According to a 2019 scientific review in the Journal of Sport and Health Science, exercising can progress your immune response, decrease illness risk, and lower inflammation. The study focused on moderate to high-intensity exercise lasting less than one hour. People have typically a small number of immune cells around their bodies. Such cells usually are found around lymphoid tissues and organs like the spleen where viruses, bacteria, and other microorganisms that cause diseases are killed.

When you exercise, the lymph and blood flow increases when the muscles contract. This helps increase the circulation of immune cells which make them present in all your body at even higher levels. Exercising uses highly specialized immune cells for example the T cells and the natural killer cells find pathogens and remove them.  

Working out gives you an immediate immune response, however, it takes consistency for this response to persist, or else the immune response will go away. It is important to work out frequently and up to 5 times per week to induce an immune response that is consistent and helpful for your health. A study published in 2011 in the British Journal of Sports Medicine found that doing aerobic exercise for 5 days or more per week can decrease the number of upper respiratory tract infections such as common cold, after 12 weeks by 40% or more.

The immune response to exercising is like housekeeping. If you clean your house more than 5 times per week, it will look clean the whole week. If you clean it once per week it will look dirty and messy a few days later. Exercise helps your immune system protect your body and get rid of bacteria and viruses. So to keep this system active, you need to work out more frequently. Regular exercising keeps the immune system active and ready to protect you and keep sickness-causing germs away.

Exercising also decreases inflammation in your body which is another way to improve your immunity and protect your health. Research has found links between the levels of inflammation markers and exercising. People who exercise have lower levels of inflammatory markers and vice versa. this also affects immunity as when immune cells are fighting inflammation, the whole immunity system is put under threat making it harder to fight infection. Therefore, for a lower inflammation level in your body, stick to a regular training routine.

What's the best type of exercise to boost your immunity?

Three types of exercises are most recommended to improve immunity; aerobic, HIIT. And strength training. If you chose aerobic exercise, aim to reach 60% of your VO2max and more than 70% of your heart rate. As for HIIT, studies are still debating whether it affects immunity or not. Finally, strength training is considered a smart strategy for improving immunity, but it is important not to do severe lifting to keep the muscles healthy.

Source:

https://www.health.com/fitness/does-exercise-boost-immunity