A wireless system consisting (G-SENSOR, BTS, It) of an inertial sensor composed by a triaxial accelerometer, a magnetic sensor, and a triaxial gyroscope that positioned on L5 allows to perform gait analysis for healthy and patological subjects, to analyze and measure spatio-temporal and angular parameters during specific clinical tasks ( e.g. Timed Up and Go, Sit to Stand). The same system could be used in athletes evaluation and sport applications (e.g. vertical jump measurement).