Body Composition refers to the chemical composition of the body and more specifically fat mass and free fat mass. Body composition is used to describe the percentages of fat, bone and muscle in human bodies. Because muscular tissue takes up less space in our body than fat tissue, our body composition, as well as our weight, determines leanness. Fat-free mass is composed of all of the body’s nonfat tissue including bone, muscle, organs, and other types of connective tissue.
Body composition is a better indicator of fitness than most other forms of measurement as it takes into account more than just simply body size and weight. Body composition has important obligations in terms of health and physical performance. Excessive body fat leads to obesity and enhances the risk of developing a number of medical, social and psychological disabilities. Performance benefits are also associated with good body composition as excessive body fat is associated with decreased athletic performance in activities where the body mass must be moved through space. A high body fat percentage will negatively impact on an athletes speed, endurance, balance and agility, and jumping ability Body composition can be weighed in a variety of ways, four methods are recognized as the most popular, densitometry (Hydrostatic Weighing), bioelectric impedance, near Infrared Inheritance and skin fold fat thickness.
Densitometry or hydrostatic weighing is considered the gold standard in terms of body composition accuracy. Hydrostatic weighing is used to measure body density, from which body composition and percentage body fat may be estimated, based on Archimedes’ principle (the weight loss under water is directly proportional to the volume of water displaced by Body Volume). This method provides good results in terms of accuracy however is expensive to complete due to the equipment involved.
Bioelectric impedance aactually determines the electrical impedance, or opposition to the flow of an electric current through body tissues which can then be used to calculate an estimate of total body water (TBW). This can then be used to estimate fat-free body mass and body fat. Recent technological improvements have made BIA a more reliable and therefore more acceptable way of measuring body composition. BIA is also considered a relatively cheap method of measuring body composition however accuracy and therefore validity of results in comparison with other methods are considered suspect.
Infrared Inheritance principally includes light absorption and reflection using near-infrared spectroscopy. A probe is placed on the skin above the site to be measured. The amount of energy that is reflected indicates the composition of the tissue directly under the probe. The final of the four principal methods and one of the most important methods in terms of relevance to this experiment is skin fold thickness method. The skin fold method is the most widely used method due its ease of use and low cost completion.
The skin fold method includes measuring skin fold with callipers at a variety of sites on the body, the choice of sites depend on which skin fold method is used. The values obtained are used to estimate body density, relative body fat, or fat-free mass using the correct calculation for the method chosen by the experimenter for example Durnin and womersley. This method relies heavily on the training and experience of technician and the correct identification of skin fold site.