Inflammation may play a key role in why exercise helps guard against cancer, a new study shows. According to a small study from the University of Queensland in Brisbane, Australia, the body’s inflammation immediately after exercise may help to slow cell growth and reproduction, including the growth of tumor cells.
Researchers recruited a small group of 20 men who had survived colon cancer. During the study, they asked 10 of the participants to work out strenuously three times a week. The exercise included pedaling on a stationary bicycle rigorously for four minutes, resting for three, and repeating the sequence three more times.
The 10 participants worked out for a month. Three days after the month-long session ended, researchers drew blood from the participants.
Researchers also drew blood from the other 10 participants who had been asked to complete the same workout session, but only once. These participants had their blood drawn before the workout, immediately following the workout, and two hours after the workout.
A small amount of the participants’ blood was added to Petri dishes containing human colon-cancer cells. Researchers counted the number of cancer cells in each dish over the course of 72 hours.
The Petri dishes containing blood that was taken from participants immediately following a single workout had far fewer cancer cells than the dishes with blood drawn two hours after exercise. There was no similar decline in the number of cancer cells in the dishes from the participants who had worked out for a month.
In the blood taken from participants immediately after exercising, there was a large increase in molecules involved in inflammation. Inflammation can help to slow down the reproduction of cells.
According to the senior author of the study and physiologist Tina Skinner, a temporary increase in inflammatory markers immediately after exercising may help to jam the growth of cancer cells. But, she says, although the changes in the participants’ blood were effective they were also temporary.
“We would recommend that exercise be embedded as part of standard practice for people living with and beyond cancer,” said Skinner.
These temporary effects of exercise may also be able to help patients living with breast cancer who are overweight or obese.
Approximately 22 out of 10,000 women between the ages of 50 and 54 will be diagnosed with breast cancer in the next year. Fat cells produce estrogen, which can be problematic for those who have gone through menopause because it prolongs the body’s exposure to the hormone, which increases the risk of cancer.
A separate study published in JAMA Oncology found that rigorous exercise such as gymnastics, which has been around for over 2,000 years, dramatically lowered the heart disease risk for overweight and obese breast cancer survivors.
“This study further supports the idea that aerobic and resistance exercise, which has been shown to favorably affect metabolic syndrome in women with early-stage breast cancer, reduces the 10-year risk of cardiovascular disease significantly, as … further evidence that lifestyle changes can be very important in patients including those with breast cancer,” said Dr. C. Kent Osborne on the study.
Skinner says it’s unclear how intense or prolonged a patient’s exercise ideally would need to be for effective treatment. She also says it isn’t clear if the effects would extend equally to other types of cancer. For instance, 23,800 adults are diagnosed with brain and spinal cord cancer every year.
However, the National Cancer Institute points out that there’s a relationship between physical activity and lowered risk of colon cancer, breast cancer, and endometrial cancer. That said, regardless of cancer type, it’s worth exercising 30 minutes a day or one hour three times a week.