Toschke Julia Anna, von Kries Rüdiger, Rosenfeld Eva, Toschke André Michael
Division of Epidemiology, Institute of Social Pediatrics and Adolescent Medicine, Ludwig-Maximilians University of Munich, Munich, Germany.
Clin Nutr. 2007 Aug;26(4):416-20. doi: 10.1016/j.clnu.2007.03.009. Epub 2007 May 18.
BACKGROUND & AIMS: Physical activity (PA) is a major determinant of obesity. Accelerometers have been reported to provide valid measures among adults. However, studies among preschoolers rarely report positive findings. To assess the day-to-day variability of accelerometers in preschoolers.
Uni-axial accelerometer (Actigraph monitor AM 7164-2.2) counts including one weekend from the time of getting up in the morning until bedtime.
On average, boys showed 899 counts per minute (cpm) compared to 764 for girls (p<0.01; overall mean 828 cpm). Intra-individual correlation for accelerometry data between single days of examination was low with Pearson correlation coefficients between r=0.31 and 0.51. Furthermore, child's body mass index (BMI) and accelerometer measures were not related to each other (Pearson's correlation coefficient r=-0.06). Subsequent analyses showed higher measures (+50%cpm; p<0.01) for instruments placed in front of the umbilicus compared to instruments placed at the right hip.
Measurements of uni-axial accelerometers showed a low reliability among preschoolers. Uni-axial accelerometers placed on elastic belts might measure PA with low precision among preschoolers under free-living conditions possibly due to slipping instruments. This might explain lacking findings of an association between PA and obesity in studies among preschoolers.
身体活动（PA）是肥胖的主要决定因素。据报道，加速度计可在成年人中提供有效的测量结果。然而，针对学龄前儿童的研究很少报告出阳性结果。为评估加速度计在学龄前儿童中的日常变异性。
单轴加速度计（Actigraph监测仪AM 7164 - 2.2）记录从早晨起床到就寝时间的活动量，包括一个周末。
平均而言，男孩每分钟显示899计数（cpm），女孩为764计数（p<0.01；总体平均值828 cpm）。检查单日之间加速度计数据的个体内相关性较低，Pearson相关系数在r = 0.31至0.51之间。此外，儿童的体重指数（BMI）与加速度计测量值之间没有相关性（Pearson相关系数r = -0.06）。后续分析表明，与放置在右髋部的仪器相比，放置在脐部前方的仪器测量值更高（+50%cpm；p<0.01）。
单轴加速度计的测量在学龄前儿童中显示出较低的可靠性。在自由生活条件下，放置在弹性腰带上的单轴加速度计可能在学龄前儿童中测量PA的精度较低，这可能是由于仪器滑动所致。这可能解释了学龄前儿童研究中PA与肥胖之间缺乏关联的研究结果。
