Nose or mouth? How your breathing determines your sports performance

Written by Jill Engelsman-Gamma

You're seeing them more and more in competitions like HYROX: athletes wearing nose strips while their mouths are wide open during exercise. But does that really work? And more importantly:
do we still understand what we're trying to support when it comes to breathing during exercise? The discussion about nose or mouth breathing isn't about a trick. It's about how your body handles exertion, stress, and recovery, at the intersection of breath chemistry, breath mechanics, and nervous system regulation.

Nasal breathing: more efficient than often thought

Nasal breathing does more than just move air. It filters, warms, and humidifies the air, but most importantly, it creates a different breathing rhythm. Calmer. Deeper. More regulated. This directly influences your nervous system: you switch more easily between exertion and recovery. Additionally, CO₂ plays a crucial role. Not only how much oxygen you take in is important, but especially how well you can utilize that oxygen. Breathing too fast and too much through the mouth lowers CO₂ too much, making oxygen less efficiently released.
The result: more breathing effort, but less effective output.

Why we switch to mouth breathing so quickly

During intensive exercise, ventilation automatically increases. The mouth then becomes the easiest route. That's not wrong, it's an emergency mechanism. But the problem arises when this pattern persists, even when it's not necessary. This often leads to an "over-breathing loop": you breathe more than you physiologically need, which further activates your system. The effort feels harder. Control decreases. Breathing itself becomes a stressor.

Breathing does not start in sport, but at rest

How you breathe during exertion is strongly connected to your baseline state. Stress, work pressure, sleep, and recovery determine how your nervous system reacts under load. Prolonged tension leads to increased muscle tension and less efficient breathing mechanics. This can even exacerbate physical complaints or injuries. That's why breath training doesn't start with technique, but with regulation.

 Breath chemistry and breath mechanics

Breath training broadly consists of two layers:

1. Breath Chemistry
   CO₂-tolerance, slowing down breathing rhythm, learning to cope with internal stress stimuli. This can be done through nasal breathing, gentle training, and sometimes breath holds.
   
   
2. Breath Mechanics
   How your body supports breathing: posture, diaphragm, rib mobility, and relaxation.
   
   Think of:

• relaxed shoulders
• long neck
• tongue against the roof of the mouth
• active but free ribs
• and a well-functioning diaphragm
  
  This is where the 360° breathing that supports nasal breathing originates.

Supply and demand: where things often go wrong

Breathing is always a response to supply and demand. How intense is the exertion, and how much does your body actually demand? Many athletes react too quickly with over-ventilation. This causes the system to enter a higher state of activation than necessary. And precisely there arises the feeling of "it's harder than it needs to be".

Pacing and regulating: controlover your system

At higher intensities, full nasal breathing is often not feasible, which is realistic. But regulation is always possible.

For example by:

• controlled exhalation through pursed lips
• conscious moments of relaxation
• switching between high and low breathing (gear breathing)

This way you steer your system instead of it steering you.

And the role of nasal strips?

Nasal strips can be valuable, but not as a "quick fix". For people with narrowed nasal passages or anatomical limitations, they can literally improve airflow. But in many sports contexts, you see them while breathing remains primarily mouth-driven. Then the function shifts: from physiological support to awareness. And the latter can be quite interesting.

Training versus competition

The greatest benefit of nasal breathing is usually not in competition, but in training. Especially in relaxed zone 2 training, nasal breathing could be fundamental.
Nasal strips can help there as:

• physical support
• and as a reminder to return to nasal breathing

Finally

Breathing is not secondary in sports. It is a regulatory system that determines how you perform, recover, and deal with stress. Those who can control their breath ultimately control their entire system. Control your breath, control your state of mind. 

Question

Where do you find the greatest benefit? In technique, in awareness, or in bringing back calmness to your system?