a shaking which starts whenever the person is involved in physical motion by choice instead of being still. These shaking episodes are actually typical in those with Parkinson's disease. Additionally known as volitional tremor. Reference: intention tremor.
ACTION TREMOR: "Michael J. Fox, an unfortunate victim of Parkinson's Disease, doesn't let his illness take him away from the spotlight- hence, his action tremor's are rather noticeable by others when he is on television these days."