This paper presents the laboratory validation of the ASSIST-FEEv3, a cable-driven elbow-assisting device that is designed to facilitate flexion and extension assisted movements. The proposed device is a lightweight and portable solution, ensuring user accessibility in both home and clinical settings. The validation process includes operational performance through controlled exercise tests according to a properly designed protocol. The evaluation involves a series of motion trials, during which data acquisition and real-time monitoring give the characterization of the device effectiveness. This assisting device has the potential to expand exercise opportunities beyond clinical settings, even into domestic environments for elderly people.