Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5874007 | Journal of Science and Medicine in Sport | 2016 | 6 Pages |
ObjectivesDescribe (1) time-segment specific changes in physical activity (PA) into adolescence, (2) differences in change in PA between specific time-segments (weekdays-weekends, in-school-out-of-school, out-of-school-weekends, lesson-time-lunch-time), and (3) associations of change in time-segment specific with overall PA.DesignLongitudinal observational study (4-year follow-up).MethodsChildren from the SPEEDY study (n = 769, 42% boys) had PA measured by accelerometer for at least three days at ages 10.2 ± 0.3, 11.2 ± 0.3 and 14.3 ± 0.3 years. Changes in moderate-to-vigorous PA (ÎMVPA, minutes â¥2000 counts/minute [cpm]) and total PA (ÎTPA, average cpm) during weekdays, weekends, in-school, out-of-school, lesson-times and lunch-times, were tested using three level (age, individual, school) mixed-effects linear regression. Differences in ÎMVPA/ÎTPA between time-segments were tested using time-segment Ã age interaction terms. Associations of four-year time-segment specific ÎMVPA/ÎTPA with four-year overall ÎMVPA/ÎTPA were tested using two level (time-segment specific ÎMVPA/ÎTPA, school) mixed-effects linear regression.ResultsMVPA and TPA declined in all time-segments, except lesson-time MVPA. Annual ÎMVPA and, for boys only, ÎTPA was greater on weekends than weekdays (beta ± SE for interaction term: boys, â3.53 ± 0.83 min, â29.64 ± 7.64 cpm; girls, â2.20 ± 0.64 min) and out-of-school (boys, â4.36 ± 0.79 min, â19.36 ± 8.46 cpm; girls, â2.44 ± 0.63 min). ÎMVPA and ÎTPA during lunch-time was greater than during lesson-time (boys, â0.96 ± 0.20 min, â36.43 ± 6.55 cpm; girls, â0.90 ± 0.13 min, â38.72 ± 4.40 cpm). ÎTPA was greater out-of-school than in-school (boys, â19.89 ± 6.71 cpm; girls, â18.46 ± 6.51 cpm). For all time-segments, four-year ÎMVPA/ÎTPA was positively associated with four-year overall ÎMVPA/ÎTPA (all p < 0.042), except for girl's in-school and lunch-time TPA.ConclusionsInterventions focused on PA maintenance could target all time-segments, but weekends and out-of-school may be particularly advantageous due to the relatively large declines observed.