Why am I sore sometimes after a treatment and is this common?

Yes, soreness can be an after-effect of the treatment and it is common to experience it. Soreness or tenderness can result from the pressure used to release the restrictions in your tissue, and can also be a result of under-hydration either before or after the treatment. If the body is not being properly hydrated after the session to flush out the toxins and metabolic wastes, they may be re-deposited into the muscular system causing tenderness.