Everybody moves throughout the day, and to move, we use muscles. Dancing, snapping your fingers, waving to your neighbor outside washing his car all of these activities use muscles. However, to build strength in specific muscles, you must be sure to give them appropriate exercise. You can exercise muscles to build strength in three ways.
With isometric exercises
with isotonic or dynamic resistance exercises
In the previous lesson you learned that isometric contraction occurs when a muscle tries to shorten but shortening is prevented. In isometric exercises, your muscles contract at high intensities but don't change their length. The most common way to get that contraction is to press against an immovable object, such as a wall or a piece of furniture. Your muscles develop strength at that point in their range of motion.