Does Working Out Lower Your Immune System?
Q: I’m sick of going to the gym but can going to the gym actually make me sick? In other words, does working out lower your immune system?
A: Regular exercise at a moderate intensity can improve the immune system so you experience less frequent illness and less severe symptoms when sickness does occur. The only way you increase the risk of exercise not having that overall effect on immune function is by overtraining, or working out too hard or too much without sufficient rest time between training bouts. Under that circumstance, routinely working out without allowing the central nervous system the opportunity to recover from the demand that’s repeatedly placed on it can compromise the immune system and render you susceptible to frequent infections.
Over the course of weeks and months, exercise can strengthen the immune system or weaken it, as occurs with overtraining. As for the immediate effects of exercise on immune function, there’s a belief that exercise results in a significant loss of neutrophils, lymphocytes, and other immune cells in the bloodstream, which lowers immunity and exposes you to infections in the 3 to 72 hours it takes for levels to return to normal. Supported by studies in the 1980s and 1990s, the described “open-window” hypothesis doesn’t appear to be true, however.
During exercise, more immune cells than usual get released into the bloodstream with the elevation of the heart rate. When exercise stops, it’s indeed true that there’s a reduction in the circulating immune cells but that’s not because they’re destroyed, as posited by the “open window” hypothesis. Instead, the white blood cells get redistributed to the lungs and other locations throughout the body where they’re better able to identify viruses and bacteria. So a single bout of exercise actually boosts immunity, which is an effect that lasts for about three hours.
Given that exercise has a positive effect on the immune system in the short and long term, it’s really not the act of exercise itself that you have to worry about with regard to getting sick by engaging in the activity. That concern should be reserved primarily for the other factors that influence the body’s response to disease and infection, such as inadequate sleep, fatigue, poor nutrition, dehydration, psychological stress, sudden and extreme temperature changes, and environmental contaminants like heavy metals, pesticides, and air pollutants, for instance.
As an example of the way that factors other than exercise can affect immune function, let’s imagine that you went to the gym following several days of little to no sleep. While the workout would prompt immune cells to flood your bloodstream and hunt down pathogens, that may not be enough to ward off an infection in the subsequent hours because the lack of sleep may hinder the ability of other body processes to launch an appropriate immune response.
For the most part, going to the gym and working out won’t open you up to illness in the near and distant aftermath of a workout. But as stated, there are variables to consider to make sure that the conditions are right so they don’t predispose you to getting sick despite working out. With that said that exercise raises your defense from disease during and upon termination of doing it, that mainly applies to things like cold and influenza viruses — not shit like gonorrhea, chlamydia, and HIV. So yeah, if you were reading this and got excited at the possibility of having unprotected sex with a rando sometime after working out on the assumption that your workout temporarily makes your body invincible to all manner of infection, then you might want to hold off on that!
Now, does anyone else have a fitness or nutrition question of their own that they want to ask?
Glossary: exercise, fitness, gym, intensity, nutrition, work out, workout
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