Spasticity is a condition of muscles that is a velocity resistance to stretch. What that means to a child and to a parent is that if you move the limb slowly, you have a difference than if you move that limb fast. Spasticity restricts movement and it creates a break on the system. It's as if they're trying to move, but they're held back. By treating spasticity, you may improve the range of motion or the action of the movement.

Cerebral Palsy affects body movement, muscle control, muscle coordination, muscle tone, reflex, posture and balance. Depending on the part of the brain that is injured depends on how someone’s muscle tone will be effected. For people with spastic CP they have increased muscle tone because of the part of the brain that's injured. If causes very tight muscles which in turn effects the movement of the joints and of the limbs. For others who have dyskinetic CP they lose the ability to have voluntary control over their muscles, and they can have jerky and uncontrolled movement patterns.