Abstract
Accurate body composition analysis is crucial for a comprehensive understanding of health and performance. While dual energy X-ray absorptiometry (DXA) is a widely accepted laboratory method, 3D scanners offer a convenient alternative. However, the validity of these technologies in resistance-trained adults remains uncertain. PURPOSE: This study compared the accuracy of professional and smartphone-based 3D scanning technology with DXA for estimating fat-free mass (FFM) and body fat percentage (BF%) in muscular, resistance-trained individuals. METHODS: Resistance-trained participants who met prespecified criteria for BF% and fat-free mass index (FFMI) were evaluated using DXA (GE iDXA), a professional 3D scanner (Size Stream SS20), and a smartphone-based 3D scanner (Size Stream Me Three Sixty). Thirty-one individuals were included in the present analysis, including 14 females ([mean ± SD] age: 29.1 ± 8.8 y, body mass: 66.5 ± 6.1 kg, height: 165.0 ± 5.7 cm, DXA BF%: 22.6 ± 3.4%, DXA FFMI: 18.9 ± 1.2 kg/m2) and 17 males (age: 28.8 ± 8.7 y, body mass: 83.5 ± 8.9 kg, height: 177.0 ± 7.3 cm, DXA BF%: 13.5 ± 3.8%, DXA FFMI: 23.1 ± 1.6 kg/m2). The agreement between DXA and 3D scanning estimates of FFM and BF% were examined through the coefficient of determination (R2), Bland-Altman analysis, and validity statistics. RESULTS: The R2 values between DXA and professional 3D scanning FFM estimates were 0.53 (females), 0.89 (males), and 0.92 (all) [p<0.001 for each], while the R2 values between DXA and smartphone-based 3D scanning were 0.60 (females), 0.86 (males), and 0.92 (all) [p<0.001 for each]. In the total sample, smartphone-based 3D scanning significantly underestimated FFM by 4.1 ± 3.6 kg (p<0.01), while professional 3D scanning did not (mean difference: -1.3 ± 3.8 kg; p=0.07). For BF%, the R2 values between DXA and professional 3D scanning were 0.18 (females; p=0.13), 0.14 (males; p=0.15), and 0.35 (all; p<0.001), while the R2 values between DXA and smartphone-based 3D scanning were 0.08 (females; p=0.33), 0.00 (males; p=0.79), and 0.47 (all; p<0.001). In the total sample, smartphone-based 3D scanning overestimated BF% by 5.3 ± 4.6% (p<0.01), while professional 3D scanning did not (mean difference: 1.3 ± 5.0%; p=0.15). Minimal proportional bias was observed when all participants were combined, but some instances of sex-specific proportional bias were noted. CONCLUSION: The FFM results from the professional 3D scanner generally aligned with DXA, while systematic underestimation of FFM was observed for the smartphone-based 3D scanner. Both 3D scanning methods demonstrated poorer performance in females than males for FFM, as well as poor overall performance for BF% estimation. These results highlight the need for further refinement of 3D scanning technologies before they are widely used for the assessment of body composition in muscular, resistance-trained adults.
Recommended Citation
Francis, Sieneh P.; Rodriguez, Christian; Florez, Christine; Tinoco, Ethan; Paulo Cardoso, Joao; Rasco, Jaylynn; Whitson, Julia; and Tinsley, Grant
(2025)
"Comparison of 3-Dimensional Scanning and Dual-Energy X-Ray Absorptiometry for Body Composition Estimation in Muscular, Resistance-Trained Adults,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
Iss.
17, Article 55.
Available at:
https://digitalcommons.wku.edu/ijesab/vol2/iss17/55