This is a simulation of an alternative for a Downward-facing dog pose for those who cannot do inversions on the mat.   It also works well for a quick stretch at any time of the day when a Downward-facing Dog is not practical.
It is the upper body portion of the Downward-facing dog pose that is felt.  The stretch is primarily through the shoulders and upper back. It aids in improving posture and strengthening the upper back.  Do not force the stretch.  Keep your shoulders down and depressed as you lift your arms.  Keep your elbows as straight as possible.  Be mindful to keep your navel to the spine without arching your low back excessively.
Be sure to have the permission of your healthcare provider before doing this or any other physical activity.