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Campus Now

Spring Verdure Issue (May. 2015)

Frontline of Research

Introducing advanced research which contributes to society.

Too much sitting reduces healthy life expectancy!?
Large-scale survey to realize a society for a long, healthy life

Koichiro Oka
Professor, Faculty of Sport Sciences, Waseda Univesity

Decreasing activity level
Lifestyle habits and health risks in modern society

Graduate students use computers at standing desks installed in the Oka Laboratory.

A variety of health risks are expanding throughout modern society. Although almost all people recognize the impact that lifestyle habits such as diet and exercise have on health, there are few people who know that too much sitting results in heightened health risks.

During the last several dozen years, there have been major changes in our style of living and working. In the 1960s, work which involved physical movement accounted for more than half of all jobs. Today, such work comprises only 20% of all jobs. Instead, there has been an increase in deskwork. There are some people who spend almost their entire workday sitting in front of a computer, from arriving at the office in the morning until leaving at night. Even when not performing deskwork, there are many people who spend the majority of their day sitting. For example, sitting down and watching television at home, or driving vehicles in regions which lack convenient public transportation.

According to guidelines for a long, healthy lifestyle issued by the Ministry of Health, Labour and Welfare (MHLW), people should walk or engage in commensurate physical activity for one hour every day. By actively moving the body, it is possible to prevent metabolic syndrome and cancer in the middle-aged, and the dementia which is often seen in the elderly. However, despite understanding that exercise is good for physical and mental health, less than 30% of people actually perform the recommended level of exercise. People only take action when they find it enjoyable and are satisfied with the results. Moreover, scientific technology in society has made it possible for people to avoid moving their bodies. For example, when both stairs and an escalator are available, I think that even the majority of healthy people will naturally use the elevator. When viewing the daily activity level of an adult Japanese person during waking hours (Figure 1), it can be seen that low intensity physical activity and sitting comprises 95% of that time. This means that recommended physical activity more than moderate or high intensity comprises only 5% of our waking hours. It is said that if these trends continue, the current state of inactivity will continue to worsen without anyone noticing, and result in a global problem similar to a pandemic in the future.

Japanese people sit longer than any country in the world—How can we encourage them to stand up?

According to international comparative research of sitting time for adults in 20 countries throughout the world, the total average daily time spent sitting by Japanese people is longer than any other country. Put simply, this means that many Japanese people sit too much. This does not mean that the act of sitting is bad. My message is that prolonged periods of sitting lead to inactivity and may heighten health risks. In Australia, research was conducted to study the relationship between total daily sitting time and total mortality risk. This research found that adults who sit for a total of 11 hours or longer per day have a total mortality risk that is 1.4 times greater than adults who sit for less than 4 hours per day (Figure 2). Even more, even when engaging in the amount of physical activity recommended by the WHO, total mortality risk still increases when total sitting time is too long. Prolonged sitting also causes obesity, diabetes, cancer and coronary heart disease. It has even been reported to affect cognitive functions and contribute to depression. Recently, this type of statistical data has resulted in increased attention for research related to health risks caused by too much sitting. The question of how to decrease time spent sitting is being debated throughout the world.

The most important factor for the future of Japan is how we can create a health-conscious environment. Personally, I am conducting research for reducing long periods of continuous sitting when performing deskwork. As a general guideline, I believe that you should stand up from your chair and move your body at least once every 30 minutes to 1 hour. However, it is not easy to perform deskwork in a standing position. Therefore, in my laboratory, I have installed standing desks and workstations which make it easy to switch between working in a sitting and standing position, thus enabling computer work while standing. Unfortunately, maintaining mental and physical health is not enough of a reason to encourage corporations to implement such standing workstations. Therefore, I am working to conduct a medical and economic evaluation by surveying the relationship between work time spent sitting and productivity, absentee rates, and other criteria.

Large-scale follow-up study project
WASEDA'S Health Study: Contributing to a society for a long, healthy life

In Japan today, there is a lack of surveys which substantiate the theory that too much sitting has an adverse affect on health. In response, the Waseda University Faculty of Sport Sciences has started the large-scale follow-up survey project WASEDA'S Health Study since 2014. Through a long-term (20 years) follow-up for the secrets to a long, healthy life among alumni, the survey will clarify the relationships between current lifestyles and future health risks. As part of the project, the same surveying and measurement is performed every 5 years for alumni over 40 years of age and their spouses.

From quite long ago, Harvard University pioneered the use of such a follow-up survey by targeting male graduates. The data from the Harvard survey has been the basis of many research results. WASEDA'S Health Study will rival the Harvard survey and will propose a strong message to society.

In addition to substantiating research papers, the valuable data accumulated from the survey will contribute to the health of alumni by providing feedback on the results of health examinations and physical measurements. It will also contribute to the correction of social health disparities through active proposals for application to national policy and systems for promoting health.

For information on participation, please visit https://wasedas-health-study.jp/survey/

Koichiro Oka
Professor, Faculty of Sport Sciences, Waseda Univesity

Koichiro Oka earned his doctorate degree in the Waseda University Graduate School of Human Sciences in 1999. After working as a Research Associate in the School of Human Sciences, Waseda University, as a member of Research Fellowship for Young Scientists at the Japan Society for the Promotion of Science and Tokyo Metropolitan Institute of Gerontology (formerly Tokyo Metropolitan Foundation for Research on Aging and Promotion of Human Welfare) and as chief of the JSPS Office for Emergency Measures to Prevent the Need for Nursing Care, he was appointed Associate Professor in the Faculty of Sport Sciences at Waseda University in April 2006. He has worked in his current position since April 2012.

Koichiro Oka Laboratory