It’s a quite common problem, you’ve just got yourself into your running shoes for the first time in years, you’re feeling good, then you get hit with a cold or the flu and it sets you back. What’s the best solution? Should you make a herbal tea, sink into the sofa and get some rest? Or persevere with your exercise routine? Before we move onto that question, it’s important to think about what happens to your body, and in particular, your immune system, when you exercise.

Exercise and the immune system

When you perform exercise at a higher intensity (over 7 on the RPE scale) for sustained periods, it causes something known as ‘immunosuppression’, which means that it decreases the function of your immune system. However, this is only a temporary effect, and within 12 hours or so, your immune function will be back to its pre-exercise level.

More importantly, however, is the positive long-term impact that exercise has on your immune function. Your immune system is made up of lots of different cells working in unison to fight infections and diseases, such as white blood cells and natural killer cells. Over time, exercise increases the number and performance of these microscopic wonders. This means the fitter you are, the better your immune system will function!

One study compared the number of natural killer cell activity between marathon runners and sedentary individuals, and found that the marathoner’s natural killer cell activity was 57% higher than those in the sedentary group!

Back to the original question, should you exercise when you’re unwell?

We know that when you exercise at a high-intensity for a sustained period, it will cause your immune function to decrease temporarily. When you are unwell, you need your immune system to be working at its capacity to help fight the virus or infection, so completing high-intensity exercise is not recommended during these times.

However, what research has also shown is that lower intensity exercise (less than 7 on the RPE scale), does not cause immunosuppression. In fact, movement is essential in maintaining circulation and communication between the body’s systems.

Keep it low

When you’re unwell, although you may be feeling like exercise is the last thing you want to do, low-intensity exercise can ensure that your body’s systems are working effectively. This will give your immune system the opportunity to fight off the illness.

Below we have put together a list of different exercises and activities that you can do when you are unwell:

  • Walking

To summarise, when you are unwell, of course, you’ll need your rest. It’s important to keep in mind that sleep is essential in the recovery from illness or infection, so try to get in a few extra hours if possible too! But spending a small amount of time doing some gentle exercise could help support your body’s systems, ensuring they are at their best to fight off the illness!

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