Reliability of body composition assessment using A-mode ultrasound in a heterogeneous sample

Background/Objectives: Several studies have addressed the validity of ultrasound (US) for body composition assessment, but few have evaluated its reliability. This study aimed to determine the reliability of percent body fat (%BF) estimates using A-mode US in a heterogeneous sample. Subjects/Methods: 144 healthy adults (81 men, 63 women), mean (SD) age 30.4 (10.1) years, BMI 24.6 (4.7) kg/m², completed 6 consecutive measurements of subcutaneous fat thickness at 8 anatomical sites. Two testers alternated measurements using a BodyMetrix instrument. Four BodyView software formulas were used to compute %BF: 7-sites Jackson and Pollock (JP7), 3-sites Jackson and Pollock (JP3), 3-sites Pollock (P3), and 1-point biceps (BIC). Results: The formula with the most sites (JP7) provided the best reliability: ICC = 0.979 (Tester 1, T1) and 0.985 (Tester 2, T2); TEM = 1.07% BF (T1) and 0.89% BF (T2); MDC = 2.95% BF (T1) and 2.47% BF (T2). Intertester bias was −0.5% BF; intertester ICC = 0.972. Intertester MDC was 3.43% BF overall, 3.24% BF for men, 3.65% BF for women. Conclusions: A-mode US is highly reliable for %BF, with greater precision in men than women. Examiner performance contributes to variability and should be managed to improve precision.