The vertical jump is a complex, multi-joint movement that requires muscle coordination best improved by specific skill development. Muscular strength definitely contributes to vertical jump performance. Whether or not a person's jump performance will improve by concentrating on strength depends on how strong the person is at the start of the training program. Studies show that vertical jump performance improved significantly following strength training in subjects who began with only average strength. Power is an even more important contributor to vertical jump development than strength.
Power is the ability to exert force quickly through a vertical distance.
It has been shown that traditional strength training methods using slow, controlled movements do not necessarily produce great improvements in ones vertical jumping ability. On the other hand, vertical jump training using light loads increases a person's ability to rapidly develop force, i.e. power. There is a reflexive increase in stimulation to the muscles brought about by the sudden stretch, and there is a storage of elastic energy in the muscles and tendons that is recovered during the subsequent jump, making it more powerful. Studies show that jump training increases the height of jumps preceded by counter movements. Plyometric jump training increases the overall neural stimulation of the muscle, but this adaptation requires time to develop.