GIVE YOUR IMMUNE SYSTEM A BOOST

EXERCISE also improves the blood flow through the tissues, giving your immune cells a better chance of getting to anywhere they are needed. During exercise, increased levels of a hormone called catecholamine stimulates the white blood cells to flow into the bloodstream, improving immunity throughout the body.

This explains why people who regularly perform more than two hours of moderate exercise a day have 30 per cent fewer chest infections than those with a sedentary lifestyle

And while few of us will ever train as hard as this, anyone who does two-three hours of moderate exercise a week will still see benefits to their immune system.

This is particularly important as we get older, too, because our immune systems become less efficient with age.

Exercise is also important for boosting the immunity of anyone who is overweight or obese as their bodies produce fewer natural killer cells (a type of white blood cell) and cytokines (small proteins which coordinate the body’s response to infection) — both are key parts of our natural defence system. When you exercise you set off a chain of chemical processes in your body that results in greater activity by your own natural killer cells.

And as your body finds its own natural defences boosted, so your immune system perceives less need to circulate inflammatory chemicals to combat disease. High levels of inflammation can, over time, cause cell mutation, as we’ve seen — so this is another mechanism by which regular exercise directly helps to reduce your cancer risk. Moderate, regular exercise also reduces blood levels of prostaglandins, which is beneficial as these compounds play a role in dealing with injuries such as wounds — but can also trigger chronic inflammation if they are present in excessive quantities.

Regular exercise directly lowers blood levels of the hormones oestrogen and leptin. This may explain the fact that post-menopausal women who exercise have a lower risk of hormonerelated tumours such as those of the breast, uterus and ovary than those who don’t.