The positive effects of physical exercise on our immune system

A strong and efficient immune system is essential, especially when our defences are attacked by external factors such as stress, changing seasons, incorrect nutrition and unhealthy lifestyles, all of which are present in our daily lives. The mix of these factors can cause greater vulnerability and therefore lead to a weakening of our defensive system.

The immune system defends us from attacks by potentially dangerous micro-organisms.  So how do we strengthen the immune system? And what is the role of exercise and diet?

Let us consider that the immune system is, in fact, a system, not a single entity. In order to function well it needs the correct balance between several variables. For years, scholars have been studying the role that diet, exercise, psychological stress and other factors have on the immune response.

There are various lines of study and many different interpretations of the results, but what everyone agrees on is that strategies aimed at adopting a healthy lifestyle are the first step to give a significant hand to our immune system.

The right choice to strengthen the immune system

On the shelves of supermarkets and pharmacies there are many products that claim to improve or strengthen our immune defences. To date, however, the concept of improving immunity through individual products makes little scientific sense. Trying to improve the cells of the immune system is particularly complicated because these cells are made up of different types, and they respond to different forms of pathogens in a variety of ways.

Which are the cells that should be strengthened? Which ones should be increased? And if so, in what number? While scientists may not know all the answers, they tend to agree that the right choice is certainly to opt for a Wellness lifestyle: eating in a healthy and balanced way, exercising regularly and managing stress.

A sedentary lifestyle contributes negatively to overall health and is related to the development of chronic diseases such as cardiovascular disease, obesity, type 2 diabetes and metabolic syndrome.

The basic elements of a healthy and Wellness lifestyle are:

• Not smoking;
• Adopting a healthy diet rich in fruits and vegetables;
• Exercising regularly;
• Maintaining a healthy body weight;
• Consuming alcohol in moderation;
• Getting enough sleep;
• Washing hands frequently;
• Minimising stress.

Regular exercise is a fundamental pillar of a healthy lifestyle. It improves cardiovascular health, helps to lower blood pressure, helps control body weight and protects against countless diseases.

Exercise, an ally to improve the immune system

Exercise has long been known to be fundamental in the prevention of major chronic diseases, and scientific research has for years been concerned with understanding the mechanisms underlying the benefits of movement. Among the many lines of research, those involved in studying exercise-induced changes in metabolic status indicate that these would also influence improving immune function.

The mechanisms underlying these benefits are different and include:

• improved humoral immunity (the production of antibodies that bind to viruses, bacteria and substances foreign to the body);
• stimulation to the release of a range of substances (e.g. MAEPK/ERK, AMPK, TOR) associated with improved antigen recognition (substances recognised as dangerous by the immune system);
• Activation of autophagy which plays a key role in the elimination of intracellular pathogens and the induction of adaptive immune response.

Can exercise also help improve our immune system and keep us healthy?

As with nutrition, physical exercise contributes to general health and thus indirectly benefits the immune system. But the exercise also has a direct function as the improvement of blood circulation allows the body to bring the substances needed to function properly to the cells of the immune system more effectively. But what is the correct intensity of exercise? Many studies have been done on this subject, especially with athletes, and it is now clear that extremely intense exercise can lead to an increased susceptibility to infection as soon as the training session or competition is over.

What about moderate exercise? Can it help the immune system to stay healthy?

Scholars recommend exercising at moderate intensities, while avoiding too high intensities that could have counterproductive effects. Moderate exercise on the other hand causes positive improvements in the immune system and a reduction in upper respiratory tract diseases. During each moderate exercise session, there is increased recirculation of immunoglobulins, neutrophils and natural killer cells that persist for up to 3 hours after exercise. This exercise-induced increase in the immune cells of the innate immune system is temporary, but it improves overall resistance against pathogens.

Now, even if the mechanisms are not clear, it can be said with certainty that training regularly at a moderate intensity helps to keep the immune system healthy and efficient. It is good practice to train two, or even better, three times a week, by performing a combination of aerobic and strength exercises at moderate intensities. At home, the ideal exercises are those performed with aerobic equipment such as a bike or treadmill.  And when you’re not exercising? It is good to stay active in a simple and effective way: walking.

Nutrition and immune system

Like any army, the immune system must be fed correctly and regularly. Scientists have long realised that those who live in poverty and are malnourished are more vulnerable to various types of infections. There is evidence to support that deficiencies in zinc, selenium, iron, copper, folic acid, and vitamins A, B6, C and E alter the immune response.

What can we do then? The answer is simple: adopt a healthy diet, rich in fruit and vegetables and low in saturated animal fats. If you think your diet is low in micronutrients (minerals and vitamins), then it may help to take a multivitamin and mineral supplement. Be cautious though, as taking mega doses of a single vitamin or mineral salts instead is not necessary and could even be harmful. To be safe, you should always consult with your doctor before adding supplements to your diet.

Stress and immune system

Modern medicine has begun to recognise the close relationship between body and mind. Many diseases, ranging from hives to cardiovascular problems, are closely related to stress. The functioning of the immune system also has a strong relationship with the state of stress levels, and scientists are actively studying the mechanisms underlying this relationship. When scientists study the relationship between stress and immune function, they generally do not dwell on a single acute element of stress, but rather try to study the effect of so-called chronic stress, which has more substantial effects as it is present for a very long time.

Chronic stress is the stress generated by interpersonal relationships within families or with friends, what we experience with colleagues at work or what is generated by a continuous stimulation to do more at work.

Despite the obvious difficulties in measuring the relationship between stress and immunity, scientists agree that it plays an important role in modulating the effectiveness of the immune system. They similarly agree that stress should be managed and controlled. How? There are countless ways to manage stress, ranging from meditation and yoga to many other techniques available today. Once again though, physical exercise plays an important role, especially low-intensity aerobic exercise.

• Harvard Health Publishing
• Harvard Medical School, How to boost your immune system
• Amalesh Mondal, Sarmishtha Chatterjee, Exercise and Immunity: A Correlated Mechanism
• David C. Nieman, Moderate Exercise Improves Immunity and Decreases Illness Rates