How Much Exercise Is Healthy for Your Immune System?

There is no question that exercise is healthy. Regular training not only strengthens your body, but also can improve your mood by decreasing stress and increasing endorphins, which are potent chemical signals in the brain that regulate pain perceptions and also trigger feelings of euphoria. But can too much of a good thing be bad? Turns out that constantly challenging your body can cause stress, especially on your immune system.


What is the immune system?

The immune system is the central regulator of your body’s defense to infection. Whether it be bacteria, viruses, or fungi, if the body detects a foreign pathogen (i.e. fancy word for bacteria, virus, or fungi), your body will mount a tightly regulated and coordinated response to fight off the infection. This response involves two branches of the immune system: the innate and adaptive systems. Think of the innate as the first line responders. This branch first encounters the infection and then “warns” the adaptive system to get ready to fight off the infection. With both arms working in unison, the immune system is able to reign in the pathogen and clear the infection.


How is my immune system affected by exercise?

While physical activities strengthen the immune system, the dose makes the poison, even when it comes to exercise. The immune system reacts to exercise both immediately, and also in the long term. Depending on the duration and intensity of your workouts and recovery phases, your body will either find or lose its balance. By pushing your individual limits too often and without the necessary rest and recovery in between, you’ll end up weakening your immune system. A weakened immune system can lead to increased risk for infection as well as elevated rates of illness. Therefore, it is important to learn and know your boundaries when it comes to working out.


Is there such thing as too much exercise?

Especially after hard training sessions it’s vital to listen to your body. After a hard workout, the number of immune cells in your body are temporarily reduced, as is their power for fending off intruders. Pushing yourself to your limits during a workout can be really dangerous for your immune system. The respiratory tracts are especially affected: coughing and a running nose often go hand in hand with long endurance training. Three hours and up to several days after an intense sports session, your risk of getting sick is increased and your body’s defenses are weakened.  


How can I strengthen and support my immune system?

Training in reasonable “doses” helps to boost your immune system.  Just don’t sign up for a 100K or an Ironman without having the proper training base. Start slow and build up distances incrementally. Also, focus on sufficient rest and recovery periods that will not only boost your health but also improve your performance. R&R can come in the form of a good night’s sleep, logging some couch time (hi there, Netflix!), and/or eating a nutritious and balanced diet.


If you’re sick, you’re sick

You feel a lack of energy while first signs of a cold start appearing? Even a little cold can really throw your body off track. If you feel first symptoms, avoid hard training sessions. Your body needs a lot of energy to fight off a cold or flu. If you continue working out, you’ll contribute to weakening your immune system even more. And that’s definitely not what you want to do. When you’re sick, accept it. Go easy, take care of yourself and wait until you feel better!



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