Exercise and the immune system: what is the link?

Exercising and moving our body provides many benefits to the human body. Not only does it improve our cardiovascular and bone health, but it also helps to manage weight, reduce the risk of disease and improve our ability to do normal day-to-day tasks. So does that mean exercise improves our immune system?

Well, there can be a ‘yes’ and ‘no’ answer to this question. Whilst yes, exercising has an immense benefit to our immune system, it is important to note that this varies between the type, frequency, duration and intensity of the exercises you are undertaking.

Firstly, let’s start with understanding what our immune system

The immune system is the body’s key defender against infections and illnesses. This vital system protects our body from harmful substances, germs and bacteria that can make us unwell. It is a system that works hard in the background, however, once it stops working effectively due to coming into contact with aggressive germs or other external factors, it loses its strength to fight off bugs and causes us to become sick. 

There are many ways we can support our immune system to be strong including eating well, ensuring we have abundant sources of vitamins and minerals, having adequate rest and reducing stress in our day-to-day lives, minimising our intake of alcohol and exercising regularly.

So what kind of exercise helps our immune system?

According to the research, moderate-intensity style training is the best type of exercise to support our immunity. This includes exercise that is around 70% of our maximum heart rate, so a balance of moderate cardiovascular and resistance-based training is key.

Is there such a thing as too much exercise?

Absolutely! It is important to know how much exercise we should be doing to help our immunity, but it is important to note that undertaking vigorous types and amounts of exercise on a regular basis can have a detrimental effect on our immune system. This is because intense exercise is putting our body into a stressed state for an extended period of time, which is not optimal when it comes to preserving the energy required to support our immune system.

So what types of exercise are the most beneficial to support our immune system?

Let’s start with moderate-intensity cardiovascular exercise. This is where our heart rate is steady and is not in a heightened state (as mentioned above, hovering around 70% of our maximum heart rate). This could include exercises such as walking, slow-paced running, swimming or cycling to name a few. The implementation of cardio exercise increases our blood flow, stimulating our immune cells to circulate around our body at a higher rate to find and fight off pathogens and viruses that may be circulating in the body.

For resistance-based training, we would be focused mostly on the hypertrophy style of training, where we are undertaking a number of repetitions and sets that stimulate muscle atrophy, rather than powerlifting style training which is focused on an exercise (for example the squat) and loading the bar with a significant amount of weight for a lower number of reps. Doing a hypertrophy-specific style of training, 8-15 repetitions and 3-4 sets per exercise 2-3 times a week, is encouraged to ensure we are creating the building blocks for muscle protein synthesis. Whilst resistance-based training isn’t necessarily directly supporting the immune system, it is supporting our overall body composition and metabolism, leading to maintaining a healthier body weight and body composition, reducing the inflammation a higher weight can cause to the body.

What about High-Intensity Interval Training?

There is mixed research regarding the effectiveness of High-Intensity Interval Training (HIIT)-based training on our immune system, however, the impact is in the type and frequency of this style of training. When focusing specifically on your immunity, focusing on the recommendations above would be more effective to see an improved result. However, if you are undertaking HIIT-based training, whether it is in the form of HIIT classes, sprinting or more vigorous training such as cross fit, it is then important to be focusing on recovery to allow your body to move into a rest and digest state.

The reason it is important to focus on rest and recovery after this style of training is that to enable our immune system to work efficiently, we want to be reducing inflammation wherever we can (and HIIT-based training is likely increasing this inflammatory effect due to the intensity of the training). According to an article from Dr Nieman, “when immune cells try to function with inflammation, it puts the immune system in a chronically inflamed state”, making it harder for our body to fight infection.

Should I be exercising when I am sick?

Similar to the point above, it depends on the impact the illness you are experiencing is having on your body. If you have had a couple of days off the gym due to a sore throat and you are seeing an improvement, starting to move again might be supportive for you. However, if you are still experiencing symptoms or if the symptoms you have are getting worse, taking some more time off exercise is likely going to lead to you getting back into your regular exercise routine a lot quicker.

The main point here however is how you transition back into exercise after you have been unwell. Some tips include:

• Starting off with some small walks and getting the blood flowing again. If you had been running previously, perhaps just check in with a walk and see how your body feels afterwards before you start running again.
• If you have been resistance training, drop back the weights! It is likely that your body needs a bit of time to get back into lifting the same weight you were when you were in full health, and you don’t want to cause an injury.
• Maybe start with some stretching and activation instead of going into a complete workout routine – again allowing the blood to flow through the muscles without high impact.
• Speak to your doctor if you are uncertain as to whether you are safe to return to your normal routine.

So does exercise boost your immunity? It is one thing in conjunction with many other health-benefitting activities or routines that you can implement to support a healthy immune system. Regular exercise in conjunction with a healthy diet, ensuring rest and recovery is a prominent part of your routine and reducing your consumption of alcohol all help to improve and regulate your immune response which is important when living a healthy life.

And if you are feeling like you are falling ill and you want to make sure your body has the adequate line of defence to fight it off, giving your body the opportunity to rest so it can get back to full health is likely the best way to get back into your regular routine a lot quicker!

Written By Paige: Female fitness expert at MotivatePT – Reps Level 3 Qualified / Pre & Post Natal