BACKGROUND: Promoting physical activity in youth is important for health, but existing physical activity interventions have had limited success. We aimed to inform intervention design by i) describing drop-out, continuation and uptake of specific activities over the transition to adolescence; and ii) examining Variety (number of different activities/week) and Frequency (number of activity session/week) of activity participation and their associations with changes in objectively measured physical activity from childhood to adolescence.
METHODS: At age 10.2±0.3 and 14.2±0.3 years, 319 children in the SPEEDY study (46% boys) wore GT1M Actigraph accelerometers for 7 days and provided self-reported participation (never, once, 2 to 3 times or four or more times, over the last 7 days) in 23 leisure-time activities. Associations of change in moderate-to-vigorous intensity PA (MVPA) (≥2000 counts/minute) and change in total physical activity (TPA) (average accelerometer counts/minute) with exposure variables Z-score transformed (change in) Variety and Frequency were examined using multilevel linear regression, clustered by school, in simple and adjusted models.
RESULTS: The number of children ever reporting a specific activity ranged from 30 ('Hockey') to 279 ('Running or jogging'). Some activities were susceptible to drop-out (e.g. 'Skipping') but others were commonly continued or taken up (e.g. 'Household chores'). Overall, Variety and Frequency declined (mean±SD ΔVariety -3.1±4.4 activities/week; ΔFrequency -7.2±12.0 session/week). ΔMVPA and ΔTPA were not associated with Variety or Frequency at baseline, nor with ΔVariety or ΔFrequency (p>0.29 in all models).
CONCLUSIONS: Popularity of specific activities as well as drop-out, continuation and uptake should be considered in future intervention development. Activities that are commonly continued or taken up may be more valuable to encourage in interventions than those with low participation or high drop-out. We did not find evidence to support the idea that Variety and Frequency may be key elements to include in future interventions.