Validity of B-Mode Ultrasound for Body Composition Assessment in the Field

Introduction: Identifying an accurate, user friendly alternative to skinfold calipers may allow for accurate assessment of body composition in more applied settings, such as various training and competition venues. The purpose of our study was to determine the validity of B-mode ultrasound (BMUS) for body composition assessment by comparing this method to values obtained using air displacement plethysmography (ADP). Methods: Twenty-four active runners underwent two forms of body composition assessment during a single lab visit; ADP and BMUS. ADP body density was estimated using an air displacement chamber in combination with measured lung volume. BMUS body density was estimated from measuring the Jackson-Pollock 7 site skinfolds with a portable, app-based ultrasound device to determine subcutaneous fat thickness. Images were analyzed using proprietary software. Body density values for both methods were converted to body fat percentage using the Siri equation. A paired samples t-test was used to compare values obtained from ADP and BMUS. Results: There was no difference between ADP (18.3 ± 7.3%) and BMUS (17.2 ± 7.6%; p = 0.1) for percent body fat. Conclusions: BMUS provides a valid method for assessing body composition when compared to ADP, thus providing a portable, accurate method for assessing body composition in applied settings.