In this step, the carbon dioxide levels in your body are intentionally reduced through deep breathing. By taking deep breaths while breathing slightly faster than usual, you help your body transition into a more relaxed state. This technique doesn't significantly increase the oxygen levels in your blood, as they are already high. Instead, it triggers relaxation by reducing carbon dioxide.

The deep diaphragmatic breathing (initiating from the stomach) stimulates the vagus nerve, a crucial part of the parasympathetic nervous system. This reduces the body's fight-or-flight response, promoting a state of calm and relaxation. These effects are key to the benefits of this breathing technique and also prepare your body for the next phase.

As you expel carbon dioxide and flood your body with oxygen, your cells are saturated with oxygen, eliminating the need for alternative methods of cellular respiration. This shifts your blood pH from the normal 7.4 to a more alkaline state, potentially reaching 7.75 or higher. The significance of this alkaline shift is that the sensors responsible for detecting acidity in your body become impaired, preventing them from activating pain-inducing receptors. As a result, you experience a reduction in pain sensitivity.

You may experience tingling sensations or light-headedness, which are common effects of lower carbon dioxide levels in the blood. Some individuals might also experience muscle cramps due to oxygen binding more tightly to their red blood cells under these conditions.

By the end of this intense breathing session, your blood is highly oxygenated and more alkaline, and you are ready to move into the second phase of the exercise.

Now, you hold your breath after breathing deeply. This lowers the oxygen level in your blood for a short time. This might sound strange, but it's actually good for your body. It triggers some positive changes, like releasing adrenaline and making adjustments to help you cope with low oxygen levels.

The purpose of this phase is to decrease the blood O2 level from ~100% to a safe but unnaturally low level for a short period of time. The body responds to this short stress in a variety of very positive ways (a valid example of hormesis) – that form the majority of the health benefits of this exercise.

Remember that in general you can hold your breath until your blood CO2 levels rise above a certain threshold? After reducing the CO2 levels in Phase #1, we can hold our breath much longer until the CO2 eventually rises that high – this can be 3-4 minutes for some people.

However your body is using up O2 throughout the retention, so after about 1 minute your blood O2 is lower than it can normally get. When the O2 level drops far enough, it triggers the body into doing a couple of cool things:

• • After (very approximately) 90 seconds, a significant amount of adrenaline (epinephrine) is produced.

• • The hypoxia-inducible factor 1a gene is expressed, to help the body make adjustments to better thrive in a low-O2 environment.

After holding your breath, you take a deep breath again and hold it briefly. This helps reset your body's oxygen levels. Your body uses oxygen more efficiently now, which is good for you.