Bone and Body Composition Research Group, Carnegie School of Sport, Leeds Beckett University, Headingley Campus, Leeds, UK.
Faculty of Health and Social Sciences, Leeds Beckett University, City Campus, UK.
Eur J Clin Nutr. 2018 Jan;72(1):148-153. doi: 10.1038/ejcn.2017.110. Epub 2017 Jul 19.
BACKGROUND/OBJECTIVES: Extensive work has addressed the validity of bioimpedance (BIA) measurements and the effect of posture on fluid homeostasis. However, limited research has investigated effects of subject preparation. This study aimed to determine the precision of total body water (TBW) and extracellular water (ECW) measurements using a stand-on multifrequency BIA (MFBIA seca mBCA 514/515), in three pre-test procedures: supine, sitting, and following walking, with specific reference to the influence of sex and body mass index (BMI).
SUBJECTS/METHODS: Fifty three healthy, ambulatory men (n=26, age:32.5±9.4 years) and women (n=27, age:35.2±10.3 years) received repeat MFBIA measurements (six measurements from 0 to 15 min). Agreement and precision were evaluated for each condition and paired time points.
Significant TBW sex differences from supine posture were observed for walking (females) and sitting (males) postures. For BMI (⩽24.9 kg m) significant TBW differences from supine were observed for both sitting and walking and significant ECW differences from sitting were also observed with both supine and walking. There was no significant effect of sex or BMI (⩾25.0 kg m) on ECW measures. Irrespective of sex or BMI, there was close agreement in TBW and ECW precision over the three protocols.
Practitioners can have confidence in the precision of TBW and ECW measurements within a 15 min time period and pre-testing conditions (supine, sitting or walking) in healthy subjects, though must be cautious in assessments when pre-test postures change. Further research to examine the impact of pre-testing procedures on stand-on MFBIA BIA measurements, including subjects with fluid disturbance, is warranted.
背景/目的：大量研究已经探讨了生物阻抗（BIA）测量的有效性和体位对体液平衡的影响。然而，关于受试者准备的研究有限。本研究旨在确定使用站立式多频 BIA（MFBIA seca mBCA 514/515）进行总体水（TBW）和细胞外液（ECW）测量的精密度，在三种预测试程序中：仰卧、坐姿和步行后，特别参考了性别和体重指数（BMI）的影响。
受试者/方法：53 名健康、可走动的男性（n=26，年龄：32.5±9.4 岁）和女性（n=27，年龄：35.2±10.3 岁）接受了重复 MFBIA 测量（0 至 15 分钟内六次测量）。评估了每个条件和配对时间点的一致性和精密度。
从仰卧位观察到步行（女性）和坐姿（男性）体位时 TBW 的显著性别差异。对于 BMI（⩽24.9kg/m），从仰卧位观察到坐姿和步行时 TBW 存在显著差异，从坐姿观察到仰卧位和步行时 ECW 也存在显著差异。性别或 BMI（⩾25.0kg/m）对 ECW 测量值没有显著影响。无论性别或 BMI 如何，在三个方案中，TBW 和 ECW 的精密度都有很好的一致性。
在 15 分钟的时间内，健康受试者在预测试条件（仰卧、坐姿或步行）下，可以对 TBW 和 ECW 测量值的精密度充满信心，但在评估时必须谨慎，因为预测试体位可能会发生变化。需要进一步研究，以检查预测试程序对站立式 MFBIA BIA 测量值的影响，包括有体液紊乱的受试者。
