As you are well aware, there are many applications for repeated motions. They can address deficits in mobility, strength, neural tension, DTR's, movement patterns, pain and more. One of the things that stood out to me the most when I was first learning about repeated motions, was how it applied to extremities through the spine. Just because there wasn't "radicular pain," neural symptoms, or central pain, didn't mean that we should just ignore the spine altogether.
Having recently started at my new position, I have taken over several cases from other PT's. One older individual started PT with leg pain (no back pain), which is now resolved, but he was still having difficulty lifting his leg for ascending stairs or performing bed transfers. Upon examination, he had some passive hip mobility restrictions but his active SLR and hip flexion mobility were both significantly less than passive mobility. He also had significant restriction with lumbar extension (no major SGIS limitation noted). From my experience, a lot of hip mobility, strength and pain issues are resolved with treatment to the lumbar spine, even when no pain is present. I proceeded with some lumbar mobilizations. Following the lumbar treatment, he had full hip flexion PROM and nearly symmetrical active SLR.
Now I may not fully understand the mechanism of why these changes have occurred, but I try to relate it to neural physiology. With any restriction in neural mobility, we see a loss in axoplasmic flow, which makes it easier for nerves to not function appropriately. I always relate it to a "kink" in the hose with water running through out. I simply try and help the patient get the "kinks" out by either performing a manual treatment or teaching the patient an exercise the gets the joints moving better that are limiting the nerve. What I try and apply to each patient is: start with assessing the spine (no matter the patient complaint!) and work your way down. By treating any restrictions you see, you will at the worst improve that areas mobility. You may, however, start to see some trends with subjective reports responding to spinal treatment.
-Dr. Chris Fox, PT, DPT, OCS