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Should you exercise when sick?

How to keep your immune system happy when working out.


You’re pumped because you’ve been working out on the regular with your new exercise training routine.  And suddenly…you feel a cold or flu come on.  Thank you universe for hating you.  Right?!

Murphy’s Law.  We’ve all been in this position before.

Want in on a secret?  Sneaking in some exercise when sick isn’t always a bad idea.  In fact, if you do things correctly, promoting proper movement within your body can actually promote a stronger immunity and help you fight that annoying bug!


Exercise when sick?

Should you sweat it out?

Or rest and recover?



When your body is faced with a foreign attack, your immune system works hard to defend you.  There are 2 major types of immunity: innate (natural immunity, or what you were born with), and adaptive (acquired immunity, or what you develop over time).



Every day, bacteria, viruses, fungi, and parasites challenge our immune systems.  The environments that we encounter are a breeding ground for germs – yucky, but true!  The most common invaders can cause anything from your common cough and cold, to sinus infections, the flu, throat infections, tonsillitis, ear infections, to name a few.

Activities to consider when you’re sick include those of the low impact, low cardiorespiratory-challenge type, such as:

  • Walking
  • Light jogging
  • Swimming (but be sure to warm yourself up immediately after getting out of the water!
  • Biking
  • Qi gong
  • Tai chi
  • Yoga

Activities to avoid when you’re sick include those of the high impact, high cardiorespiratory-challenge type, such as:

  • Heavy weight lifting or power lifting
  • Endurance training
  • Sprint training or hill training
  • High intensity interval training
  • Power lifting and explosive movements or activities
  • Team sports and contact sports
  • Exercise in extreme temperatures (this can mean extreme heat, or cold)



(i) One-Time Exercises:

Brief Vigorous Exercise: No immune suppressing effect

Moderate Intensity Exercise Session: Can boost your immunity

Prolonged vigorous exercise session: Depresses your adaptive immune system

(ii) Chronic Exercises:

Chronic Resistance Training: Stimulates innate imunity

Chronic Moderate Exercise: Strengthens adaptive immunity



In a nutshell: Not moving at all and being sedentary, or on the other hand, moving too much and over exercising can lower your immunity, while something in the middle can improve immunity.  So just like Goldilocks says, the trick is finding something “juuust right!”




Of course, there are a number of variable things that we experience – some that we can control – and others that we cannot control – that can also affect our immune systems, for example:

Stress & Mood: Under situations of increased stress, cortisol and inflammation levels rise, which can have an profound effect on your immune system.  Increased cortisol levels have a widespread effect on your body and can affect everything from your mood, sleep patterns, digestion, the way your body holds onto adipose tissue (fat), the way you perceive pain.  If you add the stress of prolonged vigorous exercise, you might be overloading your body and immune system.

IL-6: IL-6 is a compound that is released by your body after prolonged intense exercise.  Increased amounts of this hormone can lead to fatigue, flu-like symptoms, and in some people, a depressed mood.

Age: Unfortunately, our innate immune systems become less efficient and can break down as we get older.  Although there’s not much we can do about aging, we can help to offset the process by staying in good physical shape, eating a well-balanced, nutritious diet, and making sure we receive adequate rest so we can heal and recover.  In general, a higher level of fitness is protective as it may help to limit your body’s stress response to exercise.

Gender: Women rejoice! Estrogens (female hormones) generally enhance immunity, while androgens (male hormones) can suppress it.  This could explain why many women tend to do better with colds and flu than men.

Sleep: As mentioned above, not getting enough rest can have a negative effect on your immune system.  Poor quality sleep and/or chronic sleep deprivation increases cortisol levels in our bodies, which increases inflammation and decreases immunity.


Some illness can indicate serious infections or underlying health issues.  If you aren’t feeling better and recovering, see your doctor immediately.  Ease back into exercise in proportion to the length of your sickness.  If you were sick for 3 days, take 3 days to ease back in.


If you feel health and simply want to prevent getting sick:

  • Stay moderately active most days of the week.
  • If you participate in high-intensity workouts, make sure you’re giving your body enough rest and recovery time.
  • Manage extreme variations your environment and stress levels, get plenty of sleep, wash your hands often.


If you are already feeling sick, let your symptoms guide you:

  • In addition to exercise stress, consider the other stresses you may be managing  in your life, or example psychological stress, environmental, personal stress, work stress.
  • With a cold / sore throat (with no fever, or body aches / pains), easy and light exercise is likely fine as tolerated.  You probably should avoid vigorous activity, no matter how long in duration.
  • If you have a systemic illness with fever, elevated heart rate, fatigue, vomiting, diarrhea, muscle and joint pain / weakness, and enlarged lymph nodes, get some rest!  If you have a serious illness or virus and you exercise and/or subject your body to more stress, you could potentially be causing problems by over challenging your body and your immune system.


What the expert, Dr. John Berardi, of Precision Nutrition has to say: “Unless you’re feeling like a train wreck, I always recommend low intensity, low hear rate “cardio” during the first few days of sickness.  Generally I prefer 20-30 minute walks done either outside (in the sunshine) or on a home treadmill (if you can’t get outside).  If you keep the intensity low and the heart rate down you’ll end up feeling better during the activity.  And you’ll likely stimulate your immune system and speed up your recovery too.  But even if you don’t speed up your recovery, you’ll feel better for having moved.


**Disclaimer: This article is not meant to be a replacement for medical advice. If you are suffering from any cold, flu, or unusual health symptoms, please see your healthcare provider for appropriate management**


Author: Dr. Katie Au

B.Sc. Kin (Hons), D.C., D.Ac, CSCS, FCCRS©, ART®, GT®

Toronto Chiropractor | Acupuncture Practitioner | Certified Strength and Conditioning Specialist


Reference: Dr. John Berardi, Precision Nutrition

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