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Joint associations of physical activity and screen time with overweight among japanese adults

Yung Liao1*, Kazuhiro Harada23, Ai Shibata3, Kaori Ishii3, Koichiro Oka3, Yoshio Nakamura3, Takemi Sugiyama4, Shigeru Inoue5 and Teruichi Shimomitsu5

Author Affiliations

1 Graduate School of Sport Sciences, Waseda University, Nakamura Laboratory 2-579-15 Mikajima Tokorozawa, Saitama 359-1192, Japan

2 Japan Society for the Promotion of Science, Sumitomo-Ichibancho Bldg., 6 Ichibancho, Chiyoda-ku, Tokyo 102-8471, Japan

3 Faculty of Sport Sciences, Waseda University, 2-579-15 Mikajima Tokorozawa, Saitama 359-1192, Japan

4 Baker IDI Heart and Diabetes Institute, Level 4, 99 Commercial Road, Melbourne VIC 3004, Australia

5 Department of Preventive Medicine and Public Health, Tokyo Medical University, 6-1-1, Shinjuku-ku, Tokyo, 160-8402, Japan

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International Journal of Behavioral Nutrition and Physical Activity 2011, 8:131  doi:10.1186/1479-5868-8-131

Published: 30 November 2011



Although both insufficient physical activity (PA) and high screen time (ST) are independent risk factors for obesity, how the combination of sufficient/insufficient PA and high/low ST could increase obesity risk among the adult population of Japan is not known. This study examined joint associations of PA and ST with overweight among Japanese adults.


An Internet-based survey collected data on height, weight, self-reported time spent in PA and ST, and sociodemographic variables from 2832 adults. Respondents were categorized into sufficient PA/low ST, sufficient PA/high ST, insufficient PA/low ST, or insufficient PA/high ST categories as per public PA guidelines and the median of ST. Logistic regression analysis examined the odds ratios (OR) of being overweight (body mass index, ≥ 25 kg/m2) according to the categories of PA and ST.


In comparison with the sufficient PA/low ST category, participants in the insufficient PA/high ST category were significantly more likely overweight (OR, 1.48; 95% confidence interval [95%CI), 1.14, 1.93) after adjusting for sociodemographic variables. A significantly higher OR for overweight (including obesity) among insufficient PA/high ST category was also observed in men, but no significant association was found in women.


Both insufficient PA and prolonged ST contribute to overweight and obesity among Japanese adults. Public health initiatives addressing obesity in Japan need to consider both promoting PA and reducing ST, especially in men.