What happens to the body when I sit for more than 6 hours a day? The risk of 12 chronic diseases is increased

▎ WuXi AppTec content team editor

"Can lie down and never sit, can sit and never stand", is the "principle" that many people uphold in their daily lives, whether at home or out, they must find opportunities to lie down, sit, and brush their mobile phones, watch videos, and take a nap. Sedentary has become one of the most common ways of life today.

But did you know that sedentary is actually an act that is harmful to health and even reduces lifespan? Sedentary staying has been found not only to be associated with an increased risk of cancers such as colorectal and endometrial cancer, but also to increase the risk of all-cause death.

A new study published in the well-known medical journal The Lancet sub-journal EClinicalMedicine found that sitting for more than 6 hours a day was associated with an increased risk of 12 common chronic noncommunicable diseases; if the 1 hour of sitting time per day was replaced with different intensities of physical activity, it also helped reduce the risk of 4-10 chronic noncommunicable diseases.

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The new study analysed data from the UK biobank and included 360047 participants. At the time of joining the study, none of the participants had chronic noncommunicable diseases, with an average age of 55.8 years, with 54.5% of the participants being female.

The researchers counted basic information such as the participants' age and gender, sedentary time, physical activity at different intensities, sleep time, alcohol consumption, smoking status and body mass index (BMI) and other lifestyle information, and measured the participants' health information such as blood pressure, blood sugar and blood lipids.

In addition, the researchers also counted the participants' disease information on 45 chronic noncommunicable diseases during the follow-up period, such as cardiovascular diseases such as ischemic heart disease, respiratory diseases such as chronic obstructive pulmonary disease (COPD), kidney diseases such as chronic kidney disease, and neurological diseases such as dementia.

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The researchers found that among all participants, 11.8%, 37.6%, 32.0%, and 18.6%, respectively, were sedentary for ≤2 hours/day, 2.1-4.0 hours/day, 4.1-6.0 hours/day, and >6 hours/day.

Male participants were more likely to exhibit sedentary behavior. Of the participants who spent >6 hours/day of sitting, 60.8% were male and 39.2% were female.

After removing other factors, the researchers found that sedentary activity was associated with an increased risk of chronic noncommunicable diseases.

Participants with≤ sedentary >6 hours/day had an increased risk of 12 chronic noncommunicable diseases, including migraine (47%), rheumatoid arthritis (38%), chronic obstructive pulmonary disease (33%), diabetes mellitus (30%), gout (26%), chronic kidney disease (25%), chronic liver disease (21%), asthma (20%), thyroid disease (17%), depression (16%), and diverticular disease (16%) ) and ischemic heart disease (11%).

If all participants reduced their daily sedentary time to less than 6 hours, 3.7% to 22.1% of chronic noncommunicable diseases, including migraine (22.1%), rheumatoid arthritis (17%), chronic obstructive pulmonary disease (14.9%), chronic liver disease (13.8%), diabetes mellitus (12.1%), depression (11.9%), chronic kidney disease (11.1%), asthma (10.8%), thyroid disease (7.1%), gout (5.9%) Diverticular disease (5.8%) and ischemic heart disease (3.7%).

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The researchers also found that for all participants, replacing 1 hour of sedentary time per day with different intensities of physical activity was associated with a reduced risk of 4-10 chronic noncommunicable diseases.

Specifically, replace 1 hour of sedentary time each day with:

Low-intensity physical activity, associated with a reduced risk of 4 chronic noncommunicable diseases, including diabetes mellitus (2%), chronic kidney disease (5%), diverticular disease (2%) and depression (2%);

Moderate physical activity, associated with a reduced risk of 6 chronic noncommunicable diseases, including diabetes mellitus (6%), chronic kidney disease (6%), chronic obstructive pulmonary disease (4%), diverticular disease (2%), chronic liver disease (6%) and dementia (12%);

High-intensity physical activity was associated with a reduced risk of 10 chronic noncommunicable diseases, including diabetes mellitus (15%), chronic kidney disease (11%), chronic obstructive pulmonary disease (19%), diverticular disease (7%), depression (9%), chronic liver disease (12%), ischemic heart disease (9%), lung cancer (14%), inflammatory bowel disease (15%), and sleep disturbances (15%).

In addition, the findings also showed that for participants who > 6 hours/day of sedentary time, if they replaced 1 hour of sedentary time per day with:

Low-intensity physical activity that does not have a clear beneficial effect on the risk of chronic noncommunicable diseases;

Moderate physical activity was associated with an 8% and 21% lower risk of COPD and dementia, respectively;

High intensity of physical activity was associated with a reduced risk of five chronic noncommunicable diseases, including diabetes mellitus (27%), depression (11%), chronic liver disease (15%), diverticular disease (20%) and sleep disturbances (31%).

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Researchers analyze that sedentary habitation can cause obesity, which is a risk factor for many diseases, including cardiovascular disease, cancer and so on. Increasing physical activity not only helps maintain a healthy weight, but also helps to reduce inflammation, strengthen immunity, improve self-awareness, etc., which in turn helps to reduce the risk of a variety of chronic noncommunicable diseases.

However, the mechanism of the effect of sedentary and physical activity on the risk of chronic non-communicable diseases is not yet clear, and more research is needed.

Since this study was observational, it only showed the effects of sedentary and varying intensities of physical activity on the risk of multiple chronic NCDs and did not show a causal relationship. Moreover, the study also has some limitations, such as the reliance of sedentary time on participants' recalls, which may be biased, which will also have an impact on the results of the study.

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The study concluded by recommending that in order to improve health, improve quality of life, and extend lifespan, each of us should reduce our sedentary time, engage in more physical activity, and reach the recommended amount of the World Health Organization.

According to the Recommendations of the World Health Organization:

Children and adolescents aged 5 to 17 years should have at least 60 minutes of moderate to high-intensity physical activity per day; at least three times a week should include activities to strengthen muscles and bones.

Adults over 18 years of age should engage in at least 150 minutes of moderate-intensity physical activity per week, or at least 75 minutes of high-intensity activity per week, or a combination of moderate-intensity and high-intensity activity to achieve this equivalent amount; at least two days per week should engage in activities that strengthen the main muscle group.

For special groups, such as pregnant women, chronically ill patients, people with disabilities, etc., it is recommended to exercise under the guidance of doctors and sports professionals.