Abstract
Background
Calibration algorithms applied to the Youth Activity Profile (YAP) self-report questionnaire in the US have accurately estimated moderate-to-vigorous physical activity (MVPA) and sedentary behaviour (SB). However, the efficacy of the calibration algorithms may vary when applied to different populations. We aimed to: (1) assess the accuracy of US-generated YAP calibration algorithms for MVPA and SB with English youth, (2) validate English-specific YAP calibration algorithms, (3) examine their potential surveillance utility to assess compliance to MVPA guidelines.
Methods
Four primary schools and five secondary schools were recruited. Four-hundred-and-two participants (aged 9-16 years; 212 boys) wore SenseWear Armband Mini devices (SWA) for eight days and completed the YAP on the eighth day. For aim (1) the original US calibration algorithms were applied to the YAP scores, which were matched to SWA-estimated in-school, out-of-school, and weekend MVPA and out-of-school SB data. For aim (2) new calibration algorithms for the equivalent time-segments were generated from the English YAP data using quantile regression. The algorithms were applied in an independent cross-validation sample, and individual- and group-level agreement were assessed using bias, mean absolute percent error (MAPE) and equivalency tests, respectively. For aim (3) the utility of the English YAP algorithms to assess compliance to MVPA guidelines was examined using kappa, sensitivity, and specificity.
Results
Agreement between the US calibration algorithms and SWA estimates of MVPA and SB was poor. Group-level MAPE for the English YAP-estimates of in-school, out-of-school, and weekend MVPA ranged from 3.6% to 17.3%. Bias for these estimates were 17.2 (34.4), 31.6 (14.0), and -4.9 (3.6) min·week-1, respectively. Out-of-school SB was over-predicted by 109.2 (11.8) min·week-1 (MAPE=11.8%). Predicted YAP values were within 15%-20% equivalence of the SWA estimates. Classification accuracy of the English YAP MVPA estimates for compliance to 60 min·day-1 and 30 min·school-day-1 MVPA recommendations were 91%/37% and 89%/57% sensitivity/specificity, respectively.
Conclusions
The English YAP generated robust group-level estimates of MVPA and SB and has potential for surveillance to monitor compliance with MVPA guidelines. The YAP’s accuracy may be further improved through research work with more representative UK samples to enhance the calibration process and to refine the resultant algorithms.
Validity and Calibration of the Youth Activity Profile
