Fryette's laws of spinal coupling can be a difficult concept to grasp. They are not taught in depth in PT school, but we frequently hear about them as if we are supposed to follow them as 'laws of movement.' In reality, these laws have questionable validity. In fact, the term law should be taken loosely. These guidelines should be carefully utilized in diagnosing spinal conditions.
With that being said, the theories of spinal coupling can assist with your examination and treatment. if the lumbar spine is in a neutral position, sidebending creates contralateral rotation (Law 1). For example, left sidebending should cause a simultaneous right rotation. If the spine does not start in neutral, sidebending and rotation occur in the same direction. For example, a patient with increased lordosis does not start in neutral. When they sidebend left, they will also rotate left. The video below does a very nice job portraying these 2 patterns.
In addition to spinal coupling, remember to assess for the order of movement, a loss of movement, aberrant movements, pain or stiffness, and uniformity of the spinal curve when performing lumbar spine active range of motion.. Learn more by reading my Lumbar Spine AROM post!