Vol. 48: 'Sitting is the new smoking'—what is the evidence?

Prolonged sitting is, in itself, a health risk comparable to smoking.


Vol. 19 Vol. 19: Is '8,000 steps a day' enough? Sorting out the 'correct answer' for exercise. | Dr. O discussed the '8,000 steps a day' guideline and exercise recommendations. In that installment, I briefly mentioned that 'sitting continuously for more than 30 minutes has a negative impact on blood sugar levels,' but this time, I will delve into 'sedentary time' as an independent risk factor.

While it is well known that 'lack of exercise is bad for the body,' the fact that 'sitting too much is, in itself, bad for the body' is still surprisingly little known.

Recent research has revealed that even if you exercise regularly, sitting for long periods is an independent health risk. A meta-analysis by Biswas et al. (Ann Intern Med 2015), which integrated 47 studies, showed that prolonged sedentary behavior increases the risk of all-cause mortality, cardiovascular disease, cancer, and type 2 diabetes, independent of physical activity levels.

Even if you think you are fine because you go to the gym for an hour a day, if you spend more than 10 hours of the remaining 23 hours sitting, you cannot completely cancel out the negative effects. This is one of the reasons why it is said that 'sitting is the new smoking.'

However, there is an important caveat here. A meta-analysis by Ekelund U et al. (Lancet 2016), which integrated data from over 1 million people, showed that if you engage in 60 to 75 minutes of moderate-to-vigorous physical activity per day, the increased mortality risk from prolonged sitting is almost entirely offset. In other words, the accurate understanding is not that 'exercise is meaningless,' but that 'if you have a sufficient amount of exercise, the risk is greatly reduced.' While excessive sitting is an independent risk, there is no need to underestimate the power of exercise.

It is known that Japanese people have some of the longest sedentary times in the world. In a 20-country comparative study by Bauman et al. (Am J Prev Med 2011), the median sedentary time for Japanese people on weekdays was approximately 7 hours (420 minutes), which was among the longest in the countries surveyed. There is an aspect where the culture of 'working diligently' creates the health risk of long hours of desk work as a byproduct.

The solution is surprisingly simple. Even just 'standing up for 1 to 2 minutes every 30 minutes' is effective. Intervention studies have shown that simply breaking up prolonged sitting with short breaks significantly suppresses the rise in postprandial blood glucose and blood triglycerides (Dunstan et al., Diabetes Care 2012, etc.). Going to the restroom, getting tea, or standing up to take a phone call—even these small actions make a difference.

Standing desks are also a valid option. By using an adjustable auxiliary stand (starting from around 10,000 to 20,000 yen) and spending a few hours a day standing, you can reduce your total sedentary time. There are reports that this is effective in reducing lower back pain and maintaining concentration. If your workplace environment makes it difficult to 'stand up every 30 minutes,' consider changing the environment itself.

Vol. 19 Vol. 19: Is '8,000 steps a day' enough? Sorting out the 'correct answer' for exercise. | Dr. O wrote about '8,000 steps a day' + this time's 'stand up every 30 minutes'—I believe combining these two is the most practical prescription for physical activity in the modern age. The latter becomes increasingly important for those who focus on desk work.
This is the simplest and most effective prescription for those who do desk work: 'Stand up every 30 minutes'—please start today.

Source:
Biswas A, Oh PI, Faulkner GE, et al. “Sedentary time and its association with risk for disease incidence, mortality, and hospitalization in adults: a systematic review and meta-analysis.” Ann Intern Med. 2015;162(2):123-32.
Bauman A, Ainsworth BE, Sallis JF, et al. “The descriptive epidemiology of sitting. A 20-country comparison using the International Physical Activity Questionnaire (IPAQ).” Am J Prev Med. 2011;41(2):228-35.
Dunstan DW, Kingwell BA, Larsen R, et al. “Breaking up prolonged sitting reduces postprandial glucose and insulin responses.” Diabetes Care. 2012;35(5):976-83.
Ekelund U, Steene-Johannessen J, Brown WJ, et al. “Does physical activity attenuate, or even eliminate, the detrimental association of sitting time with mortality? A harmonised meta-analysis of data from more than 1 million men and women.” Lancet. 2016;388(10051):1302-10.
Ministry of Health, Labour and Welfare 'Physical Activity and Exercise Guide for Health Promotion 2023' https://www.mhlw.go.jp/content/001194020.pdf

*The content of this note is the author's personal view. It has no relation to the views of the medical institution to which the author belongs. While I have paid close attention to the accuracy of the content, I would appreciate it if you could point out any inappropriate content.