Power tumbling is tumbling that is done on an elevated runway, often referred to as a rod floor, that gives gymnasts extra spring to perform very high flips and skills. Not only does the tumbling series often end with huge twists and flips, but this tumbling differs from other forms of gymnastics tumbling because the competitor will generally perform many flips in a row, as the runway is very long and allows gymnasts to connect more skills than they can on an artistic gymnastics floor. 

Source: www.flogymnastics.com