blind study to receive either capsules containing a placebo or Ca-HMB (3 g/d) for the 8-wk study. Skin fold estimations of body composition as well as computerized tomography (CT) and dual X-ray absorptiometry (DXA) scans were measured before the study and immediately after the 8-wk training program. HMB supplementation tended to increase fat-free mass gain (HMB, 0.8 +/- 0.4 kg; placebo, -0.2 +/- 0.3 kg; treatment x time, P = 0.08). Furthermore, HMB supplementation increased the percentage of body fat loss (skin fold: HMB, -0.66 +/- 0.23%; placebo, -0.03 +/- 0.21%; P = 0.05) compared with the placebo group. CT scans also indicated a greater decrease in the percentage of body fat with HMB supplementation (P < 0.05). In conclusion, changes in body composition can be accomplished in 70-y-old adults participating in a strength training program, as previously demonstrated in young adults, when HMB is supplemented daily.

Evaluation of anthropometric equations to assess body-composition changes in young women

Healthy young women who engage in an exercise program may lose fat that is not reflected in body weight changes because of concurrent gains in fat-free mass (FFM). This study addressed the question of how well anthropometry-based predictive equations can resolve these changes. Several widely used skinfold-thickness- or circumference-based equations were compared by using dual-energy X-ray absorptiometry to study 150 healthy young women before and after 8 wk of Army basic combat training (average energy expenditure: 11.7 MJ/d). Women lost 1.2 +/- 2.6 kg fat (mean +/- SD) and gained 2.0 [corrected] +/- 1.5 kg FFM. Fat loss (r = 0.47), but not FFM gain (r = 0.01), correlated with initial fatness. Thus, for many women who lost fat, body weight did not change or increased. Fat loss was associated with a reduction in abdominal circumference but this alone was not a consistent marker of fat loss. One circumference equation and one skinfold-thickness equation yielded the smallest residual SDs (2.0% and 1.9% body fat, respectively) compared with the other equations in predicting body fat. The sensitivity and specificity of the best equations in predicting changes in percentage body fat were not better than 55% and 66%, respectively. These data suggest that for women, anthropometry can provide better estimates of fatness than body mass index but it is still relatively insensitive to short-term alterations in body composition. Not surprisingly, the circumference equation that includes the most labile sites of female fat deposition (ie, waist and hips instead of upper arm or thigh) proved to be the most reliable.

Short-term protein and energy supplementation activates nitrogen kinetics and accretion in poorly nourished elderly subjects

An increase in protein intake exerts a stimulating effect on protein kinetics in children, young adults, and healthy elderly persons. However, there are few data on the response to such dietary changes in malnourished elderly subjects, despite important medical implications in this population. The objective of this study was to determine the metabolic response to short-term nutritional supplementation in moderately malnourished elderly subjects. The influence of 10 d of supplementation (1.67 MJ/d and 30 g protein/d) on body composition, resting energy expenditure, and whole-body protein kinetics was studied in 17 malnourished elderly patients and 12 healthy young adults. A control group of 6 malnourished elderly patients received no supplementation. Supplemented elderly subjects had a significantly greater fat-free mass gain than did unsupplemented elderly subjects (1.3 and 0.1 kg, respectively; age effect, P < 0.05; diet effect, P < 0.02) and a significantly greater increase in fasting rate of protein synthesis than did young supplemented subjects (0.6 and 0.2 g*kg FFM(-1)*11 h(-1); age effect, P < 0.05). The net protein balance in the supplemented elderly subjects in the fed state was positively correlated with protein intake (r(2) = 0.46) and in the fasted state was negatively correlated with protein intake (r(2) = 0.27). The sum of these regressions is a line with increasingly positive net diurnal protein balance produced by increasing protein intake. These data provide evidence of a short-term anabolic response of protein metabolism to dietary supplementation in malnourished elderly patients that is likely to improve muscle strength and functional status.

Obesity and physical activity.

Three aspects of obesity and physical activity are reviewed: whether the obese are inactive; how the activity level can be increased; and which are the effects of an increase in physical activity in combination with a reduction of energy intake. The focus is on an objective approach that is, activity associated energy expenditure as measured with doubly labelled water. Activity associated energy expenditure increases with body mass index while the average physical activity level does not change. The majority of obese subjects is moderately active. An increase in the activity level of obese subjects is limited by the ability to perform exercise of higher intensity. Training programs obese subjects can cope with are until now not rewarded by weight loss. A possible loss in fat mass is compensated by a gain in fat-free mass. Obese subjects can only reach a significant weight loss with an energy restricted diet. Mild energy restriction will already result in very significant weight loss when one complies with the diet. An increase in physical activity is necessary to compensate for the reduction in activity induced energy expenditure and should be facilitated by the lower body mass.

Direct and correlated responses to selection for efficiency of lean gain in mice.

Improvement in feed efficiency when selection is based on gain:feed ratio has often been accompanied by a reduction in feed intake. The following four criteria were used in mass selection for improved lean gain efficiency in mice with an objective of evaluating changes in lean gain and intake: 1) gain deviation, animals selected had the greatest gain in fat-free mass (FFM) after adjustment to a constant intake; 2) intake deviation, mice selected had the least feed intake after adjustment to a constant gain in FFM; 3) intrinsic efficiency, similar to the second criterion except that adjustment was also made for average weight maintained during the period; and 4) a positive control that used the ratio of gain in FFM: feed intake as the selection criterion. A fifth line, in which a male and a female were selected at random from each litter, served as a negative control. Experimental animals were outbred mice of the CF1 strain. Two replicates of the five lines were included in the study. Twelve males and females were pair-mated within each line-replicate combination each generation. Feed disappearance was measured from 25 to 42 d. Mice were scanned to obtain an electrical conductivity measurement for prediction of FFM. After six generations of selection, realized heritabilities for gain:feed, gain deviation, intake deviation, and intrinsic efficiency were .00 +/- .04, .04 +/- .29, .35 +/- .08, and .28 +/- .06, respectively. There were no differences among lines for gain:feed ratio. The correlated response in feed intake reduction was significant in the intake deviation and intrinsic efficiency lines (-.17 +/- .05 and -.21 +/- .04 g x d(-1) x generation(-1), respectively). The realized genetic correlations between the ratio and gain deviation, intake deviation, and intrinsic efficiency were .83 +/- .15, .01 +/- .04, and .21 +/- .12, respectively. Litter size was depressed in all selected lines.

Energy utilization and growth in breast-fed and formula-fed infants measured prospectively during the first year of life

This study is the first to report approximations of energy requirements for male and female breast-fed and formula-fed infants based on individual estimates of total daily energy expenditure (TDEE) and energy deposition derived from total body fat (TBF) and fat-free mass (FFM) gain as determined by total-body electrical conductivity. In 46 healthy, full-term infants the effect of > or = 4 mo of exclusive breast-feeding compared with formula feeding on macronutrient and energy intake, TDEE, energy deposition, and growth were investigated prospectively. Metabolizable energy intake (MEI) was assessed from macronutrient intake by test weighing (MEI-TW) and from the sum of TDEE and energy deposition (MEI-Pred). At 1-2, 2-4, 4-8, and 8-12 mo of age MEI-Pred averaged 431 +/- 38, 393 +/- 33, 372 +/- 33, and 355 +/- 21 kJ x kg(-1) x d(-1) for boys, and 401 +/- 59, 376 +/- 25, 334 +/- 33, and 326 +/- 17 kJ x kg(-1) x d(-1) for girls. No significant difference between breast-fed and formula-fed infants was found with respect to weight, length, head circumference, TBF, FFM, and TDEE at all ages, or for gain in length, weight, TBF, and FFM. MEI-TW was significantly different between feeding groups at 1-4 mo of age (formula-fed being greater than breast-fed, P < 0.005). This feeding effect, however, was not significant for MEI-Pred (MJ/d). MEI-TW differed from MEI-Pred only in breast-fed infants at 1-4 mo (P < 0.05 at 2-4 mo). The data from this study indicate that energy requirements in infants are lower than the recommendations in guidelines currently in use.

Effect of two different creatine supplementation products on muscular strength and power

To compare different types of creatine supplements on indices of strength and endurance, 48 males (22.3 ± 0.6 y) participated in a 21d study. Subjects consumed creatine in a powder (CRp), in a solid form of gelled candy (CRs) or a carbohydrate placebo was taken in a solid, gelled candy (PLBs) or in powder form (PLBp). All supplements and placebo were fed in a double blind regime at a dose of 20 g/day for 5 days followed by lOg/day for 16 days. Pre‐testing on day 1 included body composition (hydrostatic weighing) and 5, 10‐s sprints on a Monark cycle ergometer. Subjects pedaled against an opposing force of 0.834 N per kg body mass (0.085 kp • kg−1) with a 40‐s rest between each sprint (SPR). On day 2, subjects performed a 1 repetition maximum (1RM) lift on a leg press and 5 sets of 30 maximal voluntary contractions (total = extension + flexion) on a Kin Com Isokinetic Dynamometer at 180°/s with a 45‐s rest between each bout. Statistical analysis showed that CRp and CRs group supplementation resulted in a significant increase in group mean total body weight (1.5 ±0.2 and 1.6 ±0.3 kg), respectively and fat free mass (FFM) (2.3 ± 0.5 and 2.7 ± 0.6 kg), respectively. PLBp resulted in a group mean increase in FFM (1.3 ± 0.6 kg) but not in body weight (0.6 ± 0.3 kg). There was no change in the PLBs group mean weight (0.1 ± 0.3 kg) or FFM (0.1 ± 0.3 kg). Supplementation for 21 d resulted in a significant increase in the 1RM of the leg press for CRp (63.1 ± 6.7 kg), and CRs (52.9 ± 11.9 kg). There was no change in the group mean 1RM for each of the placebo groups (PLBp: 32.3 ± 12.4 kg; PLBs: 30.6 ± 6.7 kg). The peak power and fatigue index were not significantly different between groups in the post anaerobic sprints, however, mean power output was higher in CRp and CRs compared with PLBs and PLBp. Isokinetic tests revealed no significant difference in total peak torque among the four groups as a result of supplementation. Total work was significantly greater in CRs and CRp compared with PLBc. There was no difference in CRp, CRs and PLBp. The percent decline in force were significantly lower in CRs and CRp compared with PLBp and PLBs, indicating less fatigue during the 30 contractions. These results indicate that subjects supplemented with CR whether in powder or solid form showed a significantly greater gain in FFM and indices of strength compared with subjects fed a placebo.

Hormone replacement therapy does not augment gains in muscle strength or fat-free mass in response to weight-bearing exercise.

Lower extremity strength and fat-free mass were examined in 58 postmenopausal women aged 60-72 yr. Subjects were studied before and after an 11-mo control period (n = 16) or before and after an 11-mo weight-bearing exercise training program designed to generate relatively high ground reaction forces (n = 42). Twenty-two of the exercisers initiated hormone replacement therapy (HRT) at the outset of exercise and continued HRT for 11 mo. Hip extension and abduction strength were assessed using a hand-held dynamometer. Force production during knee extension and flexion was evaluated on an isokinetic dynamometer at 60, 90, and 180 degrees/s. Simultaneous knee and hip extension strength was also assessed on a leg press machine. Total body and lower extremity fat-free mass were determined using dual-energy x-ray absorptiometry. There were no significant changes in muscle strength or body composition in control subjects. Both exercise groups had significant increases in fat-free mass and in all strength measures. Fat-free mass increased from 38.8 +/- 4.3 to 39.7 +/- 4.3 kg in the exercise group and from 37.7 +/- 3.9 to 38.9 +/- 4.6 kg in the exercise-plus-HRT group. The average relative increase in strength was 16.2 +/- 11.0% in the exercise group and 17.0 +/- 13.0% in the exercise-plus-HRT group. Women receiving HRT did not have a gain in fat-free mass or in strength over and above that demonstrated by the women not on HRT. Our results provide evidence that HRT does not augment the increases in muscle mass or strength that occur in response to weight-bearing exercise in older women.