We're headed into the end of the year! Along with the school holidays, Christmas and cooler weather, also comes influenza. Did you know Singapore has 2 big flu seasons? One in June, and the other in December.  

Picture this scene. You fill up your water bottle at the gym, bend down to tie your shoelaces, and stand up -- just in time to catch a thorough spraying from a guy sneezing next to you. Gross. 

You're thinking, "doesn't this coughing, sneezing, inconsiderate dude belong at home resting?! Not here infecting all the gym equipment!" Well, this results in the age old question: when you are not feeling well, should you "sweat it out" by exercising or recuperate in bed? Let's clear the confusion once and for all. 

Your immune system

Every single day, bacteria and viruses are attacking our bodies. It's a germy jungle out there. Thankfully, your immune system has a way of protecting itself. It does this through physical barriers like mucus lining in your nasal passages, chemical barriers like stomach acid, and producing protective cells like white blood cells. 

Things that affect your immune system

First, let's get one thing clear: There's a difference between "working out" and "physically moving the body." A workout in which you find yourself sweating hard, breathing heavily, and feeling some physical discomfort, awakens a stress response in the body. When we are healthy, our bodies can easily adapt to that stress. In fact, this adaptation is what makes us fitter and stronger over time. But when we are sick, the stress of a tough workout can be more than our immune systems can handle.

So, should you exercise when feeling sick?

Prolonged vigorous exercise is definitely out when you are feeling under the weather (no marathon running, duh). But some non-strenuous movement can actually help your immune system to battle the flu germs. These are activities such as: Walking, yoga, light swimming, and low-intensity cycling. 

These activities are not super intense until it poses serious immunity-compromising stress on the body. But they boost your heart rate sufficiently enough to help your body fight illness. Research shows that even one session of moderate exercise seems to strengthen the adaptive immune system. Even better if you do it regularly.

Also, it's important to return to your strenuous workout routine gradually. A good tip to follow is to return to heavy exercise in proportion to how long you were sick for. So if you were sick for three days, take three days to ease back in. 

One final note: For the sake of the rest of us, we suggest exercising at home and avoiding team sports while you are sick. All it takes is a single cough, sneeze or touch and bam! -- you've spread your virus to the whole gym...