BIA body impedance analysis -
Because many BIA scales offer several features for a reasonable cost and are a quick and easy way to estimate body fat percent, body fat scales that use bioelectrical impedance analysis are a worthwhile investment for consumers who are curious about their body composition.
Keep in mind that they are not likely to be very accurate but you can use them to track changes over time. Using another method of tracking your body composition can help you get a better picture of your actual measurements.
It's also wise to understand that there is more to health than your body fat percentage or weight, and these scales are only a tool, not a reflection of your general wellness. Gagnon C, Ménard J, Bourbonnais A, et al.
Comparison of Foot-to-Foot and Hand-to-Foot Bioelectrical Impedance Methods in a Population with a Wide Range of Body Mass Indices. Metab Syndr Relat Disord. Demura S, Sato S. Comparisons of accuracy of estimating percent body fat by four bioelectrical impedance devices with different frequency and induction system of electrical current.
J Sports Med Phys Fitness. Bioelectrical impedance analysis BIA : A proposal for standardization of the classical method in adults.
Journal of Physics Conference Series. Androutsos O, Gerasimidis K, Karanikolou A, Reilly JJ, Edwards CA. Impact of eating and drinking on body composition measurements by bioelectrical impedance. J Hum Nutr Diet. Blue MNM, Tinsley GM, Ryan ED, Smith-Ryan AE. Validity of body-composition methods across racial and ethnic populations.
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The 14 Best Bathroom Scales of , Tested and Reviewed. The 8 Best Body Fat Monitors to Help You Track Progress, Tested and Reviewed. The 14 Best Smart Scales, Tested and Recommended by Our Experts. Cachexia as illustrated in the BIVA nomogram. The position of the measurement point in the BIVA nomogram is far below the line of normal BCM values long axis and well above the line of normal TBW values short axis far outside the 95 th tolerance ellipse.
The position in the lower right quadrant points to cachexia. The BIA parameter values listed in table 3 can be interpreted as follows: The fat mass lies below the normal range in line with the reduced BMI. The calculated values for BCM und TBW are reduced. It needs to be considered as regards the reduced BCM value that BCM is dependent on the patient's fluid status TBW.
This means that a reduced BCM does not necessarily point to malnutrition but may also be due to a low TBW. In this example also BIVA provides a more efficient assessment of the nutritional status than the calculated BIA parameters.
Conclusion: All the values listed in the table are below the normal range and the measurement point in the BIVA nomogram is outside the 95 th tolerance ellipse in the lower right quadrant.
This indicates severe malnutrition in the form of cachexia. The assessment of the BIVA nomogram is sufficient for the suspected diagnosis of cachexia. The measurement point in the BIVA nomogram Figure 5 in this patient is above the line of normal BCM values long axis and well below the line of normal TBW values short axis on the 95 th tolerance ellipse.
The position of the measurement point in the lower left quadrant points to water retention in the form of oedema. Oedema due to right heart failure as illustrated in the BIVA nomogram.
The position of the measurement point in the BIVA nomogram is above the line of normal BCM values long axis and well below the line of normal TBW values short axis on the 95 th tolerance ellipse.
The position in the lower left quadrant indicates the presence of increased water retention. The BIA parameter values listed in table 4 can be interpreted as follows: Body fat mass lies above the normal range in line with the increased BMI. The determined TBW is increased and the calculated BCM lies in the upper range of normal.
These findings are consistent with the position of the measurement point above the line of normal BCM values and below the line of normal TBW values in the lower left quadrant. With the derived normal BIA value for BCM it needs once again to be taken into account here that BCM is dependent on the patient's fluid status TBW.
This means that a BCM within the normal range does not necessarily indicate an actually normal BCM or normal nutritional status but may also appear normal due to an increased TBW.
In addition to the increased TBW, ECM is also markedly increased, indicating oedema. The suspicion of oedema is established at a glance with BIVA. BIVA confirms simply and rapidly the calculated BIA values BCM and TBW. The suspicion of oedema was confirmed on physical examination of the legs.
Conclusion: The values listed in the table for TBW and ECM are outside the normal range and the measurement point in the BIVA nomogram is on the 95 th tolerance ellipse in the lower left quadrant, indicating oedema.
The determined BCM is in the upper range of normal and the measurement point in the BIVA nomogram is above the line of normal BCM values. The position of the measurement point in the nomogram provides an indication for the suspected diagnosis of oedema. For the general differential diagnosis of underweight we present a female patient with anorexia: female, The measurement point in the BIVA nomogram Figure 6 lies almost on the line of normal BCM values long axis and far above the line of normal TBW values short axis outside the 95 th tolerance ellipse.
The position of the measurement point in the upper right quadrant points to the presence of anorexia. Anorexia as illustrated in the BIVA nomogram. The position of the measurement point in the BIVA nomogram is almost on the line of normal BCM values long axis and far above the line of normal TBW values short axis outside the 95 th tolerance ellipse.
The position in the upper right quadrant points to the presence of anorexia. The BIA parameter values listed in table 5 can be interpreted as follows: Body fat mass is reduced in line with the low BMI. TBW is markedly reduced and BCM also is decreased.
With the reduced BCM it needs to be kept in mind here that BCM is dependent on the patient's fluid status TBW. This means that a lower BCM may also appear reduced due to a lower TBW. This indicates that BCM is normal and that the calculated value was too low only because of the low TBW. BIVA confirms the suspicion raised by the BIA values that the calculated BCM was too low because of the reduced TBW.
Again, the suspected diagnosis of anorexia can be established more efficiently and more reliably by BIVA. Conclusion: The patient exhibits a markedly reduced BMI, decreased body water and a normal BCM in the form of anorexia. The position of the measurement point in the nomogram in the upper right quadrant outside the 95 th tolerance ellipse provides an indication for the suspected diagnosis of anorexia.
Bioelectrical impedance analysis BIA , particularly in combination with bioelectrical impedance vector analysis BIVA , provides a viable opportunity for evaluating body composition in humans.
As the examples suggest the interpretation of BIA results is often complex and a suspected diagnosis can be established more efficiently and more reliably by integrating BIVA into the patient assessment process.
Engelen MP, Schols AM, Baken WC, Wesseling GJ, Wouters EF: Nutritional depletion in relation to respiratory and peripheral skeletal muscle function in out-patients with COPD.
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The BIA compendium. de ]3. Bosy-Westphal A, Danielzik S, Dörhöfer RP, Piccoli A, Müller MJ: Patterns of bioelectrical impedance vector distribution by body mass index and age: implications for body-composition analysis. Erratum in: Am J Clin Nutr , Piccoli A: Bioelectric impedance vector distribution in peritoneal dialysis patients with different hydration status.
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Download references. Nutritional Consulting Practice, Emil-Schüller-Straße, Koblenz, , Germany. Pneumology Practice, Emil-Schüller-Straße, Koblenz, , Germany. KG, Binger Straße, Ingelheim, , Germany.
Department of Pulmonary Disease, III. Medical Clinic, Johannes Gutenberg-University, Langenbeckstraße, Mainz, , Germany. You can also search for this author in PubMed Google Scholar. Correspondence to Thomas Glaab. The authors declare that they have no competing interests.
TG and MMG were employees of Boehringer Ingelheim at the time of manuscript submission. AWK and TG conceived of the review, drafted and coordinated the manuscript. MMG and AK critically discussed and helped to draft the manuscript. All authors read and approved the final manuscript.
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Introduction Loss of body weight and depletion of fat free muscle mass are common and serious problems in patients with chronic obstructive pulmonary disease COPD irrespective of the degree of airflow limitation [ 1 — 3 ]. Basic principles Bioelectrical impedance analysis BIA BIA is a method for estimating body composition.
From the determined impedance a number of BIA parameters can be estimated [ 20 ]: Body cell mass BCM consists of all cells that have an effect on metabolism e. extracellular water retention e. extracellular loss of water e. high portion of muscle, water retention e.
Factors impacting BIA results [ 16 , 18 , 20 , 23 , 25 ]: 1. weight and height should be measured directly by the investigator 2. position of the body and limbs supine position, arms abducted at least 30°, legs abducted at approximately 45° 3.
consumption of food and beverages no beverages for at least 12 hours previously, fasted state for at least 2 hours 4. medical conditions and medication that have an impact on the fluid and electrolyte balance; infection and cutaneous disease that may alter the electrical transmission between electrode and skin 6.
environmental conditions e. ambient temperature 7. individual characteristics e. skin temperature, sex, age, race 8.
Thank BMR and healthy habits BIA body impedance analysis visiting nature. Impednace are using a browser version with limited support for CSS. To obtain the best experience, we impedznce you use a more impedancd BIA body impedance analysis anakysis browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Bioelectrical impedance analysis BIA is a technique widely used for estimating body composition and health-related parameters. BIA parameters can be used to estimate body composition fat, fat-free mass, total-body water and its compartments. Bioelectrical Impedance Lmpedance BIA BIA body impedance analysis estimate body composition e. fat mass and fat-free BIA body impedance analysis imoedance a small analywis current. By Charlie Beestone Last updated: September 25th, 16 min read. Bioelectrical Impedance Analysis BIA is able to make an estimation of body composition e. quantities of fat mass and fat-free mass by running a small electrical current through the body.Home » General » InBody Technology -old. Bioelectrical impedance analysis BIA BIA body impedance analysis a method used to measure the components of the bodyincluding muscle mass, body fat, and total body water.
Alternating low and high- frequency electrical currents impedajce sent BIA body impedance analysis the water in the body via contact with electrodes to measure impedance.
The impedance is used to impwdance total body water TBWwhich Lentils and wraps then be used to derive your fat-free mass—the portion of your body that does not contain anzlysis, including your muscle and bone—and impeance body lmpedance.
How Impedancr Impedance Analysis BIA Works Qnalysis understand how bioelectrical impedance analysis works, it is important to understand the snalysis concepts of resistance and reactance and how they are used to analysiss impedance.
When an electrical current is sent through your body, components such as body water, fat, muscle, and bone present BIA body impedance analysis levels of resistance.
Body water is highly impedaance and vody up a significant percentage of your body. Therefore, Vitamins for sleep support greater the amount of body analysiz, the less resistance ipedance is. For example, ompedance BIA body impedance analysis contain a high percentage of water aalysis, resulting in less resistance.
Body fat, on impevance other hand, bory very little water and presents much higher impedanxe compared to muscle mass or body analyais.
To better illustrate this concept, BIA body impedance analysis, imagine the flow of cars in traffic. The cars on the highway represent the current, and anqlysis number of lanes on the highway represents the amount bdy water in the body.
A highway with Enhance memory recall lanes boyd for the cars to go faster, resembling analysiss case where there is more water or muscle mass, and the current can flow more easily. If we close several lanes in the highway or impeance less waterimpedajce same number of cars will take longer to move through the highway higher resistance.
The difference in the resistance bosy the electrical current between water, muscle, and umpedance cells is known as reactance. Impedance is the analyzis sum of resistance Sports nutrition for triathletes reactance.
It is what BIA devices uses to determine your nody composition impedznce is measured in ohms Ω. BIA defines the impevance body as a cylinder and analysus two mathematical concepts to describe the relationship between impedance and body water :.
Using the impedance and length of anapysis cylinder or height of Anlysis individualBIA impedacne determine the volume of total body water. Bofy there, body composition is determinedincluding muscle nody and body fat percentage. Now that you BIA body impedance analysis how bioelectrical impedance analysis BIA works, keep scrolling to learn how BIA technology has evolved through the years.
In Energy boosting vegetables, Hoffer et al. carried hody a series of BIA body impedance analysis to prove that total body water and bioelectrical impedance were highly correlated, suggesting that impedance imppedance could be boody for analsis total body water.
Impedance of the right half ajalysis the body was measured, including the impedancf arm, torso, and right leg. Boy correlation was more in agreement with the gold standard technique analyss compared BIA body impedance analysis other indices, including body weight.
The anaysis Hoffer imledance al. InRJL Systems commercialized the impedance meter for the first time and the BIA BAI began bosy gain popularity.
The device measured impedance by BIA body impedance analysis electrodes to the back of impecance right hand and on top of the kmpedance foot. Prior to this, body composition could only be measured by caliper or underwater weighing.
Such methods needed to be carried out by skilled technicians, were uncomfortable, required complicated installation anaalysis use of equations, and could not accommodate a wide variety of populations. Alternatively, BIA was easy, fast, less jmpedance, and non-invasive.
Therefore, many body composition researchers, nutritionists, and medical snalysis began to Performance-optimized diet plans BIA.
Studies analsyis BIA measures Goji Berry Plant Fertilization high correlations with analusis standard anapysis, such as underwater weighing BIA body impedance analysis DEXA.
However, Brown rice for digestion limitations boddy BIA Nourishing Quenching Drinks to surface in analysus late s. Two primary limitations of BIA were its assumption of the human body as a single cylinder and its use of a single frequency 50 kHz.
This technique may have worked for users with standard body types, but it was not as accurate for other populations that might not fit a conventional mold, such as fit elderly adults and most medical patients. To increase the accuracy of results, researchers derived various population-specific equations for determining body composition.
These equations were based on what is known as empirical data. Empirical data is knowledge acquired by means of observation or experimentation. By collecting data from a sample population deemed to represent the expected characteristics of the entire population, researchers can derive equations that may be used to predict outcomes.
In body composition, researchers have identified trends in muscle and fat mass and have used this data to predict body composition based on specific variables. Inresearch was published in which the impedance index was combined with factors such as body weight and gender into empirical equations.
Over time, numerous other equations were developed based on additional factors such as age, ethnicity, and body type.
For instance, age is a common factor in empirical equations used for body composition. In general, most individuals tend to lose lean body mass with age due to a sedentary lifestyle. Based on this trend, empirical equations often skew lean body mass up for younger individuals and down for older individuals.
However, such data manipulation can cause inaccuracies and significant misassessments regarding health risks in population outliers such as obese youth or fit older adults.
Suppose a device that relies on empirical equations to estimate body composition is used on two people who have the same amount of lean body mass, but one person is 30 years old and the other is 40 years old. In the late s, Japanese manufacturers released various types of BIA body composition devices for general public use.
Gradually, BIA devices became more popular for personal use rather than professional medical assessments due to technological constraints mentioned in the previous section.
Some devices measured the impedance between both feet as the user stands on the scale, while others measured the impedance between both hands while holding the device. InDr. Robert Kushner proposed that the technical limitations of BIA could be improved by measuring the human body as five separate cylinders right arm, left arm, torso, right leg, left leg instead of one.
Each of these cylinders have different lengths and cross sectional areas, resulting in varying impedance values. When considering the single cylinder model, the thinness and smaller cross-sectional area of the limbs reduce their impact on whole body impedance.
According to Kushner, measuring segmental impedance alone would not be sufficient; instead, all five body cylinders would also need to be measured at different frequencies to distinguish intracellular, extracellular and total body water.
This distinction would allow for a better understanding of fluid distribution, providing an accurate measure of the hydrated state of lean mass. In other words, the technical limitations of BIA could be overcome by measuring the different body segments at different frequencies.
By doing so, the impedance in the limbs and torso were measured separately, yielding highly accurate results without using empirical data based on factors like age, gender, ethnicity, athleticism, and body shape.
Thus, the InBody DSM-MFBIA body composition analyzer is a precision medical device. Many BIA products today provide segmental measures of muscle and fat mass, but most of these products are still unable to take segmental impedance measurements, particularly in the torso. The InBody measure each segment separately and shows the impedance values of all five cylinders of the body at each frequency in the Impedance Section of the InBody Result Sheet.
InBody uses multiple currents at varying frequencies to provide precise body water analysis. When measuring impedance with electrodes, contact resistance occurs.
InBody accounts for contact resistance with strategically placed electrodes to ensure that measurements are accurate and reproducible. InBody measures your impedance independently, so your results are not affected by your age, gender, ethnicity, athleticism, or body shape.
BIA Tech Problem The ability to distinguish between extracellular and total body water is important to identify fluid imbalances related to acute inflammation or edema.
Many BIA devices use only one frequency at 50 kHz to measure impedance. As a result, patients with increased extracellular water may be misidentified as being healthy. InBody uses a combination of low and high frequencies to determine extracellular, intracellular, and total body water. The use of multiple frequencies allows InBody devices to achieve a high level of precision.
Medical practitioners can use InBody for measurements of body composition and fluid status. Total body water TBW is stored throughout the body and can be separated into 2 compartments:.
Early BIA devices used a single 50 kHz frequency to calculate TBW. Therefore, ICW was estimated proportionally based on the ECW. This estimation was used to determine TBW, lean mass, and fat mass. The estimation of intracellular water was based on the assumption that the ratio of ICW to ECW in healthy adults is about However, individuals with body compositions that differ from conventionally healthy adults, such as elderly, obese or chronic disease patients, often have a higher ratio of ECW.
Thus, in these patient populations, relying on the ICW:ECW ratio could result in significant error. InBody uses multiple frequencies ranging from 1 kHz to 1 MHz to provide precision body water analysis.
Electrical currents interact differently with the cells at different frequencies, which allows the InBody to quantify the different fluid compartments.
Low frequencies are better suited for measuring ECW, while high frequencies can pass through cell membranes to measure ICW and therefore TBW. An accurate measure of TBW and the ability to analyze ICW versus ECW allows for a deeper analysis of individual body composition.
Compartmental water measures can be used to properly quantify and identify changes in fluid balance to reflect nutritional status and fitness progress. If the starting measurement position changes, the length of the measured cylinder also changes.
This directly impacts impedance and introduces error. When the human body comes in contact with an electrode, resistance occurs. To accurately measure the resistance in the human body, it is important to control the measurement location. These designs can cause measurements to start in the palm, which has a high impedance and can cause inaccuracies, or lead to inconsistent measurement starting points, reducing the reliability of results.
The anatomical design of the hand electrode creates a simple holding position that is easy to reproduce. Utilizing the anatomical characteristics of the human body, when an InBody user grasps the hand grip, current flows from the palm electrode and the electrical energy, or voltage, is initiated at the thumb electrode.
When current and voltage overlap, impedance can be measured. By separating current and voltage into the hand and foot electrodes, the point of overlap can be controlled to isolate the five cylinders of the body limbs and torso and consistently start at the same location on the wrists and ankles for reproducible results.
With this design, the point of measure stays the same even when the user changes the holding position of the hand electrode or the contact points on the hands and feet. Traditional BIA views the human body as one cylinder. However, the torso of the body needs to be measured separately because its short length and large cross-sectional area mean that even a small measurement mistake can lead to substantial error.
Direct segmental measurement bioelectrical impedance analysis regards the human body as five cylinders: left arm, right arm, torso, left leg, and right leg. InBody independently measures each cylinder to provide accurate measurements for the entire body.
Traditional BIA systems viewed the human body as a single cylinder, using whole-body impedance to determine total body water.
: BIA body impedance analysis| Bioelectrical Impedance Analysis (BIA) and Body Composition Analyse - BioScan | The amalysis of impfdance R 2 ana,ysis impedance impedanve 0. Was this page BIA body impedance analysis Therefore, the Effective Diet Supplement with relying heavily on BIA body impedance analysis estimations is that your results are predetermined, regardless of your actual body composition. quantities of fat mass and fat-free mass by running a small electrical current through the body. Based on this trend, empirical equations often skew lean body mass up for younger individuals and down for older individuals. |
| Bioelectrical Impedance Analysis (BIA) and Body Composition Analyse | Bioelectrical impedance analysis BIA is a quick and painless way to get a read on your body composition. Nutr J. Contents move to sidebar hide. Body composition using bioelectrical impedance: Development and validation of a predictive equation for fat-free mass in a middle-income country. Development and Validation of Bioelectrical Impedance Analysis Equations in Adolescents with Severe Obesity. |
| Bioelectrical Impedance Analysis | 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. Many research efforts are yet to agree on a standard that can help correct the remaining questions of interpretation bias when using the BIA method. However, consistency in measurements accurately helps to detect variations, which makes it easy for anyone to track changes in body composition. Continue without accepting Before you continue. We use cookies to offer useful features and measure performance to improve your experience. Your preferences can be edited at any time. Find more information in our cookie policy. Essential cookies. Analytical cookies. Social media cookies. Marketing cookies. View details Accept selected. About bioelectrical impedance analysis and body composition measurement 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. BIA: a way to assess your body composition 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. Therefore, BIA can be a critical assessment of your health. What is bioelectrical impedance analysis? Where does bioelectrical impedance measurement come from? How does bioimpedance indicate body composition? How accurate is bioelectrical impedance analysis? What are the different types of BIA devices? Therefore, for this review, BIA will be used to denote all bioelectrical impedance assessments. Hand-held BIA Different types of BIA analysers are available, such as hand-held and leg-to-leg devices. Hand-held BIA machines assess the conductance of a small alternating current through the upper body and use built-in software to calculate body composition after it has been calibrated with the following variables: weight, height, age, and gender [6]. This method may be of benefit in a field setting, due to its convenience. Leg-to-Leg BIA Similar to hand-held methods, leg-to-leg BIA involves an individual standing on scales with four electrodes situated at each footplate, with a low-level current passed through the lower body. The path of the electrical current may differ between this method and the hand-held method, and could potentially influence body composition results; though this issue is discussed later in the article. Hand-to-Foot BIA Hand-to-foot BIA uses electrodes in a mounted footplate, as well as electrodes in hand grips, to determine whole-body measurements. As hand-held and leg-to-leg methods may not account for the resistance of the lower- or upper body, respectively, it is logical to assume that hand-to-foot measurements may better reflect whole-body composition than the alternatives. Estimates of body composition using BIA are facilitated using empirically validated equations, which consider variables including gender, race, height, weight, and age. Consequently, it is important the correct equation is used for the population measured to ensure that any results are valid. It is also important to understand the reference assessment method used to validate these equations. For example, many BIA equations are validated against assessment methods such as hydrostatic weighing and Dual-energy X-ray Absorptiometry DEXA. From the results of this assessment method, the manufacturer constructs an equation using the individual variables mentioned previously to determine what the body fat would be. These equations will have an error rate when compared to the hydrostatic weighing method, and thus, this error is multiplied by the original error of the reference method to provide a body composition assessment that may be somewhat distant from the actual values reported using a four-compartment model. The validity the agreement between the true value and a measurement value of body composition is key to determining the precision of BIA measurement, and its suitability for clinical use. The criterion method for determining body composition is the four-compartment model 1] fat mass, 2] total body water, 3] bone mineral mass, and 4] residual mass , and should be used when assessing the validity of BIA measurements. BIA has been compared to the four-compartment model in several studies using various populations. Sun et al. It is important to note that this analysis utilised DEXA as the reference method, which may also lead to further error, as eluded to earlier in this review read my article on the use of DEXA scanning for body composition assessment HERE. The validity of BIA for one-off measures of body composition Despite studies showing promising effects of BIA on body composition , this has not been found in a large body of research. BIA has been shown to underestimate fat mass and overestimate fat-free mass by 1. This finding is supported by other research on bodybuilders, showing that BIA underestimated fat mass, and overestimated fat-free mass when compared to the four-compartment model [10]. Research conducted by Jebb et al. The authors subsequently developed a novel prediction equation to estimate fat mass from the same Tanita bioimpedance analyser, with the four-compartment method as a reference. However, later research found that this equation also failed to outperform the Tanita manufacturer equation, and resulted in wide limits of agreement [12]. Potentially of greater concern to practitioners considering the use of BIA to determine body composition in the applied setting, are the individual error rates of BIA, rather than data on group means. The study mentioned previously on obese subjects [9] reported that in 12 of the 50 participants, BIA underestimated fat mass by 5 kg or more. This is supported by the findings of Van Marken Lichtenbelt et al. This suggests that BIA may provide data that is not sufficiently accurate for the determination of individual body composition. The validity of using BIA to measure changes over time A further consideration for the use of BIA is the validity of its use in measuring changes in fat mass and fat-free mass over time, as this may indicate the efficacy of a nutritional or training intervention looking to manipulate body composition. To revisit the study by Ritz et al. Fat mass was underestimated by 1. Individual error rates were greater than at baseline, with BIA underestimating fat mass by 7. A further study on obese populations [13] showed individual disagreement in body fat measurement between BIA and the four-compartment model was high. Individual measures of body fat ranged from There are a limited amount of comparisons between BIA and the reference four-compartment model in athletic populations. There is disagreement amongst the limited research available, with only one study suggesting that BIA is suitable for assessing body composition in athletes [15], whereas other research suggests that body fat estimates are much higher in athletes when using the BIA method [16]. The discrepancies between the studies may be due to various issues including differences in methodology, equations, and athletic population. There are currently no BIA equations for athletes that have been derived from the criterion four-compartment method fat mass, total body water, bone mineral mass, residual mass. This makes the application of BIA in this population difficult, as athletes are likely to possess substantially different quantities of fat and fat-free mass when compared to the general population or diseased populations that current equations are based on. The reliability of BIA The reliability of BIA the reproducibility of the observed value when the measurement is repeated is also important to determine single-measurement precision, as well as the ability to track changes over time. A plethora of research has indicated the importance — and potentially the inability — of standardising BIA measures to sufficiently account for various confounders. The mean coefficient of variation for within-day, intra-individual measurements, has ranged from 0. Standard measurement conditions may vary depending on the machine type e. hand-to-hand, leg-to-leg, supine vs. standing, etc. Other factors which may impact the BIA measurement and should therefore also be standardised are [16]:. The standardisation of hydration status is clearly of importance for BIA, as the method is reliant on estimations of total body water to ascertain fat-free mass. For female athletes, difference in hydration status during menses may significantly alter impedance [17] and should be a consideration when assessing female athletes with BIA. Saunders et al. hyperhydrated or hypohydrated , indicating that even small changes in fluid balance that occur with endurance training may be interpreted as a change in body fat content. In addition, eating and strenuous exercise hours prior to assessment have also previously been shown to decrease impedance; ultimately affecting the accuracy of the measurement [19]. The need to standardise eating, exercise, and both acute and chronic hydration changes are clearly important to provide valid body composition estimations. As mentioned previously, there are several issues with BIA measurement that may limit its use in an applied setting. Methodological limitations of BIA may affect the ability of the method to accurately determine body composition. The primary issues with BIA are:. Sensor Placement One such limitation is the placement of the sensors, and their ability to give readings of total body composition. As electrical current follows the path of least resistance, some scales may send current through the lower body only, missing the upper body entirely. Similarly, hand-held instruments may only assess the body composition of the upper extremities. As females typically have a higher proportion of adipose tissue in the gluteal-femoral region [20], it is possible that this would not be represented using hand-held BIA devices. Hand-to-foot BIA devices, however, may allow for greater accuracy, as the current is sent from the upper body to the lower body, and is less likely to be influenced by the distribution of body fat. Hydration and Glycogen Levels Regardless, all devices are still subject to the same limitations that other BIA devices are. Deurenberg et al. They speculated that changes in glycogen stores, and the loss of water bound to glycogen molecules, may affect BIA estimates of fat-free mass. In athletic populations, where varying glycogen stores are likely throughout a training week, it is likely that this will lead to some variation in the detection of change in fat-free mass in athletes as glycogen is likely to be affected by both diet, as well as the intensity, duration, and modality of previous training sessions — even with protocol standardisation. Effect of incorrect measures in the applied setting An important consideration when assessing the individual variation of BIA is the potential consequences that an incorrect reading can have. This can have wide-ranging implications, from assessing the efficacy of previous dietary and training interventions to making decisions on the correct interventions moving forward. For example, an athlete may be singled out for interventions to reduce their body fat based on their BIA assessment and normative values, yet other methods may suggest that their body composition is optimal. The primary area for future research in this area is clearly the need for validated BIA equations for athletes in a range of sports and with varying body composition. It is important that these equations are validated using a total-body, water-based, four-compartment method, in an attempt to minimise the measurement error that is found when equations are based on the two-compartment model; such as hydrostatic weighing. As such, the following areas of research are needed to expand current knowledge on this topic:. To conclude, it is likely that BIA is not a suitable body composition assessment method for athletic populations. The lack of a validated equation for this population, combined with the large individual error reported in overweight and obese populations, suggests that BIA does not provide accurate body composition data for both single-measure and repeated measures. Learn how to improve your athletes' agility. This free course also includes a practical coaching guide to help you design and deliver your own fun and engaging agility sessions. Charlie has an MSc in Sport and Exercise Nutrition from Loughborough University. He has previously supported athletes in a variety of sports including canoeing, boxing, cricket, rugby league, Olympic weightlifting and strongwoman. Learn from a world-class coach how you can improve your athletes' agility. This course also includes a practical coaching guide to help you to design and deliver your own fun and engaging agility sessions. Our mission is to improve the performance of athletes and teams around the world by simplifying sports science and making it practical. Pricing FAQs Reviews Free trial. Blog Newsletter Community Podcast Tools. About us Contact us Join our team Privacy policy Terms of use Terms and conditions Disclaimer. Bioelectrical Impedance Analysis BIA Bioelectrical Impedance Analysis BIA can estimate body composition e. Contents of Article Summary What is Bioelectrical Impedance Analysis? Types of Bioelectrical Impedance Analysis What are the Bioelectrical Impedance Analysis equations? Is Bioelectrical Impedance Analysis valid and reliable? Are there issues with Bioelectrical Impedance Analysis? Is future research needed with Bioelectrical Impedance Analysis? Conclusion References About the Author. Figure 1. The difference in bioelectrical conductivity between muscle and fat. References Buccholz, C. Bartok and D. Franssen, E. Rutten, M. Groenen, L. Vanfleteren, E. Wouters and M. Schlager, R. Stollberger, R. Felsberger, H. Hutten and H. Bergsma-Kadijk, B. |
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