The open window effect

The Open Window Effect | Sports Nutrition

Rarely is a risk so close to an opportunity.

Risk Immunological Gap

For years, scientific studies have repeatedly shown that we have an increased susceptibility to infections after strenuous training sessions or competitions - also called the open window effect. This 'immunological gap' cannot be avoided and the so-called gap becomes larger and larger with an increase in load intensity and/or load duration. Athletes on the edge of overtraining have a particularly large gap and are especially at risk.

How is this effect created? Quite simply:

During sports, heart rate and blood pressure are increased. The body releases various stress hormones such as adrenaline and cortisol. Influenced by these hormones, the white blood cells, also called leukocytes, multiply. They handle a large part of the immune defense.

After athletic exertion, our body needs recovery. The leukocyte level even drops below the level that existed before the exertion. The period between this low level of leukocytes and the restoration of the regular number is called the immunological gap or the open window effect.

Too little recovery time, too hard and too long training before the end of the body's immune and recovery processes, as well as stress, by the way, lead to significantly prolonged periods of time with an immune system that is not fully functional. So it is equally important to protect and support the immune system.

The chance

On the other hand, studies show that our body cell doors are very wide open for a maximum of one hour after strenuous training sessions. Recent studies even talk about only half an hour! During this time, it is much easier for our body to transfer absorbed nutrients into the body cells to accelerate the regeneration process and to support the immune system.

The result

If we look at both, we get a simple conclusion and clear instruction for action on nutrition immediately after exercise:

Instead of standing in the cold or wind to make small talk or do other things, it makes sense to warm up the body as quickly as possible and to supply important nutrients within the first 30 minutes after finishing the session. Because in this time our body can absorb the nutrients much faster and easier. 

First and foremost, these include:


Carbohydrates to eliminate acute energy deficit and replenish glycogen stores.


Amino acids or proteins for the regeneration of muscles, ligaments and tendons.


Vitamins and minerals to strengthen the immune system. Here above all vitamin C, zinc and sodium.

Whether this is done through the intake of suitable foods or through special recovery products and dietary supplements is up to each individual. Foods that are more difficult to digest certainly have the disadvantage of not being absorbed within the first 30 minutes.