Sitting Time Linked to Higher Risk of Death from All Causes

A study from the American Cancer Society finds a link between long periods of leisure time sitting and a higher risk of death from all causes, including 14 of the 22 causes of death measured by the study. This includes 8 of the 10 most common causes of death. The study was published online June 29, 2018 in the American Journal of Epidemiology.

Previous studies have linked prolonged sitting time with death from cancer, heart disease, and “all other causes.” To examine the other causes of death in detail, the new study used data from the American Cancer Society CPS-II Nutrition Cohort, which included 127,554 people who had no major chronic diseases when they joined the group, and who were followed for 21 years. During the study’s follow-up time, 48,784 people died.

Risks of death among those who reported the most leisure time sitting were higher from cancer, coronary heart disease, stroke, diabetes, kidney disease, suicide, lung disease, liver disease, peptic ulcer and other digestive disease, Parkinson’s disease, Alzheimer’s disease, nervous disorders, and musculoskeletal disorders.

Screen time has increased sitting time

As technology has advanced during the last few decades, sitting time has increased. One Australian study estimated that 90% of non-work time was spent sitting, and more than half of that sitting time was spent on the computer or watching TV. Previous studies have shown that prolonged sitting time raises risk of death even for people who get healthy amounts of moderate or vigorous physical activity when they aren’t sitting.

In the American Cancer Society study, prolonged leisure time sitting was associated with a 19% higher rate of death from all causes combined compared to sitting less than 3 hours per day. The study defined prolonged sitting time as 6 or more hours a day.

According to lead author Alpa Patel, PhD, American Cancer Society Sr Scientific Director, Epidemiology Research, “While we still have yet to understand how to quantify what a safe amount of sitting time may be, what is clear is that individuals should take any opportunity to take breaks in sitting time and cut down sitting time to whatever degree they can.”

Possible explanations

The study was not designed to find out why excess sitting time is linked to an increased risk of death. However, the authors offer several possible explanations.

• Time spent sitting might be taking the place of activity, including light levels of daily activity. Health effects of light levels of activity have not been studied.
• Time spent sitting may be associated with other unhealthy activities; for example, snacking while watching TV.
• Time spent sitting has a negative impact on the body’s hormone levels and the way the immune system works. This may be a factor in the link between sitting time and mortality.

Tips for getting more movement into your day

According to Patel, the study adds to the collective body of evidence that reducing sitting time is important for a healthy lifestyle. She said, “Advances in technology have encouraged us to be sedentary, so we need to be mindful about finding ways to move.” Patel says adding a few minutes of activity to break up sitting time throughout the day at work and during leisure time can add up. She suggests:

• Standing and folding laundry while watching TV
• Doing a few simple exercises or stretches while you watch
• Getting up and doing something instead of skipping through TV commercial breaks
• Taking short breaks at work to walk around your office building
• Walking up the escalator or stairs instead of taking the elevator
• Using the farthest bathroom from your desk

American Cancer Society guideline for physical activity

The American Cancer Society recommends adults get at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity activity each week (or a combination), preferably spread throughout the week.

For kids, the recommendation is at least 60 minutes of moderate- or vigorous-intensity activity each day, with vigorous-intensity activity occurring at least 3 days each week.