We know fitness plays a positive role in our cardiovascular system, mental health, strength, and body composition, but we sometimes forget what else it does for the body. One of the unseen physiological adaptations that fitness can positively influence is our immune system’s health.

The immune system is incredibly complex and the research that links fitness to it is continuing to evolve. What we do know is that fitness can play a role in positively influencing our immune system’s health and functionality. This is key to understand, especially as we head quickly into cold and flu season.

In this article, we’re going to discuss what the immune system actually is and what it does, and how fitness may positively influence it.

‌‌‌‌What Is the Immune System?
The immune system is not just one thing—in fact, it’s an incredibly complex network composed of cells, tissues, and organs in the body. It’s a system in the body that we rarely recognize as constantly working to maintain our state of healthy homeostasis or consistent equilibrium.

When we encounter germs and bacteria from our external environment and they get into the body, they multiply at varied rates depending on what they are. When the rate exceeds our immune system’s capabilities, this is what we deem as an infection. The immune system then works to counter and prevent the multiplication of whatever germs and bacteria get into the body that will take us away from our homeostasis and lead to infection.

More specifically, the immune system works to identify different types of cells, then acts upon them if necessary. When identifying normal, healthy, and unhealthy cells, the immune system will recognize cues from unhealthy cells called danger-associated molecular patterns (DAMPs). Viruses and certain forms of bacteria can also release signals that our immune system recognizes as pathogen-associated molecular patterns (PAMPs).

These signals cue the immune system to respond in a way to counter whatever PAMPs they’re encountering in the body. Different types of viruses and bacteria will vary when it comes to the signals they produce, and our immune system will respond in a means that it deems best.

One of the coolest features of the immune system is how it essentially keeps a log of pathogens that it has encountered before, so it knows how to counter them in the future when it recognizes similar unhealthy cells and signal patterns.

The intricate network of cells, tissues, and organs that make up the immune system can be influenced by a variety of internal and external factors. And this brings us to the topic of fitness and the immune system. Various forms of exercise produce different physiological responses in the body and some of them have been suggested to play a positive role in our immune system’s functionality.

Learn more about the immune system:

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6 Signs Your Immune System Could Use a Boost
‌‌‌‌How Does Exercise Influence the Immune System?
As mentioned earlier, it’s important to remember that research linking fitness to immune health is continuing to evolve. The questions of how much is enough, how hard should you train, and how often are all questions that are frequently being explored.

It’s also useful to remember that it’s not an “all the time” kind of ordeal with fitness improving immune system health. For example, if one’s immune system is already compromised and the intensity of exercise exceeds a threshold that the body can handle, then exercise can be counterproductive for immune system functionality. After all, some forms of exercise produce fairly high amounts of internal stress on the body.

Again though, this is a case-by-case basis, and we have to remain cognizant of the bigger picture, which is… exercising regularly has been suggested to positively benefit our immune system’s health and that is critically important, especially from a long-term health perspective.

One of the main reasons that exercise has been suggested to positively impact the immune system is that it can enhance our body’s recirculation of immunoglobulins, anti-inflammatory cytokines, neutrophils, NK cells, cytotoxic T cells, and immature B cells. All of these have been suggested to play a role in positively increasing the immune system and metabolic health.

In other words, exercise can increase our body’s means of circulating key players in immune system support when countering pathogens. It’s important to note that this benefit is suggested to be most prevalent with exercise bouts that are roughly 60-minutes or less in nature.

The takeaway here is that when consistently performed, acute exercise bouts can be beneficial for the immune system’s health for a variety of reasons, and these bouts can positively influence healthy metabolism function.

As stated earlier, too much exercise has been suggested to have a counterproductive response in the immune system. When we exercise intensely, the body produces stress-related hormones to counter the stress we’re actively producing on the body.

If the intensity of exercise exceeds our body’s thresholds for managing the stress-related hormones, then we may experience periods of transient immune dysfunction, or a slightly weakened immune system. By understanding this, we can begin to create a game plan for intense exercise to promote better means of recovery and adaptation.

‌‌‌‌Building a High-Quality, Immune-Boosting Fitness Routine
Because our immune system’s functionality can become suppressed when exercising as stress-hormones pass the threshold of what our body can handle, we need to be strategic with our exercise programming, recovery tools, and nutrition.

Here are a few practical tips for anyone that trains hard often that wants to ensure they’re ramping up intensity accordingly and optimizing recovery.

1. Training Recommendations
For lifters, follow a training program that accounts for de-loads and ramp-up periods. This will provide your body with better means of increases in load management and give the body strategic periods of rest on a regular basis.
For cardiovascular athletes, increase training intensity slowly in small increments. Generally, an increase of less than 10% of your training intensity for a training week is a good and manageable strategy.
2. Nutrition Recommendations
Eat a balanced diet that is composed of high-quality nutritionally dense foods. Include plenty of vegetables, fruits, complex carbohydrates, and lean meats to ensure you’re getting plenty of micronutrients.
Be mindful of your pre- and post-workout nutrition. Consume complex carbs and complete proteins post-exercise to support recovery.
Consume plenty of water throughout the day to ensure natural hydration levels are met.
3. Sleep Recommendations
Try to go to sleep at the same time consistently every night to support the body’s natural circadian rhythm.
For those training hard, try to sleep a minimum of seven hours to ensure your body is resting enough to fully recover.
4. Supplement Recommendations
Supplements may play a role in immune system support, especially if we’re not naturally consuming enough of something that can support our immunity.

Some supplements that might be worth exploring include:

CoQ10: A naturally produced antioxidant that has been suggested to play a role in healthy cell growth and maintenance
Zinc: A trace element that helps support our immune system’s health and functionality
Vitamin D: A vitamin that plays a role in a variety of physiological processes and supports our body’s absorption of key minerals
These are only a few suggestions for anyone that likes to train hard and wants to ensure they’re providing the body with the tools it needs to recover.