Bioelectrical impedance analysis or BIA is a simple and non-invasive test measuring how low-voltage electric currents circulate through the body with the help of electrodes. Because BIA helps to distinguish how body fat , muscles, and body water are distributed in your body tissues, it is widely used to determine your body composition.

Bioelectrical impedance analysis BIA , or bio-impedance, is the measurement of the resistance of biological tissues to the flow of a low-voltage current. The human body is composed of different types of tissues, which have different levels of electrical conductivity. With a voltage around 70 microamperes μA , the current will go mainly through the most conductive tissues, such as water or muscles.

By measuring the voltage drop between source and receiver electrodes, BIA determines the resistance level of these tissues to the passage of the current. A four-electrode configuration for BIA between the right arm and right leg.

Although the first electrical impedance tests date back to Georg Simon Ohm , its application to the human body and the measurement of biological tissues was theorized in the second half of the 20th century. Impedance measurement in clinical medicine.

With time and a growing interest in body composition, other methods emerged. Bioelectrical impedance analysis is now widely used in the medical field to distinguish the amount of body water, body fat and skeletal muscle in a body. The analysis first obtains total body water TBW.

This is the amount of fluid that can be found inside and outside your body cells. Using ratios of bioelectrical impedance measured at a separate frequency, complex equations then estimate the amount of fat-free mass within the body.

The amount of body fat is finally deducted from the total weight. Note: Bioelectrical impedance is also a method used in cardiology to assess pulse wave velocity, another biomarker that determines the stiffness of the arteries to infer cardiovascular health. Learn more about pulse wave velocity.

The signal used in bioelectrical impedance analysis is totally safe and painless for both adults and children, but note that bioelectrical impedance is not recommended for people with pacemakers.

On one hand, many scientific publications attest to the reliability, precision and accuracy of the BIA method in providing valid estimates of total body water in individuals.

On the other hand, there is still a need for standardization and consensus on certain factors that may alter the test results. Because muscles are largely composed of water, dehydration decreases the amount of fluids and electrolytes that might lower the conduction of these tissues.

As a result, fat-free mass is more likely to be underestimated. Hydration levels vary widely throughout the day, which explains why consistency is an important factor in accurate BIA estimation. However, fat-free mass is still often underestimated in children.

Because the equations that interpret the fat-free mass based on total body water results rely on reference population segments, the body composition estimate might be inaccurate for people considered to be overfat. People wearing metal implants may experience an underestimated body fat reading.

However, this reading will remain constant over time, so they can successfully track their changes in body composition.

Many devices have been designed to measure bioelectrical impedance with increased accuracy and convenience over the years.

Using the same measurement method, they mainly differ in terms of the number of electrodes and which section of the body is being measured vs.

which one is being estimated. Beyond the design of these devices, what matters is also the nature and complexity of the algorithm performed to estimate total body water and fat-free mass based on the received frequencies. To build these algorithms, scientists use body fat standards that can vary.

Using smart scales to measure your body composition can help you reliably and cost-effectively track changes if the measurement remains at a consistent level. These scales have the ability to send the electrical current up one leg and down the other leg.

Before using, users must set their age, height, and sex. Also called hand-to-hand impedance devices, they measure arm and upper trunk bioimpedance.

These common BIA devices are composed of four electrodes, each of which are placed on half of the body left or right , sending a current from the arm through the body and down the leg.

The Direct Segmental Multi-Frequency BIA or DSM-BIA is the most advanced, and also the most expensive, device providing bioelectrical impedance analysis.

This device divides the body into 5 segments and independently measures the impedance for each segment. Bioelectrical impedance analysis BIA remains a quick and safe method for estimating body composition in adults. This is why this cost-effective alternative is widely used in clinics and in sports medicine and other health-related fields.

The results correlate strongly with the respective gold standard and qualify our seca mBCA to be medically applied. Additional information on the patient's health can be obtained by means of phase angles. The seca mBCA is ideally adapted to the working conditions in hospitals and medical practices.

After all, in order to obtain a truly meaningful BIA measurement bioelectrical impedance analysis , we need to look beyond the many technical requirements.

For one thing, the device has to be quick and easy to use for medical staff. For another, the measurement results have to be reproducible under normal clinical working conditions. These exact considerations went into the development of the seca mBCA The seca mBCA is the mobile solution for bioelectrical impedance analysis BIA.

Its low weight, good handling and precise measurement technology make it very efficient and versatile. Its technology is one of-a-king in the world because fat mass, muscle mass, and body water are determined with a newly developed measuring mat.

It is automatically networked by Wi-Fi to the touchscreen monitor, which can store up to , measurements. This enables many patients to be measured and courses of therapy to be reliably documented for years. Go to list view. Contact press office.

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Parallel capacitance is not affected by weight or body fat. It is a measure of cell membrane health and can change dramatically depending on disease or health.

As cells take on nourishment and vitality progressing toward health, their parallel capacitance increases. Inversely, as cells lose their energy and vitality, their capacitance goes down. A body builder, for example, would have a high parallel capacitance and low resistance, or more cell volume, because he is extremely muscular and fit.

A malnourished AIDS patient would have a low parallel capacitance due to lower muscle density. We can conduct a series of follow-up BIA test to monitor your health and measure your progress. To ensure best results please observe the following pre-test guidelines:. No exercise, no sauna, do not eat any food or drink caffeine or any liquids, within 4 hours prior to the test.

No alcohol consumption within 24 hours prior to taking the test. Drink 4 cups of water 1 hour prior to taking the test. You should drink All your water within a short period of time, so one hour prior to test time you COMPLETED Preparation.

It is suggested to drink warm water, if you have issues digesting 4 cups of water in a minute period. Females, report day of your menstrual cycle on day of test. The conductive medium in the body is water. Standardizing pre-test preparation will reduce the influence of temporary hydration or dehydration on test results.

Are you a grape or a raisin? What is parallel capacitance? Bioimpedance Analysis BIA Pre-Test Preparation To ensure best results please observe the following pre-test guidelines: No exercise, no sauna, do not eat any food or drink caffeine or any liquids, within 4 hours prior to the test.

The resistance R, which is a pure ohms resistance of the electrolyte-containing total body water, and 2. The reactance Xc, the capacitive resistance, which is present due to the condenser-like properties of the body cells. By measuring the phase angle, the determination and a differentiation of both of these components of impedance is possible.

Phase angle Modern BIA devices have phase sensitive electronics that enable you to take the measured total resistance and differentiate between the two components resistance and reactance.

The measurement's formula is built on the knowledge that the condensers in the alternating current circuit lead to a time delay t, meaning the current maximum is ahead in time of the voltage maximum. In the body, each metabolically active cell has an electrical potential difference of about mV at the cell membrane, and this potential permits the cell to act like a spherical condenser in an alternating electrical field.

Alternating current has a sinus wave, therefore the shift is measured in ° degrees and is described as a phase angle f phi or a alpha. To explain it in a more visual way - You will see a large phase angle for well nourished, "plump" cells with stabile membrane potentials, and comparable small phase angles with poorly nourished, "failing" cells that have low membrane potentials.

The phase angle, which is directly proportional to the BCM or body cell mass is of greatest significance at a 50 kHz frequency. Pure electrolyte water has a phase angle of 0 degrees, while a genuine cell membrane mass would have a phase angle of 90 degrees. Contrary to the cells of the BCM, fat cells have hardly any metabolic activity and cannot be detected by phase sensitive measurements because of their minimal membrane potential.

Fat cells are pure storage cells. The phase angle is used as a general measure of the membrane integrity of the cells. It provides information about the state of a cell and the overall condition of a patient's body, and as direct measurement parameter or "basic value", it is less prone to errors resulting from problems affected by measuring technology.

Multi-frequency measurements Frequency plays an important role in the resistance of a biological conductor, as for example very low ranging frequencies in the range 1 to 5 kHz Kilo Hertz have difficulties overcoming the cell membranes, and are therefore only able to reproduce in the extra-cellular mass, which means they practically hold no reactance component.

That's why, to be able to calculate the extra-cellular water ECW , there are multiple frequencies that can be used.

As the frequency increases, so does the phase angle and with it the capacitive resistance reactance. The maximum frequency is reached at about 50 kHz. Higher frequencies will cause both, the resistance and the reactance to decrease again.

Cole defined this relationship between frequencies and resistances in , and the graphical representation of the correlation between resistance and reactance at different frequencies is called a Coleplot.

The use of multi-frequency analysis provides an improved differentiation with regard to cell loss or water displacement, by assessing variations in mass of the extra-cellular mass ECM and the body cell mass BCM. This process is especially beneficial in patients with a changed grade of hydration in the lean body mass, and patients with serious illness such as kidney or heart failure, or patients with edema and diseases that require the crucial monitoring of water balance dialysis, intravenous nutrition.

This multi-frequency analysis has many advantages. Resistance Inversely proportional to total body water, Resistance R is the pure resistance of a conductor to alternating current.

Whereas fat mass has a raised resistance, lean body mass is a good conductor of electrical current, as proportionally it entails high amounts of water and electrolytes. Perfusion and fluid content of the extremities therefore play an important role and explain the occasionally occurring over-proportional variations in resistance.

They arise because of the influence of external conditions, such as ambient temperature and air-pressure, as well as internal factors such as for example congestion caused by illness and physical activity. All of these conditions affect the water content of the extremities. This may also happen with very low water content of the extremities caused by high pressure or coldness.

The resistance measurement will be very much above the normal range with the result of this calculation method. The body water and therefore the lean body mass will tend to be too low and the body fat will be calculated as too high.

In another scenario, if the circulation in the extremities is increased or congested, the resistance shifts downwards. Body water and lean body mass appear too large, and calculations of the body fat will appear as too low in the results.

It is important to remember that the human body is never static, but functions with the help of a dynamic system, and that changes of the body water occur hourly and change on a daily basis.

A current B. can therefore only be a snapshot of a dynamic system and of the condition at that point in time. That's why several repeat and response measurements of the individual will provide a more accurate picture and improve the assessment of body composition.

Reactance The resistance that a condenser exerts to an alternating current is called Reactance Xc. Due to their protein-lipid layers, all cell membranes of the body act like mini-condensers and reactance therefore is an assessment of the body cell mass.

General Principles Bioelectric impedance measurements BIM is the term representative for a variety of traditional and new noninvasive procedures and technologies that use electric current. With the help of one or more surface electrodes, a tiny amount of electrical current is activated and is detected at surface electrodes placed elsewhere on the body, once the resultant electricity pulse has passed through.

As it quickly proceeds through the various physiological sections of the body, and passes through, a drop in voltage occurs. The current encounters impedance or resistance inherent in the fluids and tissues it passes through the various areas, among them the intracellular space, the lymphatic system, the bloodstream and others.

The drop in voltage delivers indirect information about the physical properties of the sections, where current has passed through. Alternating Current Bioelectric Impedance Analysis BIA : Among the various number of A.

BIA models that are presently on the market, most are used for the obliquely measurement of total body water and to estimate the fat content of the body. BIA, which uses alternating current A. as the most common form of testing, employs A.

Various systems, varying broadly in complexity and design, operate with a wide range of intensities, frequencies and currents. For the patient, the amount of electricity delivered to the body is generally hard to even detect and far below any level that would result in cellular or tissue damage.

Once electric currents at or above 50 KHz are used, they flow non-selectively through extra cellular spaces as well as intracellular ones, as has been confirmed by various A. BIA studies. Once current has been sent to active tactile electrodes at a frequency at 50 KHz, its intensity enables the system to measure the reactance and resistance between 2 other passive tactile electrodes tetra-polar mode.

BIA and Its Calculated Parameters Total Body Water TBW Impedance measurements provide a quite accurate picture of electrolyte water contained in tissue. Orally ingested water, which has not yet been absorbed by the body, is not measured; the same goes for ascites, because it is not part of the lean body mass.

Administered solutions, however, are detected immediately. Lean Body Mass LBM The lean body mass is for the most part made up of inner organs, muscles, the skeletal system and the central nervous system, and refers to the tissue mass of the body that contains no fat.

These organ systems, although morphologically very different, contain matching functional structures. All of them contain matrix substance and extra-cellular fluids that support the metabolic exchange and assist in substrate transport and are made of cells that execute the synthesis and metabolism processes in the body.

In cases of for example edema or intensive car patients, where the quantity of lean body mass hydration is pathological, irregular calculations may be gathered for body cell mass, lean body mass, and extra-cellular mass - the secondary parameters - and will make the assessment of BIA measurements more difficult.

It helps in these cases, to look at the initial assessment and values for resistance, phase angle and reactance. The lean body mass contains of two subdivisions. One is the body cell mass BCM, also referred to as the motor of the organism, and the other one is the connective tissues and transport medium, the extra-cellular mass ECM.

Body Cell Mass BCM All tissue of the human organism entails to a certain degree Body cell mass, and the sum of all cells that are actively involved in the metabolic processes is called BCM.

While it is rather a functionally defined section and not so much an anatomically one above all, it consists all of the cells of the inner organs and muscles, with the muscles and the highest percentage to constitute the largest part of the BCM.

Connective tissue with low fibrocyte content however only makes up a small percentage of the entire BCM, and adipocytes, due to their low energy metabolism are not at all considered being part of the BCM.

Consequently, the sum of adipocyte cells therefore forms its own compartment in the body. Included in the BCM are the following tissue forms: the smooth muscles, the cells of the skeletal muscle system, the inner organs, the cardiac muscles, the blood, the gastrointestinal tract, the nervous systems and the glands.

As all of the body's metabolic function is performed within the cells of the BCM, the BCM is the main specification for the analysis of a patient's nutritional state.

It is also used as the standard specification for establishing the calorific requirement of the body and for the assessment of energy consumption. In addition to the catabolism, the BCM also performs work on the anabolism including the keeping up of synthesis and cell structures for the ECM: For example the transportation proteins and enzymes, and the formation of connective tissue fibres, cartilage tissues and bones.

A person's body cell mass is a fractional constituent of the lean body mass, and a number of factors, such as age and physical condition or genetics constitution type play a role in the BCM that is available in an individual.

A higher percentage of body cell mass present in lean body mass is for example found in young people with high physical activity, such as competitive athletes.

Their muscles are trained in the maturation phase of the body, and as a result, this higher proportion tends to be found in these individuals throughout their lives persistent hypertrophy of the muscle cells. Age is also a factor in BCM.

Older persons that are active, however, can retain their BCM to a large degree. These are optimal figures for BCM in the lean body mass. In view of the easy measuring methods for the assessment of the body composition, only phase sensitive BIA can be regarded to determine the BCM, and the maintenance of the BCM should be the main goal in any form of nutritional therapy.

A reduction of the body cell mass in BIA happens because of a genuine substantial loss of body cell mass, that can however also be accompanied by a temporary intracellular water loss. Extra-Cellular Mass ECM The extra-cellular mass ECM is the term for the lean body mass that exists outside the cells of the BCM.

Skin, elastin, collagen, tendons, bone and fasciae are the established connective tissue structures of the ECM, with the fluid parts consisting of plasma, interstitial and trans-cellular water.

Trans-cellular water is the description of fluids that are present in the body cavities, for example the contents of the gastro-intestinal lumen and the spinal fluid, while non-physiological trans-cellular fluids appear as ascites, or as pericardial or pleural effusions.