The Dangers of Prolonged Sitting–Increased Risk for 6 Cancers, Cardiovascular Disease

Less sitting and more frequent aerobic activities such as brisk walking may lower your risk of cancer.

Being sedentary for prolonged periods is becoming increasingly prevalent worldwide, yet many studies have shown that it increases the risk of cancer, cardiovascular disease, and overall mortality. Prostock-studio/shutter stock

Sedentary lifestyles are becoming more prevalent globally. With the increase in the number of people working from home during the pandemic, some of us are now barely even leaving the house. Many studies have shown that sedentary behavior is closely associated with increased risk of—and lower survival from—six types of cancer, as well as diabetes and cardiovascular disease.

A sedentary lifestyle refers to sitting or lying down for six or more hours a day (except sleeping), lack of obvious physical movement in daily life, and therefore, low energy consumption. According to an article published by Harvard Medical School, an estimated 67 percent of older adults sit for more than eight hours a day, while only 28 to 34 percent of those aged 65 to 74 are physically active.

Sitting for Long Periods Increases Risk of Cardiovascular Disease, Death

A sedentary lifestyle increases the risk of death and disease. In 2022, JAMA Cardiology published a study involving a large cohort that analyzed the results of sedentary duration against overall mortality rate and major cardiovascular diseases. Of the 105,677 participants, 58.6 percent were female and the average age was 50.4 years. The average sitting time was 4 hours per day and the median follow-up time was 11.1 years.

The study found that participants in the group that sat for 8 hours or more per day, compared to those who sat less than 4 hours per day, had an increased overall mortality rate of 20 percent and an increased risk of major cardiovascular disease of 21 percent. The more sedentary/lower activity group also had significantly increased rates of diabetes, depression, physical disorders, and chronic diseases.

Another retrospective study involving more than 1 million people found that adults who sit for more than 9 hours per day have a significantly higher risk of death.

However, the authors of the paper also mentioned that those who engaged in about 60 to 75 minutes of daily moderate to vigorous physical activity did not have an increased risk of death even after sitting for more than 8 hours per day.

Sitting for Long Periods of Time Increases Cancer Risk

Sitting still for long periods is also a risk factor for cancer. Many studies have shown that sedentary behavior is associated with an increased risk of various cancer types. In 2022, the European Journal of Epidemiology published an umbrella review in which researchers included 14 meta-analyses from 77 original studies, covering 17 different cancer sites and including more than 200,000 cancer cases. Studies also found that sedentary behavior significantly increases the risk of six types of cancers as follows:

1. Breast—8 percent
2. Colon—25 percent
3. Prostate—8 percent
4. Rectal—7 percent
5. Endometrial—29 percent
6. Ovarian—29 percent

Moreover, sedentary behavior can also lower the survival rate of cancer patients. Among colorectal cancer patients, sedentary behavior after diagnosis increases their specific risk of death by 61 percent.

Aerobic Exercise Reduces Risk of 9 Cancer Types

Evidence from the World Cancer Research Fund International shows that physical activity can reduce the risk of colon, breast, and endometrial cancers and can also help maintain a healthy body weight. In the United States, nearly half of adults do not get enough aerobic exercise, and 77 percent of high school students do not get sufficient physical exercise.

In 2023, a cohort study published in the BMJ’s sister journal, the British Journal of Sports Medicine, analyzed the relationship between cardiorespiratory fitness (CRF) and the risk of cancer in different parts of the body. The study included 1,078,000 young men who had been followed for an average of 33 years. Researchers divided CRF levels into three categories: high, moderate, and low.

CRF usually refers to a person’s ability to perform aerobic exercise, that is, the ability of the heart to pump blood and the lungs to inhale oxygen. The entire body needs oxygen to burn the energy stored in the body and turn it into heat energy, which is used by organs and muscles that need heat energy to move. Aerobic exercise includes brisk walking, rope skipping, running, swimming, and cycling, among others.

The study found that higher CRF was linearly related to lower risk of nine cancer types as follows:

1. Head and neck—19 percent
2. Esophageal—39 percent
3. Stomach—21 percent
4. Pancreatic—12 percent
5. Liver—40 percent
6. Colon—18 percent
7. Rectal—5 percent
8. Kidney—20 percent
9. Lung—42 percent

Frequency of Activities Most Important

Koichiro Oka, a professor at the School of Sports Science at Waseda University in Japan, believes that prolonged sitting is a “silent killer.” He said that in general, calf muscles are continuously employed to maintain posture while standing, and thigh muscles are exercised when walking. This muscle contraction associated with physical activity stimulates metabolic functions related to blood sugar and triglycerides (neutral fat). On the other hand, lower body muscles contract less when sitting or lying down than when standing or walking. Therefore, sitting for prolonged periods will reduce metabolic function, lead to increased blood sugar and triglyceride concentrations, and result in various diseases.

Due to the COVID-19 pandemic, many people are sitting more than ever before. Mr. Oka believes that the frequency rather than the intensity of physical activity is most important in combatting the negative effects on the body of prolonged sitting. He suggested that you try not to sit for more than 8 hours per day and that you get up from your seat every 20 to 30 minutes to practice some light activities, including light squatting, standing up from your seat, standing on tiptoes, or making yourself a cup of coffee. He also notes that health conditions such as back and neck pain and emotional states improve by reducing sedentary behavior by about one hour per day.

For people who spend a lot of time watching TV at home, he recommends getting up every 30 minutes and moving around as much as possible, not using the remote control when switching TV channels, completing some household chores (such as cleaning or washing dishes), and standing up and walking around or stretching the body during commercials. All of these light activities in daily life are essential to maintaining and improving physical and mental health.