How to Use Breathing to Improve Exercise Endurance

If you don’t have any access to cardio equipment, or just find cardio machines boring, there are other techniques to improve endurance. When I say endurance, I’m talking about the tolerance to that ‘burning’ feeling your muscles get when exercising. 

This one might get a little technical, so hang in there. We have to understand some basic biochemistry to get through this. 

You may have heard that the ‘burn’ while exercising is lactic acid. That’s not technically true. Your body can use both lipids and carbohydrates as fuel. The body prefers to use lipids for energy because they produce more energy (ATP). The trade off is that it’s a slower process for the body. Carbohydrates are more readily available, yet produce less energy. So, when you are just sitting around, or doing low intensity exercise, you’re primarily using lipids. As intensity increases, the body will start to use more carbohydrates out of pure demand. 

Carbohydrates are stored in the muscle in the form of glycogen. Glycogen is broken down into lactic acid, which in turn is immediately dissociated into lactate and hydrogen ions. Lactate is a great fuel source, but its by-product, hydrogen ions (H+) are literally acid. This is what causes the burning sensation. 

As you exercise, this acid starts to build up. The body has a few mechanisms to buffer this. In the muscle cell itself, carnosine soaks up the hydrogen ions. In the bloodstream, bicarbonate does the same thing. The body is great at adaptation, so if you incrementally expose the body to this mild stress, these buffering mechanisms become more efficient. Just like resistance training, progressive load has the long term effect of making you stronger. 

It turns out that you can induce an acidic environment simply through breathing. The more oxygen in the bloodstream, the more alkalinic, the more CO2, the more acidic. So you can leverage this by limiting the volume of breathing because exhaling through your mouth off gasses CO2. 

This is where nasal breathing comes into play. Nasal breathing has many benefits including the stimulation of nitric oxide production which dilates the blood vessels (good for cardiovascular system). But, because you can’t exhale as strongly through your nose versus your mouth, it will increase CO2 build up, causing an acidic environment. If done during a low intensity exercise, such as walking, it is enough of a stressor to stimulate adaptation to the system. In other words, a mildly acidic environment during exercise will improve your body’s ability to buffer hydrogen ions. If you do this consistently, your body will be able to handle acidic environments during workouts better, leading to greater output. This is the idea of physiologic flexibility. 

Some call this CO2 tolerance, or the CO2 advantage. I wrote another blog that describes a test you can do to see how well you tolerate the buildup of CO2, you can read it here. 

So all you have to do is find a light exercise that you can do while only nasal breathing. For most, it’s walking. Perhaps you start with short bouts and increase over time. Make it something that easy so you don’t quit doing it, because it can be uncomfortable. If you are strongly feeling the urge to breathe through your mouth, that’s ok, go ahead and do that. Now you know your threshold. Progress over time and notice how it translates to other forms of exercise.