Hibbing Paul R, Bassett David R, Crouter Scott E
The University of Tennessee.
Res Q Exerc Sport. 2020 Sep;91(3):514-524. doi: 10.1080/02701367.2019.1688227. Epub 2020 Feb 5.
: To assess changes in criterion validity when modifying cut-points for use in different epoch lengths. : Simulated free-living data came from 42 adolescents (2-hr each) and 29 adults (6-hr each) wearing a hip-worn accelerometer and portable indirect calorimeter (Cosmed K4b). K4b data were classified as sedentary behavior (SB), light physical activity (LPA), or moderate-to-vigorous physical activity (MVPA), and compared to estimates from accelerometer data processed with three youth and three adult cut-points in six epoch lengths (1, 5, 10, 15, 30, and 60-s). A cut-point of 100 counts per minute was used for all SB estimates. : For both adolescents and adults, SB estimates in all but 60-s epochs were significantly higher than the criterion, by 18.4%-78.4% (all < .02). CPS had varied effects on youth LPA, ranging from favorable effects for one cut-point (1.9% underestimation in 1-s epochs, versus 40.2% overestimation in the originally-calibrated epoch length; < .01 and = .91, respectively) to unfavorable effects for another (41.8% underestimation in 1-s epochs, versus 9.8% underestimation in the originally-calibrated epoch length; < .01 and = .39, respectively). Adult LPA estimates in 30-s or 60-s epochs were closest to the criterion (within 5.2%-37.3%, = .0001-0.49). Youth MVPA estimates in 60-s epochs were closest to the criterion (within 9.5%-53.2%, all < .05), whereas adult MVPA estimates in 1-s epochs were closest to the criterion (within 6.6%-34.2%, = .02-0.59). : Cut-point modification is not universally beneficial, and thus it is not recommended.
评估在修改用于不同时段长度的切点时标准效度的变化。模拟的自由生活数据来自42名青少年（每人2小时）和29名成年人（每人6小时），他们佩戴髋部加速度计和便携式间接测热仪（Cosmed K4b）。K4b数据被分类为久坐行为（SB）、轻度身体活动（LPA）或中度至剧烈身体活动（MVPA），并与在六种时段长度（1、5、10、15、30和60秒）下用三种青少年和三种成人切点处理的加速度计数据估计值进行比较。所有SB估计值均使用每分钟100次计数的切点。对于青少年和成年人，除60秒时段外，所有时段的SB估计值均显著高于标准值，高出18.4% - 78.4%（均P < 0.02）。切点修改对青少年LPA有不同影响，从对一个切点有有利影响（在1秒时段低估1.9%，而在原始校准的时段长度中高估40.2%；分别为P < 0.01和P = 0.91）到对另一个切点有不利影响（在1秒时段低估41.8%，而在原始校准的时段长度中低估9.8%；分别为P < 0.01和P = 0.39）。30秒或60秒时段的成人LPA估计值最接近标准值（在5.2% - 37.3%范围内，P = 0.0001 - 0.49）。60秒时段的青少年MVPA估计值最接近标准值（在9.5% - 53.2%范围内，均P < 0.05），而1秒时段的成人MVPA估计值最接近标准值（在6.6% - 34.2%范围内，P = 0.02 - 0.59）。切点修改并非普遍有益，因此不建议这样做。
