Body composition refers to the proportions of bone, muscle and fat within the body. In assessing our body composition, we contrast the mass of bones, muscles and organs - our lean body mass - with body fat. Body composition is generally assessed using one of the following methods:
Body fat determination
Body Mass Index (BMI)
Somatotypes Somatotyping refers to the body type or physical classification of the body. The body is categorised as either
Endomorph - round and soft body shape (fatness)
Mesomorph - square, hard, prominent muscles (muscularity), or
Ectomorph - fragile, small bones, this muscles (leanness).
Research has shown that each person is made up of various proportions of all three characteristics and can be rated accordingly.
Body Fat The average female body has about 25% body fat while the average male body has 15-20% fat. This may account in part for differences between the sexes in physical performance, as the greater percentage of fat carried by females does not contribute to energy production (serving simply as a store) and it takes energy to move the fat when we exercise. An average 60kg female, for an example, would be carrying five to six kilogram more non-energy-producing tissue than an average male of the same weight. Physically active people possess considerably less total body fat than sedentary people. Percentage body fat is calculated in one of two ways:
Densitometry: This involves total body immersion in a vulumeter (water tank), which measures body density (specific gravity). The body can be divided into two body parts: lean body mass (LBM) and fat mass (FM). Since LBM and FM have different densities it is possible to determine the relative proportion of each by immersing them in water.
Skinfold measurement: Skinfold callipers are used to measure skinfold thickness at various sites on the body. A formula is used to determine the percentage of body fat.
While neither of these methods is particularly accurate in measuring the proportion of body fat, densitometry is the more accurate of the two. However, densitometry requires considerable expertise and expensive equipment, whereas skinfold measurement is simple. Both techniques are best used for monitoring change in composition rather than the actual percentage of body fat. For example, if the skinfold readings at each site decrease in the post tests it is likely that percentage body fat has declines.
Body Mass Index A common approach to assessing an individual's body composition is to calculate the body mass index (BMI). To determine an individuals BMI, divide their body weight in kilograms by their height in metres squared. The normal acceptable range for males is 20.1 to 25.0 and for females is 18.7 to 23.8.
Information provided by the BMI is indicative only and is in fact quite misleading when applied to certain types of athletes - particularly those with a mesomorphic body types - for example, footballers, rugby players and weightlifters.
You can calculate your BMI by going to this website: https://heartfoundation.org.au/your-heart/know-your-risks/healthy-weight/bmi-calculator (Malpeli, Horton, Davey, Telford, 2006).