Sedentary Behavior in Portuguese Youth: The Seasonality Effect

Introduction Sedentary behavior (SB) is directly associated with a greater risk of death from cardiovascular problems, cancer and all causes. Moreover, SB is directly associated with obesity in children. This study examined whether there was a significant seasonal variation in objectively measured SB in Portuguese youth across five months of data collection.

Methods A total of 344 participants (aged 14.7 ± 2.04), 196 girls and 148 boys, were assessed in five months. SB was assessed with the Actigraph GT1M accelerometer for 7 consecutive days (15 seconds epochs). Gender patterns of SB were assessed for 5 distinct month periods: February; March; April; May; June. The difference in the amount of SB was assessed with a gender-by-month comparison using a ANOVA.

Results Participation in SB varied by gender and month of assessment. The ANOVA for SB revealed significant main effects for Gender (F= 22.62).

Discussion The weather or sunlight exposure cannot be changed, but knowledge of how weather conditions affect youth SB can help to adapt recommendations to diminish its effects. The seasonal patterns suggest that interventions must be modified during different seasons of the year, to specifically decrease SB in winter months.