Each athlete will attend one meeting in which he will perform four tests: Squat jump test, Drop jump test, one leg jump test and jumps 30 seconds test. The tests with and without the infra patellar strap will be performed using The Optojump measuring system (Microgate, Bolzano, Italy). In addition the athlete will grade his pain severity with and without the infra patellar strap, using The Visual Analog Scale (VAS).There will be no follow up, all the data will be collected in one session.