One of the many tools yoga philosophy provides for understanding the human system is the prāṇa vayu model, which describes how energy flows to keep our system working.
Prāṇa is life energy. It's presence is the difference between something being alive or inanimate. And the unobstructed movement of prāṇa throughout our system makes us vibrant and healthy.
Each of the vayus is a description of how and where prāṇa moves to accomplish energetic tasks in our system.
The prāṇa vayu is located in the chest and head area and is responsible for intake (such as in eating, breathing in and seeing the world around you).
The samāna vayu is located in the midsection, around the stomach and upper digestive organs responsible for absorption and integration.
The apāna vayu is located in the lower abdomen and pelvic region. It is associated with elimination, the menstrual cycle, childbirth and general letting go.
The udāna vayu is responsible for communication and self-expression. It is located in the throat, and is accessed in the area that stretches from the chest to the face.
The vyāna vayu is diffused throughout the body. It is responsible for circulation, sensation and connection.
How to apply the prāṇa vayu system in yoga practice
We can have some influence over the flow of prāṇa in one of the vayus by moving the area (āsana), modifying breathing and bringing attention to a space. We can also use meditation and connection with various objects, gestures (as in mudra and nyāsam) and sound (chanting) to effect different aspects of the human system.
In time, I will share some ideas for using yoga tools like poses, breathing and meditation to influence the various areas of prāṇa flow.
But to begin with, it's helpful to consider how we can observe a disturbance in prāṇa (prāṇa prakopa).
Since the flow of prāṇa is what makes a body work well, noticing what's not working so well in the body/mind/emotions is a good start for choosing a vayu to work with.
For example, painful menstrual cramps, diarrhea, constipation or IBS would be a strong indication that the apāna region needs some attention. If a person doesn't make eye contact or speaks very softly, or on the other hand, speaks without consideration, working with the udāna region would be useful.
Once you can see a connection between an area of pain or difficulty and one of the vayus, you have some direction for choosing appropriate yoga techniques for bringing balance to that space.
Please remember that yoga practice we should never seek to control the system. Yoga practice is an opportunity to build or repair a relationship with the system, and the techniques you choose will work best if supportive and nourishing, not demanding or harsh. Especially where there is agitation in the system, go slow, be kind and choose a gentle approach.