Piriformis Syndrome
Piriformis syndrome is often cited as the cause for hip and leg pain. The thinking is that due to the proximity of a muscle called piriformis to the sciatic nerve, it can cause pain down the leg. This came from the observation that in some cases, the sciatic nerve can pierce the muscle belly of piriformis, resulting in compression of the sciatic any time piriformis became active. Anatomically this is conceivable, however the incidence rate is very low. Piriformis can become a problematic muscle, along with many others in the vicinity.
The back side of your hip is loaded with muscles, big ones like glutes and small ones that are called the external rotators. These muscles all work in similar fashion, in that they compress the back side of the hip and glue it to the pelvis while turning the leg outward. The result can be your center of gravity being pushed forward over your toes. Piriformis is a part of this process, being one of the small rotators, however it rarely acts alone. Larger muscles that overlay the small ones bring them along for the ride.
A large proportion of our musculature is on our back side and utilizing those muscles to help us move within the world is often a default pattern. They are big, strong muscles that can do a lot of work and recruiting them for tasks is useful. That being said, overutilizing those muscles, and smaller variations like piriformis can result in problems. If we spend time training muscles like glutes, lats, traps, calves, etc. they will grow larger and become more active. That activity alters bone and joint position, limiting access to other positions if exercise programming is not strategic. Should that activity become sufficient to compress the space around the pelvis that houses the sciatic nerve, pain in the leg can arise. Piriformis did contribute to this process in that it moves in similar directions as the big glute muscles but can have an effect due to proximity and it can close off the last bit of space needed for the sciatic nerve.
Piriformis syndrome is anatomically a real possibility, albeit rare. There seems to be a more complex mechanism for the pain developed with this clinical presentation, however. Activities like foam rolling, mobility work and developing the ability to create internal rotation are all means by which you can reduce these muscle activation patterns and restore space where it was lost. The foam roller may promote decreased motor output and following it with something like a split squat may make use of that decreased output by creating an inward turn.
Austin Ulrich, Physical Therapist
