तस्मिन् सति श्वासप्रश्वासयोर्गतिविच्छेदः प्राणायामः
II.49 tasmin sati śvāsa-praśvāsayor gati-vicchedaḥ prāṇāyāmaḥ
When āsana is accomplished, prānāyāma, breath control follows. This consists of the regulation of the incoming and outgoing breaths.
बाह्याभ्यन्तरस्तम्भवृत्तिर्देशकालसंख्याभिः परिदृष्टो दीर्घसूक्ष्मः
II.50 bāhyābhyantara-stambha-vṛttiḥ deśa-kāla-sankhyābhiḥ paridṛṣṭo dīrgha-sūkṣmaḥ
[Prānāyāma] manifests as external, internal, and restrained movements of breath. These are drawn out and subtle in accordance to place, time, and number.
Prānāyāma, or breath control, is the fourth limb in the eight limb path. It, together with āsana make up the physical practice of this path. As we become more subtly aware of our physical bodies, we also become more aware of the internal energy shifts and physical sensations effected by the breath.
The breath is the most basic, most obvious example of the joining of opposites we discover through the practice of yoga. It is one of the best things to focus on during our practice because it is always there. If you are alive the breath is there. The breath and the mind are intimately connected. This relationship is the most basic element of a deep yoga practice. As you stretch the body you free the breath. As you extend the breath you settle the mind.
Prāna is your vital energy. It is responsible for organizing and influencing all perceptions, patterns, sensations, and functioning of the mind. Prāna is your life force. Somewhat confusing, but non the less an obvious correlation, prāna is also the term used for the inhaling of breath (there is no life without inhale). It is the physical pattern or rising up, blossoming. Apāna, on the other hand, governs the physical and neurological patterns within the body associated with grounding, relaxing and stabilizing. Like yin and yang these two opposites are inseparable. To rise you must root. Without the rising there is no point to the rooting.
As you meditate on this and use it to help you in your āsana practice, the mind begin to settle, to recede from the outer sense world, and focus on one point, the breath. These next steps are the next two limbs of the practice, pratyāhāra and dhāranā, Eventually leading to meditation and liberation, the final two limbs. Without the ethical limbs, the yamas and niyamas, the mind would be too distracted by the outside world. Without āsana the body would not be open and flexible enough to allow the breath to flow freely and allow you to control it. Yet as we learn how to control the breath, and therefore slow down the mind, we become more intentional in our relationships and our actions, and the body is able to relax and let go of tensions easier. As we practice meditation, it becomes easier to focus on the breath. Hence we again see the interconnection of all the eight limbs as a complete practice.
There are many different prānāyāma practices and exercises. All help with balancing or even manipulating the prāna and apāna aspects of the breath. Breath control is essential to a good yoga practice and honestly will be helpful in your every day life. Exercising the breath is one of the most effective ways to reduce stress and anxiety as well as help you slow down to make better, more mindful decisions in your life. The best part is it can be done anywhere, at any time, without anyone noticing. It helps you be able to help yourself.
“The Yoga Sutras of Patañjali” by Edwin F. Bryant
“The Mirror of Yoga” by Richard Freeman