Power Of Body Weight Research Articles

Calf muscle abilities are related to sprint performance in male Rugby Union players

ObjectivesTo examine the strength of the relationship between plantarflexor power and strength-endurance metrics and 10-m sprint times in male Rugby Union players. A secondary aim was to examine the strength of the relationship within calf muscle metrics. DesignObservational cross-sectional correlational. SettingField-based. ParticipantsSixteen male Rugby Union players in the National Provincial Championship. Main outcome measuresParticipants completed three single-leg calf muscle tests: bodyweight power, weighted power, and strength-endurance. Data were recorded using the Calf Raise application. Three-to-four days later, average and best 10-m sprint performances were collected using timing lights. ResultsThere were large significant correlations between 10-m sprint performances (average and best times) and calf muscle power (weighted) and strength-endurance (total displacement and work) metrics (r = −0.503 to −0.628). There were large significant correlations between bodyweight and weighted power, weighted power and strength-endurance (total displacement and work), and most strength-endurance metrics (r = 0.520 to 0.943). ConclusionsOur findings emphasise the importance of triceps surae muscle power and strength-endurance for maximal-effort accelerations and sprint performances in Rugby Union. Our data indicate that weighted power and total work from strength-endurance tests are the most useful metrics for further investigation in the context of short sprints and acceleration.

Validity, reliability, and normative data on calf muscle function in rugby union players from the Calf Raise application

ABSTRACT We examined the validity and reliability of biomechanical outcomes extracted using the Calf Raise application of three calf muscle tests. We then established normative calf muscle function values for male rugby union players accounting for rugby-related factors (position, level) alone and together with clinical factors (age, leg dominance, BMI, previous injury). In total, 120 athletes performed three single-leg calf muscle tests. Twenty athletes participated in application validation; 18 in test–retest reliability; and all in establishing normative equations. Validity of application outcomes against 3D motion and force plate data was good-to-excellent (CV ≤ 6.6%, ICC ≥0.84). Test–retest reliability was good across outcomes following familiarisation (CV < 10%, ICC ≥0.83). Forwards produced superior power than backs during the bodyweight (59 W, p = 0.007) and weighted (73 W, p < 0.001) power tests. Playing level influenced power outcomes (p < 0.009). Super Rugby players were more powerful than Club (both power tests), Provincial (both power tests), and International (bodyweight power). Backs completed more repetitions (3 repetitions, p = 0.001) and positive displacement (30 cm, p = 0.001) than forwards during endurance testing. When accounting for clinical factors; BMI, age, and previous injury explained some of the differences observed between positions and levels. This study provides initial benchmark values of calf muscle function in rugby union.

Feeding Ecology and Development of Juvenile Black Ducks in Maine

Feeding Ecology and Development of Juvenile Black Ducks in Maine

Mechanisms regulating oocyte recruitment and skipped spawning in Northeast Arctic cod (Gadus morhua)

To examine mechanisms that affect fecundity, atresia, and skipped spawning in Northeast Arctic cod ( Gadus morhua ), we conducted an experiment where wild-caught cod (&gt;60 cm) kept under restricted food regimes were subjected to monthly biopsies and hormonal and physical measurements. The power of body weight as a fecundity proxy increased until the presumed end of follicle proliferation in early November; thereafter, it remained stable. Atresia occurred in most females, but for maturing females, mainly close to spawning. Eighteen percent of the females had small gonads with predominantly previtellogenic oocytes at sacrifice in January. These females were past-spawners, verified by postovulatory follicles in their gonads. These “skippers” had lower condition than maturing cod from December, smaller livers upon sacrifice, and lower plasma 17β-estradiol values from early November. Until November, oocytes developed similarly for all females, but in November, oocyte development was arrested at the early cortical alveoli stage and atresia occurred in all skippers. In summary, fecundity and skipped spawning seem highly influenced by energy reserves during early vitellogenesis and was limited to females only. Finally, skippers were identifiable long before the predicted onset of spawning, which could have implications for forecasting of egg production and hence stock–recruitment relationships.

04/01160 Productivity benefits of industrial energy efficiency measures: Worrell, E. et al. Energy, 2003, 28, (11), 1081–1098

Partitioning of digestible energy for maintenance and growth was examined in fast growing rainbow trout via multiple regression analysis. Data from 292 groups of rainbow trout fed a large variety of different diets for which digestible energy intake can be assumed as the factor limiting growth were used in the analysis. Intake of digestible energy, energy retention and protein as well as lipid gain had been quantified for each group of trout. Multiple regression suggested that maintenance requirement for digestible energy was dependent on the 0.43 power of body weight in grams. Depending on growth rate, maintenance requirement contributed to between 10 and 30% of the total digestible energy requirement. The utilisation of digestible energy that was available for retention proved to be dependent on fat concentration in the diet. Effects of dietary crude protein concentration or water temperature on digestible energy utilisation could not be determined for this data set. Daily digestible energy requirement (kJ) could be best predicted by 1.31 BW0.43 (g)+retained energy (kJ/day)/[0.66 (1+0.000652 g fat/kg dry diet)]. Assuming a partial efficiency of DE utilisation above maintenance for fat retention of 0.9, a partial efficiency of DE above maintenance for protein retention of 0.54 was calculated. An inter-laboratory approach is suggested to obtain a wider range of experimental data and, therefore, to improve the suitability of models for general application.

Assessing the dose-dependency of allometric scaling performance using physiologically based pharmacokinetic modeling

The performance of allometric scaling of dose as a power of body weight under a variety of extrapolation conditions with respect to species, route, exposure intensity, and mechanism/mode of action, remains untested in many cases. In this paper, animal–human internal dose ratio comparisons have been developed for 12 chemicals (benzene, carbon tetrachloride, chloroform, diisopropylfluorophosphate, ethanol, ethylene oxide, methylene chloride, methylmercury, styrene, tetrachloroethene, trichloroethene, and vinyl chloride). This group of predominantly volatile and lipophilic chemicals was selected on the basis that their kinetics have been well-studied and can be predicted in mice, rats, and humans using physiologically based pharmacokinetic (PBPK) models. PBPK model predictions were compared to the allometric scaling predictions for interspecies extrapolation. Recommendations for the application of the allometric scaling are made with reference to internal dose measure (mode of action) and concentration level. The results of this assessment generally support the use of scaling factors recommended in the published literature, which includes scaling factors of 1.0 for risk assessments in which toxicity is attributed to the parent chemical or stable metabolite, and −0.75 for dose–response assessments in which toxicity is attributed to the formation of a reactive metabolite from an inhaled compound. A scaling factor of 0.75 is recommended for dose–response assessments of orally administered compounds in which toxicity is attributed to the parent chemical or stable metabolite and 1.0 for risk assessments in which toxicity is attributed to the formation of a reactive metabolite from a compound administered by the oral route. A dose-dependency in the results suggests that the scaling factors appropriate at high exposures may differ from those at low exposures, primarily due to the impact of saturable metabolism.

Dose Scaling and Extrapolation Across Age Groups

This paper considers how the logic of cross-species dose scaling applies (or does not apply) when extrapolating among differently sized humans, and specifically, when extrapolating to children. Scaling children's doses by a power of body weight predicts that they would be less sensitive to chemicals than adults, owing to faster clearance. Possible countervailing factors, however, are the role of quicker pharmacodynamic processes, differences between interspecific and ontogenetic allometry, and the complex role of inherent differences in the metabolism and physiological system of immature bodies, the last leading to uncertainty in extrapolation but not necessarily to systematic sensitivity among children. The issue of scale per se does not appear to provide a basis for positing a systematically greater sensitivity of children to toxic substances

Maintenance requirement for digestible energy and efficiency of utilisation of digestible energy for retention in rainbow trout, Oncorhynchus mykiss

Partitioning of digestible energy for maintenance and growth was examined in fast growing rainbow trout via multiple regression analysis. Data from 292 groups of rainbow trout fed a large variety of different diets for which digestible energy intake can be assumed as the factor limiting growth were used in the analysis. Intake of digestible energy, energy retention and protein as well as lipid gain had been quantified for each group of trout. Multiple regression suggested that maintenance requirement for digestible energy was dependent on the 0.43 power of body weight in grams. Depending on growth rate, maintenance requirement contributed to between 10 and 30% of the total digestible energy requirement. The utilisation of digestible energy that was available for retention proved to be dependent on fat concentration in the diet. Effects of dietary crude protein concentration or water temperature on digestible energy utilisation could not be determined for this data set. Daily digestible energy requirement (kJ) could be best predicted by 1.31 BW 0.43 (g)+retained energy (kJ/day)/[0.66 (1+0.000652 g fat/kg dry diet)]. Assuming a partial efficiency of DE utilisation above maintenance for fat retention of 0.9, a partial efficiency of DE above maintenance for protein retention of 0.54 was calculated. An inter-laboratory approach is suggested to obtain a wider range of experimental data and, therefore, to improve the suitability of models for general application.

Oxygen consumption of a Chaoborus species from a neotropical reservoir (socuy reservoir, Venezuela)

AbstractOxygen consumption of all four larval instars of a Chaoborus species from Socuy Reservoir in western Venezuela was studied under laboratory conditions at 25°C. On a logarithmic basis, oxygen consumption per organism increased as a smooth, linear function of body weight (0.49 power of body weight). Observed rates were lower than other Chaoborus species with comparable body weight at the same temperature. Oxygen consumption per unit weight decreased from smaller to large instar larvae. With the exception of instar I, values of oxygen consumption per unit weight were lower than values reported for other Chaoborus species. The results suggest that our species have low energy demands for maintenance, and are consistent with suggestions about high efficiency in use of energy in genus Chaoborus.

東シナ海で漁獲された主要１０魚種のターゲットストレングスの測定

The dorsal aspect target strength functions of ten species of fish collected by bottom trawl were measured at two frequencies. The average TS were calculated with respect to fish tilt angle distribution, which is assumed to have a mean value of -5 degrees and a standard deviation of 15 degrees. Both maximum TS and average TS were normalized with the fish length (L[cm]) squared and the 2/3 power of body weight (W[g]), namely, TS=20logL+A, TS=20/3log W+B.The results obtained were as follows:(1) The target strength is generally higher at low frequency (25kHz) than at high frequency (100kHz). But for two species (Chub mackerel and Kandari), neither maximum nor average TS differ between low and high frequencies.(2) The target strength of Silver pomfret, a bladderless fish, is clearly lower than that of bladder fish at two frequencies.(3) The normalized TS (A or B) were calculated for the maximum TS (Amax or Bmax) and average TS (Aavg or Bavg). The results are: Amax = -63 - -59 dB, Aavg = -68 - -64 dB at low frequency; Amax = -65 - -59 dB, Aavg = -72 - -65 dB at high frequency, and Bmax = -52 - -45 dB, Bavg = -57 - -50 dB at low frequency; Bmax = -54 - -45 dB, Bavg = -60 - -52 dB at high frequency.

Basis for body weight exponent (0.75) as a scaling factor in energy metabolism and risk assessment.

The basis that led to the adoption of the exponent (0.75) as a scaling factor for the relationship between body weight and energy metabolism is presented. In the risk assessment formulation, it may be appropriate to use the 0.75 power of body weight as a scaling factor for carcinogenicity data obtained from animal studies.

Interspecies Scaling of Anesthetic Potency

Anesthetic potency data for 11 volatile anesthetics were correlated against body weight in multiple mammalian species, including man. The results indicate that the alveolar concentration necessary to produce anesthesia is approximately constant across species. Because alveolar ventilation rates scale with the 0.75 power of body weight, this implies that administered dose measured in mg/kg0.75/day produces the same anesthetic effect in all species. This analysis provides further support for the use of a mg/kg0.75/day interspecies scaling metric for acute toxic effects.

The relationship between abundance and body size in British birds

THE relationship between abundance and body size is the subject of considerable debate in ecology1–15. Several data sets spanning a large range of body sizes show linear negative relationships between abundance and weight l–6 when these are measured on a logarithmic scale. But other studies of the abundances of species from single taxa, such as birds, which span a narrower range of body sizes reveal either little or no relationship, or a triangular relationship 9–15. Errors in estimating abundance might obscure relationships that do exist over a narrow range of body sizes. We describe here the relationship between body weight and abundance in British birds, whose population size estimates are unusually good. Abundance across all species declines with a −0.75 power of body weight, which conforms with the energetic equivalence 'rule'2,16. There is, however, a significant positive relationship between abundance and body weight within lower taxa. Those tribes that do not share recent common ancestry with other British birds are most likely to show a positive relationship across their constituent species. We thus show that phylogenetic relatedness might be an important indicator of the structure of the relationship between body size and abundance.

Paracellular intestinal absorption of glucose, creatinine, and mannitol in normal animals: relation to body size

Mice, rats, or rabbits were provided with a liquid diet of 10-12% glucose (Glc), 0.5-1% creatinine, 1-2% mannitol, and mannitol labeled with 3H on a terminal carbon. Average rates of ingestion of Glc were greater than maximum rates of active, carrier-mediated Glc transport reported for the intestines of these species. The discrepancy was small in mice but increased exponentially with body weight (BW). Ingestion-absorption of Glc increased exponentially with the 0.73 power of BW as expected from metabolic rate, whereas active transport, estimated from the literature, varied exponentially with the 0.50 power of BW. It is estimated that in humans the ingestion-absorption rate of Glc may be 10-20 times greater than active transport. In the presence of Glc, 50-65% of the ingested creatinine was recovered in urine compared with 75-85% recovered after intraperitoneal or subcutaneous injections. The amount of creatinine recovered in urine depended on the amount of ingested Glc, as predicted from the effects of Glc on width and permeability of absorptive cell junctions. Eighty percent or more of the 3H label on mannitol was recovered in urine or other body fluids, although most of the [3H]mannitol was oxidized to [3H]water after being absorbed intact from the intestine. It is concluded that in the presence of Glc, creatinine and mannitol (together with Glc, amino acids, and other small nutrients) are absorbed passively by solvent drag between absorptive cells, as found previously in anesthetized rats (J. R. Pappenheimer and K. Z. Reiss. J. Membr. Biol. 100: 123-136, 1987). The ratio of solvent drag to carrier-mediated transport increases exponentially with BW and may account for the capacity of human intestines to absorb large amounts of Glc during prolonged exercise, Glc tolerance tests, or oral Glc-saline therapy for dehydration.

Tissue Dosimetry for Reactive Metabolites

In recent pharmacokinetically based risk assessments for methylene chloride, Andersen et al. argued that total reactive metabolite (TRM) divided liver weight was the proper measure of dose to target tissue, while the EPA argued that TRM divided by body weight to the two-thirds power was more appropriate. We demonstrate that the proper tissue metric for a reactive metabolite is dependent upon the mode of deactivation: metabolic or spontaneous. It is argued that the most appropriate measure of tissue dosimetry is: (1) TRM divided by the three-fourths power of body weight if the reactive metabolite is metabolically deactivated; or (2) TRM divided by body weight if the reactive metabolite is spontaneously deactivated.

Liver aspartate aminotransferase activity as a power function of body weight

Total liver enzyme activity ( E) for aspartate aminotransferase (ASAT; EC 2.6.1.1) per gram body weight ( W) decreases in six species as body weight increases from mice to cattle according to the equation E W 0.85 = c , where c is a constant. The 0.85 power of body weight thereby provides a reference standard for the direct arithmetic comparison of liver ASAT activities in six species with different body weights. The use of W 0.85 should provide a tool in clinical studies in which data from experimental animals must be related to humans, e.g., in establishing the relationship between drug dosage (or toxicity) and body weight.

A statistical model for species extrapolation using categorical response data.

Predictions of human health risk for single chemicals are often based on animal studies and hence require some sort of adjustment for species differences in toxic susceptibility. In the past, either the animal dose has been divided by an uncertainty factor or the dose has been transformed by a mathematical model into a human equivalent dose. A generalization of the allometric model previously used for carcinogens, the so-called "surface area model," is investigated here for use with graded severity response data for noncarcinogenic systemic toxicity. Statistical methods for estimating one of the model's parameters, the power of body weight, are proposed and tested on simulated and actual toxicity data. Early results indicate reasonable accuracy if data are available for a large number of dose groups.

The effect of acclimation temperature on energy metabolism as a function of body weight in rats

1. 1|Energy metabolism of 38 rats acclimated to 10, 20 and 30°C was measured at these ambient temperatures and the regression equations over body weight were calculated. 2. 2|Expressing metabolic rate as M = kW n , the results showed that the value of n is apparently variable according to the acclimation and measurement temperatures. 3. 3|It was also shown that the 2 3 power of body weight is a suitable parameter to express metabolic rate, regardless of acclimation or environmental temperatures.

Similarity in Energy Budgets of Animal Populations

(1) The objective of the paper is to suggest some basis for general patterns which have been observed between various components of energy budgets in animal populations. (2) If all components in energy budgets of animal populations are scaled to a constant (-0.75) power of body weight, it follows that, within a group of metabolically similar animals: production (P) will be proportional to respiration (R) and vice versa, i.e. that the relationship between log production v. log respiration will have a slope equal to one; that production efficiency (PIP + R) will be independent of body size; and that the relationship between production and standing crop (P/B) should vary as body mass raised to the -0-25 power. There is good agreement between these predictions and empirical results reported in the literature. (3) It appears that previous analysis of production and respiration in animal populations have identified several groups of metabolically similar animals. Those with high maintenance costs, e.g. homeotherms, have lower production efficiencies than animals whose maintenance costs are relatively low, e.g. poikilotherms. This pattern also appears to hold at smaller scales of observation; for example, carnivores appear to have higher production efficiencies and lower metabolic rates than herbivores. (4) The present study demonstrates the utility of large-scale interspecific comparisons for generating reasonable and testable hypotheses about certain ecological relationships and provides additional insights into existing empirical generalizations.

Organ scaling in mammals: The liver

1. 1. Values for liver weight, in growing and adult male and female mammals, both terrestrial and aquatic, as well as values for hepatic blood flow, blood volume and oxygen consumption are submitted to linear (log-log) regression analysis. 2. 2. The slope of the regression line for liver weight on adult body weight in adult mammals was found to be 0.886. No statistically significant difference was found between male and female, nor between terrestrial and aquatic mammals (at the 1% confidence level). 3. 3. Over about four orders of magnitude there is (on present evidence) a tendency for the mammalian liver to grow as about the 0.94 power of body weight (pre- and post-natal). 4. 4. The slopes of the regression lines for hepatic blood flow, blood volume and oxygen consumption were found to be 0.91, 0.86 and 0.69, respectively. 5. 5. The mean hepatocyte size in fixed tissue of rats was found to be 7400 μm 3. 6. 6. It is argued that the slope of the regression line for hepatic oxygen consumption in mammals generally is likely to fall in the range 0.67–0.77.