BHCS2014 Clinical Physiology Instrumentation And Techniques


As the name suggests body composition is exactly what the body is made up of. Overall our bodies are made up of the same constituents like muscles, bones, tissues, organs and fat. The proportionate distribution of such constituents, most importantly the proportion of fat and lean mass present on an individual’s body is a determining factor for their health and wellbeing. Body composition has increasing become a topic of discussion in the fields of medicine, health and fitness. By keeping track of one’s body composition and interpreting them correctly one is able to build a healthier and happier lifestyle. Body composition has been established to be related to various diseases like diabetes, hyperlipidemia, coronary heart disease, hypertension, pulmonary disorders and so on (Schols, Broekhuizen, Weling-Scheepers and Wouters 2005). Considering the vast array of health problems associated with it is obvious that body composition has become a widespread evaluation method for practitioners.

Various methods have been developed over the years to measure the body composition with relevance to nutritional assessments. However no technique has been yet developed that can measure the body fat of an individual directly. % body fat can only be measured based on relationships between body fat and other parameters that are measureable directly (Heyward and Wagner 2004). All the prevalent methods correctly have certain advantages as well as disadvantages. Some degree of error can be observed in all the methods. Body compartments that need to be measured in a particular clinical condition must be determined beforehand in order to choose the correct method for measurement of body composition. Body compartments have been classified into a five level organizational model which provides a structural framework for studying body composition at different levels. The different levels of composition include Atomic, molecular, cellular, tissue-organ and whole body. At an atomic level body mass is composed of Hydrogen, Oxygen, Nitrogen, Calcium, Sodium, Potassium, Chlorine, Phosphorus, Calcium, Magnesium and Sulpher. The molecular level of composition can be modeled into different components that may include fat mass, total body water, total body protein, bone mineral, soft tissue mineral, carbohydrates, and fat free mass. At a cellular level the components are cells, extracellular fluid, extracellular solids and fat mass. Adipose tissue, skeletal muscles, bone, visceral organs and other tissues comprise of the tissue-level body composition model. Finally, the whole body model consists of head trunk and appendages (Lee and Gallagher 2008). The 2-compartment model that classifies body into fat mass and fat free mass are generally used to estimate body composition of adults. However, certain assumptions like the fat free mass comprise of water, protein and mineral plays an important role in determining the accuracy of the measurement. In case of infants the 2 compartment approach is not ideal as the fat free mass is changing with the growth of the infant. For accurate measurement in infants the 4 compartment model is being utilized which involves boy mass or weight, total body volume, total body water and bone material (Fields and Goran 2000).

There are several methods of measuring body composition of which our focus will be calculating body fat using anthropometric measurement and using bioelectrical impedance analysis. One of the most commonly used clinical assessment tool is Body Mass Index. It is measured by dividing an individual’s body weight in kilograms by height in meters squared. It provides an index that determines whether the weight of the individual is proportionate to his/her height giving an overall idea about their fitness. The major limitation of this process is it does not differentiate between fat free and fat mass of the body often leading to ambiguous results in case of athletes or people with higher lean mass (Garrouste-Orgeas et al. 2004). However, studies have still shown a clear correlation between elevated BMI and incidence of certain health issues. Individuals can be classified into underweight, normal, overweight and obese in terms of BMI.

Another commonly used method of measuring body composition is measurement of girths of the body. Various girth measurements such as waist, abdomen, hips and thighs provide estimates of body proportions and consequently body composition. The main limitation of this method is that it does not provide any insight regarding the fat and fat-free components of the body (Wier, Jackson, Ayers and Arenare 2006). Waist to hip ratio is often utilized in clinical scenarios to estimate obese people and the degree of obesity.

Skin fold measurements is a method used to measure % body fat in a person. It is a relatively cheap and noninvasive method that can fairly accurately provide an insight regarding the body fat percentage in an individual. The procedure of measurement must be accurately performed to get optimum results and trained professionals should be employed for that matter. Another important aspect is locating the site of measurement that can greatly influence the obtained results. While measuring skinfold certain precaution are necessary such as avoiding measurement after exercise as it can shift the body fluid causing error in measurements.

Bioelectrical impedance analysis is efficient method to determine body composition and the proportion of body fat to lean mass in an individual. It is an integral tool to measure health status for health practitioners and nutritionist (Kyle et al. 2004). It is a relatively noninvasive method where two electrodes one on the right hand and another on the right leg of an individual is placed and imperceptible electrical current is passed through the body. The water content in the body affects the flow of electrical current and that impedance is measured.


Subject1: UEL student, male (age=24; height=1.75; weight=69kg; BMI=22.5)

The height and weight of the subject were measured using stadiometer and standard weighing machine. Any belongings were removed before performing the measurement. The BMI of the sunject was calculated from the weight and height measurements. Skin fold measurements were taken on 4 different regions namely biceps, triceps, subs cap and the suprailliac. The measurements were repeated thrice and the mean and difference were calculated.
Various equipment that were used for the measurements are Skinfolds callipers, electrical impedance device (tanita testing), weight scale (calibrated to Zero before taking any measurements).

Triceps skin fold was measured after asking the subject to place his arms in a relaxed position to the side of his body. The measurement was taken at a location halfway between the olecreanon process and the acromian.
Biceps skin fold was measured with the vertical fold of the arm just above the belly of the biceps.
Sub scapular was measured at a location 1-2 cm below the inferior angle of the scapula with a diagonal fold.
Finally, Superiliac skin fold was also measured with a diagonal fold at a location superior to the iliac crest.

Skinfold Measurement 1 Measurement 2 Difference Differenece2 
Bicep 4.00 3.00 -1 1 
Bicep 4.00 3.40 -0.6 0.36 
Bicep 5.00 3.00 2 4 
SUM 13 9.4 5.36 
Mean 4.3 3.13
TEM (abs) 1.6
TEM (rel) 43

TEM (rel) = 1.6/ 3.7 = 0.37 x 100 = 43 
Skinfold Measurement 1 Measurement 2 Difference Differenece2 
Triceps 17.8 6.9 10.9 118.81 
Triceps 11.3 6.0 5.3 28.09 
Triceps 12.4 6.5 5.9 34.81 
SUM 41.5 19.4 181.71 
Mean 13.8 6.5
TEM (abs) 9.5
TEM (rel) 94
TEM (rel) = (9.5 / 10.15) x 100 = 94 

Skinfold Measurement 1 Measurement 2 Difference Differenece2 
Subscabula 16.0 11.0 5 25 
Subscabula 17.2 10.6 6.6 43.6 
Subscabula 18.0 11.1 6.9 47.61 
SUM 51.2 32.7 116.2 
Mean 17.06 10.9
TEM (abs) 7.6
TEM (rel) 54
TEM (rel) = (7.6 / 13.98) x 100 = 54 
Skinfold Measurement 1 Measurement 2 Difference Differenece2 
Suprailliac 19 17.0 2 4 
Suprailliac 20.0 19.2 0.8 0.64 
Suprailliac 22.0 20 -2 4 
SUM 61 56.2 8.64 
Mean 26.17 28
TEM (abs) 2.1
TEM (rel) 271
TEM (rel) = (2.1 / 27.1) x 100 = 271 
Technical error of measurement is used in anthropometry to control the precision and accuracy of the measurements undertaken. It is an accuracy index and assesses the measurement quality and control (Perini, Oliveira, Ornellas and Oliveira 2005).


Skin fold measurement taken by skinfold calliper can only measure a certain kind of fat in the body- the subcutaneous adipose tissue fat found underneath the skin. Although studies have shown that it is almost 98% accurate in measuring the body fat of an individual and the body composition consequently, it has certain limitations. As it can only measure subcutaneous body fat it cannot produce efficient results for obese or skinny individuals. On the other hand bioelectrical impedance analysis can measure body composition of healthy subjects as well as patients accurately. A TEM less than 5% is considered normal by many studies. Bu tin our experiment a TEM of 23-43% has been observed. This can be contributed to error in measuring techniques, lack of training before taking measurements and use of non-precise equipment.


Fields, D.A. and Goran, M.I., 2000. Body composition techniques and the four-compartment model in children. Journal of Applied Physiology, 89(2), pp.613-620.

Garrouste-Orgeas, M., Troché, G., Azoulay, E., Caubel, A., de Lassence, A., Cheval, C., Montesino, L., Thuong, M., Vincent, F., Cohen, Y. and Timsit, J.F., 2004. Body mass index. Intensive care medicine, 30(3), pp.437-443.

Heyward, V.H. and Wagner, D.R., 2004. Applied body composition assessment (No. Ed. 2). Human Kinetics.

Kyle, U.G., Bosaeus, I., De Lorenzo, A.D., Deurenberg, P., Elia, M., Gómez, J.M., Heitmann, B.L., Kent-Smith, L., Melchior, J.C., Pirlich, M. and Scharfetter, H., 2004. Bioelectrical impedance analysis—part I: review of principles and methods. Clinical nutrition, 23(5), pp.1226-1243.

Lee, S.Y. and Gallagher, D., 2008. Assessment methods in human body composition. Current opinion in clinical nutrition and metabolic care, 11(5), p.566.

Perini, T.A., Oliveira, G.L.D., Ornellas, J.D.S. and Oliveira, F.P.D., 2005. Technical error of measurement in anthropometry. Revista Brasileira de Medicina do Esporte, 11(1), pp.81-85.

Schols, A.M., Broekhuizen, R., Weling-Scheepers, C.A. and Wouters, E.F., 2005. Body composition and mortality in chronic obstructive pulmonary disease. The American journal of clinical nutrition, 82(1), pp.53-59.

Wier, L.T., Jackson, A.S., Ayers, G.W. and Arenare, B., 2006. Nonexercise models for estimating VO2max with waist girth, percent fat, or BMI. Medicine and science in sports and exercise, 38(3), pp.555-561.

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