Breathing is a huge area within research and scientific thought and there are endless topics to cover, particularly around exercise. In this this Sciencecast, want to concentrate on the differences between oral (mouth) breathing and nasal breathing in exercise.

Nasal breathing has become very trendy in the last few years in the strength and conditioning world with whole workouts being prescribed using only nasal breathing, with all sorts of claims as to the performance benefits to be gained. So let us dig into the real evidence as to what effects the different breathing styles can have.

For the most part breathing is a subconscious practice and, when effort is kept low during exercise (below 60% maximal capacity), nasal contribution to breathing is fairly pronounced. This also recedes as exercise intensity increases.

There is no ‘correct’ proportion of nasal to mouth breathing in exercise and there is huge individual variation depending on training status, preference, nasal anatomy and clinical history. In fact studies have shown that there is no effect on the differing contribution of nasal breathing in maximal exercise on fitness level, in other words fitness levels were not influenced by how much nasal breathing is performed at peak.
 
So, it appears nasal breathing techniques do not contribute to improved fitness, but another hypothesis for their use is on filtering of airborne particles. This is based on nasal breathing being able to filter out more airborne particles than oral breathing given the added complexity of the nasal anatomy, however current evidence does not support this theory. Even if it did it is near on impossible to estimate if this would affect performance or health in the long term either way.

But there is some definitive good news for nasal breathing. There does appear to be an area that nasal breathing has quite a significant benefit on health and performance. At lower aerobic-loaded exercises, think resistance exercise or walking, nasal breathing seems to have a long term effect on energy economy. This occurs as nasal breathing naturally lowers breathing frequency and allows for a more efficient transportation of oxygen and carbon dioxide, leading to more efficient energy production. Over time this can lead to a more economic performance (i.e. you can work harder for longer) and therefore a greater capacity prior to fatigue.

Therefore, nasal breathing should correctly be advised in certain areas of exercise. Generally individuals should be advised to breathe as they choose during higher intensity exercise, unless a clear problem has been detected, as to not try and overcomplicate the body’s natural ability.

Those who suffer from exercise related asthma attacks should be advised against consistent nasal breathing, but those who don’t should work on it at lower intensities of exercise and in resistance training for health and performance benefits.

“I wake up every day and I think, ‘I’m breathing! It’s a good day” – Eve Ensler

Photo by Max van den Oetelaar on Unsplash