Where Does the Time Go? Patterns of Daily Physical Activity in Adolescent Youth as Measured by Accelerometry

Introduction: Despite known benefits of regular physical activity for health and well-being, many studies suggest that levels of physical activity in young people are low, with the majority of youth not meeting the minimum 60-minute daily moderate to vigorous PA (MVPA) guideline for health. The purpose of this study was to explore daily patterns of physical activity in early adolescent youth, and identify whether those meeting the 60-minute daily guideline exhibited a different daily PA pattern to those not meeting the guideline.

Methods: 716 adolescents (11 – 13 years) were asked to wear an Actigraph accelerometer for a 9-day period, and had their height and weight measured. BMI was calculated and classified using the Cole et al. (2000) cut points. Accelerometer data sets were included in analysis if participants had > 10 hours wear time for a minimum of 3 weekdays and 1 weekend day. Data was processed applying the Evenson et al. (2008) cut points to give average daily, weekday, weekend day, before school, lunch time, after school, and evening minutes of MVPA.

Results: 415 participants met the inclusion criteria and had data included in analysis. Based on BMI 76.2% of participants were classed as normal weight, 21% overweight, and 3% obese. Participants accumulated an average of 52 minutes of MVPA per day, and were significantly more active on weekdays than weekend days (p = 0.000). 66% of participants met the minimum 60-minute daily MVPA guideline. Both males and females were significantly less active in the evening compared to the other three time periods (p < 0.001). Participants that met the 60 minute PA guideline were significantly more active than those that didn’t in the lunchtime, after school and evening periods (all p<0.001), but no significant differences were observed in the before school period.

Conclusion: Understanding patterns of PA participation in youth should be a central concern in the development of targeted PA interventions. Findings suggest that those meeting the guidelines are accumulating their 60 minutes across the day- being more active than those not meeting the guidelines in the school lunchtime, afterschool and evening periods. This would point to these three-time periods as potential times when less active youth have scope to increase their activity levels. Future research should examine the reasons when some youth choose to be active during these periods while others don’t, with a view to developing strategies for intervention.

References: Evenson KR, Cattellier D, Gill K, Ondrak K, McMurray RG. J Sports Sci. (2008)26:1557-65. Cole, Tim J., Mary C. Bellizzi, Katherine M. Flegal, and William H. Dietz. Bmj (2000) 320, no. 7244: 1240

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