Regular running strengthens the body – but is that really true, and does it apply to all types and intensities of training? Or can exercise actually make you sick? How physical activity affects the immune system, what runners should pay attention to – and the role sleep, nutrition, and recovery play.
Author:
Dr. Brigitte Stigler, MD, Specialist in Orthopedic Surgery and Traumatology, Sports Medicine SEMS, Medbase Winterthur WIN4
Running Regularly – Does It Really Boost the Immune System?
Yes, definitely. People who exercise regularly are sick less often. Physical activity improves blood circulation — even in the mucous membranes — which strengthens the immune system. Hormonal processes also play a role: moderate endurance training promotes the release of anti-inflammatory hormones.
By the way, exercise doesn’t just influence the immune system — it can also have a positive impact on mental stress such as anxiety, depression, or burnout.
When Does Training Become a Strain on the Body?
Too much exercise can have the opposite effect. In particular, intense workouts or sudden increases in training volume can weaken the immune system. Typical warning signs include persistent fatigue, poor recovery, declining performance, or trouble sleeping. In that case, it’s time for a break.
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What Is the Open Window Effect?
After a tough run or interval session, the immune system is especially challenged. This is known as the Open Window effect. During this phase, the body is more susceptible to infections. That doesn’t mean you’ll catch a cold right away — but it’s a sensitive period. That’s why recovery, healthy eating, and enough sleep are essential.
How Long Does It Take to Recover After a Race?
After a demanding race, the immune system needs time. A competition is like a mini-trauma that the body must process. Energy stores are depleted and need to be refilled. The Open Window effect can last up to three days. Total recovery time depends on your fitness level and how intense the effort was. A return to resting heart rate is one indicator of sufficient recovery. Recovery measures such as walking, massages, warm/cold baths, or alternative activities like light swimming can help.
Recovery Is Key
Good sleep, high-quality nutrition, and rest are just as important as the training itself. Eight hours in bed are useless if sleep quality is poor. A balanced diet with carbs, protein, and healthy fats supports recovery and strengthens your defenses.
Tip: Three main meals plus snacks and enough fluids help prevent energy and nutrient deficiencies.
How Much Training Is Enough — and How Much Is Too Much?
The general rule: 80 percent base training, 20 percent high intensity. This is especially important for beginners. Also, take at least one rest day per week. You know you’re in base training when you can still talk while running — your heart rate should be around 60–70% of your maximum.
Running With a Cold – Yes or No?
A mild cold isn’t necessarily a reason to skip training. What matters is how you feel. If you have a fever or body aches: definitely rest. If it’s just a runny nose, an easy run is okay — no pressure, no pace.
Returning to Training After an Infection
Once all symptoms are gone — no cough, no fever, no fatigue — it’s still best to wait about a week before easing back into training. When in doubt, it’s better to do one more light session than to start hard too soon.
What Recreational Athletes Often Get Wrong
Training too hard, too few rest days, too much ambition. People who work full-time and still train over 10 hours a week often don’t have enough time to recover — that’s a risk. Stress also weakens the immune system. So it’s crucial to learn to listen to your body.
Training in All Weather – Good for Immunity?
Outdoor activity is great for the immune system — sunlight boosts vitamin D production. But whether it’s summer or winter, the body needs time to adapt to the conditions. In summer, stay hydrated; in winter, dress warmly and be mindful of your breathing.
Tip: Listen to your body — not just your watch.
In Summary
If you want to stay healthy, don’t just focus on run-specific training — take care of yourself as a whole. Strength training, proper nutrition, recovery, and body awareness all matter just as much. And most importantly: don’t focus only on performance data — pay attention to how you feel.
WHO IS MEDBASE?
Medbase is the largest multidisciplinary sports medicine network in Switzerland, offering specialized services in sports medicine, sports physiotherapy, performance diagnostics, and training advice. Their services are tailored to athletes, clubs, and sports federations of all activity levels.
One reply on “Running for health – What really strengthens the immune system”
Muy pertinentes los temas. Consistente, clara y sencillas las explicaciones. Gracias