Independent and Combined Associations of Physical Activity and Sedentary Behavior with Depressive Symptoms Among Japanese Adults

This paper concerns the use of the Internet in the research process, from identifying research issues through qualitative research, through using the Web for surveys and clinical trials, to pre-publishing and publishing research results. Material published on the Internet may be a valuable resource for researchers desiring to understand people and the social and cultural contexts within which they live outside of experimental settings, with due emphasis on the interpretations, experiences, and views of `real world' people. Reviews of information posted by consumers on the Internet may help to identify health beliefs, common topics, motives, information, and emotional needs of patients, and point to areas where research is needed. The Internet can further be used for survey research. Internet-based surveys may be conducted by means of interactive interviews or by questionnaires designed for self-completion. Electronic one-to-one interviews can be conducted via e-mail or using chat rooms. Questionnaires can be administered by e-mail (e.g. using mailing lists), by posting to newsgroups, and on the Web using fill-in forms. In "open" web-based surveys, selection bias occurs due to the non-representative nature of the Internet population, and (more importantly) through self-selection of participants, i.e. the non-representative nature of respondents, also called the `volunteer effect'. A synopsis of important techniques and tips for implementing Web-based surveys is given. Ethical issues involved in any type of online research are discussed. Internet addresses for finding methods and protocols are provided. The Web is also being used to assist in the identification and conduction of clinical trials. For example, the web can be used by researchers doing a systematic review who are looking for unpublished trials. Finally, the web is used for two distinct types of electronic publication. Type 1 publication is unrefereed publication of protocols or work in progress (a `post-publication' peer review process may take place), whereas Type 2 publication is peer-reviewed and will ordinarily take place in online journals.

Recent epidemiologic evidence points to the health risks of prolonged sitting, that are independent of physical activity, but few papers have reported the descriptive epidemiology of sitting in population studies with adults. This paper reports the prevalence of "high sitting time" and its correlates in an international study in 20 countries. Representative population samples from 20 countries were collected 2002-2004, and a question was asked on usual weekday hours spent sitting. This question was part of the International Prevalence Study, using the International Physical Activity Questionnaire (IPAQ). The sitting measure has acceptable reliability and validity. Daily sitting time was compared among countries, and by age group, gender, educational attainment, and physical activity. Data were available for 49,493 adults aged 18-65 years from 20 countries. The median reported sitting time was 300 minutes/day, with an interquartile range of 180-480 minutes. Countries reporting the lowest amount of sitting included Portugal, Brazil, and Colombia (medians ≤180 min/day), whereas adults in Taiwan, Norway, Hong Kong, Saudi Arabia, and Japan reported the highest sitting times (medians ≥360 min/day). In adjusted analyses, adults aged 40-65 years were significantly less likely to be in the highest quintile for sitting than adults aged 18-39 years (AOR=0.796), and those with postschool education had higher sitting times compared with those with high school or less education (OR=1.349). Physical activity showed an inverse relationship, with those reporting low activity on the IPAQ three times more likely to be in the highest-sitting quintile compared to those reporting high physical activity. Median sitting time varied widely across countries. Assessing sitting time is an important new area for preventive medicine, in addition to assessing physical activity and sedentary behaviors. Population surveys that monitor lifestyle behaviors should add measures of sitting time to physical activity surveillance. Moreover, the use of objective measures to capture the spectrum of sedentary (sitting) and physical activity behaviors is encouraged, particularly in low- and middle-income countries commencing new surveillance activities. Copyright © 2011 American Journal of Preventive Medicine. All rights reserved.

The obesity epidemic is attributed in part to reduced physical activity. Evidence supports that reducing time spent sitting, regardless of activity, may improve the metabolic consequences of obesity. Analyses were conducted in a large prospective study of US adults enrolled by the American Cancer Society to examine leisure time spent sitting and physical activity in relation to mortality. Time spent sitting and physical activity were queried by questionnaire on 53,440 men and 69,776 women who were disease free at enrollment. The authors identified 11,307 deaths in men and 7,923 deaths in women during the 14-year follow-up. After adjustment for smoking, body mass index, and other factors, time spent sitting (> or = 6 vs. or = 6 hours/day) and physical activity (<24.5 metabolic equivalent (MET)-hours/week) combined were 1.94 (95% CI: 1.70, 2.20) for women and 1.48 (95% CI: 1.33, 1.65) for men, compared with those with the least time sitting and most activity. Associations were strongest for cardiovascular disease mortality. The time spent sitting was independently associated with total mortality, regardless of physical activity level. Public health messages should include both being physically active and reducing time spent sitting.