Rope skipping is also a very basic form of a type of exercise called plyometrics. Plyometric exercises involve repetitive explosive movements, such as jumping up and down or catching and throwing a medicine ball. The idea is to execute the movement with as little downtime as possible between repetitions. This, in effect, trains muscles to be powerful and explosive, and utilize the kinetic energy inherent in athletic movements in the most efficient way.
A second, more efficient and correct method is to use an infrared laser placed at ground level. When an athlete jumps and breaks the plane of the laser with his/her hand, the height at which this occurs is measured. Devices based on United States Patent 5031903, "A vertical jump testing device comprising a plurality of vertically arranged measuring elements each pivotally mounted..." are also common. These devices are used at the highest levels of collegiate and professional performance testing. They are composed of several (roughly 70) 14-inch prongs placed 0.5 inches apart vertically. An athlete will then leap vertically (no running start or step) and make contact with the retractable prongs to mark their leaping ability. This device is used each year at the NFL scouting combine.