Agreement of bioelectrical resistance, reactance, and phase angle values from supine and standing bioimpedance analyzers

Abstract

Objective. Bioimpedance devices are commonly used to assess health parameters and track changes in body composition. However, the cross-sectional agreement between different devices has not been conclusively established. Thus, the objective of this investigation was to examine the agreement between raw bioelectrical variables (resistance, reactance, and phase angle at the 50 kHz frequency) obtained from three bioimpedance analyzers. Approach. Healthy male (n = 76, mean ± SD; 33.8 ± 14.5 years; 83.9 ± 15.1 kg; 179.4 ± 6.9 cm) and female (n = 103, mean ± SD; 33.4 ± 15.9 years; 65.6 ± 12.1 kg; 164.9 ± 6.4 cm) participants completed assessments using three bioimpedance devices: supine bioimpedance spectroscopy (BIS), supine single-frequency bioelectrical impedance analysis (SFBIA), and standing multi-frequency bioelectrical impedance analysis (MFBIA). Differences in raw bioelectrical variables between the devices were quantified via one-way analysis of variance for the total sample and for each sex. Equivalence testing was used to determine equivalence between methods. Main results. Significant differences in all bioelectrical variables were observed between the three devices when examining the total sample and males only. The devices appeared to exhibit slightly better agreement when analyzing female participants only. Equivalence testing using the total sample as well as males and females separately revealed that resistance and phase angle were equivalent between the supine devices (BIS, SFBIA), but not with the standing analyzer (MFBIA). Significance. The present study demonstrated disagreement between different bioimpedance analyzers for quantifying raw bioelectrical variables, with the poorest agreement between devices that employed different body positions during testing. These results suggest that researchers and clinicians should employ device-specific reference values to classify participants based on raw bioelectrical variables, such as phase angle. If reference values are needed but are unavailable for a particular bioimpedance analyzer, the set of reference values produced using the most similar analyzer and reference population should be selected.

Reference Percentiles for Bioelectrical Phase Angle in Athletes

“…Second, our outcomes were obtained from the use of a foot-to-hand technology (BIA 101, Akern, Florence, Italy), and a 50 kHz sampling frequency. Therefore, given the lack of agreement between BIA technologies and sampling frequencies [ 41 , 42 , 43 ], the current findings cannot be extended to different technologies (e.g., BIA in standing position) and sampling frequencies. Lastly, although the use of empirical Bayesian framework allowed us to ‘share’ information across sports with lower number of participants, measures of sports disciplines with high sample sizes may have an outsized influence on the estimates of the smaller sports.…”

Generalized bioelectric impedance‐based equations underestimate body fluids in athletes

“…Furthermore, there is now a wide range of commercial BIA devices, used in research articles, that do not provide information on the equation used for measuring body fluids in athletes 23,24,27,34 . In this regard, it is important to consider that BIA‐based equations should be applied using raw bioelectrical parameters obtained with devices and sampling frequencies similar to those with which they were developed 35 . In fact, numerous studies show how different outcomes are obtained using different devices and sampling frequencies 35,36 .…”

“… 23 , 24 , 27 , 34 In this regard, it is important to consider that BIA‐based equations should be applied using raw bioelectrical parameters obtained with devices and sampling frequencies similar to those with which they were developed. 35 In fact, numerous studies show how different outcomes are obtained using different devices and sampling frequencies. 35 , 36 These inaccuracies in assessing body fluids at the group and particularly the individual level may compromise an adequate assessment and monitoring of body fluids over the competitive season.…”

Precision and accuracy of bioelectrical impedance analysis devices in supine versus standing position with or without retractable handle in Caucasian subjects

“…Inaccuracy in subjects with low FM% may also be explained by the difficulty of whole-body BIAs in assessing visceral fat compared to DXA [28,29]. Another reason may be the difference in conduction of the electrodes depending on their type and placement on the body [19,30]. For BIA sup , the self-adhesive disposable electrodes were placed on the wrists and ankles, whereas for BIA std4 and BIA std8 , the stainless plate electrodes were in contact with the palms of the hands and the soles of the feet.…”