Amplitude refers to the size or range of movement. What we see with Parkinson’s disease is movements become small; and small movements make movements hard to do, think small shuffling steps, difficulty writing or doing up buttons, reduced arm swing.
So when you are exercising you need to concentrate on making your movements as big as your full available range of movement in your body, and this will be much bigger than what you actually perceive.
Over time your movements are likely to or have become under scaled and research is indicating that this is caused by sensory changes within the brain and that you perceive that your movements are normal size when they are small.
By focusing on the size of your movements you can overide these changes but it takes a lot of effort and concentration on a regular basis. Sometimes it requires a friend or family member to help you see if you are changing how you move. Often when we move big it feels abnormal as if you are moving too big, but this is a normal response as your sensory perception has changed. SO remember if it feels too big its probably just right.