Rush Elaine C, Crowley Jennifer, Freitas Ismael F, Luke Amy
Division of Sport and Recreation, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand.
Obesity (Silver Spring). 2006 Feb;14(2):252-7. doi: 10.1038/oby.2006.32.
To assess the reliability of the standing measurement of hand-to-foot bioimpedance compared with measurements made in the lying position.
In 205 volunteers 6 to 89 years of age, 111 males and 94 females from six ethnic groups, effects of posture, time, and age on hand-to-foot resistance were studied over a range of body size. The effect of time in a position on resistance was also recorded in a small subset (n = 10), and repeat measurements over 3 days at the same time of the day were recorded in another subset (n = 12).
Lying impedance was consistently higher than standing, with the relationship (resistance lying/resistance standing) for the children (5 to 14 years) being 1.031, progressing to a ratio of 1.016 in those > 60 years. The time spent static in either position did change resistance measurements-a decrease of up to 9 Omega (mean 5 Omega, 1.0%) over 10 minutes of standing and an increase of up to 7 Omega (mean 3 Omega, 0.7%) with lying.
In the field, measurements of hand-to-foot bioimpedance can be made in the standing position, and, with appropriate adjustment, previously validated recumbent equations can be used. Given that errors in the measurement of height and weight also affect the reliability of the derivation of body fat from bioelectrical conductance, the errors that may arise from a more practical standing measurement rather than lying are minimal.
评估与卧位测量相比，立位测量手足生物电阻抗的可靠性。
在205名年龄在6至89岁之间的志愿者中，包括来自六个种族群体的111名男性和94名女性，研究了姿势、时间和年龄对不同体型范围内手足电阻的影响。还在一小部分受试者（n = 10）中记录了在某一姿势下停留的时间对电阻的影响，并在另一小部分受试者（n = 12）中记录了在一天中的同一时间连续3天的重复测量结果。
卧位阻抗始终高于立位，儿童（5至14岁）的（卧位电阻/立位电阻）关系为1.031，在60岁以上人群中该比例为1.016。在任一姿势下静态停留的时间确实会改变电阻测量值——站立10分钟电阻下降高达9Ω（平均5Ω，1.0%），卧位时电阻增加高达7Ω（平均3Ω，0.7%）。
在实际应用中，可以进行立位手足生物电阻抗测量，并且经过适当调整后，可以使用先前验证过的卧位方程。鉴于身高和体重测量误差也会影响从生物电阻抗推导身体脂肪的可靠性，与卧位测量相比，更实际的立位测量可能产生的误差极小。
