A new study suggests that the total amount of time that people spend sitting is associated with a higher risk of death from cancer. Replacing some of this sedentary time with light physical activity appears to reduce the risk.
Getting regular physical activity is a proven way for people to lower their chance of developing cancer and dying from it.
The American Cancer Society recommend getting at least 150 minutes of moderate-to-vigorous physical activity each week.
However, research suggests that fewer than one-quarter of adults in the United States actually achieve this.
A more attainable goal may be to reduce the amount of time that we spend sitting.
An analysis of previous studies linked sedentary behavior to higher cardiovascular and cancer mortality. However, all these studies relied on people’s own reports of how much time they spent sitting.
The new study, by scientists at the University of Texas MD Anderson Cancer Center in Houston, drew on the data of 8,002 adults aged 45 years and older who joined the ongoing REGARDS study between 2003 and 2007.
Objective measure.
As part of that study, the researchers strapped accelerometers to participants’ hips to provide an objective measure of their activity levels over a period of 7 days.
In the 5 years after this, 268 participants (3.3%) died of cancer.
The researchers found that participants with the greatest total sedentary time had a 52% increased risk of dying from cancer compared with those who had the least sedentary time. However, there was notable uncertainty as to the exact size of the effect, with the best estimate ranging from a 1% to a 127% increased risk.
Participants with the longest bouts of uninterrupted sedentary behavior had a 36% higher risk of cancer mortality compared with those with the shortest.
The researchers adjusted both results to account for other variables that might have affected cancer mortality, including the participants’:
*overall physical activity levels
*age
*smoking status
*alcohol consumption habits
*body mass index (BMI)
*preexisting conditions
To get an insight into the potential benefits of becoming less sedentary, the researchers modeled the effects of replacing 30 minutes of sedentary time per day with physical activity.
For moderate-to-vigorous exercise, such as cycling, this led to a 31% lower risk of dying from cancer. For light exercise, such as walking, this led to an 8% lower risk.
