Kairos encloses the potential of multiple traditional machines in a single device: the compressed air technology, easy to operate, makes it suitable for rehabilitation applications as well as for sports training, even in the eccentric phase. The special feature of this device is the possibility given to the therapist to safely set exercises in concentric contraction but especially eccentric. Kairos is recommended for the functional rehabilitation of the upper and lower limbs. During the eccentric contraction, the force applied by the muscle appears to be three times that the one developed during the concentric phase. Therefore, the exercises in the eccentric phase represent a preventive treatment against any potential muscular damage.