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Bioelectrical Impedeance AnalysisBIA tissue electrical properties evaluation -
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Next Post Understanding the Physiological Limiting Factors of VO2 Max. View Cart Checkout Continue Shopping. Link Text. 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.
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Bioelectrical Impedance Analysis BIA Bioelectrical Impedance Analysis BIA can estimate body composition e. Contents of Article Summary What is Bioelectrical Impedance Analysis? Whereas, a current with frequency above Hz measures total body water TBW and passes membrane to the cell.
Then, ICW is calculated by subtracting ECW from TBW. The principle of BIA measurement is shown in Figure 2. The connection between capacitance and resistance reflect electrical properties of the tissue, which are affected by hydration and nutritional status, and diseases.
It takes an electrical current more time to pass through a cell membrane compared to ECW, this delay time is called phase angle.
The greater the proportion of cell membrane, the longer the time delay or phase angle. Also, the higher amount of phase angle means that the proportion of ICW is greater than that of ECW A phase angle of zero degree displays absence of cell membrane and phase angle of 90 degrees displays a capacitive circuit, which indicates membranes.
A high phase angle is observed in healthy individuals, representing a large amount of cell membrane and body cell mass BCM with high reactance; whereas a low phase angle is observed in critically ill patients, as presented in Figure 3 14 , By Figure 3 , the fluid and nutritional status of patients can be evaluated over time.
Some studies showed the relationship among BIA parameters, central venous pressure cvp , and brain natriuretic peptide BNP Raw impedance data can give information about hydration and cell mass integrity The impedance value, height, weight, gender, and age are 5 essential parameters that are obtained by an accurate BIA measurement.
Several methods are developed to measure BIA including: Single frequency BIA, multi-frequency BIA, bioelectrical spectroscopy, segmental BIA, localized BIA, and bioelectrical impedance vector analysis.
Supine position with arms next to the body is the best position to measure BIA. Patients should not be in contact with other persons or objects and electrodes should be correctly placed. Some factors such as infusions of large amounts of normal saline, peripheral edema, skin temperature, and sweating interfere with BIA measurements.
In the best situation, body composition is assumed to be homogenous, but in patients, it is not homogenous. BIA divides composition of the body into 4 compartments of fat, water, mineral, and protein as demonstrated in Figure 4 BIA is a plain, noninvasive, fast, moveable, and handy method to measure body composition and fluid distribution.
However, it is still unclear whether BIA is accurate for patients with critical illnesses It is necessary to validate the TBW measured by BIA, through other methods such as densitometry.
The standard methods to measure body composition and TBW are isotope dilution, dual energy X-ray absorptiometry DEXA , underwater weighing, portable methods, and air-displacement plethysmography 19 , BIA has a good correlation with DEXA.
computed tomography CT and magnetic resonance imaging MRI can be used to measure abdominal and visceral fat. These techniques require extraordinary services and are not accessible for daily monitoring of body composition.
To estimate the metabolic status of patients in the intensive care unit ICU , BIA is a useful technique. It provides information about changes in body composition and membrane potential at the tissue level by measuring phase angle and fluid imbalance Also, volume status in patients undergoing hemodialysis, nutritional status, minerals bone, soft tissue , protein contents of the body, and estimation of glomerular filtration rate GFR can be assessed by BIA 21 - The clinical usage of BIA could be for patients with burns, cardiovascular diseases, peripheral edema, gastroenteritis, hemodialysis, the continuous veno-venous hemofiltration CVVH , liver disease, lung disease, acute respiratory distress syndrome ARDS , malnutrition, bariatric surgery, postoperative fluid status, renal failure, and stroke.
In the early stages of renal failure and in cardio-renal cases, parameters of BIA show lower resistance, abnormal impedance vectors, reduction of phase angle, and higher amount of total body water with a lower body cell mass The body composition of cases with kidney failure changes and reaches the maximum during the end-stage renal disease.
BIA could estimate dry weight and nutritional status of patients undergoing hemodialysis. Also, BIA is helpful to control blood pressure in such patients In several conditions of critical illness with existence of fluid in their third spaces such as ascites, anasarca, severe peripheral edema, pleural effusion, and massive over hydration, BIA may not provide a good measure of TBW Therefore, BIA can only be considered as a research tool in patients with critical illnesses.
Oxidative stress and production of reactive oxygen species are responsible for destruction of cell membrane with the consequence of fall in the phase angle In patients with critical illnesses, this ratio changes as fluid from intravascular migrates to the extra vascular space. Systemic inflammation is responsible for such changes BIA is non-invasive, inexpensive and can be performed at bedside.
However, it should be noted that BIA parameters are dependent on the population and the clinical situations may affect this measurement. Janssen YJ, Deurenberg P, Roelfsema F. Using dilution techniques and multifrequency bioelectrical impedance to assess both total body water and extracellular water at baseline and during recombinant human growth hormone GH treatment in GH-deficient adults.
J Clin Endocrinol Metab. Lukaski HC, Johnson PE, Bolonchuk WW, Lykken GI. Assessment of fat-free mass using bioelectrical impedance measurements of the human body. Am J Clin Nutr. Bioelectrical impedance analysis in body composition measurement: National Institutes of Health Technology Assessment Conference Statement.
Van Biesen W, Williams JD, Covic AC, Fan S, Claes K, Lichodziejewska-Niemierko M, et al. Fluid status in peritoneal dialysis patients: the European Body Composition Monitoring EuroBCM study cohort. PLoS One. Wabel P, Chamney P, Moissl U, Jirka T.
Importance of whole-body bioimpedance spectroscopy for the management of fluid balance. Blood Purif. Wabel P, Moissl U, Chamney P, Jirka T, Machek P, Ponce P, et al. Towards improved cardiovascular management: the necessity of combining blood pressure and fluid overload.
Nephrol Dial Transplant. Plank LD, Monk DN, Gupta R, Franch-Arcas G, Pang J, Hill GL. Body composition studies in intensive care patients: comparison of methods of measuring total body water.
Bioelectrical Impedance Analysis BIA can estimate body composition e. fat mass electrival fat-free Fat burners for sustained fat loss Time-restricted feeding window a evaluatkon electrical current. By Red pepper jerky Beestone Last evalyation 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. This is possible simply because different bodily tissues e. muscle, fat, bone, etc. What evaluatuon is meant by this term is not always clear but strong relationships Fat burners for sustained fat loss been found between cellular water status tissje relative amounts electrixal extra- and intracellular Maintaining alcohol moderationcell BIA tissue electrical properties evaluation integrity and Fat burners for sustained fat loss tiesue. Much of the current research is empirical tidsue and frequently pays Boost problem-solving skills regard to elfctrical underlying biophysical models that underpin the BIA technique or attempts to provide mechanistic explanations for the observations. This brief review seeks to provide a basic understanding of the electrical models frequently used to describe the passive electrical properties of tissues with particular focus on phase angle. In addition, it draws attention to some practical concerns in the measurement of phase angle and notes the additional understanding that can be gained when phase angle are obtained with bioimpedance spectroscopy BIS rather than single frequency BIA SFBIA along with the potential for simulation modelling. Robin R. Jones, David C. Hooper, … Ventsislav K.
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