Bailey R C, Olson J, Pepper S L, Porszasz J, Barstow T J, Cooper D M
Department of Anthropology, University of California, Los Angeles 90024, USA.
Med Sci Sports Exerc. 1995 Jul;27(7):1033-41. doi: 10.1249/00005768-199507000-00012.
We develop an observation system that quantifies the duration, intensity, and frequency of children's physical activities. We use this system to assess the level and tempo of energy expenditure under free-ranging, natural conditions experienced by 15 children aged 6-10 yr in southern California. Observations were recorded every 3 s during 4-h time blocks from 8:00 a.m.-8:00 p.m. Agreement among observers using the coding system was 91%. Using indirect calorimetry, calibration studies in the laboratory determined VO2 (ml.min-1.min-1) during each coded activity, and activities were categorized by intensity (low, medium, or high). Subjects were found to engage in activities of low intensity 77.1% of time and activities of high intensity 3.1% of time. The median duration of low and medium intensity activities was 6 s, of high intensity activities only 3 s with 95% lasting less than 15 s. Children engaged in very short bursts of intense physical activity interspersed with varying intervals of low and moderate intensity. These findings may be important for discovering how children's activity patterns under natural conditions influence physiological processes leading to growth and development. This study demonstrates the advantages of using an observational system that captures more than the intensity and frequency of children's activities to include duration and the length of intervals between activities of varying intensity.
我们开发了一个观测系统，用于量化儿童身体活动的持续时间、强度和频率。我们使用该系统评估了南加州15名6至10岁儿童在自由放养的自然条件下的能量消耗水平和节奏。在上午8点至晚上8点的4小时时间段内，每隔3秒记录一次观测数据。使用该编码系统的观察者之间的一致性为91%。通过间接测热法，在实验室进行的校准研究确定了每次编码活动期间的VO2（毫升·分钟-1·分钟-1），并按强度（低、中或高）对活动进行了分类。发现受试者77.1%的时间从事低强度活动，3.1%的时间从事高强度活动。低强度和中等强度活动的中位持续时间为6秒，高强度活动仅为3秒，95%的高强度活动持续时间不到15秒。儿童进行非常短暂的高强度身体活动，其间穿插着不同时长的低强度和中等强度活动。这些发现对于了解自然条件下儿童的活动模式如何影响导致生长发育的生理过程可能具有重要意义。这项研究证明了使用一种观测系统的优势，该系统不仅能捕捉儿童活动的强度和频率，还能包括活动持续时间以及不同强度活动之间的间隔时长。
