The research aims to measure the ability of muscle of athletes through: - The design of an electronic device to measure the ability of muscle for athletes. - Rationing and calibrating the device scientifically The sample was selected from intentional way of players from different sports and registered EU and the Egyptian federation (15) boys Player , and (10) girls players and the most important results were designing The device has a high degree of validity and reliability calibrated by specialists from the Faculty of Engineering, where the work was done as follows: - Testing calibration distances using Tool Maker Microscope accurately 0.001 mm and found that ready-under calibration gives an error in the approximate distances as far as 0.0333 of a millimeter. - time performance measurement test using Programmable logic controller with mechanical sensor and show that the device is in the calibration gives an error in the approximate distances as much as approximately 0.099 of a second