Knowledge Bank

Background: The body composition of athletes is frequently evaluated in sports nutrition using bioelectrical impedance analysis (BIA) due to its non-invasive technology, wide availability, portability, and low-cost association. There is limited research assessing the reliability of the newer BIA devices on the market. Objective: Evaluate the reliability of four BIA devices across five serial encounters within typical uses. Methods: This second-generation study recruited a convenience sample of 8 Sports Nutrition Laboratory personnel to collect estimated body fat percentage at a total of 5 encounters over a two-week period on 4 selected BIA devices. The BIA devices included: InBody 770, Tanita Body Composition Analyzer SC-331, Omron HBF-306CN, and Greater Goods Digital Home Scale. The repeatability and variability of estimations for body fat percentage were analyzed across devices for five time points using the GLIMMIX procedure. Results: There were no significant differences in body fat percentage for each method across the five encounters (P>0.05). Variation in mean body fat percentage ranged from 0.8-1.5%. Deviations in individual body fat percentage across the 5 encounters were wide. Conclusions: The BIA devices used in this study may be reliable methods of tracking body composition over time. Professionals, as well as lay users, must be aware of the potential variability between body composition measures per assessment. The variation in body fat percentage between the devices encourages users to consistently use one device rather than multiple devices to collect body composition data.