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Tanita Body Composition Assessment (BIA)


Medical doctors seldom measure the aerobic capacity or muscular strength of patients during an annual checkup. They might have you stand on a medical scale to determine your 'weight', but that information by itself is practically useless. Body "weight" only reflects the influence of gravity on mass but composition of mass is by far more important to know for health and performance.

In 1953 the Metropolitan Life Insurance Company developed the first height/weight tables to calculate the degree of health risk based on individual weight status. This data was based on male and female "averages" calculated from the company's client base. In 1983 the tables were revised and in 1986, improvement on frame size determinations were implemented with the elbow breadth or wrist circumference measurements used to classify frame size.

Unfortunately height/weight tables give no indication as to the degree of either obesity or leanness on an individual basis. In the individual clinical setting, height/weight tables can also provide grossly inaccurate conclusions about an individual's health risk. Estimation of body fat percentage using height & weight alone compared to whole body air displacement (plethysmography) or under water weighing (hydrodensitometry) is considered very poor.

Health Canada and many health professionals now refer to and use the Body Mass Index (BMI) as an alternative to height/weight tables but BMI is not an accurate method for the determination of body composition, especially for athletes. BMI is calculated by dividing a person's weight in kilograms by their height in metres squared. As a weight-to-height ratio, BMI cannot differentiate between fat or lean tissue, therefore it is not recommended as a component of fitness testing.

BMI is a reasonable standard for calculating body composition and health risk only in those who are sedentary, as excess weight-to-height ratios typically indicate excess fat. But who wants to use a standard based on a sedentary model, a model prone to disease and premature death. To get well and stay fit society has to look ムup' at health rather than ムdown' at disease, and generally speaking you'll always get what you focus on.

Body composition assessment could help protect all of us from unnecessary degeneration and decay if it was utilized by medical doctors as a routine in-office screening tool. An accurate analysis of body composition can detect trends in the loss of functional lean mass, including bone mass, organ tissue and muscle tissue, and acts as a warning beacon regarding the accumulation of excess bodyfat. It can also determine the ideal amount of water each of us should drink every day, as well as provide guidelines for optimum protein consumption. Body composition assessment can also help determine ideal dosages for many sports supplements, such as creatine, glutamine and HMB. In these cases the quantity of these supplements is based on lean mass, rather than total weight, and without a body comp you can't be precise.

Body composition technology varies in terms of method, application, cost, reliability and practicality. I've used bioelectrical impedance analysis (BIA) for many years now with excellent results. The Tanita brand foot-to-foot TBF-300A portable professional model has a 440 lb (200 kg) weight capacity with gender, adult and athletic modes. It provides a print-out that includes fat mass, fat-free mass, fat percentage, total body water, raw impedance, basal metabolic rate and desirable ranges, all of which can be interfaced with specialized health management computer software.

Tanita BIA scales use a leg-to-leg system based on pressure contact foot pad electrodes. Prior to analysis, the subjects' age and height are entered. To prepare for the test, the subject simply removes their shoes and socks and stands barefoot and motionless on top of what looks like a standard, horizontal, square weight scale with thin metal foot pads on the surface of the scale. A painless, low-level voltage electrical signal with a frequency of 50 kilohertz is then passed through the subject, up one leg from one electrode, and down the opposite leg to the receiving electrode. Impedance or opposition to the flow of the electrical current is what the analyzer measures.

The electrical current travels from foot-to-foot through the body and always follows the shortest pathway of least resistance. Bioelectrical impedance is based on the assumption that the body acts as a cylinder with a fixed signal frequency. Impedance to current flow through the body is directly related to conductor length or height and inversely related to cross-sectional area.

The leg-to-leg portable Tanita system is non-invasive and extremely practical for application by a clinician, personal trainer or health care provider. I prefer this particular method for the ease of measurement and speed, as the actual process from start to finish takes only about half a minute to complete. At the end of the test, subjects often remark "Is that it?"

Researchers at the Department of Nutrition and Dietetics, Harokopio University, Greece, sought to validate a prediction method equation for estimating the body composition in dancers using the bioelectrical impedance analysis method of assessment. The fat-free mass of 42 young female professional dance students was estimated by four different methods; DEXA, BIA, simple anthropometry and skinfold thickness. This study, published in Medicine & Science in Sport & Exercise, Vol. 32, No. 1, pp. 228-234, 2000, determined that BIA is a reliable method for assessment of bodyfat.

Tanita technology has been clinically compared to DEXA, hydrodensitometry and conventional supine BIA methods in research with comparable results in terms of accuracy. For additional research info please visit www.tanita.com

BIA can also be utilized as a means of measuring biological age or vital age, which ideally should be lower than your chronological age. According to Dr. William Evans, author of BioMarkers, The 10 Keys to Prolonging Vitality, the first and most important biomarker of aging is determined by lean mass followed by strength, basal metabolic rate (BMR) and body fat percentage.

Obesity increases the rate of human morbidity and mortality and is recognized as an independent risk factor in coronary artery disease, type II diabetes, hypertension and many forms of cancer. BIA helps track the effectiveness of any weight management program and can play a useful role in the development of health & fitness improvement strategies.

Body composition assessment provides valuable information about our structural make-up, which can help determine ideal body weight and identify certain health risks. Standard scales measure total weight but provide no reference to lean mass or fat mass. Over time in the absence of weight-bearing resistance exercise and sufficient protein intake, adults tend to lose healthy lean mass and gain unwanted body fat, even without an apparent change in weight.

For most sports, a high lean mass to fat mass body composition ratio is associated with superior performance, although too little fat can compromise body health and biological function, especially in female athletes. Excess fat is detrimental to athletic performance because it adds non-force-producing mass. You can't flex fat and excess fat is a liability. Based on the fact that force conforms to Einstein's equation of E = mc2, we know that strength from power producing muscle is the key to athletic speed and therefore superior performance.