- Research shows that high-intensity exercise can reduce the risk of metastatic cancer.
- Researchers found that there were 72% fewer metastatic cancer cases in people who reported regularly exercising at a high intensity compared to those who did not engage in physical exercise.
- Experts explain the findings and the cancer-reducing benefits of exercise.
We all know that exercise is good for you, but new research shows just how beneficial regular exercise can be for our health.
A study from Tel Aviv University, published in Cancer Research, is the first to investigate the impact of exercise on the internal organs in which metastases (secondary cancerous growths) usually develop, like the lungs, liver, and lymph nodes. And what the researchers found was truly remarkable: aerobic exercise may reduce the risk of metastatic cancer by 72%.
In a press release, lead researchers Carmit Levy, Ph.D., and Ytach Gepner, Ph.D., said that these findings added new insight, showing that high-intensity aerobic exercise, which derives its energy from sugar, can reduce the risk of metastatic cancer by as much as 72%. “If the general message to the public so far has been ‘be active, be healthy,’” they say, “now we can explain how aerobic activity can maximize the prevention of the most aggressive and metastatic types of cancer.”
The study included both mice and humans—mice trained under a strict exercise regimen, and healthy human volunteers were examined before and after running.
Human data was also obtained from an epidemiological study that monitored 3,000 individuals for about 20 years—during that time, 243 new cancer cases were recorded. Researchers found that there was 72% less metastatic cancer in participants who reported regularly exercising at a high intensity, compared to those who did not engage in physical exercise.
The mice exhibited a similar outcome, which enabled the researchers to use the animal model to better understand what might be leading to the reduction in cancer. They found that aerobic activity significantly reduced the development of metastatic tumors in the lymph nodes, lungs, and liver of the mice. The researchers hypothesized that in both humans and model animals, this outcome is related to the body’s ramped-up use of glucose for fuel induced by exercise.
“Examining the cells of these organs, we found a rise in the number of glucose receptors during high-intensity aerobic activity—increasing glucose intake and turning the organs into effective energy-consumption machines, very much like the muscles,” said Levy in the press release.
According to the researchers, this happens because the organs must compete for sugar resources with the muscles, which are known to burn large quantities of glucose during physical exercise. As a result, there is less glucose—therefore energy—available for the cancer to metastasize, or grow and spread.
On top of these encouraging findings, Levy explains that “when a person exercises regularly, this condition becomes permanent: the tissues of internal organs change and become similar to muscle tissue.” We all know that sports and physical exercise are good for our health. However, this study in particular examines the internal organs, and discovered that exercise changes the whole body, so that the cancer cannot spread, and the primary tumor also shrinks in size, says Levy.
What is metastatic cancer?
Metastatic cancer is a cancer that spreads to another place which is not the primary location of the cancer, says Carolina Gutierrez, M.D., cancer rehabilitation specialist with McGovern Medical School at UTHealth Houston and an attending physician at TIRR Memorial Hermann.
How does exercise affect your internal organs where metastases typically develop?
We knew from previous observational studies that exercise has a very important positive impact that can range from decreased risk of recurrence to decreased risk of getting certain cancers, but we didn’t really understand how that works, says Marlene Meyers, M.D., medical oncologist at NYU Langone Perlmutter Cancer Center.
Dr. Meyers explains that this study actually sought to look at what happens in mice. “Essentially, what it showed was that mice who exercised at high intensity had an increase in glucose receptors or sugar receptors in these organs.” She notes that the feeling from the researchers is that this increase in receptors competes with the glucose (sugar) that might go to cancer cells, which gives them the energy to spread.
How does exercise reduce your risk for cancer?
There are many reasons why exercise can reduce your risk for cancer, says Dr. Gutierrez. “Exercise helps maintain a healthy weight and body composition, reduces fat, helps with glucose levels, and helps control high blood pressure. It also helps reduce the risk of diabetes, insulin resistance and in turn reduces a person’s overall cancer risk.”
However, when it comes to how high intensity exercise in particular affects your cancer risk, the science is less clear. “We do know that any exercise can decrease the risk of recurrence in some cancers, so it’s not clear specifically whether high intensity makes as big a difference versus regular exercise, or how long you have to sustain high intensity exercise or how often,” says Dr. Meyers.
In this study, the researchers defined high intensity exercise as exercise where your heart rate is 80-85% of maximum pulse rate, says Dr. Meyers. Due to these findings, she says that “high intensity exercise may be the type of exercise that actually can increase glucose receptors.” In the end, Dr. Meyers says that these findings do support what we know about exercise, “but doesn’t clearly say what we should be recommending for humans.”
The bottom line
Exercise is good for you, says Dr. Gutierrez. “It will help you with your overall health and reduce the risk not only of cancer but of metastases.”
However, Dr. Meyers warns that we need to take these promising findings with a grain of salt. “When we see these retrospective studies, we’re relying on what people report…There are many other factors that go into reduced risk, whether it’s exercise alone, exercise and nutrition, where you live, your family history,” she explains.
Future studies need to be more randomized, especially in our survivor populations, says Dr. Meyers.
Also, a reminder that exercise is not a substitute for medical care or cancer screenings, and it’s not an end all be all, says Dr. Meyers. “Even professional athletes get cancer,” so although exercise can do a whole lot of good for you, there’s no cure for cancer yet.
Madeleine, Prevention’s assistant editor, has a history with health writing from her experience as an editorial assistant at WebMD, and from her personal research at university. She graduated from the University of Michigan with a degree in biopsychology, cognition, and neuroscience—and she helps strategize for success across Prevention’s social media platforms.