DOES THE TANITA BIOELECTRICAL IMPEDANCE DEVICE (TBF-105) ACCURATELY DETERMINE BODY COMPOSITION FOR INACTIVE AND ACTIVE INDIVIDUALS

Abstract

830 This study's purpose was to ascertain how accurately the TBF-105 (TBIA) device measured body composition when the TBIA adult (TAD) versus athletic(TAT) equations were applied to the device's impedance measurements. Body composition was analyzed on thirty-five subjects (19 females, 16 males) using TBIA, Valhalla BIA (VBIA), hydrostatic weighing (HW), and a 4- site skinfold(4SF) equation. Based on an activity questionnaire with a score range of 1-100, subjects were classified as active (n=15; AC=77.3 ± 11.8) or non-active (n=19; NA = 31.9 ± 14.9) with no classification group overlap occurring. VO2 max also was estimated using the non-exercise equation of Thompson et al., 1992. HW values were used as the reference standard. This study's results indicated that the TAD equation significantly overestimated% body fat (%BF) in the NA group by 35.0% and 59.3% for females and males respectively compared to HW. When the TAT equation was used for the AC male group,%BF was also significantly overestimated compared to HW by 32.3%. However, in AC females, the TAT equation was very similar to the group's HW values (TAT = 25.8% vs HW = 25.9% BF values). The VBIA% BF values were very similar to HW for both active groups. (AC Males = -2.0%; AC Females< 1.0%). The NA female subjects were moderately over-estimated by the VBIA assessment 4.1% (VBIA = 27.8%; HW 26.7%) while the NA males VBIA significantly overestimated their% BF by 25.8%. However, because these subjects were uncharacteristically lean for low-activity individuals, the absolute difference in%BF was just 2.5% compared to HW. In comparison with all BIA measures, the 4SF equation results were nearly identical to HW for all groups except NA males (Absolute differences: AC Males = -0.8%; AC Females = +0.9%; NA Males = 3.6%; NA Females = -0.4%). When subject's were subdivided based on aerobic capacity (Low = 27.5 ± 4.5; Normal = 41.1 ± 5.2, ml•kg 1•min4), the TAD equation significantly overestimated the HW%BF by 22.6% and 37.4% respectively. In contrast, the TAT equation%BF values were not significantly different for either group compared to HW. In conclusion, these results indicated that despite the ability to select equations accounting for differences in physical activity patterns of fitness with the TBIA device, significantly large differences in body fat measurements were observed when compared with HW or SF measurements in this population.