Metzger Jesse S, Catellier Diane J, Evenson Kelly R, Treuth Margarita S, Rosamond Wayne D, Siega-Riz Anna Maria
Departments of Epidemiology, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA.
Med Sci Sports Exerc. 2008 Apr;40(4):630-8. doi: 10.1249/MSS.0b013e3181620ebc.
We used latent class analysis (LCA) to assess patterns of physical activity among adults, using the 7 d of accelerometer data from the 2003-2004 NHANES.
For each participant, we determined the daily minutes of moderate-to-vigorous physical activity (MVPA), vigorous physical activity (VPA), and minutes of MVPA that occurred in bouts of 10 min. Participants were then categorized into patterns of activity, using LCA and adjusting for sociodemographic characteristics.
For overall MVPA, five classes of physical activity were defined, including two least active classes, which averaged less than 25 min of MVPA per day and represented 78.7% of the total study population. The most active class averaged 134 min of MVPA per day and comprised 0.9% of the population. The results for bout minutes of MVPA were similar to the patterns produced for overall MVPA, with the exception of a "weekend warrior" class with moderate levels of physical activity Monday through Friday but with a much higher level of activity on the weekend, particularly on Sunday. This class represented 1.8% of the population. Only 1.4% of all days achieved 10 min or more of VPA, and in 91.1% of all days, participants accumulated less than 1 min of VPA. The LCA analysis of VPA did not produce stable results, because of the small number of participants registering any minutes of VPA.
Our results indicate that a very large portion of the U.S. population may be classified into patterns of physical activity that represent low levels of MVPA throughout the week. The LCA analysis provided a novel approach for assessing patterns of objectively measured physical activity in epidemiologic studies.
我们使用潜在类别分析（LCA），利用2003 - 2004年美国国家健康与营养检查调查（NHANES）中7天的加速度计数据，评估成年人的身体活动模式。
对于每位参与者，我们确定其每天中等至剧烈身体活动（MVPA）的分钟数、剧烈身体活动（VPA）的分钟数，以及持续10分钟及以上的MVPA分钟数。然后，利用LCA并根据社会人口统计学特征进行调整，将参与者分类为不同的活动模式。
对于总体MVPA，定义了五类身体活动模式，其中包括两类最不活跃的模式，这两类模式平均每天的MVPA少于25分钟，占总研究人群的78.7%。最活跃的一类平均每天有134分钟的MVPA，占人群的0.9%。MVPA的每次持续时间的结果与总体MVPA产生的模式相似，不同的是有一个“周末战士”类别，该类别周一至周五的身体活动水平中等，但周末的活动水平要高得多，尤其是在周日。这类人群占总人群的1.8%。所有日子中只有1.4%达到了10分钟或更长时间的VPA，在所有日子的91.1%中，参与者积累的VPA少于一分钟。由于记录任何VPA分钟数的参与者数量较少，对VPA的LCA分析未产生稳定结果。
我们的结果表明，美国很大一部分人口可能被归类为在一周内MVPA水平较低的身体活动模式。LCA分析为在流行病学研究中评估客观测量的身体活动模式提供了一种新方法。
