It’s a well-established idea: exercising regularly is good for your immune system. In fact, some research suggests it may reduce the risk of contracting upper respiratory infections, such as the common cold. All it takes is 30 minutes of moderate exercise five times a week to reap the benefits.
Since exercise is good for our immune system, some people might think that exercising while sick can help “flush out the sickness”. Unfortunately, when it comes to the common cold, for example, there is no evidence that exercising during illness can shorten it or make it less painful…
A well-explained upstream benefit
There are several reasons why physical exercise is beneficial for our immune system.
The first can be partly explained by the hormones that are released when we exercise. These are the catecholamines, better known by their most famous representatives, adrenaline and noradrenaline. These hormones play an important role in the functioning of our immune system by causing the rapid release of important immune cells that help detect the presence of viruses or other pathogens in the body.
They also increase the number of transfers of our immune cells between the blood where they circulate and the tissues where they may have to intervene – which is important in helping them detect and prevent diseases caused by viruses or other agents. pathogens. Research shows that exercise is a way to increase the levels of these vital hormones in our bodies.
Second point: when we practice a sports activity, the blood flow increases in order to help our body to face its increased demands imposed by the exercise. This high blood flow puts greater stress on our blood vessels, which releases specific immune cells from the lymphocyte family, natural killer cells and T cells. These lymphocytes, which can lie dormant on the walls of our blood vessels , both play an important role in destroying virus-infected cells in our body.
Physical exercise can have other beneficial effects for our fight against infections. For example, older people who exercise regularly for a month have been shown to heal skin wounds faster than members of a control group who did not exercise. This faster healing process reduces the risk of viruses and bacteria entering the body through skin wounds.
All of these mechanisms can, together, improve our immune response and thus reduce the risk of contracting infections. And you don’t have to be a regular at the gym to reap the benefits. Studies have shown that when people who did not exercise started brisk walking regularly for 40 to 45 minutes, five days a week, they saw their symptoms of upper respiratory tract infection decrease by 40 50% compared to a control group.
And when you are already sick?
Despite these benefits, it’s unclear if exercising during a cold will help you put away your tissues faster than if you didn’t.
No study has actually really looked into this at the moment, largely because it would be difficult to conduct this type of study – not least because a portion of the participants would have to be infected with a virus. to determine whether the exercise has an effect or not. Not only would this be difficult to achieve, but it is also ethically questionable.
But since exercise is good for the immune system, why couldn’t exercising during an infection improve our defenses? It seems logical…
Well, it’s already important to remember that exercise can stress the body. While beneficial in certain circumstances, it can also make immune cells less able to respond to pathogens. This may be partly because the body needs more oxygen and stored energy (in the form of glucose) when we exercise – which our immune cells also need to carry out their fight. . If the body is fighting an existing infection and at the same time is exposed to the stress of exercise, the immune response will not necessarily benefit if energy resources have to be shared.
But if there is currently no evidence that playing a sport during a cold can help you recover faster, this does not necessarily mean that you should abstain! There are just a few precautions to take.
First thing, there are a few cases where exercising is inadvisable: if you have a fever, muscle aches or vomiting, etc.
Then, you have to know how to listen to your body. If your symptoms are primarily above the neck (like a runny nose or congestion), start by exercising at a lower intensity than usual to see how you feel. If all goes well, you can gradually increase the intensity. But if this extra activity makes you feel worse, stop the effort and rest.
Another thing: think of yourself, but also think of others! If you want to exercise while you’re sick, go for it…but be careful if you’re around other people. Airway infections (colds, etc.) are contagious, so it is best not to go to the gym or gym and practice outside or at home to avoid infecting your neighbors.
Regular exercise is a great way to prepare the immune system to fight off different kinds of infections, including colds and maybe even Covid… But don’t feel like you have to engage in physical activity if you’re sick and tired . Often the best remedy for a common cold is rest and proper hydration. Having been active before will have limited your risk of finding yourself in this unpleasant situation…
This review was written by John Hough, Lecturer in Sport and Exercise Physiology at Nottingham Trent University (England).
The original article was translated (from English) then published on the site of The Conversation.