Physical Activity and Your Immune System

All aspects of our lifestyle can have an effect on our immune system and in this resource we will be looking at research around physical activity.

(The following commentary includes our own resources and material compiled from resources within the website. We like this site because it compares different areas of research on single and regular exercise.)  

How does exercise affect your immune system?

There is no easy answer, but this is an exciting area of research, with many findings coming to light. In general, researchers have recently focused on two broad approaches:

  • What does a single exercise session do to the immune system?

  • What does regular exercise do to the immune system?

Exercise is a form of positive stress on our body. Whether studying the effects of single sessions or regular exercise, researchers generally study the immune system response experienced by people during and/or after exercise.

Single Sessions
It is known that even a single session of physical activity has a temporary effect on our immune system. The stress response caused by a single session depends on how fit we are and how hard we exercise during the session.

After a session of moderate intensity exercise (e.g. 30 minutes, involving heavy breathing and light sweating) the immune system can change. More white blood cells will circulate and some will function differently. For this type of moderate intensity workout, there is no real benefit or detriment to the immune system.

If the exercise intensity is very high and is done for a long period of time (e.g., over an hour), it can be strenuous on the body. This type of stress response can make aspects of the immune system not work as well. Athletes who train very hard may be more likely to be at risk for colds after heavy training sessions or competitions.

Research has also found that after an exercise session the immune system returns to normal within one hour, for most people. This return can take longer when the workout has been heavy (long duration and high intensity).

It's during the one-hour window of "immune recovery" when athletes and others who train hard may be more susceptible to colds. The risk may be higher when heavy training sessions are done back-to-back, because the immune system doesn't get a chance to balance itself out or return to normal between sessions.

For a typical workout (e.g., light/moderate intensity, less than an hour), our immune system is not greatly affected. In fact some researchers argue that a light/moderate workout may actually help to ward of a cold.

If you are training at a higher intensity or for longer periods and experiencing regular fatigue/colds/flu etc, you may just wish to consider carefully the research described in bullet points 2,3,and 4 above. Also, if you are recovering from any illness or infection you may wish to follow the type of workout in the last bullet point to allow your immune system to strengthen again. This may take a week or two. Obviously, if you are struggling to shake off infection you should seek medical advice from your GP.

Regular Exercise

Research findings about regular exercise are equally interesting.

Those who exercise regularly have slight differences in their immune system compared to those who don't exercise regularly. These differences may have many protective benefits for our body and within the immune system itself.

A major difference is a decrease in prolonged inflammation for those who exercise regularly. For example, in people with heart disease, researchers argue that this decrease in inflammation can help to play a role in the prevention of heart disease and diabetes.

Researchers have also found that for those who exercise regularly, the immune system has a blunted stress response. This indicates the immune system has adapted to regular exercise and can tolerate this kind of stress much better. Just like our muscles adapt to exercise over time, so does our immune system.

Time to Get Moving!

In general, research has shown that regular, moderate physical activity can be beneficial to your immune system.


  • take your time, your immune system and the rest of your body will need time to adapt to regular exercise.

  • start at a duration and intensity level you can easily manage. For some that may be 30 minutes, for others, it may be 10 minutes.

  • keep in mind that positive changes in your immune system are just one small additional benefit you will get from regular exercise. There are many other health benefits as well, such as improved cardiovascular fitness and endurance, and improved flexibility, muscle strength and balance.


  • light and moderate exercise won't be harmful, and in some cases may make you feel better when you are feeling a little under the weather.

  • it's okay to have a heavy workout, but it's not necessary to do a heavy workout every day. Your body and immune system need a chance to rest and return to a normal state.


  • when you are following a heavy training regime, keep an eye on your health (e.g., watch for signs of feeling worn out or cold/flu symptoms) and try to minimise other risk factors for colds and viruses. Research has shown that consuming carbohydrates before a heavy training session may help to ward off drastic immune changes, making you less susceptible to colds.

  • other research has shown that vitamin C may also help to ward off drastic immune changes. Please click here for extra helpful information on which nutrients support your immune system.

  • if you are feeling unwell, it may be best to delay your heavy training session until you are feeling better.

© 2012 7Futures Ltd. Registered Office: Laurel Drive, 7 George Fox Lane, Fenny Drayton, Nuneaton, Warwickshire, CV13 6BE.

Registered in England and Wales No. 7945762

© 2012 7Futures Ltd. Please note that, at 7Futures, our role is to help educate and encourage our clients to take positive responsibility for their wellbeing. We are not medical doctors and are not able to offer individual medical advice. We always recommend you should discuss with your GP or other medical professional before making any changes you hope will impact your wellbeing, or that of your current/future family.  7Futures Ltd offers generic information which is for educational purposes only. The information we provided is not a prescription system and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. As such our materials, videos products and communications are for general information purposes only and should not be read as a personal recommendation for specific changes in lifestyle behaviour, nutrition, or exercise. Please click here for a clear description of our services and the relationship with you as a client. You should not participate in any of our services until you have studied this is for your benefit.

Mark Davies