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Biomedical subjects

J V Durnin

Publications and source records attributed to J V Durnin.

At least 19 recordsLinked to original sources
PubMed1997

Skinfold thicknesses: is there a need to be very precise in their location?

Skinfold thicknesses represent a comparatively simple and reasonably accurate assessment of body fatness which is an important part of the estimation of nutritional state. However, much emphasis is placed on the necessity to be very precise in the exact position of the skinfold being measure and there is frequently concern, also, about the variability of the measurement by different observers using different types of caliper. Fifty-three women and forty-five men had four skinfolds (biceps, triceps, supra-iliac and subscapular) measured first at the standard sites (Tanner, 1953; Edwards et al. 1955), and then at deliberately chosen sites about 20 mm distant from the "correct' ones. The effect on the estimation of body fatness by this manoeuvre resulted in a difference of usually less then 1% and, at a maximum, 3%. In the light of the uncertainty of the basic assumptions which are made in extrapolating from skinfolds (or indeed densitometry, total body water, total body K, and others) to body fatness, these technical errors assume comparatively little importance.

Adult↗
PubMed1996

A longitudinal study of changes in body composition and basal metabolism in physically active elderly men.

Ageing in the elderly is usually characterised by loss of fat-free mass (FFM) and reduction in basal metabolic rate (BMR). These age-related changes probably vary in rate, timing and extent between subjects in response to differences in leisure or occupational physical activity, disease and several other factors. Information on rates of change in BMR and FFM is limited by study design (most published work is cross-sectional rather than longitudinal), and possibly by methodology (use of imprecise and/or biased methods for assessment of changes in body composition). In the present study BMR and body composition were first measured in 22 physically active elderly men (mean age 62) in good health and measurements were repeated 6.5 years later. Changes in BMR, FFM and percentage body fat were small and not statistically significant over the time period (paired t, P > 0.05). The study suggests that physically active elderly men in good health in this age range can show very small age-related declines in BMR and FFM.

Aged↗
PubMed1996

Ability of biolectric impedance to predict fat-free mass in prepubertal children.

Measurements of body composition are being made increasingly widely in pediatrics. Tetrapolar whole body impedance (BI) is particularly suitable as a method of estimating body composition in children and is therefore the subject of great interest at present. However, the ability of BI to accurately estimate fat-free mass (FFM) in children is unclear, and users of BI are faced with a growing choice of prediction equations for estimation of FFM. Studies in adults have suggested that choice of prediction equation can have a profound effect on the estimate obtained. The aim of the present study was to measure the ability of four published pediatric BI equations to predict FFM in 98 Caucasian prepubertal children (mean age 9.0 y). For three of the published equations, limits of agreement between predicted and reference FFM were wide and distinct biases were apparent. With mean FFM of 25 kg, the equation of L. Cordain et al. overestimated reference FFM (95% CI +2.1 to +3.1 kg), whereas those of P. Deurenberg et al. (95% CI -1.9 to -2.9 kg) and F. Schaefer et al. (95% CI -1.4 to -2.5 kg) systematically underestimated reference FFM. The equation of Houtkooper et al. (95% CI -0.2 to +0.8 kg) predicted FFM with negligible bias and had narrower limits of agreement relative to the reference method than the other three equations tested. We conclude that the ability of BI to predict body composition in children depends on the equation chosen and that the general applicability of BI equations cannot be safely assumed. Cross-validation of BI equations is recommended before they are used routinely for estimation of body composition in children.

Body Composition↗
PubMed1995

Determination of body composition from skinfold thickness: a validation study.

Measurement of body composition is proving increasingly important in clinical nutrition and research. Skinfold thickness is a simple means of estimating body composition which is widely used in children, but there is little information on its validity. There has been a proliferation of equations for estimation of body composition from skinfolds, but some doubt as to their general applicability. The aim of the present study was to validate five currently used equations for this purpose in a sample of 98 healthy prepubertal children (64 boys, 34 girls), mean (SD) age 9.1 (1.7) years by comparison of estimates from each equation with measurements of fatness derived from hydrodensitometry. Differences between methods were determined by calculation of biases and limits of agreement. Limits of agreement between predicted and measured fatness were wide, particularly in the girls, and some distinct biases were apparent. Choice of prediction equation therefore has a substantial influence on the estimate of fatness obtained when using skinfolds in children. The existing published equations are associated with large random errors or significant systematic errors. For the time being skinfolds might best be regarded as indices (rather than measures) of body fatness in individuals, or means of estimating body fatness of groups. Estimating the total body fatness of individual prepubertal children using skinfolds, on the basis of this evidence, is not advisable at present.

Adipose Tissue↗
PubMed1994

The influence of body fat content and bone diameter measurements on body dissatisfaction in adult women.

This study investigated the simultaneous influence of various anthropometric factors on body dissatisfaction in adult women while controlling for psychological and behavioral factors known to covary with it. Multiple regression analyses confirmed that neuroticism, skeletal frame size, and percent body fat were positively, and age and physical activity inversely, related to dissatisfaction. Subsequent analyses substituted separate bone diameter measurements in place of the composite frame size variable and found that hip diameter, correcting for fatness, was a more salient factor in the determination of body dissatisfaction than the more general estimate of frame size. In pursuit of the perfect ultra-slender body women are encouraged to diet and exercise for weight loss more than ever before. It appears, however, that anatomical factors that are resistant to change by caloric restriction or physical activity, are a significant influence in the degree to which women report discontent with their body shape.

Adolescent↗
PubMed1994

Measuring the body composition of elderly subjects: a comparison of methods.

There is a paucity of data on differences between methods for the assessment of body composition in elderly subjects. Studies on younger adults suggest that such differences are of some practical significance at the individual level. In the present study the following methods of estimating percentage body fatness (BF%) were compared in healthy elderly men and women (mean age 70 (SD 6) years: densitometry; skinfold thickness; total body water; bioelectrical impedance (BIA) using an age-specific predictive equation and the manufacturers' equation; body mass index (BMI). Though BF% estimates from the various methods tended to be highly correlated with those from densitometry and with each other, differences between methods at the individual level were marked. In particular, the age-specific equations based on BMI and BIA systematically overestimated BF% relative to the other methods. Biases between BF% estimates derived from densitometry, skinfolds, BIA (manufacturers' equation) and total body water were less marked, indicating little evidence of systematic differences between these methods in elderly subjects. Individual differences between methods were slightly greater than those reported in some studies of younger adults, but this may be of little practical significance, and may be considered inevitable in view of variability between and within subjects in the extent to which the underlying assumptions of these two-component methods are met in elderly subjects.

Aged↗
PubMed1994

Low body mass index, physical work capacity and physical activity levels.

In a normal population the distribution of body mass index (BMI) is such that a certain proportion of the population is likely to be at low values without necessarily being malnourished. However, although they may have low BMIs without being malnourished, they could certainly be physiologically and physically disadvantaged. An attempt is made to dissect out the probability of work capacity and physical activity being influenced by changes occurring in the human body with diminishing BMI. The conclusion reached is therefore that before physical activity is affected, the BMI would probably have to be 17 or less, although it is possible that work capacity might be reduced before this level is reached. In any case, work requiring the use of the body mass - such as carrying loads, digging or shovelling earth or coal, pulling or cycling a rickshaw, stone splitting etc.- would impose a greater stress on people of low BMI.

Adult↗
PubMed1993

Body composition correlates of weight dissatisfaction and dietary restraint in young women.

Previous research found that when Body Mass Index (BMI) was statistically controlled in a multiple regression model, the percentage of body fat accounted for no additional variance in dietary restraint scores among women although, on its own, it was a significant predictor of this variable. These results imply that anatomical factors, besides fatness, influence dieting behaviour. The present study was designed to compare the relative influence on dietary restraint and weight dissatisfaction, of three body composition measures, each of which contributes in a different way to subjective impressions of body size (viz. BMI, body fat content, and skeletal frame size). Measures of emotional reactivity ('neuroticism'), body dissatisfaction, , and body focus were also included in the regression model. Results indicated that these psychological variables were strongly and positively related to restraint. Frame size was also a significant predictor of restraint and weight dissatisfaction. In fact, when frame size was controlled in the regression model, neither percentage of body fat nor BMI were able to explain any additional variance in restraint scores. These findings indicate that weight concerns and dieting behaviour are influenced, at least among young women, more by the size of their skeletal structure than their degree of adiposity. The irony of these findings is obvious and disheartening. An anatomical feature which is essentially resistant to change by dieting or exercise appears to be a primary influence in women's weight dissatisfaction and their tendency to diet. It is acknowledged, however, that this relationship may not obtain among very obese women.

Adipose Tissue↗
PubMed1993

Energy requirements in human pregnancy, in human nutrition and parasitic infection.

The energy requirement of pregnancy reflects a problem which contains a great deal of uncertainty. To supply the theoretical energy needs for the increases in maternal and foetal tissues and to cover the elevated basal metabolic rate involves an amount equivalent to an extra 250-300 kcal/day on average, but in real-life situations there is seldom a rise in dietary energy of a comparable quantity. Data from co-ordinated longitudinal studies in four countries, together with results from other published papers, show energy intakes increasing by only 100-150 kcal/day, and only in the third trimester. Although it is difficult to demonstrate, the probability is that there are energy savings in reduced physical activity which compensate for the larger energy needs.

Energy Intake↗
PubMed1991

'Slimming.'.

Explore the source record for details and available documents.

Diet, Reducing↗
PubMed1991

Practical estimates of energy requirements.

The scientific genealogy of those who studied human energy expenditure is reviewed. The genealogic review is followed by a discussion of the basal metabolic rate as the basis for calculations of energy requirements in humans.

Basal Metabolism↗
PubMed1991

Women who gain more fat during pregnancy may not have bigger babies: implications for recommended weight gain during pregnancy.

The correlation between infant birthweight and the amount of fat gained during pregnancy (estimated as the change in maternal weight between 10 weeks gestation and 2-3 weeks postpartum) was studied in 115 healthy, parous, urban Scottish housewives. There was very little correlation between these variables (r = 0.13, falling to r = 0.07 after birthweight was adjusted for initial maternal weight and length of gestation), i.e., women who gained more fat during their pregnancies did not give birth to heavier babies. This suggests that for most women one of the principal effects of increasing food intake during pregnancy may be to increase maternal fat gain rather than promote fetal growth, and that efforts to increase birthweight by encouraging greater weight gain during pregnancy may be unsuccessful.

Adult↗
PubMed1991

Aspects of anthropometric evaluation of malnutrition in childhood.

The evaluation of malnutrition by the use of anthropometry poses considerable problems if any meaningful information is to be acquired, particularly on individual children. It is possible to formulate reference values (17), for height and weight taking age into account, or perhaps as a simple ratio but there may be little relation between the assessment of malnutrition by this means and functional impairment. It is suggested in this paper that anthropometry in this context should include length or stature, weight, skinfold thicknesses (triceps, subscapular and suprailiac) and circumferences (head, upper arm, upper thigh). The reference values to be used in the assessment of malnutrition are not very satisfactory, and there are objections to the simple use of the NCHS (9) data. It would be more desirable to use values obtained on "well-fed" indigenous populations, although these hardly exist at the present time. Well-controlled surveys are urgently needed on length or stature, weight, skinfolds, and circumferences of appropriate populations if anthropometric evaluation of malnutrition is to be anything other than a crude assessment. At a more complex level, the relationship of these anthropometric variables to various functional tests also needs investigation.

Anthropometry↗
PubMed1991

Energy requirements of pregnancy.

The energy requirements of pregnancy is a topic of considerable uncertainty because the apparent energy costs--to supply the energy required for the changes in maternal and fetal tissues and to cover the increase in BMR (basal metabolic rate), amounting to the equivalent of an extra 250-300 kcal/d--are rarely paralleled by actual findings. However few studies have investigated this problem in a controlled, longitudinal, and statistically acceptable fashion. In the present study, measurements of energy intake, BMR, body weight and fatness, physical activity, and mechanical efficiency of movement, were made on 162 women in Scotland at 2 to 4 weekly intervals throughout pregnancy and data from 98 of these women were also obtained in the pre-pregnant state. Data from a parallel study in Holland are also given. The gains in body weight, fatness, the fetal and placental weights, and the increase in BMR were all at the normal expected values. However, increases in energy intake were of the order of only 100 kcal/d during the second and third trimesters. Comparatively small reductions in physical activity, which would be very difficult to measure precisely, are described which could account for the difference between actual energy intakes and the energy costs of pregnancy.

Adult↗