If you exercise regularly, you have a lower risk of developing cancer – as compared to your peers who may not work out.

This is believed to be because the rise in adrenaline that results from exercising, helps to increase the production of, and activates the cells that destroy cancerous tumours.

For example, a Norway study published in the International Journal of Cancer showed that men who exercised once a week had 30 per cent lower chance of getting prostate cancer compared to those who did not exercise at all. Increasing the frequency and duration of the exercises, reduced this risk further.

Dr. Joanna Lin, 51, a medical oncologist at the Gleneagles Medical Centre, also agrees with this. She said, “Yes, exercise does help to reduce the risk of developing cancer, most commonly breast and colon cancers. Other cancers that are affected by exercise are prostate, uterus (womb) and lung ones.”

She added, “It does this in a variety of ways. The most obvious is a reduction in body fat. Excess body fat produces excess female hormones which are a risk factor for breast and uterine cancers, and other hormones and inflammatory mediators which can increase the risk of other cancers.”

For example, a 2007 study done by the National Cancer Institute in the United States, found that 34,000 new cases of cancer in men (4 per cent) and 50,500 in women (7 per cent) had been due to obesity. Though the percentages had varied amongst different types of cancers, the same study found that it was as high as 40 per cent for endometrial (inner lining of the uterus) and oesophageal (throat) cancers.

Added Dr. Lin, “Exercise also improves immunity and body defence mechanisms.”

For example, this could mean that a regular exercise regime, could ward off common colds – as it may help to flush bacteria out of the lungs before it develops into a full-blown cold. Also, exercise strengthens the body’s natural immune system, thus making it more effective in detecting and warding off illnesses before they infect the body.

Moderate to high intensity exercises are the most useful

So exactly what types of exercise then, does the oncologist recommend? She said, “The best sorts of exercise are moderate to high intensity ones, about 30 to 60 minutes per day.”

Such exercises that can work up the heart rate and may include running, cycling and swimming. And for the benefits to be reaped, one must be exercising in the medium to high heart rate zones, which equates to at least 65 to 70 per cent of one’s maximum heart rate.

So it is no wonder that Dr. Lin herself is an Ironman triathlete – having successfully completed the gruelling 3.8km swim, 180km bike ride and 42.195km run, more than once.

Said the doctor, “I have tried over the years to tell friends and family members, and especially patients, how important exercise is to their general health, not just for cancer prevention. I try to lead by example, and hope that this has helped convince some of them to start thinking about exercise as a regular lifestyle choice.”

People make excuses about exercising

However, the oncologist feels that many people, though they know about the benefits of exercising, keep on procrastinating regarding the beginning an workout regime. Said Dr. Lin, “Many of them are just too lazy to start and maintain a level of exercise that is beneficial. They give themselves a variety of excuses not to start. Unfortunately, sometimes it takes a significant life event to make people start exercising.”

She added, “I think the best way is to ask oneself if there is an activity that they enjoy, for example, walking in the park in the evenings whilst listening to music, dancing, and so on, then slowly build it up from there.”

Exercise can help cancer patients recover faster

However, exercising does not purely aid in the prevention of cancer. It also helps current cancer patients. Added the doctor “Exercise has been shown to help cancer patients recover faster and possibly help with cancer treatment.”

She also cited an article written about a February 2016 study done by researchers from the University of Copenhagen – on mice suffering from lung cancer tumours. Two groups of mice were used in the study – one group had exercise wheels to run on, but the other was not given any.

The mice in the study, who had spent time running on the wheels, had their tumours shrunk by 50 per cent as compared to the mice who did not get exercise wheels. Based on this, the researchers believed that the adrenaline produced by such high-intensity workouts, help to ward off the cancer cells.

More achievable for cancer survivors to exercise

But despite this though, Dr. Lin admitted that it may be hard for cancer patients to adopt a vigorous exercise regime though – due to the nature of their condition as well as the side effects of the cancer treatment. She said, “It can be challenging for cancer patients to undergo vigorous exercise while they are on treatment, so often they can try and do some light to moderate exercise, or whatever their body can tolerate.”

She added, “Exercise for cancer survivors is probably more important and achievable. This has been shown in several studies – which have proven that regular exercise in cancer survivors reduce the chance of relapse and increases their chances of survival, in particular, breast and colon cancer survivors.”