Differences in the activity intensity distribution over the day between boys and girls aged 3 to 17 years
Physical activity (PA) protects against non-communicable diseases and mortality across the lifespan. Childhood is a critical period of life as most lifestyle habits, including PA, are likely to originate early and carry forward into adolescence and adulthood. However, physical activity tends to decrease in early ages, from childhood to adolescence, with girls being less active than boys. Understanding the timing of these sex differences is crucial to develop strategies for promoting equal PA during this period.
We used accelerometer data from three cross-sectional studies in Norway and Belgium to assess sex differences in sedentary behaviour (SB) and physical activity levels (light, moderate, vigorous) throughout the day and across the full spectrum of activity intensity distribution (0 counts to 3000 counts/15s) on weekdays and weekend days, using linear regression and functional data analyses.
A total of 2507 participants aged from 3 to 17y (49.4% girls) were included in the analysis. The analysis revealed that across all age groups (preschoolers (3-5y), children (6-10y), adolescents (11-17y)), girls were less active than boys (e.g., vigorous PA difference: -16.9minutes/day (95% Confidence interval (CI): -19.3, -14.4; p-value<0.001)), particularly on weekdays during school time (8h30-15h29). Analysis using the full spectrum of activity intensity distribution revealed specific sex differences in time not moving at all (zero count-SB), with boys being more likely to have this behaviour than girls particularly during weekend days (e.g., difference = -21.0minutes/day (95%CI: -28.7, -13.4; p-value<0.001) in children).
These findings have important implications for PA interventions in youths, suggesting that successful programs should be tailored by type of day and considering school time as a potential period to promote equal opportunities for PA for boys and girls. Additionally, the use of the full spectrum of activity intensity distribution revealed sex differences in the lower end of the distribution (substantial SB) that can be masked by the use of cut-points to differentiate the activity levels.
By Jaime López García
Photo credit: LABDA project
