Why it’s best to avoid exercise when you have a cold – Edition du soir Ouest-France

Written by John Hogg, Senior Lecturer, Exercise Physiology, Nottingham Trent University (UK)

Exercising, even if it’s limited, is good for our health and our immune system. You might think that exercising when you have a cold helps you recover faster… In fact, rest and good hydration are better than physical activity.

It’s a well-established idea: exercising regularly is good for your immune system. In fact, some research suggests that it may reduce the risk of 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 may think that exercising while sick can help “get off the sickness”. Unfortunately, when it comes to colds, for example, there is no evidence that exercising while sick can shorten it or make it less painful…

The upstream benefit is well explained

There are several reasons why physical exercise is beneficial for our immune system.

The first reason can be explained in part by the hormones that are released when you exercise. These are 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 immune cell transfusions between the blood where they spread and tissues where they may have to intervene – which is important in helping them detect and prevent diseases caused by viruses or other disease-causing agents. Research shows that exercise is a way to increase the levels of these vital hormones in our bodies.

Point two: When we engage in a sporting activity, blood flow increases to help the body meet the increased demands posed by exercise. The increased blood flow puts more pressure on the blood vessels, causing the release of specific immune cells of the lymphocyte family, natural killer cells, and T cells. These lymphocytes, which can be lurking on the walls of blood vessels, play an important role in destroying virus-infected cells in our bodies.

Physical exercise can have other beneficial effects in our fight against infection. For example, it was shown that older adults who exercised regularly for a month had their wounds healed 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, together, can improve our immune response and thus reduce the risk of infection. And you don’t have to be a regular at the gym to reap the benefits. Three studies showed that when people who did not exercise regularly started brisk walking for 40 to 45 minutes, five days a week, they noticed 40 to 50 percent fewer symptoms of upper respiratory infection compared to a control group.

Regular brisk walking is sufficient to reduce respiratory infections. (Image caption: Lester Balajadia/Shutterstock/Via The Conversation)

And when do you actually get sick?

Despite these benefits, it’s not clear if exercising during a cold will help you clear your tissues faster than if you didn’t.

No study has actually looked at this at the moment, in large part because it would be difficult to do this type of study – not least because some part of the participants must have had a virus. To determine whether or not exercise has an effect. Not only would it be difficult to achieve, but it was also morally questionable.

But since exercise is good for the immune system, why can’t exercising during an infection improve our defenses? It seems logical…

Well, it is actually important to remember that exercise can stress the body. While useful in certain circumstances, it can also make immune cells less able to respond to pathogens. This may be in part because the body needs more oxygen and stored energy (in the form of glucose) when we exercise – which our immune cells also need to combat. If the body is fighting an existing infection and at the same time exposed to the stress of exercise, the immune response will not necessarily benefit if energy resources must be shared.

But if there is currently no evidence that exercising during a cold can help you recover faster, that doesn’t necessarily mean you should abstain! There are just some precautions to take.

First thing, there are some cases where exercise is not recommended: if you have a fever, muscle aches, vomiting, etc.

Next, you have to know how to listen to your body. If your symptoms are mostly above the neck (such as a runny nose or congestion), start exercising at a lower intensity than usual to see how you feel. If all goes well, you can gradually increase the intensity. But if that extra activity makes you feel worse, stop the effort and take a break.

Another thing: think of yourself, but also think of others! If you like to exercise while you’re sick, go for it…but be careful if you’re around other people. Airway infections (common cold, etc.) are contagious, so it’s best not to go to the gym or gym and exercise outside or at home to avoid infecting your neighbors.

Regular exercise is a great way to prepare your immune system to fight different types of infections, including the common cold and possibly even Covid… but don’t feel compelled to engage in physical activity if you’re sick and tired. Often the best treatment for a cold is rest and proper hydration. Being active before will reduce the risk of finding yourself in this unpleasant situation…

The original version of this article was published in Conversation.

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