Faculty of Engineering, University of Porto, Porto, PORTUGAL.
Systems and Process Engineering Centre, College of Engineering, Swansea University, Swansea, UNITED KINGDOM.
Med Sci Sports Exerc. 2020 Jan;52(1):259-266. doi: 10.1249/MSS.0000000000002119.
(i) To develop an automated measurement technique for the assessment of both the form and intensity of physical activity undertaken by children during play. (ii) To profile the varying activity across a cohort of children using a multivariate analysis of their movement patterns.
Ankle-worn accelerometers were used to record 40 min of activity during a school recess, for 24 children over five consecutive days. Activity events of 1.1 s duration were identified within the acceleration time trace and compared with a reference motif, consisting of a single walking stride acceleration trace, obtained on a treadmill operating at a speed of 4 km h. Dynamic time warping of motif and activity events provided metrics of comparative movement duration and intensity, which formed the data set for multivariate mapping of the cohort activity using a principal component analysis (PCA).
The two-dimensional PCA plot provided clear differentiation of children displaying diverse activity profiles and clustering of those with similar movement patterns. The first component of the PCA correlated to the integrated intensity of movement over the 40-min period, whereas the second component informed on the temporal phasing of activity.
By defining movement events and then quantifying them by reference to a motion-standard, meaningful assessment of highly varied activity within free play can be obtained. This allows detailed profiling of individual children's activity and provides an insight on social aspects of play through identification of matched activity time profiles for children participating in conjoined play.
（i）开发一种自动测量技术，用于评估儿童在游戏中进行的身体活动的形式和强度。（ii）使用运动模式的多元分析来描绘儿童群体中不断变化的活动。
使用脚踝佩戴的加速度计在连续五天的五个上学日里记录 40 分钟的课间活动。在加速度时间轨迹中识别持续 1.1 秒的活动事件，并将其与参考图案进行比较，该图案由在以 4 公里/小时的速度运行的跑步机上获得的单个步行步幅加速度轨迹组成。图案和活动事件的动态时间扭曲提供了比较运动持续时间和强度的指标，这些指标构成了使用主成分分析（PCA）对队列活动进行多元映射的数据集合。
二维 PCA 图清楚地区分了显示不同活动模式的儿童，并对具有相似运动模式的儿童进行了聚类。PCA 的第一组成分与 40 分钟期间的运动综合强度相关，而第二组成分则告知活动的时间相位。
通过定义运动事件并通过参考运动标准对其进行量化，可以对自由游戏中高度变化的活动进行有意义的评估。这允许对个别儿童的活动进行详细分析，并通过识别参与联合游戏的儿童的匹配活动时间模式来深入了解游戏的社交方面。
