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PubMed2002

Muscle force and muscle torque in humans require different methods when adjusting for differences in body size.

Different methods for adjusting muscle strength ( S) to normalise for differences in various estimates of body size [such as body mass ( m) or, infrequently, some other anthropometrical measurements] have been either proposed or applied when presenting the results of muscle function tests in various medical, ergonomic, and sport related studies. However, the fact that the relationship between S and body size may differ when muscle torque (measured using a standard isokinetic apparatus) and muscle force (measured using a dynamometer) are recorded has not been taken into account. To address this problem, we tested both muscle force and muscle torque under isometric conditions in six different muscle groups. The relationship assumed between S and m was S=k.m(b) and, according to a simple mechanical model based on geometrical similarity we developed, the exponential parameter b would be expected to equal 1.00 and 0.67 for torque and force, respectively. The experimentally obtained values for the parameter b were higher for muscle torque than for muscle force in five out of the six muscle groups tested ( P=0.068; Wilcoxon matched pairs test). Despite a relatively wide scatter, the mean (SD) values were also close to those predicted, being b=0.67 (0.19) (corresponding to the allometric scaling method) and b=1.02 (0.34) (corresponding to the ratio standards method) for muscle force and for muscle torque, respectively. Therefore, we concluded that the ratio standards and allometric scaling should be employed to adjust S for body size when muscle torque and muscle force, respectively, are tested.

Adult↗
PubMed1998

The significance of body size estimation in eating disorders: its relationship with clinical and psychological variables.

OBJECTIVE: To assess the relationship between body size estimation on the one hand and clinical and psychological variables on the other. METHOD: Body size estimation was tested with the video distortion method on a life-size screen in normal women (n = 45) and compared to a total of 189 female eating disorder patients (100 with restricting anorexia nervosa, 41 with binging/purging anorexia nervosa, 48 with bulimia nervosa). The subjects' cognitive responses (what they think they really look like), affective responses (what they feel they look like), and optative responses (what they want to look like) were correlated with clinical parameters (including body composition) and with the scores on a series of self-report questionnaires assessing general psychological well-being and body experience. RESULTS: No significant relationship was found between the body size estimations and the clinical variables. The cognitive and affective responses showed a moderate relationship with self-reported body attitude. Body dissatisfaction was negatively correlated with the optative response (desired body size). DISCUSSION: This study contributes to the construct validity of the video distortion method. Body size estimation includes more than just a perceptual task. Hence, the narrow notion of body image should be replaced by the more complex construct of "body experience," the multidimensionality of which should be addressed in both research and treatment of eating-disordered patients.

Adolescent↗
PubMed2002

The expression of TGFbeta signal transducers in the hypodermis regulates body size in C. elegans.

In C. elegans, a TGFbeta-related signaling pathway regulates body size. Loss of function of the signaling ligand (dbl-1), receptors (daf-4 and sma-6) or Smads (sma-2, sma-3 and sma-4) results in viable, but smaller animals because of a reduction in postembryonic growth. We have investigated the tissue specificity of this pathway in body size regulation. We show that different tissues are reduced in size by different proportions, with hypodermal blast cell size most closely proportional to body size. We show that SMA-3 Smad is expressed in pharynx, intestine and hypodermis, as has been previously reported for the type I receptor SMA-6. Furthermore, we find that SMA-3::GFP is nuclear localized in all of these tissues, and that nuclear localization is enhanced by SMA-6 activity. Interestingly, SMA-3 protein accumulation was found to be negatively regulated by the level of Sma/Mab pathway activity. Using genetic mosaic analysis and directed expression of SMA-3, we find that SMA-3 activity in the hypodermis is necessary and sufficient for normal body size. As dbl-1 is expressed primarily in the nervous system, these results suggest a model in which postembryonic growth of hypodermal cells is regulated by TGFbeta-related signaling from the nervous system to the hypodermis.

Animals↗
PubMed1999

An update on relations of body image and body size with eating disordered behaviors.

The present study examined body image and body size with eating disordered behaviors in a sample of 130 female college students to see if these problems still occur despite the publicity that this issue has received. Students (n = 35) who reported engaging in eating disordered behaviors reported being less satisfied with their bodies than students who did not report engaging in eating disordered behaviors. Also students who engaged in eating disordered behaviors perceived their body size as larger than that for students who did not report engaging in such behaviors. There was, however, no significant difference found in preference for body size between groups.

Adult↗
PubMed2000

The influence of male and female body size on copulation duration and fecundity in Drosophila melanogaster.

We studied two components of the mating system, copulation duration and early fecundity, in relation to body size in Drosophila melanogaster. Body size variation was created experimentally by varying the degree of crowding (starvation) among larvae from an inbred strain, keeping the genetics and temperature as constant as possible. Hence, in contrast to most previous studies, where genetic and environmental variation have been confounded, we aimed at investigating how much pure phenotypic variation could influence copulation duration and early fecundity. It is shown that copulation duration and fecundity both strongly dependent on female body size, but either not or much less so on male body size. Small females mate faster than medium or large females and small females have the lowest fecundity. Among males, medium-size males are more fecund than smaller or larger males, resulting in stabilising selection for intermediate male size. These results are in contrast with previous findings.

Animals↗
PubMed1997

The relationship between body size and mixed-species troops of tamarins (Saguinus spp.).

While Saguinus fuscicollis forms mixed-species troops with sympatric tamarin species in parts of its geographic range, in other parts it does not. The question is addressed whether body size divergence is a critical factor for this difference. Analysis of body size (head-body length) data shows that body size divergence ranges between 8 and 17% for associated species and between 1 and 4% for non-associated species. In associated species, the degree of body size divergence seems to correlate with the stability of mixed-species troops (i.e., time spent in interspecific association). It is concluded that body size plays an important role for niche differentiation, sympatric coexistence and the formation of mixed-species troops in tamarins.

Animals↗
PubMed2004

Body movement and physical activity energy expenditure in children and adolescents: how to adjust for differences in body size and age.

BACKGROUND: Physical activity data in children and adolescents who differ in body size and age are influenced by whether physical activity is expressed in terms of body movement or energy expenditure. OBJECTIVE: We examined whether physical activity expressed as body movement (ie, accelerometer counts) differs from physical activity energy expenditure (PAEE) as a function of body size and age. DESIGN: This was a cross-sectional study in children [n = 26; (+/-SD) age: 9.6 +/- 0.3 y] and adolescents (n = 25; age: 17.6 +/- 1.5 y) in which body movement and total energy expenditure (TEE) were simultaneously measured with the use of accelerometry and the doubly labeled water method, respectively. PAEE was expressed as 1) unadjusted PAEE [TEE minus resting energy expenditure (REE); in MJ/d], 2) PAEE adjusted for body weight (BW) (PAEE. kg(-1). d(-1)), 3) PAEE adjusted for fat-free mass (FFM) (PAEE. kg FFM(-1). d(-1)), and 4) the physical activity level (PAL = TEE/REE). RESULTS: Body movement was significantly higher (P = 0.03) in children than in adolescents. Similarly, when PAEE was normalized for differences in BW or FFM, it was significantly higher in children than in adolescents (P = 0.03). In contrast, unadjusted PAEE and PAL were significantly higher in adolescents (P < 0.01). CONCLUSIONS: PAEE should be normalized for BW or FFM for comparison of physical activity between children and adolescents who differ in body size and age. Adjusting PAEE for FFM removes the confounding effect of sex, and therefore FFM may be the most appropriate body-composition variable for normalization of PAEE. Unadjusted PAEE and PAL depend on body size.

Adolescent↗
PubMed2004

Body size measurements as predictors of type 2 diabetes in Aboriginal people.

OBJECTIVE: To investigate waist circumference, waist-to-hip ratio, body mass index (BMI), weight and hip circumference as risk factors for type 2 diabetes in Aboriginal Australians. DESIGN: Community-based cross-sectional study. SUBJECTS: In total, 915 Australian Aboriginal adults (age: 18-74 y) from a remote Aboriginal community in the Northern Territory of Australia. MEASUREMENTS: Body size measurements included waist circumference, waist-to-hip ratio, BMI, weight and hip circumference. Diabetes status was determined according to medical history and fasting and 2-h postload plasma glucose values. Logistic regression was used to calculate odds ratio for diabetes associated with 1 standard deviation (s.d.) increase in a body size measurement. The areas under the ROC curves of five body size measurements were calculated and compared. RESULTS: Risk of diabetes increased with increasing levels of body size. ORs (95% CI) for diabetes with adjustment for age and sex were 2.16 (1.75, 2.66), 1.80 (1.49, 2.17), 1.41 (1.17, 1.71), 1.81 (1.51, 2.19) and 1.84 (1.50, 2.24) associated with 1 s.d. increase in waist circumference, BMI, weight, waist-to-hip ratio, and hip circumference, respectively. The area under the ROC curve for waist circumference was significantly higher than those for other measurements. CONCLUSION: Waist circumference is the best body size measurement in predicting diabetes in Aboriginal people.

Adolescent↗
PubMed2000

Body size and risk for clinical fractures in older women. Study of Osteoporotic Fractures Research Group.

BACKGROUND: Small body size predicts hip fractures in older women. OBJECTIVE: To test the hypothesis that small body size predicts the risk for other clinical fractures. DESIGN: Prospective cohort study. SETTING: Population-based listings in four areas of the United States. PATIENTS: 8059 ambulatory nonblack women 65 years of age or older. MEASUREMENTS: Weight, weight change since 25 years of age, body mass index, lean body mass and percent body fat, and nonspine fractures during 6.4 years of follow-up. RESULTS: Compared with women in the highest quartile of weight, women in the lowest quartile had relative risks of 2.0 (95% CI, 1.5 to 2.8) for hip fractures, 2.3 (CI, 1.1 to 4.7) for pelvis fractures, and 2.4 (CI, 1.5 to 3.9) for rib fractures. Adjustment for total-hip bone mineral density eliminated the elevated risk. Results were similar for other body size measures. Smaller body size was not a risk factor for humerus, elbow, wrist ankle, or foot fractures. CONCLUSIONS: Total body weight is useful in the prediction of hip, pelvis, and rib fractures when bone mineral density has not been measured.

Adipose Tissue↗
PubMedDate not supplied

Body-size corrections for in vivo neutron activation analysis.

Differences in body size and shape can cause large variances in the results of in vivo neutron activation analysis. Preliminary body-size correction data were obtained for the delayed-gamma neutron activation facility (DGNA) at Brookhaven National Laboratory (BNL), based on phantom standards of different sizes, used in combination with computer simulations on the effect of different body sizes.

Body Composition↗
PubMed1999

Can body size predict infant energy requirements?

Traditionally, infant energy requirements have been predicted from body size or age, whereas in older children and adults, physical activity is also taken into account. However, the extent to which body size determines energy use in individual infants has not been considered. Data on 232 measurements of total energy expenditure obtained in 124 infants aged 1.5 to 12 months were used to assess the relation between body size and energy use in individuals. Age, weight, and fat free mass consistently predicted total energy expenditure with an error of 21-23%. This contrasts greatly with the error of 10% with which infant basal metabolism can be predicted from anthropometry. Body size is a poor index of the total energy requirements of individual infants, and predictive equations generated from data on healthy infants will be inappropriate for disease states where physical activity or growth is altered.

Aging↗
PubMed2006

Evaluation of association between body size and large intestinal transit time in healthy dogs.

OBJECTIVE: To compare large intestinal transit time (LITT) in dogs of various body sizes and determine whether fecal quality was correlated with LITT. ANIMALS: 6 Miniature Poodles, 6 Standard Schnauzers, 6 Giant Schnauzers, and 6 Great Danes. PROCEDURE: LITT was calculated as the difference between total (TTT) and orocecal transit time (OCTT). Minimum and mean OCTTs were determined by use of the sulfasalazine-sulfapyridine method. Minimum TTT was estimated by use of chromium and ferric oxide as color markers, and mean TTT was calculated from the recovery from feces of ingested colored plastic beads. Fecal moisture content was determined and fecal consistency was scored during the same period. RESULTS: Large-breed dogs had higher fecal moisture content and more watery fecal consistency. No association between body size and OCTT was detected, but there was a positive correlation between body size and mean TTT. Mean LITT increased significantly with body size, from 9.1 +/- 1.1 hours in Miniature Poodles to 39.4 +/- 1.6 hours for Giant Schnauzers. Significant correlations were detected among mean LITT, mean TTT, and fecal scores, whereas no correlation was observed between fecal moisture content and TTT or LITT. CONCLUSIONS AND CLINICAL RELEVANCE: LITT was correlated with fecal consistency in dogs of various body sizes. Mean LITT can be predicted from values for mean TTT in healthy dogs.

Animals↗
PubMed1998

Fighting and assessment in male cichlid fish: the effects of asymmetries in gonadal state and body size.

In fights between animals over limited resources, the larger contestant often wins. Game theoretical models of animal fighting predict that relative body size is assessed during the fight and thus determines fight duration and intensity. In addition, if the contestants differ in the value they place on the disputed resource, this can also influence the outcome, duration and intensity of the fight. We studied territorial fighting in a cichlid fish, Tilapia zillii, in relation to relative body size and gonad weight. Relative gonad weight was a much stronger predictor of fight outcome than relative body size, even when body weight asymmetries were as large as 30%. This suggested that males with large gonads were fighting harder to defend their territory, perhaps because the value of a territory correlates with the gonadal state of the individual. A detailed analysis of mouth wrestling observed during fighting suggested that relative body size is assessed. However, contestants smaller than their opponent often continued to fight in spite of their size disadvantage. Weight disadvantaged winners appeared to fight more fiercely as suggested by a negative correlation between weight asymmetry and the proportion of bites inflicted by the winner. During escalated fighting, winners and losers differed consistently with regard to a behaviour termed mouth locking. Although neither biting nor persistence in mouth locking was related to gonad weight, we propose that the fish may have been assessing asymmetries unrelated to relative body size and possibly more related to levels of cost and the motivation to persist. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2000

The evolution of body size: what keeps organisms small?

It is widely agreed that fecundity selection and sexual selection are the major evolutionary forces that select for larger body size in most organisms. The general, equilibrium view is that selection for large body size is eventually counterbalanced by opposing selective forces. While the evidence for selection favoring larger body size is overwhelming, counterbalancing selection favoring small body size is often masked by the good condition of the larger organism and is therefore less obvious. The suggested costs of large size are: (1) viability costs in juveniles due to long development and/or fast growth; (2) viability costs in adults and juveniles due to predation, parasitism, or starvation because of reduced agility, increased detectability, higher energy requirements, heat stress, and/or intrinsic costs of reproduction; (3) decreased mating success of large males due to reduced agility and/or high energy requirements; and (4) decreased reproductive success of large females and males due to late reproduction. A review of the literature indicates a substantial lack of empirical evidence for these various mechanisms and highlights the need for experimental studies that specifically address the fitness costs of being large at the ecological, physiological, and genetic levels. Specifically, theoretical investigations and comprehensive case studies of particular model species are needed to elucidate whether sporadic selection in time and space is sufficient to counterbalance perpetual and strong selection for large body size.

Adaptation, Physiological↗
PubMed2003

The maximum attainable body size of herbivorous mammals: morphophysiological constraints on foregut, and adaptations of hindgut fermenters.

An oft-cited nutritional advantage of large body size is that larger animals have lower relative energy requirements and that, due to their increased gastrointestinal tract (GIT) capacity, they achieve longer ingesta passage rates, which allows them to use forage of lower quality. However, the fermentation of plant material cannot be optimized endlessly; there is a time when plant fibre is totally fermented, and another when energy losses due to methanogenic bacteria become punitive. Therefore, very large herbivores would need to evolve adaptations for a comparative acceleration of ingesta passage. To our knowledge, this phenomenon has not been emphasized in the literature to date. We propose that, among the extant herbivores, elephants, with their comparatively fast passage rate and low digestibility coefficients, are indicators of a trend that allowed even larger hindgut fermenting mammals to exist. The limited existing anatomical data on large hindgut fermenters suggests that both a relative shortening of the GIT, an increase in GIT diameter, and a reduced caecum might contribute to relatively faster ingesta passage; however, more anatomical data is needed to verify these hypotheses. The digestive physiology of large foregut fermenters presents a unique problem: ruminant-and nonruminant-forestomachs were designed to delay ingesta passage, and they limit food intake as a side effect. Therefore, with increasing body size and increasing absolute energy requirements, their relative capacity has to increase in order to compensate for this intake limitation. It seems that the foregut fermenting ungulates did not evolve species in which the intake-limiting effect of the foregut could be reduced, e.g. by special bypass structures, and hence this digestive model imposed an intrinsic body size limit. This limit will be lower the more the natural diet enhances the ingesta retention and hence the intake-limiting effect. Therefore, due to the mechanical characteristics of grass, grazing ruminants cannot become as big as the largest browsing ruminant. Ruminants are not absent from the very large body size classes because their digestive physiology offers no particular advantage, but because their digestive physiology itself intrinsically imposes a body size limit. We suggest that the decreasing ability for colonic water absorption in large grazing ruminants and the largest extant foregut fermenter, the hippopotamus, are an indication of this limit, and are the outcome of the competition of organs for the available space within the abdominal cavity. Our hypotheses are supported by the fossil record on extinct ruminant/tylopod species which did not, with the possible exception of the Sivatheriinae, surpass extant species in maximum body size. In contrast to foregut fermentation, the GIT design of hindgut fermenters allows adaptations for relative passage acceleration, which explains why very large extinct mammalian herbivores are thought to have been hindgut fermenters.

Adaptation, Biological↗
PubMed2004

Comparing phylogenetic signal in intraspecific and interspecific body size datasets.

Phylogenetic comparative methods have become a standard statistical approach for analysing interspecific data, under the assumption that traits of species are more similar than expected by chance (i.e. phylogenetic signal is present). Here I test for phylogenetic signal in intraspecific body size datasets to evaluate whether intraspecific datasets may require phylogenetic analysis. I also compare amounts of phylogenetic signal in intraspecific and interspecific body size datasets. Some intraspecific body size datasets contain significant phylogenetic signal. Detection of significant phylogenetic signal was dependant upon the number of populations (n) and the amount of phylogenetic signal (K) for a given dataset. Amounts of phylogenetic signal do not differ between intraspecific and interspecific datasets. Further, relationships between significance of phylogenetic signal and sample size and amount of phylogenetic signal are similar for intraspecific and interspecific datasets. Thus, intraspecific body size datasets are similar to interspecific body size datasets with respect to phylogenetic signal. Whether these results are general for all characters requires further study.

Animals↗
PubMed1994

Racial differences in selection of ideal body size by adolescent females.

Cultural differences may partially account for the fact that more black women than white women are overweight in the United States. This study measured perceptions of ideal body size among 93 black and 80 white females, 14-17 years old, who were randomly selected from three public high schools in a southeastern state. The subjects' height and weight were measured along with their estimates of their mother's body size, weight control attitudes, and demographic variables. Blacks preferred a significantly larger body size than whites when asked to select ideal body size (p = 0.045). Subjects who estimated their mother's size to be larger, also selected a larger ideal body size (p = .047). Those who perceived themselves as too fat were more likely to skip meals to help control their weight, compared with those who perceived themselves as normal or too thin (p = .003). Approximately 30% of the sample was overweight or obese. There were not significant racial differences in weight or BMI. These results suggest that overweight is more acceptable among black females than among white females and may help explain why more black females are obese.

Adolescent↗
PubMed2005

Scaling of muscle power to body size: the effect of stretch-shortening cycle.

The present study investigates the relationship between muscle power recorded in vertical jumps and body size, and explores possible differences in this relationship between the concentric (CON) and stretch-shortening cycle (SSC) muscle action. Physical education students (N = 159) were tested with the performance of various CON and SSC maximum vertical jumps. The relationship between muscle power (P) and body size (S) was assessed by P=aS(b) where a and b were the constant multiplayer and scaling exponent, respectively. With respect to body mass and fat-free mass, the scaling exponents b for mean muscle power (calculated from the ground reaction force) in CON and SSC jumps were within the range 0.69-0.82 and 0.90-1.15, respectively. With respect to body height, the scaling exponent was higher (0.76-0.97 and 1.23-1.79, respectively), but the observed relationship proved to be relatively weak. However, when jump height was used as an index of muscle power, the same exponents were close to zero (suggesting no relationship with any of the indices of body size) in all the jumps except an SSC based hopping jump that demonstrated a weak but positive relation to body size. In conclusion, muscle power could scale to body size at a higher rate than predicted by geometric similarity (i.e. b = 0.67), while larger individuals could gain more when switching from CON to SSC muscle action. These findings could be based on a non-geometric scaling of transversal with respect to longitudinal dimensions and/or on different scaling rates of muscles and tendons.

Adolescent↗