Should I exercise when I’m sick?

exercise and sicknessI get this question often, especially at this time of year.

Should I exercise when I’m sick?

It’s peak season for colds, coughs, flu’s, sinusitis, tonsillitis, throat & middle ear infections at the moment so I thought I would share some insights with you.

These frustrating illnesses knock us about and really get in the way of our training goals. There are many theories out there of what to do when the old sniffles comes to town or the hammering head cold and these two would be the front runners;

“you should sweat it out” and “bed rest is the way to a fast recovery”

So which one is it?

First we need to clear one thing up. There is a difference between “working out” and “physically moving the body around”.

A structured workout routine — one where you’re breathing heavily, sweating, working hard, and feeling some discomfort — awakens a stress response in the body.

When we’re healthy, our bodies can easily adapt to that stress. Over time, this progressive adaptation is precisely what makes us fitter and stronger.

But when we are sick sometimes a tough workout and be too much for our immune systems to handle.

But before you dive for the couch, non-strenuous activity won’t harm you and it can actually do some good.

By non-strenuous activity I mean:

  • Walking
  • Riding
  • Doing the lawns

All of these activities have been proven to boost immunity.

They aren’t intense enough to put stress on the immune system. They have shown to actually help you feel better while not feeling well.

So you are probably wondering, “What about intense work outs”?

As we all know, there are different levels of work out intensity; low, moderate, high and all those other bits and pieces in between.

The other factor is what is intense for one person, may not be for another.

So I would suggest letting your own perceived level of exertion be your guide.

As a general rule, a low intensity work out will leave you feeling great and energised, and the other end of the spectrum,  a high intensity session will deliver your butt to you on a platter!

If you are feeling really sick, it makes sense to avoid having your butt handed to you.

Let’s look at why?

How exercise affects the immune system

Exercise may play a role in both our innate and our adaptive immune response.

Here’s how:

  • After one prolonged vigorous exercise session we’re more susceptible to infection. For example, running a marathon may temporarily depress the adaptive immune system for up to 72 hours. This is why so many endurance athletes get sick right after races.
  • However, one brief vigorous exercise session doesn’t cause the same immune-suppressing effect. Further, just one moderate intensity exercise session can actually boost immunity in healthy people.
  • Interestingly, chronic resistance training seems to stimulate innate (but not adaptive) immunity. While chronic moderate exercise seems to strengthen the adaptive immune system.

In the end, here’s the pattern:

  • Consistent, moderate exercise and resistance training can strengthen the immune system over time. So, by all means, train hard while you’re healthy.
  • But single high intensity or long duration exercise sessions can interfere with immune function. So take it easy when you’re feeling sick.
Here are some text book guidelines for exercising while sick


  • Day 1 of illness:
    Only low intensity exercise with symptoms like sore throat, coughing, runny nose, congested nose.
    No exercise at all when experiencing muscle/joint pain, headache, fever, malaise, diarrhoea, vomiting.
  • Day 2 of illness:
    If body temp >37.5-38 C, or increased coughing, diarrhoea, vomiting, do not exercise.
    If no fever or malaise and no worsening of “above the neck” symptoms: light exercise (pulse <120 bpm) for 30-45 minutes, by yourself, indoors if winter.
  • Day 3 of illness:
    If fever and symptoms still present: consult doctor.
    If no fever/malaise, and no worsening of initial symptoms: moderate exercise (pulse <150 bpm) for 45-60 min, by yourself, indoors.
  • Day 4 of illness:
    If no symptom relief, no exercise. Go to doctor.
    If fever and other symptoms improved, wait 24 hours, then return to exercise.
    If new symptoms appear, go to doctor.

Note: Some illnesses can indicate serious infections. So if you aren’t feeling better and recovering, see your doctor.

Also note: 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.



 So to summarise, here is an activity cheat sheet for you


Activities to consider when you’re sick.

  • Walking
  • Jogging
  • Swimming
  • Biking
  • T’ai Chi
  • Yoga

All of these would be done at a low intensity, keeping your heart rate low. They’d also preferably be done outdoors in mild temperatures. Inside is fine, though, if you can’t get outside.

Activities to avoid when you’re sick.

  • Heavy strength training
  • Endurance training
  • High intensity interval training
  • Sprinting or power activities
  • Team sports
  • Exercise in extreme temperatures

And, for the sake of the rest of us, don’t train with others. When training with others, you’re much more likely to spread your germs. Viruses spread by contact and breathing the air near sick people.

So, if you feel up to physical activity, again: do it outside or at your home.

We all thank you in advance.