It is well known that the Amplified Piezo Actuators (APA) offer large strains in static conditions and at resonance. Because many applications as shakers, anti-vibration and motors would benefit also of large dynamic strain below resonance, the maximum strain of the APA has been theoretically and experimentally investigated in this wide frequency range. The tested actuator is the APA30uXS currently used in the SPA30uXS new inertial micro piezo motor.