Assessing limb-specific reliability in body composition: a study on minimal detectable change using bioimpedance analysis

[Purpose] We aimed to assess the reliability of body composition measurements for individual limbs using a bioimpedance analyzer, with a focus on determining the minimal detectable change for each site. [Participants and Methods] This study included 55 healthy Japanese university students (28 men and 27 women). Each participant underwent two measurements using an InBody S10 body composition analyzer. Intraclass correlation coefficients and minimal detectable change values were calculated for muscle mass, water content, and phase angle at various limb sites. [Results] Muscle mass and water content measurements demonstrated high reliability across all limb sites, with intraclass correlation coefficients ranging from 0.996 to 0.998. Phase angle measurements also showed high reliability for the limbs, with values ranging from 0.936-0.975; however, reliability was lower for the trunk, with a value of 0.854. The minimal detectable change values indicated that detecting differences in trunk phase angle required a larger change than that required for limb sites. [Conclusion] Limb-specific measurements of body composition were highly reliable, showing stable and consistent muscle mass and water content. However, the low reliability of trunk phase angle measurements suggests that factors affecting trunk measurements warrant further exploration for accurate assessment.