If you've every observed a yoga class, it simply looks like the students are moving from pose to pose with the greatest of ease. Movement is certainly a part of the yoga equation, but much more is going on. An important feature of yoga is something you cannot see: the breath.
Breath is the foundation of yoga. It allows the body to move efficiently through the various poses, helps you to support the body while in a posture, and it calms the mind. Let's take a look at how the breath works in a yoga practice.
In some yoga classes, the teacher will instruct you by providing breath cues to help you move from one pose to the other: "Inhale. Extend your arms into the air. Exhale. Fold forward." The breath, in this case, helps with blood and oxygen flow to and from the heart and throughout the whole body. As a result, the body can move due to the nutrient blood flow to each muscle fiber so those muscles can relax and engage as needed. On the contrary, if you hold your breath, the body becomes tense and stressed; this makes it quite difficult for the body to move efficiently. In fact, this is quite counterproductive in the yoga practice. The idea is to bring peace and calm to the mind and body. Part of the goal is to release tension while you do yoga. Breath helps with that.
Not only does the breath help with blood flow so you can move, but it also provides a grounding sense of support when you are holding a posture. The core of the body, or your entire torso, is the center for providing strength and support in many yoga poses. Having a strong core can help you stand up straight with good posture, elevate one leg into the air for a balancing pose, or to hold yourself upside down in a headstand! How do you do all this?
There is a breath practice in yoga called Pranayama; it is basically how you control your breath while in motion or in stillness. One pranayama exercise is called Ujjayi (oo-jah-yee) Breath. It means "victorious breath." When combined with a physical engagement of the abdominal muscles (called the Abdominal Lock) you will be able to sustain many yoga postures while at the same time build core strength. Here's how...
When you practice Ujjayi, you use the muscles of your throat to create the action of breathing in and breathing out. If you open your mouth and take a slow deep breath in, you'll experience a coolness hit the back of your throat. You'll notice the muscles of your throat engaging to draw in the breath. As you exhale slowly, like you're fogging a mirror, you may feel a warmth leave your mouth. Now, if you continue to breathe in this fashion, but with your mouth closed, you'll still feel the action of your working throat muscles while air moves through your nose. This is Ujjayi Breath.
Take another full breath in using this exercise, this time, feel the air rise up to fill up your lungs. As you exhale, still with your mouth closed, draw your navel in toward your spine to engage your abdominal muscles. This is the Abdominal Lock. There are several locks practiced in yoga, but this is probably the most common. As mentioned, it helps sustain and support you as you move from pose to pose. And at the same time, you'll condition, tone, and strengthen your core muscles.
Calm Your Mind
Breath is also very much involved with settling the mind. When you take deep breaths and pay attention to your body in motion, your focus draws inward. You begin to create a greater sense of self and you become more aware of what is happening inside of you rather than what is going on outside of you. This act softens and clears the mind of the clutter that tends to distract you. With continued practice, you will notice a shift in focus: you may see that you are less distracted by and/or able to deal with the obstacles that you face on a daily basis. This calming of the mind can be done while you sit in stillness or even while in motion in other yoga classes. Both are effective; both are aligned with the intention of yoga.
So you can see, your breath is a very important factor in the realm of yoga. If you're not familiar with a Downward Facing Dog or a Crow Pose, what you do know and have at all times is your breath. Practice breathing and you're doing yoga.