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.