Rigidity (Stiffness) is considered one of the cardinal symptoms of Parkinson’s Disease. In addition to causing severe discomfort, it can also limit mobility. Unlike the stiffness associated with arthritis, the stiffness experienced by people living with Parkinson’s Disease results from damage to the nervous system not the joints. Our muscles have specialized nervous system receptors called muscle spindles. These muscle spindles act as length sensors within the muscle and are responsible for setting the baseline level of muscle tension also referred to as “muscle tone.” During fast to moderate movements such as those performed in daily lives these sensors are activated, increasing muscle tension. However, when slow, prolonged stretching occurs these sensors become inactive resulting in decreased muscle tension. Repeated flexibility training causes these sensors to desensitize over time resulting in decreased rigidity and increased mobility.