The connection between exercise and cancer has long been a mystery intriguing to both oncologists and exercise physiologists alike.
Exercise has largely been associated with lowered risk of cancer; however, there is a sort of paradox in that exercise also causes an increase in inflammation, which is a contributing factor for many cancers. A new study conducted on mice has finally shed light on the paradoxical connection between cancer and exercise. The study suggest that exercise changes the way the immune system deals with cancer by boosting adrenaline, certain immune cells and other chemicals that together reduce the severity of cancer or fight it off altogether.
To try and better understand this simultaneous phenomenon, scientists at the University of Copenhagen in Denmark closely examined what happens in mice that are at high risk for cancer. They started by gathering a group of adult lab mice, who generally love to run. They then implanted melanoma skin cancer cells into the mice before providing half with running wheels and the other half without so they remained sedentary. After four weeks, a significantly lower number of runner mice developed full-blown melanoma as compared to the group of sedentary mice.
The next step was to reverse-engineer the previous process. They began by drawing blood from both the exercising and sedentary animals and cells from any tumors in both groups. After carefully examining the samples, they found much higher levels of adrenaline in the exercising animals. They also found higher levels of interleukin-6 in the blood of the runners, which is a substance released by working muscles believed to both increase and decrease inflammation in the body. Most importantly, they found higher numbers of immune cell “natural killer” which is known to be a potent cancer fighter. Somehow these three things must be entwined.
To further discover the reasoning behind their findings, the scientists repeated the experiment with different variations. The results were remarkable. They found that the secret ingredient was the adrenaline all along. High levels of adrenaline are what sent biochemical signals to the IL-6 cells, who in turn activated the natural killer cells in the bloodstream and directed them toward the tumors.
Although it’s difficult to say whether the same process will re-occur in humans, the results are surely hopeful. It is known that running induces adrenaline in humans and also increasespo the production of natural killer immune cells. If anything will give you the incentive to get up and move, it should be this.