Are we overestimating Physical Activity prevalence in children?

Abstract

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.