Energy Balance Index Research Articles

The relationship between serum oestradiol concentration and energy balance in young women distance runners.

Reproductive dysfunction in women distance runners has been linked to an imbalance between energy intake (EI) and energy expenditure (EE) which leads to an energy deficit. To determine whether ovarian suppression is associated with an energy deficit, the relationships between serum oestradiol (E2) concentration and indices of energy balance (EB) were explored in a group of women runners with a variety of menstrual patterns and a range of activity levels. Subjects comprised 33 women distance runners of mean (SD) age 27.2 (1.8) years. Sixteen of these women were defined as eumenorrhoeic (11-13 menstrual bleeds per year during the past 2 years), 8 as oligomenorrhoeic (< or = 3 menstrual bleeds per year for 2 years) and 9 as amenorrhoeic (absence of menses for > 1 year). Their volume of running training ranged from 36 to 97 km x wk(-1) [mean (SD): 68.6 (21.4) km x wk(-1). The body mass index (BMI) and percent body fat (BF) of each subject was measured. Their mean daily energy balance (EB) was calculated by subtracting their dietary EI from their estimated EE recorded over 7 days. Serum concentrations of E2, total T3 and IGF-1 were measured from a fasting blood sample (taken in early follicular phase for Eu women). Relationships between serum E2, T3 and IGF-1, EB, BMI and BF were explored using bivariate correlation and regression analysis. The results showed that the most powerful predictors of serum E2 concentration were estimated EB (r = 0.88, P<0.001), serum T3 (r=0.94, P<0.001) and IGF-1 (r=0.84; P<0.001). Weaker correlations were observed between serum E2 and BMI (r=0.42; P=0.008) and serum E2 and BF (r=0.48; P=0.004). These relationships add support to the hypothesis that reproductive dysfunction in women distance runners is associated with an energy deficit.

Bone turnover in amenorrhoeic and eumenorrhoeic women distance runners.

Bone remodelling has not been assessed in women distance runners with chronic amenorrhoea. The purpose of this study was to compare indices of bone turnover and energy balance in runners with chronic amenorrhoea, runners with a history of regular menstrual cycles and sedentary controls. Subjects comprised 3 groups of 9 women, matched for age [mean+/-SEM: 27.2+/-1.8 yrs] and categorised as amenorrhoeic runners (AmR), eumenorrhoeic runners (EuR) and eumenorrhoeic sedentary controls (SC). Serum concentrations of bone formation markers [osteocalcin (OC), carboxy-terminal propeptide of type 1 collagen (P1CP), bone alkaline phosphatase (BAP)], E2, total T3 and IGF-1 were measured from a fasting morning blood sample. Urine levels of bone resorption markers [pyridinoline (Pyr) and deoxypyridinoline (Dpyr)] were measured and corrected for creatinine excretion. Mean daily energy balance (EB) was calculated by subtracting dietary energy intake (EI) from energy expenditure (EE) estimated from reported activity patterns over 7 days. The results showed that all bone turnover markers were lower in AmR than in EuR or SC (P<0.001: OC, BAP and P1CP; P<0.05: Pyr and Dpyr). Furthermore, when z-scores for each bone marker in runners were calculated against mean values for SC (by subtracting each measure of bone turnover from the mean value for SC and expressing the difference as a fraction of the SD of this mean value), bone resorption appeared to outweigh formation in AmR, but not in EuR. Serum concentrations of E2, T3 and IGF-1 were also lower in AmR than in EuR or SC (P<0.001: all hormones), as was EB (P<0.001). These findings suggested that in AmR there was some factor which was reducing bone turnover and in particular, bone formation. This factor might have been linked to an energy deficit and the effects of this deficit on body mass, body composition and metabolism.

Energy balance in rhesus monkeys (Macaca mulatta) subjected to long-term dietary restriction.

Male rhesus monkeys of various age groups representative of the species life span were fed ad libitum amounts (controls) or 30% less food than control monkeys of comparable age and body weight. Despite significantly lowered energy intake and body weight, the amount of energy lost in the feces, and fecal energy density (concentration) were not altered in diet-restricted (DR) monkeys, compared to age- and weight-matched controls. Absolute energy expenditure (EE; 24-hr) was consistently lower in DR monkeys, but this trend was not statistically significant. Expressed as a function of metabolic mass (body weight, metabolic body size, lean mass), 24-hr EE was not different in monkeys subjected to long-term DR, compared to controls. Calculations of net energy (intake-loss), as an index of energy balance, revealed that energy expenditure generally exceeded energy intake in all juvenile and adult group monkeys. However, this discrepancy was not statistically different from zero, suggesting that most animals were in energy balance. Also, there was no difference between control and DR animals with respect to energy balance. Diet restriction induced significant reductions in the absolute amount of lean body mass; however, percent (of total weight) lean and fat mass did not differ from controls.

Data from the Arizona FACE (Free-Air CO2 Enrichment) Experiments on Sorghum at Ample and Limiting Levels of Water Supply

Two free-air CO2 enrichment (FACE) experiments were conducted on sorghum (Sorghum bicolor (L.) Moench, a C4 grain crop) at Maricopa, Arizona, U.S.A. during the 1998 and 1999 summer growing seasons. They were conducted at ample and limited (50% of ample) supplies of water. A large and varied set of data on plant, soil, and microclimatic responses to the elevated CO2 and its interactions with the water supply was collected. The dataset assembled herein consists of many of these data, including those generally used for model validation, such as management, soils, daily and 15-minute weather, physiology (net photosynthesis, plant water potential, relative water content), phenology, biomass growth, leaf area, yield, canopy temperatures, energy balance, evapotranspiration, soil moisture, reflectance and vegetation indices, and absorption of photosynthetically active radiation. Partitioning of nitrogen between nitrate and cyanide, which affects toxicity of the sorghum forage to livestock, was measured. In addition, isotopic methods were used to trace carbon flows in both FACE and Control plots from atmosphere to plant material to soil carbon pools. The dataset is useful for validation of sorghum growth models, which get used to predict likely future sorghum productivity given projected global climate change.

Protein Supplementation of Human Milk for the Nutrition of VLBW-Infants: Human milk protein vs. meat protein hydrolysate

In 25 very low birth weight infants appropriate for gestational age the influences of different human milk (HM) preparations on weight gain, gross indices of nitrogen metabolism and energy balance were studied during the second month of postnatal life. HM was fortified either by HM-protein (HMP) or by an enzymatic meat protein hydrolysate (PH) to protein concentrations between 1.5 and 1.7 g/100 ml. The caloric densities of both HM preparations were similar between 62 and 68 kcal/100 ml. There were no differences in weight gain (MM + HMP: 18.6 +/- 3.4 g/kg/day; HM + PH: 16.5 +/- 4.1 g/kg/day), nitrogen retention (HM + HMP: 31.5 +/- 3.1 mmol/kg/day; HM + PH: 30.0 +/- 3.2 mmol/kg/day), and the preprandial estimated essential amino acid profiles between the both feeding groups. In contrast the serum concentrations of alpha-amino-nitrogen 60 minutes postprandially were elevated in the infants fed HM + PH in comparison to the infants fed HM + HMP. This high postprandial amino acid concentrations in serum in the group fed HM + PH were accompanied by increased bile acids concentrations in serum, higher renal amino acid excretion and increased fecal fat losses. The results suggest that due to the more rapid intestinal absorption of amino acids from PH than from HMP the concentrations of amino acids increase postprandially which results in a detectable increase of the newborn cholestasis in these infants. Nevertheless, the scale of these metabolic responses to feeding protein hydrolysates is small and without detectable influences on nitrogen retention or weight gain.

Capability of Surface-Based Clear-Air Doppler Radar for Monitoring Meteorological Structure of Elevated Layers

Abstract Radars and acoustic sounding systems sense properties of the turbulence structure of the atmosphere. If atmospheric turbulence can be related to the mean gradient parameters, Doppler radars and acoustic sounders can provide information about height profiles of quantities such as temperature and refractive index as well as wind in stable regions of the atmosphere. In this paper turbulent and mean quantities were measured on the 300 m meteorological tower at the Boulder Atmospheric Observatory near Erie, Colorado, and the relationships between the turbulent and mean gradient quantities were examined in order to evaluate hypotheses for simplifying the kinetic energy balance and refractive index variance equations. FM-CW radar measurements of backscattered power and Doppler spectral width were also made for comparison with tower-measured refractive index spectra and Doppler velocity spectra. Height distributions of the turbulent dissipation rate within stable layers are shown and viscous cutoff radar...

Adjustment of the components of energy balance in response to temperature change in Ostrea edulis.

1. Routine oxygen consumption (VO2μl 285 mg-1 h-1) by specimens of Ostrea acclimated to temperatures between 5° and 25°C increases with exposure temperature throughout much of the range 5 to 30°C. 2. There is little evidence of a relative suppression of the acutely-measured rate: temperature curves for routine oxygen consumption following warm acclimation. Energetic costs in Ostrea thus rise sharply with increase of environmental temperature. 3. The clearance rate (V w ,ml 285 mg-1 h-1) of Phaeodactylum measured synchronously shows a marked thermal optimum within the range 15-28°C, followed by a decline towards high exposure temperatures. 4. Maximal clearance rates of 600-750 ml water h-1 occur approximately 5°C above the temperature to which the animals have been acclimated and are adjusted according to environmental temperature. 5. The changes in filtration efficiency (V w /VO2, ml/μl) in Ostrea following thermmal acclimation are controlled by compensatory responses of the irrigation rate rather than by a relative reduction of energy losses from metabolism. 6. Because the clearance rate declines in animals acclimated to 25°C, whereas the metabolic losses increase throughout the temperature range 5 to 30°C, maximum filtration efficiency is achieved at 20°C. 7. Calculation of the energetic cost of filtration suggests that the improvement of filtration following warm acclimation offsets metabolic energy losses even at low food concentrations in Ostrea. Even if energy losses not accounted for in this study were substantial, a positive index of energy balance could be maintained during the summer months at ration levels which commonly occur in inshore waters.

Examination of the relationship between birthweight, cigarette smoking during pregnancy and maternal weight gain.

SummaryThere has been no reported systematic exploration of the hypothesis that the low birthweight of infants whose mothers smoke in pregnancy is mediated by depressed caloric intake. Using gestational weight gain as an index of energy balance, we have studied this question among 162 mothers and their liveborn singleton infants, in a poor, black, urban American community. Smoking mothers had lower mean weekly weight gain (0.73 versus 0.90 pounds per week; t=2.63; p&lt;0.01), and a strong and highly significant gradient of decreasing weight gain with increased amount smoked (0.017 fewer pounds per week gained per additional cigarette per day; F=12.45; p&lt;0.005). Women who stopped smoking before delivery had higher weight gain than those who continued; the difference was not significant, but numbers were small. Regression analyses were performed in order to quantitate the unique and joint contributions of smoking and change in maternal weight to birthweight. At least half, and usually closer to three‐quarters, of the effect of smoking on birthweight was jointly shared with maternal weight change. Smoking is in all likelihood depressing fetal growth, in large part, by depression of caloric intake, reflected by lower maternal weight gain. No other examined differences between smokers and non‐smokers accounted for these differences.

LOWER WEIGHT GAIN AMONG SMOKERS EXPLAINS MOST OF THE EFFECT OF SMOKING ON BIRTHWEIGHT

There has been no reported systematic exploration of the hypothesis that the low birthweight of infants whose mothers smoke in pregnancy is mediated by depressed caloric intake. Using gestational weight gain as an index of energy balance, we have studied this question among 162 mothers and their liveborn singleton infants, in a poor, black, urban American community. Smoking mothers had lower mean weekly weight gain (.73 vs. .90 Ibs/w; t=2.63, p< .01), and a strong and highly significant gradient of decreasing weight gain with increased amount smoked (.017 fewer 1bs/ w. gained per additional cigarette/d; F=12.45, p< .005). Women who stopped smoking before delivery had higher weight gain than those who continued; the difference was not significant, but numbers were small. Regression analyses were performed in order to quantitate the unique and joint contributions of smoking and change in maternal weight to birthweight. With all analyses, at least half, and usually closer to three quarters of the effect of smoking on birthweight was jointly shared with weight change. Smoking is in all likelihood depressing fetal growth, in large part, by depression of caloric intake, as reflected in lower maternal weight gain.No other examined differences between smokers and non-smokers accounted for these differences.

Temperature Acclimation of Mytilus Edulis With Reference to its Energy Budget

Mytilus edulis L. is shown to acclimate to high and low temperature under laboratory conditions. The warm and cold acclimation of oxygen consumption, filtration rate and assimilation efficiency are described for groups of animals maintained at three food-cell concentrations. Complete acclimation (Precht's type 2) of oxygen consumption and filtration rate occur within 14 days. There is no change in assimilation efficiency within the 28-day experimental period. The results are integrated and discussed in the context of a simple energy budget. In terms of the energy budget there exists a marked contrast between warm and cold acclimation. An “index of energy balance” is proposed in order to assess the state of the energy balance. When animals are fed above the maintenance requirement the energy budget remains in an equilibrium state during cold acclimation, whereas the acclimation to a warm temperature regime disrupts the balance and represents a physiological stress. During warm acclimation, prior to the re-establishment of an energy equilibrium the blood sugar level increases, suggesting that the animal is required to mobilize and utilize its energy reserves.

An ALGOL 60 Translator for the X1

The objective of this experiment was to study the long-term effects of supplemental oral drenching of crude glycerol (CG) on feed intake, milk yield and composition, plasma metabolites and energy balance indices of primiparous dairy cows in early lactation. Fourteen primiparous Holstein dairy cows were paired according to body weight (BW) and body condition score (BCS) at calving, and allocated at random to either a treatment or a control group. Both groups were fed a basal diet, containing 11.4 MJ kg−1 DM metabolisable energy and 103 g/kg DM metabolisable protein, twice a day. Silage (ad libitum) and a pelleted concentrate mixture with mineral mix were fed separately during the three six-day periods from days 4 to 21 post partum. An oral drench of 500 ml of CG mixed with lukewarm water was fed supplementally before the morning feedings to the treatment groups, while the control group were given no oral drench. Blood samples were collected on two consecutive days at the end of each six-day period before administration of glycerol. Results showed that long-term administration of CG increased silage intake (P<0.001), and total dry matter intakes (DMI; P=0.023). Oral drenching with glycerol increased milk yields (P<0.01), and milk lactose content (P<0.001). Supplemental glycerol had no effect on estimates for milk energy, milk constituent ratios or milk acetone content. No differences in BCS changes or on concentrations of plasma glucose, insulin, and β-hydroxybutyrate (BHB) were found between the two groups. Dairy cows given oral glycerol had lower concentrations of plasma urea (P=0.005) during the post partum period. There was a treatment and time interaction effect on the non-esterified fatty acids (NEFA) concentration (P=0.048), although this was complex, and the only period of significant differences was in the first six-day period, when NEFA concentration was higher (P=0.025) in the control group. The data indicate that prolonged oral drenching of supplemental CG in the early lactation period improves total DMI, and therefore has a positive effect on milk yield of primiparous dairy cows in this period.