The human body is extremely adaptable in its ability to accommodate itself to the physical demands put upon it. Progressive adaptation to the specific demands of a physical activity
will result in the increased ability to perform that specific physical activity. It must be stressed that the adaptation to or improvement in a specific activity will only increase the ability to meet that
demand generally, not any other. This means, referring again to our earlier example, that if players jog to build cardiovascular fitness, then cardiovascular fitness is what will result. They will not achieve
muscular endurance or strength of the level needed to sustain repeated sprinting. Training specifically designed to sustain repeated sprints must involve repeated sprinting.
Therefore, because the body's tendency is to adapt specifically to demands, volleyball training must be comprehensive and specific enough to provide the physical ability to meet the demands for strength, endurance,
and flexibility that are made on the player in the course of a game. The following are the four principles involved in specific training programs.