The Reliability and Validity of a Portable Three-Dimensional Scanning System to Measure Leg Volume

(1) Background: The study examined the reliability (test-retest, intra- and inter-day) and validity of a portable 3D scanning method when quantifying human leg volume. (2) Methods: Fifteen males volunteered to participate (age, 24.6 ± 2.0 years; stature, 178.9 ± 4.5 cm; body mass, 77.4 ± 6.5 kg; mean ± standard deviation). The volume of the lower and upper legs was examined using a water displacement method (the criterion) and two consecutive 3D scans. Measurements were taken at baseline, 1 h post-baseline (intra-day) and 24 h post-baseline (inter-day). Reliability and validity of the 3D scanning method was assessed using Bland-Altman limits of agreement and Pearson's product moment correlations. (3) Results: With respect to the test-retest reliability, the 3D scanning method had smaller systematic bias and narrower limits of agreement (±1%, and 3-5%, respectively) compared to the water displacement method (1-2% and 4-7%, respectively), when measuring lower and upper leg volume in humans. The correlation coefficients for all reliability comparisons (test-retest, intra-day, inter-day) would all be regarded as 'very strong' (all 0.94 or greater). (4) Conclusions: The study's results suggest that a 3D scanning method is a reliable and valid method to quantify leg volume.