Evaluation of multi-frequency bioelectrical impedance analysis for the assessment of body composition in individuals with obesity.

OBJECTIVE: The purpose of this study was to compare body composition measurements estimated by multi-frequency bioelectrical impedance analysis (MF-BIA) with air displacement plethysmography (ADP) in individuals with obesity. METHODS: Bariatric patients were recruited from Geisinger's Center for Nutrition and Weight Management Clinic in Danville, Pennsylvania. Sixty-two participants (age = 52.4 ± 9.3 years; body mass index = 38.9 ± 8.0 kg m-2) reported for a same-day testing visit. Body composition was measured using a common MF-BIA analyzer (InBody 720, Biospace Co., Beverly Hills, CA) and ADP. RESULTS: Strong relationships were observed between MF-BIA and ADP methods (r = 0.88-0.96, P < 0.001). There were no differences between MF-BIA and ADP measures of per cent body fat, fat mass or fat-free mass for the total sample or when examined by gender. CONCLUSIONS: The InBody 720 MF-BIA analyzer produced body composition measurements that were similar to ADP supporting the use of this technology in the obese population.

The effect of a meal on measures of impedance and percent body fat estimated using contact-electrode bioelectrical impedance technology.

BACKGROUND/OBJECTIVES: To determine the effect of a meal on impedance and percent body fat (%BF) determined using contact-electrode bioelectrical impedance analysis (BIA) technology. SUBJECTS/METHODS: Forty-three adults (23 women and 20 men) volunteered to participate in this study (age=20.5±1.1 years; body mass index=24.1±3.8 kg/m(2)). Body composition was assessed using three BIA analyzers: leg-to-leg (LBIA), segmental (SBIA) and multi-frequency (MFBIA), on two separate occasions. After a baseline measurement, subjects consumed a meal or received nothing, which served as the control (CON). Subjects were reassessed 20, 40 and 60 min following (POST) the baseline measure in each condition. RESULTS: Twenty minutes after eating (3847±900 kJ), body mass (LBIA=0.8 kg, SBIA=0.8 kg, MFBIA=0.7 kg, P<0.05), impedance (LBIA=6.0 Ω, SBIA=17.9 Ω, MFBIA=27.1 Ω, P<0.05) and %BF (LBIA=0.9%, SBIA=1.7%, MFBIA=0.8%, P<0.05) increased significantly and remained elevated at 60 min POST. During the CON trial, a consistent body mass reduction (60-80 g) and impedance increase (4-9 Ω) was observed over time resulting in a small increase in %BF (0.3-0.7%) 60 min POST (P<0.05). CONCLUSIONS: Twenty minutes after eating, %BF increased due to elevations in impedance and body mass. As such, when precision is critical, we recommend adhering to the pretest fasting guidelines to avoid meal-induced alterations in %BF estimates. In addition, use of a consistent testing schedule may minimize normal %BF variation over time.

Effect of mode selection when using contact-electrode bioelectrical impedance analyzers to estimate percent body fat in young adults.

AIM: When using bioelectrical impedance analysis (BIA) analyzers to assess body composition, a computer-programmed prediction equation referred to as a mode (i.e., standard STD or athletic ATH) must be selected prior to the assessment. This study examined the effect of mode selection on percent body fat (%BF) determined by leg-to-leg and segmental bioelectrical impedance analysis (LBIA; SBIA) in young adults. METHODS: Ninety-two young adults (52 women; 40 men) had %BF estimated using LBIA (Tanita: TBF-300A) and SBIA (Tanita: BC-418) which was then compared to air displacement plethysmography (ADP). During the BIA assessment, %BF was determined using both the STD and ATH pre-programmed modes. RESULTS: In the women, %BF (mean±SD) was significantly (P<0.001) underestimated by the ATH modes of LBIA (23.0±6.9%) and SBIA (23.4±6.2%) when compared to ADP (25.5±7.3%). In the men, the STD mode of LBIA (18.3±5%) overestimated %BF when compared to ADP (14.1±7%). All standard error of estimate and pure error values (range=3.8% to 6.3%) exceeded the recommended range for accuracy (<3.5%). CONCLUSION: The STD mode produced mean %BF values most similar to ADP in the women, whereas the ATH mode did so in the men; a finding that was consistent for both analyzers. However, large individual prediction errors and wide confidence intervals were observed regardless of the mode selected or analyzer used for the assessment. As such, when precision is critical, the prediction equations programmed in the LBIA and SBIA analyzers examined in this study cannot be recommended to measure %BF on an individual basis.

The effect of acute fluid consumption on measures of impedance and percent body fat estimated using segmental bioelectrical impedance analysis.

BACKGROUND/OBJECTIVES: To determine the effect of acute fluid consumption on measures of impedance and percent body fat (%BF) estimated using segmental bioelectrical impedance analysis (SBIA). SUBJECTS/METHODS: Seventy-six healthy, recreationally active adults (41 women; 35 men) volunteered to participate in this study (mean+/-s.d.; age, 21.0+/-1.6 years; body mass index, 25.0+/-3.2 kg/m2). Subjects had their body composition assessed on three separate occasions. After a baseline measurement, subjects consumed 591 ml of water (H2O), a carbohydrate/electrolyte drink (CHOE) or received nothing (CON). Subjects were reassessed 20, 40 and 60 min following (POST) the baseline measure in each fluid condition. RESULTS: Twenty minutes after drinking a H2O or CHOE beverage, %BF (1.1 and 1.2%), impedance (12 and 14 Omega) and body mass increased significantly (P<0.001). During the CON trial, %BF (0.3 and 0.5%) and impedance (7 and 11 Omega) also increased significantly above baseline values at 40 and 60 min POST. However, the normal hourly variability was significantly (P<0.009) less than the observed fluid-induced %BF alterations. The greatest %BF increases were observed in the lightest subjects, who were women. Fluid type had no effect on the magnitude of change POST. CONCLUSIONS: Twenty minutes after drinking, %BF estimates increased approximately 1.0% due to elevations in impedance and body mass. As such, we recommend adhering to the pretest fluid restriction guideline to avoid fluid-induced alterations in SBIA body composition measures. In addition, use of a consistent testing schedule may minimize normal %BF variation over time.

Influence of testing sequence on a child's ability to achieve maximal anaerobic and aerobic power.

The aim of the study was to examine the order of testing sequence on a child's ability to achieve maximal anaerobic and aerobic power. Thirty-two children (20 females, 12 males) between 7 - 11 years of age participated in this study. All subjects were tested on three separate occasions as follows: anaerobic power session - Wingate Anaerobic Test (WAnT) only; aerobic power session - maximal oxygen consumption (V.O (2max)) test only; and experimental session - WAnT followed by a V.O (2max) test (WAnT/V.O (2max)) or a V.O (2max) test followed by a WAnT (V.O (2max)/WAnT), each with 20 minutes of rest between the assessments. No significant differences were observed between the baseline WAnT or V.O (2max) between the two groups. No significant differences were observed for WAnT power values in either group regardless of testing sequence. Children in the WAnT/V.O (2max) group had significantly lower experimental V.O (2max) (38.6 +/- 7.6 vs. 40.6 +/- 7.4 mL . kg (-1) . min (-1); p < 0.05), RER (1.10 +/- 0.08 vs. 1.13 +/- 0.07; p < 0.05), and exercise time (472 +/- 87 vs. 511 +/- 79 s; p < 0.01) values when compared to the baseline V.O (2max) test. The results of this study indicate that when assessing a child's anaerobic and aerobic power during the same testing session, the testing sequence is of importance. However, it appears that a V.O (2max) test can be performed 20 minutes prior to the WAnT without affecting anaerobic power in children.

Effect of a maximal treadmill test on percent body fat using leg-to-leg bioelectrical impedance analysis in children.

AIM: The purpose of this investigation was to determine the effect of a maximal treadmill exercise test on percent body fat (%BF) in children using leg-to-leg bioelectrical impedance analysis (LBIA) (Tanita Model #TBF-300A). METHODS: Fifty-four children (24 females; 30 males) between 7-10 years of age participated in this study. LBIA measures of %BF were obtained immediately before and within 5 min after completing a maximal oxygen consumption test on a motorized treadmill. RESULTS: No pre- to post-test differences in %BF were observed in either group (mean difference: females 1.6%, males 1.5%). Impedance values significantly decreased postexercise (P < 0.05) in the female subjects. No significant differences were observed for fat mass, fat free mass, total body water or body weight postexercise when compared to pre-exercise values in either group. Correlations (P = 0.0001) of 0.997 were observed between pre- and postexercise measures of %BF. CONCLUSIONS: A maximal treadmill exercise test conducted prior to LBIA has no impact on %BF in children. Therefore, normal daily activities performed prior to LBIA assessment may have a limited impact on LBIA body composition measurement in children. As such, compliance with stringent pretesting exercise guidelines may not be essential when using LBIA to assess %BF in children.

The effect of acute fluid consumption on measures of impedance and percent body fat using leg-to-leg bioelectrical impedance analysis.

OBJECTIVE: To examine the effect of acute fluid consumption on measures of impedance and percent body fat (%BF) using a common leg-to-leg bioelectrical impedance analyzer system. DESIGN: Cross-sectional design with treatment order determined using a counterbalanced assignment. SETTING: University laboratory. SUBJECTS: In total, 21 recreationally active men (mean age 19.7 +/- 1.0 years; body mass index 24.2 +/- 2.3 kg/m2) volunteered to participate in this study. INTERVENTION: Subjects had their body composition assessed on three separate occasions. After an initial baseline body composition measurement, subjects consumed 591 ml of water (H2O), a carbohydrate/electrolyte drink (CHOE), or received nothing, used as the control (CON). Subjects were reassessed 20, 40, and 60 min after baseline (POST). Urine specific gravity (USG) was recorded at baseline and 60 min POST to assess hydration state. RESULTS: There were no significant changes in impedance or total body water (TBW) for any of the measurement time periods after drinking H2O or a CHOE beverage. Body weight (BW) (P < 0.0001) and %BF (P < 0.02) increased significantly 20 min POST and remained elevated at the 40 and 60 min POST time periods. After drinking, USG significantly decreased (P<0.0001) 60 min POST from baseline. For the CON trial, there were no significant changes in BW, %BF, TBW, or USG over time. CONCLUSIONS: Fluid consumption had no effect on lower-body impedance despite causing significant changes in hydration state. A slight overestimation in %BF (approximately 0.5%) was observed due to increased BW in the H20 and CHOE trials. This finding may have little practical significance when assessing body composition by LBIA.