So this is a big one that we are tackling, and we will not even scratch the surface of it's importance.  Prana, Sanskrit for life force energy (breath).  Pranayama, the first thing we do in our daily practice of Bikram Yoga.  We know the drill, it warms the body from the inside out, sets the tone for the class.  We hear these things in class, every class.  This is what is really key about Pranayama though...it takes our breathing back to a belly breathing format that was native to us when we were infants.  It re-teaches us how to be in control of our breath which allows us to control our mind and thereby, our life. 

Here is a brief physiological explanation of a very intangible concept.  When we do not focus on our breathing we breathe as most people do, using 10% of our lungs, the very topmost part of the lungs.  When we do Standing Deep Breathing Posture we roll our shoulders back, opening the chest cavity.  We breathe in which engages the diaphragm.  The diaphragm is a band of muscles under the lungs, above the abdomen.  When the diaphragm contracts it pulls the chest cage down opening the chest cavity for more capacity of the lungs.  The negative pressure pulls oxygen down into the lungs.  If done properly, 100% of the lung capacity can be filled.  Upon exhale the diaphragm relaxes, and the positive pressure naturally pushes the air out.  And did you know that when you make a snoring sound upon inhale you are compressing your diaphragm even more than just inhaling alone?  And did you also know that when you make the loud "HA" sound upon exhale that you are also contracting your diaphragm, literally squeezing all the stale air out of your lungs?

Breathing in slowly consciously taps into our parasympathetic nervous system.  This is the part of the nervous system that controls our "flight or fight" mode.  In other words, it tells the whole body to relax or panic based on the input it is receiving.  In this case it relaxes due to the deep breathing.    

It has become common to be unaware of the the role of the lungs (and the amount of oxygen they take in).  Shallow breathing anatomically causes your body to be in a state of distress.  Short, shallow breaths say to your body, "Be ready to sprint away at any time."  That is the physiological message that your body is receiving - be stressed.