One of the top marathoners in my city has leukaemia. That came as a great shock to many because this guy has been competing in marathons around the world for years, even in the Arctic and Antarctica, and he seems super fit. Few can match his stamina and endurance levels. What went wrong?

No one can say for sure in this particular case but Dr. Ben Tan, sports physician and head of Singapore’s Changi Sports Medicine Centre, warns against overdoing exercise. Regular exercise has been proven to boost the production and circulation of immune cells, the frontline soldiers against bacteria and viruses. However, going overboard will drag your immune system down.

“Excessive exercise stresses the body and taxes the immune system” says Dr. Tan. “Cortisol – a stress hormone that is released following prolonged, high-intensity exercise – suppresses the immune system.” In addition, the immune system will be made to channel its resources to repairing tissue damaged from excessive exercise, at the expense of its defence function.

The key to building up your immunity lies in REGULAR and not sporadic exercise. This is because the benefits which the immune system gains are not lasting. “The immune system is enhanced immediately after exercise, but returns to its baseline within a few hours,” he says. Regular exercise, therefore, prolongs the positive benefits.

Weekend warriors, take note! If exercising daily seems difficult to fit into your schedule, try doing something achievable, like a 20-minute walk after lunch or dinner. Take the stairs whenever possible. Park the car a little further away so you’ll have to walk a bit more. Make these little changes a daily habit, and you’ll boost your immune system and see an improvement in your health overall.