Over a month ago, I was on Instagram when I saw a video of a scientist who said, “They put the blood of people exercising on cancer cells, and the cancer cells died.”
By now, we already know that exercise is crucial for optimal health, but this angle, that the blood of people who exercise may be able to kill cancer cells, will definitely be strange to most of us.
Exercise-conditioned serum refers to blood serum collected from an individual immediately after a bout of physical exercise.
When a person exercises, their muscles, organs, and immune system secrete bioactive molecules into the bloodstream. Blood taken immediately after acute, moderate-to-high-intensity exercise is rich in these mobilised molecules.
In research settings, scientists separate the serum from this post-exercise blood and use it to culture cells in a laboratory (an in vitro environment).
This allows them to observe the direct biological effects of an individual’s “exercised” blood.
Researchers predominantly use exercise-conditioned serum in exercise oncology to understand how physical activity prevents or helps manage cancer.
Let us look at its application in research:
Tumour suppression
When various cancer cell lines (such as breast, prostate, lung, and colon cancer cells) are cultured in exercise-conditioned serum, the serum often inhibits cancer cell growth, limits cell proliferation, and promotes cell death (apoptosis), compared to serum taken at rest.
Identifying mechanisms
By analysing the post-exercise serum, scientists can pinpoint exact molecules (like the myokine Oncostatin M) or immune cells that target and slow tumour growth.
Evaluating exercise intensity
Research indicates that the cancer-suppressing effects of post-exercise serum are heavily dependent on exercise intensity.
Serum drawn after high-intensity exercise generally yields more pronounced inhibitory effects on cancer cells than serum drawn after mild activity.
Let us explore some of the research carried out on this.
Research from Edith Cowan University has shown that exercise may be a key weapon in cancer patients’ battle against the disease.
Exercise causes muscles to secrete proteins called myokines into the blood, and researchers from ECU’s Exercise Medicine Research Institute found that these myokines can suppress tumour growth and even help actively fight cancerous cells.
A clinical trial saw obese prostate cancer patients undergo regular exercise training for 12 weeks, with blood samples taken before and after the exercise programme.
Researchers then applied the samples directly to living prostate cancer cells.
Study lead, Professor Rob Newton, said the results help explain why cancer progresses more slowly in patients who exercise.
He said, “The patients’ levels of anti-cancer myokines increased in the three months. When we took their pre-exercise blood and their post-exercise blood and placed them over living prostate cancer cells, we saw a significant suppression of the growth of those cells from the post-training blood.
“That’s quite substantial, indicating chronic exercise creates a cancer-suppressive environment in the body.”
Professor Newton said he was inspired to research the link between exercise and cancer after his father was diagnosed with the illness, and his health deteriorated after he was advised to rest rather than remain active.
A Finnish study from the University of Turku, Finland, also showed that just 30 minutes of exercise can increase the proportion of tumour-killing white blood cells in the bloodstream of breast cancer patients.
White blood cells, which are part of the immune system, fight against cancer, bacteria, and viruses.
However, not all white blood cells destroy cancer cells, and some can even promote cancer growth.
The most important cell types that destroy cancer cells are cytotoxic T cells and natural killer cells.
Cell types that support cancer growth include regulatory T cells and myeloid-derived suppressor cells.
“The balance of different types of white blood cells determines whether the immune system works to destroy cancer or support it. If there are more cancer-destroying cells than cancer-promoting cells in the tumour area, the body is more capable of fighting cancer,” said lead author and doctoral researcher, Tiia Koivula, also from the University of Turku.
Twenty breast cancer patients who had just been diagnosed and had not yet started treatment participated in the study.
During the study, the patients pedalled a bicycle ergometer for 30 minutes at a resistance level of their choice.
Blood samples were taken before, during, and after exercise.
The samples were analysed to calculate the amount of different white blood cell types, and the values recorded during exercise were compared with those recorded at rest.
During exercise, the amount of several white blood cell types increased in the bloodstream.
The number of cancer-destroying cytotoxic T cells and natural killer cells increased the most.
On the other hand, the number of cancer-promoting regulatory T cells and myeloid-derived suppressor cells did not change.
The researchers also found that the proportion of natural killer cells increased significantly, while the proportion of myeloid-derived suppressor cells decreased.
Koivula said, “We found that during exercise, the number and proportion of cancer-destroying cells increase in the bloodstream, while the proportion of cancer-promoting cells either stays the same or decreases. However, it is still unclear whether these changes seen in the bloodstream also lead to changes in white blood cell counts in the tumour area.
“In this study, the number of almost all white blood cell types returned to resting values one hour after exercise. With current knowledge, we cannot say where the white blood cells go after exercise, but preclinical studies have shown that cancer-destroying cells can migrate into the tumour area.”
The researchers also analysed whether different types of breast cancer affect exercise responses in white blood cells.
They found that the larger the tumour, the less the number of natural killer cells increased. They also observed that if the breast cancer was oestrogen- and/or progesterone-receptor positive, the number of cytotoxic T cells increased less than in hormone receptor-negative cancers.
“In our previous study, we found small indications that the type of breast cancer might affect the effects of exercise on white blood cells, which is why we wanted to examine it further. However, the correlations we found were not very strong and therefore, no decisive conclusions can be drawn from the results. According to current knowledge, it is beneficial for all cancer patients to exercise, and our recent study supports this notion,” Koivula said.
Currently, exercise-conditioned serum remains strictly an experimental research tool used mainly in laboratory studies to understand how physical activity alters blood chemistry. It is not approved or used as a standard clinical treatment for patients, but it strongly underscores the health benefits of exercise.
If you do not already own athletic shoes, please get one. Your overall health will thank you if you start exercising.
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