Pranayama, or breathing technique, is very important in yoga. It goes hand in hand with the asana or pose. In the Yoga Sutra, the practices of pranayama and asana are considered to be the highest form of purification and self discipline for the mind and the body, respectively. The practices produce the actual physical sensation of heat, called tapas, or the inner fire of purification. It is taught that this heat is part of the process of purifying the nadis, or subtle nerve channels of the body. This allows a more healthful state to be experienced and allows the mind to become more calm. As the yogi follows the proper rhythmic patterns of slow deep breathing "the patterns strengthen the respiratory system, soothe the nervous system and reduce craving. As desires and cravings diminish, the mind is set free and becomes a fit vehicle for concentration."
Today I was having yoga class with Adele. Sometimes it is a real struggle to get into a pose and stay in it with dignity. In these instances I start breathing really hard, hyperventillating. Today Adele admonished me for not having a long enough inhale. My exhales are good, she said, but there's not much to exhale if I inhale almost nothing.
In six years of practice I have never paid much attention to my inhale. In the second part of my practice I made a conscious effort to lengthen the breath especially the inhale. It makes a world of difference, I can now attest to that. I felt immediately calmer, and I stayed longer in the postures. In fact, I realized, that when you are already in the posture, it's best to just forget about it, and concentrate mostly on the breathing. I found that when I did that, the posture automatically took care of itself and got better, or deeper.