Comparison of Self-Reported and Accelerometer-Assessed Physical Activity in Older Women

BackgroundSelf-reported physical activity measures continue to be validated against accelerometers; however, the absence of standardized, accelerometer moderate-to-vigorous physical activity (MVPA) definitions has made comparisons across studies difficult. Furthermore, recent accelerometer models assess accelerations in three axes, instead of only the vertical axis, but validation studies have yet to take incorporate triaxial data.MethodsParticipants (n = 10 115) from the Women’s Health Study wore a hip-worn accelerometer (ActiGraph GT3X+) for seven days during waking hours (2011–2014). Women then completed a physical activity questionnaire. We compared self-reported with accelerometer-assessed MVPA, using four established cutpoints for MVPA: three using only vertical axis data (760, 1041 and 1952 counts per minute (cpm)) and one using triaxial data (2690 cpm).ResultsAccording to self-reported physical activity, 66.6% of women met the US federal physical activity guidelines, engaging in ≥150 minutes per week of MVPA. The percent of women who met guidelines varied widely depending on the accelerometer MVPA definition (760 cpm: 50.0%, 1041 cpm: 33.0%, 1952 cpm: 13.4%, and 2690 cpm: 19.3%).ConclusionsTriaxial count data do not substantially reduce the difference between self-reported and accelerometer-assessed MVPA.研究背景：自我报告的身体活动测量指标仍在通过加速度计进行验证，但由于缺乏标准化的加速度计中等至剧烈身体活动（Moderate-to-vigorous Physical Activity, MVPA）定义，不同研究间的对比始终存在困难。此外，当前主流加速度计模型已可采集三轴加速度数据，而非仅采集垂直轴数据，但现有验证研究尚未纳入三轴加速度数据开展分析。 研究方法：本研究纳入10115名来自女性健康研究（Women’s Health Study）的参与者，要求其在2011-2014年期间，于清醒时段佩戴髋部佩戴式加速度计（ActiGraph GT3X+）共计7天，随后完成身体活动问卷。我们采用四种已确立的中等至剧烈身体活动截点，对比自我报告与加速度计评估的中等至剧烈身体活动：其中三个截点仅采用垂直轴数据（每分钟计数760、1041和1952次（counts per minute, cpm）），另一个截点采用三轴数据（每分钟计数2690次）。 研究结果：根据自我报告的身体活动数据，66.6%的女性达到了美国联邦身体活动指南标准，即每周至少进行150分钟的中等至剧烈身体活动。不同加速度计中等至剧烈身体活动定义下，达标女性的占比差异显著：760 cpm截点下为50.0%，1041 cpm截点下为33.0%，1952 cpm截点下为13.4%，2690 cpm截点下为19.3%。 研究结论：三轴计数数据并未显著缩小自我报告与加速度计评估的中等至剧烈身体活动结果之间的差异。