Continuing our discussion about the set of poses called a "vinyasa" that we began in The Most Advanced Beginner's Posture, we move from the chaturanga to upward facing dog (or urdhva mukha svanasana).
When chaturanga is properly performed, the transition to upward facing dog is seamless. From the low pushup position the transition is simply straightening the arms, sending the chest through the arms, rolling over the feet to the toenail side, and pressing down through the toenails to lift the thighs off of the mat.
In upward facing dog, the feet press into the mat, the quads engage and the knees/thighs lift, the transverse abdominis continues to be active which protects the low back and moderates the backbend, the hands continue to actively press the mat away, scapulae migrate together and away from the ears, chest is open, and gaze is forward (keeping the neck in neutral).
Often upward facing dog is rushed through on the way to downward facing dog. This results in poor muscular activation in this pose, leading the hips to sag towards the floor, the low back to hinge, and the shoulder blades to elevate towards the ears. You will also frequently see students looking up, causing hyperextension of the cervical spine/neck.
Upward facing dog is an incredibly intense backbend. It should not be the first backbend students do during class. The spine should be properly prepped with other smaller backbending poses, such as cat/cow or baby cobra.
The most common injuries you will see from an improper upward facing dog are neck pain and low back pain.