Cadaver studies and their impact on the understanding of human adiposity.

The skinfold thickness is a much-used measurement for monitoring adiposity in a wide range of medical, health, occupational and sport science disciplines. Misconceptions abound, however, in its use, particularly that of purportedly predicting body 'fat' as opposed to 'adipose tissue'. To obtain data to investigate body composition and the extent to which anthropometry can be justifiably used to predict whole-body adiposity, an extensive dissection study was undertaken on 34 cadavers. In addition, to pre-empt questions on the applicability of cadaver data to living subjects, 40 elderly in vivo subjects of the same age range were compared with the cadaver population. No significant macro-morphological differences were found between males or females in the morbid and in vivo groups. Significant findings affect our previous understanding of the predictability of whole-body 'fat'. Skinfold compressibility was by no means constant; skin thickness varied with location in both sexes, females having thinner skin than males; there were significant sex differences in adipose tissue patterning. An identical thickness of adipose tissue did not necessarily contain the same concentrations of fat. Despite this variability, a relationship was demonstrated between aggregate skinfold measures and subcutaneous adipose tissue mass (as opposed to subcutaneous fat), this relationship being more evident in men. A strong relationship was found between subcutaneous adiposity and whole-body adiposity, and between direct skinfold depth measures and whole-body adiposity. The amount of visceral adipose tissue was the same in men and women, but in the men this represented a greater proportion of their total body adiposity. Further, the use of waist-to-hip girth ratio (WHR) was identified as an important predictor of health risk. These findings demonstrate that it is not sustainable to introduce a non-quantifiable error by transforming anthropometric values (skinfolds) into predictions of percentage body fat. If subcutaneous adiposity can be predicted, then an excellent indication of overall adiposity could be obtained. Currently, skinfold measurement can yield a reasonable indication of comparative subcutaneous adiposity (better in men than in women). In neither gender is this prediction completely reliable due to both inter- and intra-individual differences in the skinfold measurement procedure.

Relationships between visceral, trunk and whole-body adipose tissue weights by cadaver dissection.

BACKGROUND: Despite the important association of central adiposity and cardiovascular and other risk factors, there are only three reported values for directly weighed visceral adipose tissue (AT). All other reported values are based on medical imaging techniques. OBJECTIVE: The study aimed to investigate the relationships between visceral, trunk and total AT weights in older men and women. METHODS: Data was obtained from the combination of two studies involving the complete dissection of 15 male and 16 female cadavers (age range 55-94 years) and allowed for compartmentation into skin, AT, muscle, bone and a residual component, divided over six body segments: head, trunk, legs and arms. Visceral AT was separated from trunk subcutaneous AT. All tissues were weighed. RESULTS: Visceral AT weights ranged from 0.3 to 5.8 kg. Mean values were 3.00 +/- 1.52 kg (mean +/- SE) for the men and 3.24 +/- 1.67 kg for the women. These were not significantly different (p = 0.68), but visceral AT weight, expressed as a percentage of total body AT weight was significantly greater (p = 0.02) in the men (16.8 +/- 5.4%) than in the women (12.9 +/- 3.5%). Correlations between visceral AT weight and the weight of subcutaneous AT of the trunk were highly significant (men, r = 0.70, women, r = 0.81, p < 0.005), with similar slopes for the two sexes. The correlation coefficients of visceral with total body AT weights were even greater (men, r = 0.83 and women, r = 0.96, p < 0.0001). CONCLUSIONS: In this sample of older Belgians, visceral AT is strongly related to total body adiposity, corresponding to an increment of about 200 g of visceral AT for every kilogram of total AT in men and about 180 g in women. Because of this relationship, techniques such as skinfold calipers and ultrasound for assessing whole body fatness from measurement of only the subcutaneous layer are thus able to account for visceral adiposity.

Cadaver-assessed validity of anthropometric indicators of adipose tissue distribution.

Although the waist-to-hip ratio (WHR) has emerged as the best anthropometric indicator of the body's adipose tissue distribution, it has never been directly validated. Waist and hip girths, and triceps and subscapular skinfold thickness were measured in 12 male and 13 female cadavers aged 55-94 y. Adipose tissue from the upper limbs, lower limbs, subcutaneous trunk and intra-abdominal regions was then separated by dissection and weighed. Adipose volumes were also determined by hydrostatic weighing. The following adipose tissue mass ratios (and corresponding volume ratios) were derived: trunk to sum of lower limbs, trunk to sum of upper and lower limbs, intra-abdominal to sum of lower limbs and intra-abdominal to sum of upper and lower limbs. Centrality index (CI-subscapular-to-triceps skinfold ratio) and WHR were regressed on the tissue mass and volume ratios of the 25 cadavers. WHR was significantly related to mass and volume ratios for the 12 men (R2=36.0-57.5%, P<0.05), except for intra-abdominal to sum of upper and lower limbs (R(2)=26.3%, P=0.09), but none of these relations was significant in the women. CI was significantly related to all mass and volume ratios only for men and women combined (R(2)=16.2-21.8%, P<0.05). The WHR was better related to all mass and volume ratios than the CI. These results, especially the strong association between WHR and the ratio of intra-abdominal to lower limb adipose masses (R(2)=35.4%, P=0.002), demonstrate a clear relation between the selected anthropometric variables (hip and waist girths, and subscapular and triceps skinfolds) and adipose tissue distribution, thus validating the use of WHR as an important predictor of health risk.

Issues in adolescent health: a challenge for nursing.

The young people of today are the greatest investment we as adults have in our future. The care and nurturing we afford the adolescent is just as important as that which we afford to children or the elderly. Although most adolescents have a preoccupation with their bodies, they do not always engage in activities that will protect and develop them. Adolescents are often exposed to peer pressure, the effects of which may impact negatively on their behaviour and their health. Many adolescent health and behavioural issues evolve from developmental changes and can manifest in a confrontational attitude toward society, parents and others. They are hormonally 'fully charged', and their adolescent sexuality can have enormous effects on their future physical, psychosocial, moral and sexual development. Nurses have a pivotal role to play in ensuring children and adolescents learn the facts relating to the consequences of engaging in unhealthy behaviour and lifestyle. Nurses must also encourage parents to model and reinforce good health practices, such as serving balanced and nutritious meals at regular times and planning positive family activities. In this paper we review some of the salient issues in adolescent health today.

Soft tissue segmentation of the body and fractionation of the upper and lower limbs.

The aim of this cadaver analyses study was to provide regression models for the prediction of major tissue components of the human body. Altogether 182 anthropometric measurements were taken bilaterally on six cadavers (3 male, 3 female). The cadavers were segmented by severance through soft tissue only and gross segments weighted in both air and water. Each limb segment was then fractionated into four components--skin, adipose tissue, muscle and bone--and each component was also weighed in both air and water. Regression equations were developed for the prediction of total segment masses from anthropometry and the prediction of intra-segmental tissue component masses from anthropometry. Weight, volume, density and percentage of body weight are given for 14 body segments and are compared with 19th and 20th century cadaver data. Ten regression equations were generated for the prediction of segmental masses and per segment the major issue components generated a total of 24 regressions.

The skinfold: myth and reality.

The interest in skinfolds, given the easy accessibility of the subcutaneous layer and its non-invasive nature, has led to a proliferation of 'skinfold' applications and formulae. To obtain data to investigate body composition methods, particularly the use of skinfolds, two separate cadaver dissection studies were undertaken, allowing for the analysis of data from 32 cadavers with more than 2500 data per cadaver. In addition, 40 elderly 'living' subjects of the same age range were compared with the cadaver population and no significant macro-morphological differences were found. The available data have clearly demonstrated that skinfold compressibility is by no means constant. Adipose tissue patterning by assessment of skinfold thickness using calipers and incision confirms significant sex differences but emphasizes the neglected importance of skin thickness. It appears that the best adipose tissue predictors are different from those used in general. Also the problem of estimating body fat content by skinfold is compounded by the fact that two identical thicknesses of adipose tissue may contain significantly different concentrations of fat. Skinfolds are significantly related to external (subcutaneous) adipose tissue. However, the relation to internal tissue is less evident and the relation with intramuscular adiposity is unknown.