Environmental Influences on Exercise Intensity and Duration in a US Time Use Study

DUNTON, G. F., D. BERRIGAN, R. BALLARD-BARBASH, B. I. GRAUBARD, and A. A. ATIENZA. Environmental Influences on Exercise Intensity and Duration in a U.S. Time Use Study. Med. Sci. Sports Exerc., Vol. 41, No. 9, pp. 1698-1705, 2009. Purpose: Rising rates of physical inactivity and obesity in the United States highlight the critical need to identify contexts and settings that are conducive to the promotion of recreational physical activity. The current study investigated whether the intensity and duration of sports and exercise bouts differ across physical and social environments as reported in a nationally representative time use survey of U.S. adults. Methods: From the American Time Use Survey (years 2003-2006), adult participants (ages >= 21 yr) who reported at least one bout of sports or exercise on the previous day were selected (N = 7700). For each exercise bout, respondents reported the activity type, its duration (in minutes), its location (e.g., outdoors, home, work, health club/gym), and with whom it occurred (e.g., alone, family members, coworkers, friends/acquaintances). Sample-weighted logistic and linear regression analyses examined differences in intensity expressed as METs (moderate, 3.0-6.0 METs, vigorous, >6.0 METs) and in duration of exercise bouts across environments. Results: Vigorous-intensity exercise was more likely when the bout occurred alone as compared with other social situations (P values < 0.001) and when at a gym/health club and at home as compared with outdoors (P values < 0.001). For both moderate and vigorous activities, exercise bouts were shorter when exercising alone versus with family members, friends/acquaintances, or multiple categories (P values < 0.001). Mean duration of exercise bouts was greater when exercising outdoors than when exercising at home, work, or at gym/health club (P values < 0.001). Conclusions: Nationally representative time use data for U.S. adults suggest that the intensity and duration of exercise bouts are differentially affected by social contexts and physical settings.