Physical activity and sedentary behavior's association with body weight in Korean adolescents.

The purpose of this study was to examine whether physical activity (PA) and sedentary behavior were related to weight status in Korean adolescents. A total of 72,399 students in Grades 7-12 participated in the 5th Korea Youth Risk Behavior Web-Based Survey (KYRBWS-V) project in 2009. Body mass index, PA, and sedentary behavior were assessed by the KYRBWS-V. The study results show that boys had higher PA and less sedentary behavior than did girls (p < .01). The amounts of vigorous PA (p < .001), moderate PA (p < .001), moderate PA for at least 60 min (p < .001), exercise for muscle strength (p < .001), walking on a weekday (p < .001), and walking on a weekend (p = .012) were less in boys who were more obese than the other boys. The time spent sitting on a weekday (p < .001) and weekend (p < .001) was higher in more obese individuals in boys. Exercise for muscle strength (p = .011) was less in girls who were more obese. Time spent sitting on a weekday (p = .005) and weekend (p < .001) was higher in more obese individuals in girls. However, vigorous PA (p < .001), moderate PA (p < .001), moderate PA for at least 60 min (p = .003), and walking on a weekday (p < .001) were higher for the more obese girls. PA and sedentary behavior could be independent factors that reduce or prevent obesity in Korean adolescents.