I found out that if you practice penultimate two-step jumping practice dunking or just jumping, it gives a MUCH better workout than any one step jumping practice. I was also able to increase my one foot jump vertical by this. I think 2-step dunking is much more powerful and waaaaaay cooler. It is also much safer because you are in more control of your body. Right now I'm 6'1" and can 2-step tomahawk and basically everything off one foot
Muscular strength and explosiveness must be developed in conjunction with flexibility if the athlete is to maximize the jumping ability and reduce the risk of injury to structures such as the Achilles tendon and knee ligaments. Flexibility, when achieved through focused stretching programs, will serve to increase the range of motion in the joints essential to jumping: the ankles, knees, and hips. A common muscular deficiency that plagues athletes who require well-developed leaping ability is a lack of flexibility and resultant strength imbalance between the quadriceps (thigh) muscles and the hamstrings, the pair of muscles responsible for the flexion and the extension of the knee. Proper stretching will assist the athlete in the maintenance of an approximate 3:2 ratio in the relative strength of the quadriceps to the hamstring. When there is a significant deviation from that proportion, the knee and the muscles themselves are at greater risk of injury.
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.