Validity of Hand‐to‐Foot Measurement of Bioimpedance: Standing Compared with Lying Position

Abstract

RUSH, ELAINE C., JENNIFER CROWLEY, ISMAEL F. FREITAS, AND AMY LUKE. Validity of hand-to-foot measurement of bioimpedance: standing compared with lying position. Obesity. 2006;14:252-257. Objective: To assess the reliability of the standing measurement of hand-to-foot bioimpedance compared with measurements made in the lying position. Research Methods and Procedures:In 205 volunteers 6 to 89 years of age, 111 males and 94 females from six ethnic groups, effects of posture, time, and age on hand-to-foot resistance were studied over a range of body size. The effect of time in a position on resistance was also recorded in a small subset (n ϭ 10), and repeat measurements over 3 days at the same time of the day were recorded in another subset (n ϭ 12). Results: Lying impedance was consistently higher than standing, with the relationship (resistance lying/resistance standing) for the children (5 to 14 years) being 1.031, progressing to a ratio of 1.016 in those Ͼ60 years. The time spent static in either position did change resistance measurements-a decrease of up to 9 ⍀ (mean 5 ⍀, 1.0%) over 10 minutes of standing and an increase of up to 7 ⍀ (mean 3 ⍀, 0.7%) with lying. Discussion: In the field, measurements of hand-to-foot bioimpedance can be made in the standing position, and, with appropriate adjustment, previously validated recumbent equations can be used. Given that errors in the measurement of height and weight also affect the reliability of the derivation of body fat from bioelectrical conductance, the errors that may arise from a more practical standing measurement rather than lying are minimal.

Assessing Adiposity

“…260 BIA also poses no risk to patients (although it is not recommended for participants with a pacemaker) and provides instant results. However, studies have shown that the validity of body fat assessment by BIA is influenced by sex, age, disease state, race and ethnicity, 261 level of fatness, environment, phase of menstrual cycle, and underlying medical conditions. 262 Studies suggest that BIA measurements validated for specific ethnic and racial groups, populations, and conditions can be used to obtain accurate measures of body fat in those populations, but not others.…”

Electrical impedance spectroscopy (EIS) for biological analysis and food characterization: a review

“…Rush et al (2006) compared the measured impedance at 50 kHz in 205 subjects in two different positions: standing and lying. The results showed that the measured impedance was slightly higher in the lying position.…”

Effects of Ventilation on Segmental Bioimpedance Spectroscopy Measures Using Generalizability Theory

“…Participants were measured in the standing position in order to avoid any orthostatic fluid shifts that would result from changing positions between standing-as the participants walked into the testing room-and the horizontal position used traditionally for performing BIS measures because it has been shown in the literature that position changes result in bioimpedance changes due to orthostatic fluid shifts (Lozano-Nieto & Turner, 2001;Zhu, Schneditz, Wang, & Levin, 2006b). Moreover, Rush, Crowley, Freitas, and Luke (2006) concluded that errors may arise from conducting BIS measures using the more practical standing position rather than lying and, therefore, proposed the use of a standing position for impedance measurements in subjects that are not bedridden. The tester measured each participant in a standing erect (anatomical position) posture with arms and legs slightly abducted to the most comfortable position.…”