Stealing most of this from Breaking Muscle (http://breakingmuscle.com/strength-conditioning/verkhoshanskys-depth-jumps-create-gains-in-max-strength) Quick summary
- The depth jump is performed when an athlete drops off a box, lands briefly absorbing the shock, and then immediately jumps as high as possible. The landing period is usually less than 0.2 seconds.
- In the short term, the depth jump leads to a higher jump than a static high jump because the athlete is absorbing momentum and kinetic energy and using it on the subsequent jump
- The effects of depth jumps are not only short term as they lead to greater strength changes and more explosiveness. It was found that highly trained volleyball players undertaking a depth jump program gained 14% in their maximal strength.