Within­ and between­day reliability of bioelectrical impedance analysis using a novel Tanita multi­frequency body composition analyzer (MC­780PMA) in healthy young adults

Background. Body composition is an important component in maintaining overall health. In clinical practice and research investigations, the Bioelectrical Impedance Analysis (BIA) method is frequently used for body composition assessment. Aim. We investigated the within-day (fasting state and after food) and between-day (test-retest) reliability and agreement of a new MC-780PMA multifrequency body composition analyzer (Tanita MC-780PMA, Japan) in measuring body mass index, body fat, fat-free mass, total body water, intracellular water, extracellular water, appendicular skeletal muscle mass, and skeletal muscle mass index in healthy young adults. Material and methods. Thirty healthy individuals (age 23.33 ± 4.08 years, 60% women) body composition was assessed three times (before food (test 1), 30 minutes after food on the same day (test 2), and one week after (test 3)) using the Tanita multi-frequency body composition analyzer MC-780PM by a qualified physiotherapist. Within- and between-reliability was assessed using the intraclass correlation coefficient (ICC [3, 1]; two-way mixed effects, consistency, single measurements, agreement). In addition, the standard errors of measurement and smallest real differences were calculated for between-day measurements for the BIA parameters of interest. Results. Good within-day reliability was noted for body mass index (ICC = 0.881) and extracellular water (ICC = 0.850). Excellent within-day reliability was noted for the remaining parameters (ICC > 0.900). Excellent between-day reliability was noted for all the chosen BIA parameters (> 0.900). Conclusion. BIA using the Tanita MC-780PM showed good-to-excellent within- and between-day reliability and low measurement errors when measuring before and/or after food intake in healthy adults. Future studies investigating the reliability of Tanita MC-780PMA in individuals with pathological conditions affecting body composition are warranted.