Objective To verify the current cut-off points of physical activity intensity for adolescents to assess moderate to vigorous physical activity (MVPA) among overweight or obese adolescents.
Methods The total activity counts, heart rate and steps indicators most commonly used to reflect physical activity intensity were adopted, and a total of 15 MVPA cut-off points standards for adolescents were included. Ninety-four overweight or obese adolescents were tested for walking and running at 3-7 km/h in a free state, while simultaneously wearing MetaMax 3B gas metabolism analyzer, polar belt and actigraph w-GT3x BT triaxial accelerometer to collect energy consumption and activities count, heart rate and steps. Kappa consistency test and paired χ 2 test were used for statistical analysis.
Results Kappa consistency coefficients (0.27-0.53) <0.60 between all cut-off points standards and the “gold standard” and the P<0.01, indicating that the consistency is varied and not strong. In the standard diagnosis of each cut points, low sensitivity (49.11–67.59), high specificity (92.50-97.65), high – LR (0.14-0.52, >0.1) and low DOR (8.26-25.19, <30) indicated high rate of misdiagnosis. Low specificity (36.75-69.41), high sensitivity (84.82-96.36) and low + LR (1.52-9.83, <10) indicated a high rate of misdiagnosis; AUC of 0.67-0.80 suggested lower diagnostic performance.
Conclusion Existing physical activity intensity cut-off points for overweight or obese adolescents were not consistent with MVPA and have low diagnostic capabilities. The following criteria of MVPA for overweight or obese adolescents are supposed.
【摘要】 目的 验证现有的青少年运动强度切点标准对超重或肥胖青少年中髙强度身体活动的判断能力, 为科学指导运 动实践提供理论支持。 方法 采用活动计数、步数和心率指标, 共纳人15个青少年中髙强度切点标准;对广州市94名超 重或肥胖青少年进行自由状态下3~7 km/h走、跑测试, 同步佩戴MetaMax 3B气体代谢分析仪、Polar遥测心率和Actigraph w-GT3x BT三轴运动加速度计采集能量消耗、活动计数、心率和步数。 结果 所有切点标准与“金标准”两者间的 Kappa 一致性系数(0.27~0.53)<0.60且差异性检验 P值均<0.01, 表明一致性不强且有统计学意义。各切点标准诊断结果中, 敏 感度低(49.11~67.59)、特异性髙(92.5~97.65)、– LR 髙(0.14~0.52, >0.1)和 DOR 低(8.26~25.19, <30)表明漏判率髙；特 异性低(36.75~69.41)、敏感度髙(84.82~96.36)和+ LR低(1.52~9.83, <10)表明误判率髙 AUC为0.67~0.80,表明诊断价 值较低。 结论 现有的运动强度切点标准判断超重或肥胖青少年中髙强度身体活动一致性不强且诊断能力低, 建立了适 宜超重或肥胖青少年中髙强度身体活动评价标准。