Immune system and exercise: how movement strengthens your defences

Do you feel constantly tired, get sick with every little infection, or fight your way through winter with endless colds? Then it's time to take a close look at the interplay between immune system and exercise. In this article I'll show you how training strengthens your defenses, and when it can weaken them. With scientific findings, practical tips and my own personal experience.

Why is the immune system so important?

Your immune system is your body's own shield against viruses, bacteria and other pathogens. It decides whether you stay healthy or get sick. A strong immune system recognizes intruders early, fights them effectively, and makes sure you recover quickly. But stress, lack of sleep, poor nutrition and too little movement weaken this natural defense.

How does exercise affect the immune system?

Regular movement has a proven positive effect on the immune system. Studies show that moderate endurance exercise increases the number and activity of important immune cells such as T cells, B cells and natural killer cells. A review study in the journal "Frontiers in Immunology" (2018) confirms: people who exercise regularly get sick less often.

• More blood flow: exercise stimulates circulation and supports the transport of immune cells
• Reduction of stress hormones: regular training lowers cortisol levels
• Better sleep quality: and with it, improved immune function
• Anti-inflammatory effects: moderate movement counteracts systemic inflammation

Free intro call

But: too much isn't good either

Even though exercise brings many benefits, excessive training can have the opposite effect. Anyone stuck in a permanent state of overtraining sleeps poorly, barely recovers, and opens the door wide to pathogens. The result: a weakened immune system. According to the so-called "open window theory," the immune system is more vulnerable to infections for several hours after extreme exertion (e.g. a marathon).

A good training program therefore accounts for not just intensity, but also recovery. Anyone who goes full throttle permanently will sooner or later get slowed down, often by illness.

Which types of training strengthen the immune system best?

Not every type of training affects your immune system equally. According to research, these three forms of training show the greatest effect:

1. Moderate endurance training such as jogging, cycling, swimming or brisk walking (3-5x per week, 30-45 minutes)
2. Strength training at moderate intensity (2-3x per week, without going all the way to muscle failure)
3. Yoga or mobility exercises to reduce stress and improve parasympathetic activity

What matters is: you should train regularly, but with sense. A combination of endurance and strength training is especially effective.

Nutrition and the immune system: inseparably linked

Exercise alone isn't enough. Your immune system also needs the right nutrients to stay strong:

• Protein is the building block for immune cells
• Vitamin D regulates the immune response (especially important in winter)
• Vitamin C, zinc and selenium have antioxidant and anti-inflammatory effects
• Omega-3 fatty acids suppress silent inflammation in the body

I recommend my clients pay attention to a balanced, nutrient-rich diet, especially during the cold season. A blood panel can also help identify deficiencies early.

A real-life example

My client Lukas, 42, constantly struggled with infections. He trained irregularly, slept poorly and worked under high pressure. Together, we adjusted his lifestyle step by step: three moderate workouts per week, walks in the fresh air, targeted micronutrient supplementation and a fixed sleep schedule.

After 8 weeks, not only was his general fitness better, he felt noticeably more energetic and stayed healthy throughout the entire winter. The combination of targeted exercise and a more mindful everyday life visibly strengthened his immune system.

My tips for a strong immune system

• Move every day. Walks count too
• Train 3 to 4x per week. But not to the point of total exhaustion
• Eat colorfully, with variety and enough protein
• Sleep 7 to 8 hours per night
• Reduce chronic stress through deliberate time-outs
• Avoid constant dieting. Too little energy weakens the immune system

Conclusion: immune system and exercise belong together

Immune system and exercise go hand in hand, but only if the training is designed sensibly. Anyone who trains moderately and regularly, gives their body recovery, and pays attention to the right nutrition benefits from a stable immune system in the long run. Especially during stressful times and cold season, this difference is what really matters.

I'm Marco Laterza, a personal trainer from Zurich. If you want to specifically strengthen your immune system, make your training smarter, or want to know which nutrition really protects you, get in touch. Together we'll bring your system into top shape.