Downward facing dog is a spinal stretch.
Though the posture tones the arms and stretches the back of the legs and though this is a prerequisite to finding the spinal stretch, those limbs are just the path to the destination.
The connection to the spine comes from opposition in the arms and legs.
The spine has a component in the muscles of the lower gut as well as those that envelope the back.
Once you’ve got enough arm strength to hold yourself in plank pose for a minute or more and once you’ve gotten enough space in the hamstrings, the backs of the legs, to lie on your back with straight legs able to go 45 degrees or more, you’re ready.
Take plank pose
Throw your hips in the air and suck the gut into the spine.
Urge your arms forward and keep them there as you
Push your thighs backward heels high.
Reach your heels away from your toes and downward
Imagine the ears to the wrists and the neck will release.
Each inhale will touch the tissue of the lower back and the exhales touch the tissue of the lower belly. You are stretching spinal muscles and the guide wire of the spine which originates in the front of the hips and attaches through the lower belly to the spine.
Hips Head Heels
One Two Three
Good Dog.