Body Composition

Body composition refers to the make-up of lean tissue and fat tissue in the body. Lean tissue is composed of muscle, bone and organs. Fat tissue is composed of three different categories: essential fat, storage fat and non-essential fat. Essential and storage fat are both necessary for the body to function, while non-essential fat serves no real purpose. Body composition according to Heyward (2006) is known as key component in an individual's health and fitness profile. Body composition is measured as a ‘fatness' test, known otherwise as obesity. Obesity is a serious health problem that reduces life expectancy by increasing your risks of developing coronary artery disease, hypertension, type 2 diabetes, Obstructive pulmonary disease, osteoarthritis, and certain types of cancer.

Thirty-eight per cent of adults had a raised waist circumference in 2009 compared to 23% in 1993. Women were more likely than men (44% and 32% respectively) to have a raised waist circumference (over 88cm for women and over 102 cm for men).

Statistics on obesity, physical activity and diet: England, 2011.

However body composition is used to test the other end of the scale, with those with anorexia, exercise addiction and cystic fibrosis can lead to serious physiological dysfunction. Thus too little body fatness. The human body needs a certain amount of body fat for normal physiological functions.

In recent laboratory sessions we used body composition techniques to measure body composition of fellow students. I am going to compare and contrast the reliability and validity of these techniques used.

To accurately assess your subjects body composition we have to make sure that these tests are valid and reliable. With regard to testing body composition, to test ‘Validity' it is the ability of a test to measure accurately, with minimal error, with the degree to which a rest or instrument measures what it purports to measure. To test ‘Reliability' is the consistency or repeatability of a measure to yield consistent and stable scores across trials and over time. (Sharkey, 2007).

To test validity of our body composition we have to do a Pearson Correlation test against our ‘gold standard' test, the Bod-pod, comparing them to the other body composition tests: skinfold and Bioelectrical impedance analysis (BIA) using Tanita BC418MA and Tanita MC180MA machines. A strong correlation between the bod-pod test and the other body composition tests will indicate validity, thus showing that these other tests are a valid measure of body fat. This will be called a bivariate correlation because we are using two different types of body composition tests.

Using Pearson's correlation method, using the second test on each machine, Tanita BC418MA had a correlation (r value) of .694 and P value (significant) of .000.