Physical activity, screen time, and sitting among U.S. adolescents

Abstract

The purpose of this study was to describe self-reported levels of sitting, moderate- to vigorous-intensity physical activity (MVPA), television viewing, and computer use in a representative sample of US adolescents and to make comparisons between sex, race/ethnicity, weight status, and age groups. Results are based on 3556 adolescents aged 12-19 years from the 2007-2012 National Health and Nutrition Examination Survey. Participants self-reported demographic, sitting, MVPA, television viewing (2011-2012 only) and computer use (2011-2012 only) variables. Height and weight were measured to calculate body mass index. On average, 7.5 hr/day were spent sitting and 34 median min/day were spent participating in MVPA, with females sitting more and participating in less MVPA than males across most demographic groups. Furthermore, obese males sat more and participated in less MVPA than nonoverweight males. Non-Hispanic white females participated in more MVPA than females in all other race/ethnicity groups. For television and computer, 38% and 22% of the sample engaged in >2 hr/day, respectively, and several race/ethnicity differences were observed. This study provides the first U.S. adolescent population estimates on self-reported sitting and updates population estimates on self-reported MVPA, television viewing and computer use. Continued efforts are needed to promote healthy active lifestyles in American adolescents.

Figure 1

Mean (95% CI) Sitting time among a nationally representative sample of US adolescents stratified by age and sex groups. ^a,b Significant differences in sitting time between the 12-13 year age group and the 16-17 year and 18-19 year age groups within the male sample (P<0.01). ^c,d Significant differences in sitting time between the 14-15 year age group and the 16-17 year and 18-19 year age groups within the male sample (P<0.01). ^e Significant differences in sitting time between the 16-17 year and 18-19 year age groups within the male sample (P<0.01). ^f,g,h Significant differences in sitting time between the 18-19 year age group and all other age groups (P<0.01).

Figure 2

Median (95% CI) MVPA among a nationally representative sample of US adolescents stratified by age and sex groups. ^a,bSignificant difference in MVPA between the 16-17 and 18-19 year age-groups within the male sample (P<0.01). ^c,d,e Significant differences in MVPA between the 18-19 year age group and all other age groups within the female sample (P<0.01).