Are we overestimating Physical Activity prevalence in children?

This is the author accepted manuscript. The final version is available from Human Kinetics via the DOI in this record.Background: Physical activity guidelines state that children should achieve at least 60 minutes of moderate-to-vigorous intensity physical activity (MVPA) on each day of the week. Accurate assessment of adherence to these guidelines should, ideally, include measurement over 7 days. When less than 7 days of data are available, researchers often report the average minutes of MVPA per day as a proxy for 7 day measurement. The aim of this study was to compare prevalence estimates generated by average MVPA per day versus MVPA assessed over 7 days. Methods: Data were collected as part of the Healthy Lifestyles Programme (HeLP). One class from each school was randomised to wear a GENEActiv accelerometer for 8 days. The percentages of children achieving an average of ≥60minutes of MVPA per day and those achieving ≥60minutes of MVPA on each of 7 days were calculated. Results: 807 children provided 7 days of data. When the average MVPA per day was calculated, 30.6% (n=247) of children accumulated ≥60 minutes of MVPA per day. Only 3.2% (n=26) accumulated ≥60 minutes of MVPA on every day of the week. Conclusions: Previous studies utilising average MVPA per day are likely to have overestimated the percentage of children meeting recommendations.This research was supported by a grant PHR project 10/3010/01 from the National Institute for Health Research (NIHR) Public health research programme. In addition, this research was supported and funded by the NIHR Collaboration for Leadership in Applied Health Research and Care South West Peninsula (PenCLAHRC). The views expressed are those of the authors and not necessarily those of the NHS, NIHR or the Department of Health