Abstract：
The study aimed to investigate the ActivityStat hypothesis by examining the presence and the timeframe of the temporal relationships among physical activity (PA) levels and stationary time (ST) in adolescents. A secondary analysis was performed on data involving 356 adolescents in Dunedin, New Zealand. Participants wore a waist-worn accelerometer for several consecutive days to assess PA levels [i.e. light PA (LPA), and moderate-to-vigorous PA (MVPA)] and ST. Bayesian continuous-time structural equation modelling (CT-SEM) was used to examine the relationship between the behaviours over time and the timeframe during which these relationships occur. Increases in LPA, MVPA, and ST were positively associated with their later behaviours until 2.5, 1.7, and 2 days later, respectively. A cross-behavioural reciprocal and negative relationship between LPA and ST was demonstrated 0.4 days later. A positive relationship between ST and MVPA was observed until about 0.4 days later. This is the first study to investigate the ActivityStat hypothesis using Bayesian CT-SEM in adolescents, examining the multivariate relationships among different behaviours and the associated timeframes. To conclude, evidence of activity synergy was suggested for the within-behavioural relationships, while behavioural compensation was noted for ST. Thus, the findings provide some support for the ActivityStat hypothesis in adolescents.
摘要：
该研究旨在通过检查青少年身体活动（PA）水平和静止时间（ST）之间的时间关系的存在和时间框架来研究ActivityStat假设。对涉及但尼丁356名青少年的数据进行了二次分析，新西兰。参与者连续几天佩戴腰部佩戴加速度计以评估PA水平[即轻度PA（LPA），和中度至重度PA（MVPA）]和ST。贝叶斯连续时间结构方程模型（CT-SEM）用于检查随时间变化的行为与发生这些关系的时间框架之间的关系。LPA增加,MVPA,和ST与他们后来的行为呈正相关，直到2.5、1.7和2天后，分别。0.4天后证明了LPA和ST之间的交叉行为互惠和负相关。直到约0.4天后观察到ST和MVPA之间的正相关。这是第一项在青少年中使用贝叶斯CT-SEM调查ActivityStat假设的研究，检查不同行为和相关时间框架之间的多变量关系。最后，活动协同作用的证据被认为是行为内关系，而ST记录了行为补偿。因此，这些发现为青少年的ActivityStat假说提供了一些支持。
