Hislop Jane F, Bulley Cathy, Mercer Tom H, Reilly John J
School of Health Sciences, Queen Margaret University, Edinburgh, Scotland, UK.
Pediatr Exerc Sci. 2012 Aug;24(3):450-60. doi: 10.1123/pes.24.3.450.
The objectives of this study were to explore whether triaxial is more accurate than uniaxial accelerometry and whether shorter sampling periods (epochs) are more accurate than longer epochs. Physical activity data from uniaxial and triaxial (RT3) devices were collected in 1-s epochs from 31 preschool children (15 males, 16 females, 4.4 ± 0.8 yrs) who were videoed while they engaged in 1-hr of free-play. Video data were coded using the Children's Activity Rating Scale (CARS). A significant difference (p < .001) in the number of minutes classified as moderate to vigorous physical activity (MVPA) was found between the RT3 and the CARS (p < .002) using the cut point of relaxed walk. No significant difference was found between the GT1M and the CARS or between the RT3 and the CARS using the cut point for light jog. Shorter epochs resulted in significantly greater overestimation of MVPA, with the bias increasing from 0.7 mins at 15-s to 3.2 mins at 60-s epochs for the GT1M and 0 mins to 1.7 mins for the RT3. Results suggest that there was no advantage of a triaxial accelerometer over a uniaxial model. Shorter epochs result in significantly higher number of minutes of MVPA with smaller bias relative to direct observation.
本研究的目的是探讨三轴加速度计是否比单轴加速度计更准确，以及较短的采样周期（时段）是否比较长的时段更准确。从31名学龄前儿童（15名男性，16名女性，4.4±0.8岁）中收集单轴和三轴（RT3）设备的身体活动数据，采样时段为1秒，这些儿童在进行1小时自由玩耍时被录像。视频数据使用儿童活动评分量表（CARS）进行编码。使用轻松步行的切点，发现RT3和CARS之间在中度至剧烈身体活动（MVPA）分钟数上存在显著差异（p<.001），在GT1M和CARS之间使用轻快慢跑的切点时未发现显著差异。较短的时段导致MVPA的高估显著增加，GT1M的偏差从15秒时的0.7分钟增加到60秒时段时的3.2分钟，RT3从0分钟增加到1.7分钟。结果表明，三轴加速度计相对于单轴模型没有优势。较短的时段导致MVPA分钟数显著增加，相对于直接观察偏差较小。
