Gaining strength has something more to do with the muscle fibers in the body and how fast it can â??twitchâ??. In order to increase vertical leap, the player also has to increase the amount of strength in the body. This will give him the explosive power to move upward when needed. There are slow muscle fibers and fast muscle fibers. So far, there has been no found scientific method in converting slow muscle fibers to fast ones, so most athletes will have to do with exercise methods such as plyometrics in order for slow muscle fibers to imitate the movements of fast muscle fibers. The size of muscle fibers in the body can actually be increased by activating the other fibers for usage. Learning the science behind all the exercises will give on a dire advantage in the training and practice department. All athletes should be knowledgeable on how their muscles work.