Muscle tone is the amount of tension (or resistance to movement) in muscles when they are at rest. Our muscle tone helps us to hold our bodies upright when we are sitting and standing. Changes in muscle tone are what enable us to move. Since tone only describes a muscle when it is inactive or resting, it is quite possible for a child with low tone to still be very strong when they exert themselves and activate their muscles. There’s a big difference between muscle tone and muscle strength.