Set-up: Start on all fours with your arms and thighs vertical.
Movement: Start the movement by bringing your head and pelvis towards each other - effectively rounding your back (the 'camel' position). Then raise your head and push your hips backwards, creating an arch in your back (the 'cat' position). With each position, extend as far as is comfortable and natural, the goal is not to force extreme range of motion, but rather to prepare the spine and back for more work.
Benefits: The cat camel can help increase thoracic spine (middle/upper back) mobility and is useful for warming up and protecting the spine. It accomplishes 'spinal flossing' - essentially lubricating it and preparing it for more strenuous activities.