J. P. Clarys

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.

Circadian variation in blood pressure responses to muscular exercise

Abstract The physiological responses to strenuous steady-rate exercise are known to vary with time of day. Less well understood are the acute reactions to abrupt short-term all-out muscular efforts. This study examined circadian variation in blood pressure responses to short-term intense exercise. Twelve males participated in an experiment that involved performance of maximal muscular efforts at six times of the day. The time points were equally spaced throughout the day and for each subject the tests were conducted within a 2-week period. Systolic and diastolic blood pressures were measured pre-exercise using sphygmomanometry and body temperature was recorded with a rectal probe. Muscle function tests consisted of (1) three slow and three fast isokinetic movements, knee extensions performed under both concentric and eccentric conditions; (2) a 20s maximal isometric contraction, and (3) a 60s fatigue loading with concentric and eccentric contractions. Blood pressures were again measured immediately after ...

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.

Cross-sectional analysis of BMI and some lifestyle variables in Flemish vegetarians compared with non-vegetarians

Epidemiological studies on vegetarians indicate that appropriately planned vegetarian diets are associated with certain health benefits, which may lower mortality and morbidity. A healthy lifestyle, such as regular physical activity and avoidance of harmful practices, such as smoking and heavy drinking, could also influence these positive health-related outcomes in vegetarians. This study reports BMI, smoking and drinking habits, engagement in physical activity, medication use and subjective health perception in a vegetarian population (women: n = 206, mean age 37.0 ± 12.3 years; men: n = 120, mean age 42.3 ± 15.9 years) as compared with a reference Belgian population (women: n = 4993, mean age 49.8 ± 18.0 years; men: n = 4666, mean age 48.0 ± 17.1 years). When considering the vegetarian group as a whole, the vegetarians had a lower mean BMI compared with the reference population (respectively 22.1 ± 3.1 kg/m2 compared with 24.6 ± 4.8 kg/m2 for women (p < 0.001) and respectively 22.6 ± 3.6 kg/m2 compared with 25.7 ± 4.0 kg/m2 for men (p < 0.001)). Vegetarians smoked less than subjects of the reference group (13.5% compared with 28.5% respectively; p < 0.001). During weekdays the percentage of subjects consuming alcoholic drinks in the two populations was comparable (32.8 in the vegetarian and 35.8 in the reference population; p = 0.159). During the weekend, more subjects of the reference population drank alcohol compared with the vegetarian subjects (70.2% vs. 58.6% respectively; p = 0.026). More vegetarians were involved in intensive physical activity (over 4 h per week) compared with the reference population (36.8% vs. 17.3% respectively; p < 0.001), while fewer vegetarians were involved in moderate physical activity (up to 4 h per week) compared with subjects of the reference group (28.2% and 51.0% respectively; p < 0.001). Percentages of subjects involved in no physical activity were comparable in both groups (vegetarians 34.9 vs. reference subjects 31.8; p = 0.625). Use of prescribed medication was lower among the vegetarians (25.5% compared with 47.3% in the reference population; p < 0.001), while use of non-prescribed drugs was comparable between both groups (34.1% in the vegetarian group and 28.2% in the reference group; p = 0.580). More vegetarian subjects perceived their health to be good to very good compared with the subjects of the reference population (90.4% vs. 77.2% respectively; p < 0.001). The significant difference for the BMI values when comparing the vegetarian males and females with the reference population cannot be completely explained by the evaluated lifestyle characteristics. However, the lower BMI values in vegetarians are in agreement with the literature.

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.

Post-mortem limitations of body composition analysis by computed tomography

Few of the indirect methods for measuring body composition have every been validated against direct human cadaver evidence. Computed tomography (CT), like NMR, has proved to be an important diagnostic tool and they appear to be the techniques of the future for body composition studies. The purpose of the present study (Cadaver Analysis Study III), undertaken at the Vrije Universiteit Brussel in a joint venture with the University of Göteborg, Sweden, was to validate tomographic measurements of volumes and areas from different tissues using data from CT-scanning of unembalmed deep-frozen cadavers and data collected by dissection of the same cadavers. Six Belgian adults were extensively measured and dissected. The body was divided into several slices for comparison of the CT image with photography of the same slice and comparison of tissue-volumes per segment for the whole body. Due to post-mortem changes and the frozen state of the cadavers, the CT measurements were greatly affected by artefacts disturbing adipose tissue (AT) and muscle area determinations. Only the bone area measurements were similar between the two techniques. However, when the volumes (per segment) of the same tissues were considered, no apparent difference was found between CT and dissection data for the muscle volume.

Morphological and constitutional comparison of age-matched in-vivo and post-mortem populations

Cadaver studies are often used as a reference in clinical studies and in-vivo Body Composition (BC). However, there is a paucity of comparative information between in-vivo and post-mortem populations. Forty living volunteers for the study (18 males and 22 females, age range 55-92 years) were age-matched with a sample of 26 well-preserved cadavers (13 males and 13 females). Twenty eight anthropometric variables were chosen, i.e. nine circumferences, eight breadths, four lengths, five skinfolds, weight and height. These were measured both in vivo and post-mortem. All measures were taken according to Martin and Saller (1957), Clauser et al. (1969) and Clarys et al. (1984). Normality verification, Variant Analysis (one way Anova) and Mollison transformations were used for the comparative treatment. Data from this study confirm that the in-vivo and post mortem macro morphology are in agreement. The best similarities were found between the female groups. This study confirms that cadaver research is reliable for the validation of in-vivo techniques and as a reference standard in the absence of other direct validation measures.

Intra-articular kinematics of the upper limb joints: a six degrees of freedom study of coupled motions

In sport, leisure and certain occupational activities, joint lesions of the upper limb are very common. To understand their aetiology in order to prevent and treat these pathologies on a scientific basis, a comprehensive knowledge of the involved stress and kinematics is imperative. For many years intra-articular joint kinematics have been described hypothetically in terms of the convex–concave principle. This principle, however, has not been validated. The in vitro research on the acromioclavicular, glenohumeral and elbow joints was performed using an electromagnetic tracking device (Flock of Birds). By recalculating the positions of the trackers to an embedded coordinate system on the joint surface, the intra-articular joint movements can be analysed. Therefore, the bony configurations and articular surface features were registered with a 3D drawing stylus (Microscribe). Thirteen acromioclavicular joints, six glenohumeral joints and seven elbows were studied. The coupled intra-articular movements were analysed using the Euler angles and finite helical axis approaches. The results of the acromioclavicular joint analysis indicate that during movements in the scapular plane a superior rotation of the clavicle was coupled with an inferior translation and vice versa, whilst during movements in the plane perpendicular to the scapular plane the anterior rotation was coupled with an anterior translation and vice versa. In the glenohumeral joint, the abduction-elevation was coupled with an external rotation. In the humero-ulnar joint, the extension was coupled with an external rotation and varus movement. This intra-articular behaviour was in contradiction to currently accepted convex–concave concepts in arthrokinematics and manual therapy. The results may have major implications for manual therapy and orthopaedic medical practice.

Measurement of three-dimensional intra-articular kinematics: methodological and interpretation problems.

Intra-articular kinematics evaluates joint motion in terms of the configuration of the joint. Therefore data are needed concerning joint kinematics as well as joint configuration. We have developed accurate measurement methods for both in vivo and in vitro evaluation. Interpretation of the processed data is more complex than simply setting up a coordinate system based on the joint configuration. Although the description of intra-articular motion in terms of Euler–Cardan or helical angles may be complete, the therapeutic interpretation may be doubtful. Using the the ulno-humeral joint during flexion–extension as an example, we found the combination of helical angles in the directions of extension/external rotation/varus. In the case of the Cardan angles, inconsistent patterns of rotation resulted from a different choice of sequence order and were different from the helical angles. The finite helical axis (FHA) provides a functional representation of the joint movement, i.e. pathways of motion, whereas the sequence dependency of Euler–Cardan angles produces problems in the therapeutic interpretation of the movement. Therefore we believe that an FHA approach should be used in intra-articular kinematics research.

Electromyography applied to sport ergonomics

The improvement of electromyographic (EMG) devices for the detection of electric potentials produced in voluntary complex movements and the evolution of methodological approaches to data acquisitio...