When we go for a run or lift weights in the gym, we are often concerned about what clothes and shoes to wear, how to warm up our muscles, or even how many heartbeats we need to reach for an effective workout.
However, we tend to overlook the effect of breathing on physical performance.
Science has a lot to say about how to get more out of our gym hours by paying attention to how we breathe.
Mechanism of oxygenation during physical exercise
We are all aware that the mission of the respiratory system is gas exchange. That is, it is responsible both for obtaining oxygen (O₂) from the outside to produce energy and for eliminating the waste product, carbon dioxide (CO₂). Therefore, it allows us to live.
But let’s analyze the process more technically. Air enters through the nose, circulating through the airways to the pulmonary alveoli, where gas exchange takes place.
From there, oxygen passes into the blood to be transported to all cells. At the same time, the CO₂ they produce is transported to the lungs for elimination.
This is how it works under normal conditions, but what happens when we exercise? Well, the muscles work much more intensely, consuming more oxygen and producing more CO₂.
The frequency goes from 15 breaths per minute at rest to about 40-60 per minute in full activity. As a consequence, the amount of incoming air increases from 12 to 100 liters.
During this extra gas exchange, our respiratory system is responsible for keeping the acidity of the blood constant, which is measured by pH, through the expulsion of CO₂.
Another detail to bear in mind is that oxygen reaches the muscles through the blood thanks to the red blood cells (the “carriers” that carry it from the lungs), specifically through the hand of a macromolecule called hemoglobin.
Well, in order for an oxygen molecule to be taken up by hemoglobin in the red blood cells passing through the lung, another CO₂ molecule is needed to allow the hemoglobin to release the oxygen at the destination site.
Ultimately, it is the amount of CO₂ in the organism that conditions the correct supply of O₂ to the muscles.
If we breathe through our mouths we are out of breath
Now that we are familiar with hemoglobin, we cannot forget a key property: the Bohr effect. It refers to the fact that, when we activate our body, there is an increase in CO₂ and, therefore, hydrogen ions, causing the pH to become acidic.
This causes hemoglobin to capture oxygen with greater affinity, achieving a greater supply of O₂ in those areas of our body where more CO₂ is released.
Therefore, by exercising, our body generates more CO₂, and the Bohr effect kicks in. In short, the Bohr effect allows our friend hemoglobin to release more oxygen the more active we are.
So when it comes to breathing, we should not just go by intuition. Although one might think that for physical exercise it is better to breathe through the mouth, if we expel air through the mouth we run the risk of losing too much CO₂.
In fact, when we run out of breath while exercising, it is not because our muscles are getting tired, but because they are not receiving oxygen properly by not having enough CO₂ for the exchange.
After reviewing scientific papers in recent years, a recent publication concluded that it’s not so clear that it’s good to use your mouth to breathe during sport.
Moreover, the evidence suggests that exclusively nasal breathing is feasible for most people at moderate levels of aerobic exercise without specific adaptation, and that this breathing approach can also be achieved during intense levels of aerobic exercise.
Airways open wider
Another reason for breathing through the nose is nitric oxide (NO), a vasodilator produced in the epithelial cells of the nasal cavity as air passes through.
Nitric oxide, among other functions, is known to be involved in chronic inflammatory processes and in modulating lung function.
And it is also a potent vasodilator that diffuses very quickly, achieving a greater opening of the airways.
This is very important for people suffering from exercise-induced asthma. In fact, it has been shown that this pathology is greatly improved by breathing through the nose.
With maximum effort, the mouth opens
We have explained that nasal breathing helps athletes perform better, especially when the effort is sustained and moderate.
Although less air enters the lungs through the nose, the air supply is sufficient to maintain activity and does not seem to cause problems.
However, things change when more demanding conditions are reached. At maximum exertion, athletes switch their breathing to the mouth automatically.
Interestingly, scientists have shown that this change occurs earlier in women than in men with increasing exercise intensity, and they explain this because women tend to have smaller noses.
In the most demanding and fastest race, the 100-meter sprint, athletes breathe through their nose and mouth simultaneously. That is, in just 10 seconds. Just watch Carl Lewis or Usain Bolt in the Olympic finals to see for yourself.
The exception of yoga and pilates
There are two exceptions to the cases we have considered above: yoga and Pilates. In these two physical exercise modalities, breathing is a very important part, and its technique is the first thing to be learned.
This is always of the nose-to-mouth type (i.e., breathing in through the nose and out through the mouth).
This is especially important in the case of Pilates, with a very determined execution that involves (and shapes) the muscles surrounding the rib cage, exercising them both when breathing in and breathing out.
Using a technique called EMG or “electromyography” to measure muscle activation in real time, the beneficial effects of Pilates breathing have been demonstrated.
Specifically, in elderly people, studies have shown the great benefit of Pilates breathing in promoting muscle activation during exercise.
And the benefits go even further: it also improves spinal alignment and prevents loss of balance.
There is, therefore, no single answer to the question of how we should breathe during physical exercise: it depends on the type of activity.
What we are convinced of is that the next time you listen to your instructor or trainer explain to you how to breathe, you won’t think: “what a drag” or “what’s the difference”. Because a good breathing routine will influence your performance.