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

Sedentary lifestyles are becoming more prevalent globally due to the proliferation of electronics, and the increase in remote occupations. Many studies have shown that sedentary behavior is closely associated with increased risk and survival rate of six cancer types, diabetes and cardiovascular disease, and overall mortality.

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 and Death

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

The study found that participants in the group that sat for 8 hours or more a day, compared to those who sat less than 4 hours per day, had an increased overall mortality rate (20 percent), and an increased risk of major cardiovascular disease (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 a 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 a 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 cancer—29 percent.

Moreover, sedentary behavior can also lead to a decrease in 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 cancer 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 August a cohort study published in the BMJ’s sister journal, 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, amongst others.

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

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.

However, the study also found that people with higher levels of CRF had a 7 percent increased risk of prostate cancer and a 31 percent increased risk of skin cancer compared with people with low CRF levels.

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 have more sedentary behaviors than ever before. Mr. Oka believes that to prevent the negative effects of prolonged sitting on the body, it is the frequency rather than the intensity of physical activity that is more important. He suggested that you try not to sit for more than 8 hours a day and 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 an 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) as well as and standing up and walking around or stretching the body during commercials. All of these light activities in daily life are essential to maintain and improve physical and mental health.