Holliday Katelyn M, Howard Annie Green, Emch Michael, Rodríguez Daniel A, Rosamond Wayne D, Evenson Kelly R
1Department of Epidemiology, University of North Carolina, Chapel Hill, NC; 2Department of Biostatistics, University of North Carolina, Chapel Hill, NC; 3Department of Geography, University of North Carolina, Chapel Hill, NC; and 4Department of City and Regional Planning, University of California, Berkeley, CA.
Med Sci Sports Exerc. 2017 May;49(5):939-947. doi: 10.1249/MSS.0000000000001190.
Determining locations of physical activity (PA) is important for surveillance and intervention development, yet recommendations for using location recording tools like global positioning system (GPS) units are lacking. Specifically, no recommendation exists for the number of days study participants should wear a GPS to reliably estimate PA time spent in locations.
This study used data from participants (N = 224, age = 18-85 yr) in five states who concurrently wore an ActiGraph GT1M accelerometer and a Qstarz BT-Q1000X GPS for three consecutive weeks to construct monitoring day recommendations through variance partitioning methods. PA bouts ≥10 min were constructed from accelerometer counts, and the location of GPS points was determined using a hand-coding protocol.
Monitoring day recommendations varied by the type of location (e.g., participant homes vs parks) and the intensity of PA bouts considered (low and medium cut point moderate to vigorous PA [MVPA] bouts or high cut point vigorous PA [VPA] bouts). In general, minutes of all PA intensities spent in a given location could be measured with ≥80% reliability using 1-3 d of GPS monitoring for fitness facilities, schools, and footpaths. MVPA bout minutes in parks and roads required longer monitoring periods of 5-12 d. PA in homes and commercial areas required >19 d of monitoring.
Twelve days of monitoring was found to reliably estimate minutes in both low and medium threshold MVPA as well as VPA bouts for many important built environment locations that can be targeted to increase PA at the population level. Minutes of PA in the home environment and commercial locations may be best assessed through other means given the lengthy estimated monitoring time required.
确定身体活动（PA）的地点对于监测和干预措施的制定很重要，但对于使用全球定位系统（GPS）设备等位置记录工具却缺乏相关建议。具体而言，对于研究参与者应佩戴GPS的天数以可靠地估计在各地点花费的PA时间，尚无相关建议。
本研究使用了来自五个州的参与者（N = 224，年龄 = 18 - 85岁）的数据，这些参与者连续三周同时佩戴ActiGraph GT1M加速度计和Qstarz BT - Q1000X GPS，通过方差分解方法构建监测天数建议。PA发作≥10分钟是根据加速度计计数构建的，GPS点的位置使用手工编码协议确定。
监测天数建议因地点类型（如参与者家中与公园）以及所考虑的PA发作强度（低和中切点中度至剧烈PA [MVPA]发作或高切点剧烈PA [VPA]发作）而异。一般来说，对于健身设施、学校和人行道，使用1 - 3天的GPS监测可以以≥80%的可靠性测量在给定地点花费的所有PA强度的分钟数。公园和道路中的MVPA发作分钟数需要5 - 12天的更长监测期。家中和商业区的PA需要>19天的监测。
发现12天的监测能够可靠地估计许多重要建筑环境地点的低阈值和中阈值MVPA以及VPA发作的分钟数，这些地点可作为在人群层面增加PA的目标。鉴于估计所需的监测时间较长，家庭环境和商业地点的PA分钟数可能最好通过其他方式进行评估。
