Scientists have long known that athletes have a lower risk of developing cancer than the rest of us. They believed this was due to their healthy diet and non-smoker status. However, a study has now found that it is actually exercise itself that helps protect against cancer and can even improve your chances of surviving the disease too.
Dr Hojman of The Copenhagen University Hospital has discovered that adrenaline released by the body during exercise is the key to these beneficial effects. Her team analysed the effect on cancer cells in mice who could run on an exercise wheel versus mice who had no exercise other than walking around their cages.
Their first finding was that when mice were exposed to a chemical known to cause liver cancer, only 33% of exercising mice got cancer compared to 75% of the non-exercising mice. What’s more, the tumours that did grow in the exercising mice were less than half the size of those in their sedentary counterparts.
This was because the cancers from exercising mice had a higher number of natural killer cells, the body’s immune cells cells. These cells target and destroy cancer cells helping to shrink the tumour. They rely on two chemicals adrenaline and IL-6 to help them function properly and these are the chemicals released during exercise. This, Dr Hojman believes, is the reason why exercise helps improve cancer survival rates.
Infact, when her team injected non-exercising mice with adrenaline and IL-6, the rodents’ immune systems attacked the tumours as effectively as if they had been exercising regularly.
Dr Hojman said that the combined hormone therapy could help people who are too old or too ill to exercise to still benefit from the cancer-fighting effects of physical exertion. However, Dr Hojman is vehemently against the idea that ‘exercise in an injection’ could put an end to the need to exercise in otherwise healthy individuals. She is keen to point out that exercising regularly has other proven benefits such as reducing chronic inflammation and the body’s fat deposits which are known to help reduce the risk of developing cancer in the first place.