In everyday physiotherapy practice, there is often no budget for expensive measuring instruments. Thus, devices such as a force plate are rarely available. Physiotherapists are always looking for inexpensive, practical and portable measuring instruments to evaluate therapy outcomes and to make reliable statements about the time for Return to Sport. Maximum jump height is a performance-determining factor in various jump-intensive game sports. In addition, the jump height serves as an important criterion to decide when an athlete can return to his usual sport after an injury. There is a new sensor on the market that measures jump height. This sensor is called Orthelligent Pro. It is shown to be a cost-effective and feasible measurement method for return to sport in physical therapy practice. So far, validity and reliability has never been tested. Therefore, this study aims to test the validity and reliability of the Orthelligent Pro for the measurement of maximum jump height. Two visits will take place 1-2 weeks apart. At the first visit, participants will complete 2x3 single-leg countermovement jumps measured by two testers each. At the second visit, three jumps are completed measured by the first tester.~The primary objective is to evaluate the intra-and intertester reliability of maximum jump height using Orthelligent Pro. The secondary objective is to test the concurrent validity of maximum jump height measured with the Orthelligent Pro compared with the gold standard which is the force plate. The primary and secondary endpoints are maximum jump height measured in centimeters.
The primary objective is to test intratester and intertester reliability of maximum jump height using the sensor Orthelligent Pro.~The secondary objective is to test the concurrent validity of maximum jump height measured with the Orthelligent Pro compared to the gold standard which is the force plate.