Validation of Accelerometer and Activity Diary to Monitor Daily Physical Activity

Objective:To test the validity of Actigraph GT3 Xaccelerometer and Bouchard activity diary on monitoring daily physical activity of youth,and provide experimental evidence for large sample size physical activity investigation.Methods:20participants took part in 4hphysical activity similar to the percentage of their daily life,validities of the 2 methods to monitor PAEE4 h,PAL and MVPA time were analyzed using the results of indirect calorimetry(IC)test as criterions.Results:1)The predicted PAL of Bouchard activity diary was not significantly different with IC test result(P0.05),while the predicted PAEE4 h was mildly higher than IC test result(predicted error was 12.81±17.02%,P0.05),the predicted MVPA time was significantly higher than IC test result(P0.01);2)GT3Xunderestimated PAEE4 h and PAL(P0.01),there was small difference between the predicted MVPA time of GT3 X and the IC test result after adjusted by bicycling time(P=0.04),the corresponding VM cutpoint was 2690counts/min;3)Bland-Altman plots indicated that the predicted values were acceptable for Bouchard physical activity diary to monitor PAEE4 hand PAL,as well as GT3 Xto monitor MVPA time.Conclusion:GT3X has good validity to monitor MVPA time,Bouchard activity diary has good validity to monitor PAL and PAEE4 h.