Sedentary Behaviors, Body Fatness and Physical Activity in Youth

Increases in sedentary behavior are often cited as reasons for overweight among youth yet sufficient evidence is rarely presented. PURPOSE To review associations between TV viewing, video/computer game use and: a) body fatness, and b) physical activity for youth aged 0–18 years. METHODS Metaanalytic review. Published English-language studies were located from computerised literature searches, bibliographies of studies and reviews, and manual searches of personal archives. RESULTS Mean sample-weighted corrected effect size (Pearson r) was the main outcome measure. Based on data from 52 independent samples (K), the mean sample-weighted effect size between TV viewing and body fatness was 0.066 (95% CI = 0.056 to 0.078; total N = 44,707). The sample-weighted fully corrected effect size was 0.084. Mean sample-weighted effect size between video/computer game use and body fatness (K=6) was 0.070 (95% CI = −0.048 to 0.188; total N = 1722; fully corrected r=0.128). Mean sample-weighted effect size between TV viewing and physical activity (K=39) was – 0.096 (95% CI = −0.080 to −0.112; total N = 141,505; fully corrected r=−0.129). Mean sample-weighted effect size between video/computer game use and physical activity (K=10) was −0.104 (95% CI = −0.080 to 0.128; total N = 119,942; fully corrected r=0.141). CONCLUSION A statistically significant relationship exists between TV viewing and body fatness among youth although it is likely to be too small to be of any clinical relevance. The relationship between TV viewing and physical activity is small but negative. The strength of these relationships remain virtually unchanged even after correcting for common sources of bias known to impact study outcomes. The media-based inactivity studied here may be unfairly implicated, at least in isolation, in recent epidemiologic trends of overweight and obesity among youth. Relationships between sedentary behavior and health are unlikely to be explained using single markers of inactivity such as TV viewing or video/computer game use. Supported by BHF Grant PG/2000124.