Is Lower-Body Bioelectrical Impedance Comparable to Whole-Body Bioelectrical Impedance in High School Students?

Abstract

Literature has shown that the use of BMI is not the most accurate assessment of overweight status since it does not account for the composition of an individual's body potentially misclassifying individuals (Heyward, 2006). As an alternative to BMI, bioelectrical impedance analysis (BIA) assesses an individual's body composition through a flow of current or impedance that measures total body water and fat free mass (Heyward & Wagner, 2004). Gold standard scales, such as a tetrapolar analyzer (WBA), analyze the whole body via four electrodes that make contact with the hands and feet. Scales are available to assess body composition by upper-body impedance (UBIA) via hand-to-hand analyzers or lower-body impedance (LBIA) via foot-to-foot analyzers. WBA can be very costly and therefore LBIA or UBIA may be more economical especially for high school fitness assessments when a BMI alternative is desired. PURPOSE: To determine if there are any significant differences in the results obtained between LBIA, UBIA, and WBA scales under identical conditions. METHODS: Participants consisted of 164 high school students (F=77, M=87) with a mean age of 15.43±1.2 yrs. Measurements were taken for each participant using all three devices and repeated at two subsequent screenings. Each device calculated the total body water (TBW), lean body mass (LBM) and fat mass (FM). Weight was measured using the LBIA and WBIA scales and manually inputted into the UPIA. Height was measured using a portable stadiometer or height rod. Statistical findings were determined using one-way ANOVA and Tukey post-hoc. Significant differences for males and females were based off the Tukey post-hoc. RESULTS: When assessing all parameters, there were significant differences in TBW and FM between the UBIA and the WBIA. Gender comparison showed significant differences (p<.05) among females in LBM and FM between LBIA and WBIA as well as between the UBIA and LBIA. There were no significant differences in LBM and FM between the LBIA and WBIA. Among the males there was a significant difference in TBW between UBIA and WBIA as well as between LBIA and UBIA. However no statistical differences were seen in TBW between LBIA and WBIA. CONCLUSIONS: Lower-body bioelectrical impedance scales are a cost effective and reliable method for determining body composition in high school students.