Are We Overestimating Physical Activity Prevalence in Children?

BACKGROUND: Physical activity guidelines state that children should achieve at least 60 minutes of moderate to vigorous 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. One class from each school was randomized to wear a GENEActiv accelerometer for 8 days. The percentages of children achieving an average of ≥60 minutes of MVPA per day and those achieving ≥60 minutes of MVPA on each of 7 days were calculated. RESULTS: A total of 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. CONCLUSION: Previous studies utilizing average MVPA per day are likely to have overestimated the percentage of children meeting recommendations.