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  • Sandy Jolles

Feeling sick? To exercise or not to exercise...

Updated: Feb 14, 2020

A common topic of confusion I hear is whether or not to exercise when sick. Is rest the best medicine? Or is it OK to sweat it out? Before we delve in, I wanted to share just a little anatomy lesson about our immune system:


We have ten times more bacterial DNA than human DNA, which really means we are composed of trillions of bacteria and microorganisms. At the same time, we're also exposed to a wide array of infectious agents, parasites, and symbiotic microorganisms. These invaders can be culpable for many upper respiratory tract infections, such as colds, influenza, tonsilitis, throat infections, and more.


Luckily, even though we're exposed to a germ jungle, we have our robust immune system to defend us against microbial invasion. These immune cells fight the invaders through our mucus membranes, spleen, and lymph nodes (so they first make contact in our mouths, gut, lungs, and urinary tracts).


The immune system has two branches: innate and adaptive. The innate immune system is our first line of defense, and includes physical barriers, chemical barriers, and protective cells. The adaptive immune system is more sophisticated and specialized by preventing pathogens from colonizing and fighting infections.


OK, let's get back to the original question: should you workout when sick? To answer this, we must first differentiate 'working out' from 'moving the body.' A heavy workout where you're sweating profusely can trigger a stress response which can make our immune systems work harder (thus, maybe not the best when you're fighting off an illness). However, with a non strenuous work out, such as gentle yoga, walking, T'ai Chi, low impact biking, etc, this can actually boost immunity. In general, a low to moderate workout will confer energy boosting enzymes without creating any immune-compromising stress on the body.


The BIGGEST thing to avoid when sick is any prolonged vigorous exercise session, such as a long run, or extremely taxing workout as it will depress the adaptive immune system for up to 72 hours. For example: in the 1987 Los Angeles Marathon, 1 out of every 7 runners became sick within a week of the race. That level of exertion puts way too much stress on the body...even if you weren't on the way to a cold!


Let your symptoms and your perceived level of exertion be your guide when it comes to exercising during a sickness...and aim to avoid heavy strength training, HIIT, or endurance straining. Lastly, please PLEASE aim to avoid the gym when you feel anything coming on. Gyms are hotbeds for spreading germs and viruses, so please come back after your sickness fog has lifted.


We all thank you! :)






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