Exercise boosts immune system

IF you want to beat colds and flu, exercise rather than extra vitamins may be your key to fending off infection.

"Did you know that exercise has been shown to boost your immunity to infections?" says Dr Linda Steyn, president of the South African Society of Physiotherapy.

The society is encouraging South Africans to start exercising during national physiotherapy back week, which runs this week until Sunday September 14.

Says Steyn: "In fact, an interesting study published recently shows that exercise increases the diversity of the friendly bacteria in your digestive system – bacteria which are intimately involved in helping our bodies thrive and fight off infections.

"We tend to think of exercise as an activity that works our muscles, making us taut and trim, but it is actually essential for the entire body, including internal organs and systems.

"Of course, exercise strengthens the heart muscle, improves our intake of oxygen and reduces blood pressure, all of which makes us healthier, stronger and better able to deal with infections. But research such as the gut bacteria research emphasises how exercise impacts on other, less well-known contributors to our immunity."

The lymphatic system, for example, is critical to our immune system; it not only helps us fight off infections but is one of our most important defences against cancers and auto-immune diseases. And the lymphatic system has no pump of its own (as the blood circulation has the heart): it is reliant on exercise to keep the lymph fluid moving.

In fact, there's some indication that lymph fluid circulates better in people who exercise regularly than those who lead sedentary lives. Moderate exercise operates directly on our immune systems, increasing the body's production of natural killer cells.

"Regular moderate exercise has an enormous impact on our susceptibility to infection," says Steyn, quoting research done by Professor Mike Gleeson of Loughborough University.

Gleeson has been studying exercise's impact on upper respiratory tract infections (URTIs).

Says Steyn: "If you have a tendency to be a couch potato, then you probably have an average risk of catching an infection – typically two to three URTIs per year. Research shows that those undertaking regular moderate exercise (for example, a daily brisk walk) can reduce their chance of catching a respiratory infection such as a cold by up to almost a third."

This effect seems to be due to an improved immune system as a cumulative effect of exercising regularly over time. But the key here is moderation.

Says Gleeson: "Conversely, in periods following prolonged strenuous exercise, the likelihood of an individual becoming ill actually increases. In the weeks following a marathon, studies have reported a two- to six- fold increase in the risk of developing an upper respiratory infection."

Says Steyn: "Strenuous exercise does put you at increased risk of infections, but for most people whose lives are relatively sedentary, a commitment to doing more gentle exercise – such as a daily walk or gentle jog – will only have a positive effect on their ability to fight off infections."

Before starting an exercise programme, get an assessment from a medical professional. This week physiotherapists will offer free assessments. Call the society on (011) 615-3170 to find out more.