Background: Components of activity that are more variable over time may be more susceptible to manipulation in activity interventions.
Aim: The present study examined variability and consistency of components of children's activity across season.
Subjects and methods: Sixty-four 9-11-year-old children wore an accelerometer for 6 days during winter and summer. Activity bouts (>or=4 s) greater than light (>or=LIGHT), moderate (>or=MOD) and vigorous (>or=VIG) intensity were recorded.
Results: Intra-individual variability of the activity components across season was greater for bout frequency (CV: >or=LIGHT = 6.6-9.9%, >or=MOD = 10.7-16.1%, >or=VIG = 17.0-26.8%) than bout intensity or duration (CV: >or=LIGHT = 3.4-7.4%, >or=MOD = 3.6-7.8%, >or=VIG = 4.2-10.0%, p<0.05) and for the frequency of >or=VIG bouts compared to the frequency of >or=LIGHT and >or=MOD bouts (p<0.05). All components of the activity pattern tended to track consistently when assessing >or=LIGHT and >or=MOD bouts (intra-class correlations (ICC) = 0.47-83, p<0.05), >or=VIG bouts in boys (ICC = 0.69-0.77, p<0.01) and frequency of >or=VIG bouts in girls (ICC = 0.82, p<0.01).
Conclusions: Bout frequency was the most variable component of activity across season. However, children tended to maintain their rank for bout frequency. It would be of interest to investigate whether bout frequency can be manipulated in an activity intervention.