Investigators expected that intense therapy performed in the sub-acute phase following the stroke would be effective in preventing elbow spasticity from occurring at a later stage (i.e. 3-4 months after the stroke), the latter being quantified by means of the Modified Ashworth Scale (MAS). Similarly to other phase-II studies in the field of post-stroke rehabilitation, the present study will include only one group of patients. As a secondary objective, similarly to other studies with robot-assisted therapy, investigators wiil test the ability of this system to be used for assessing rehabilitation outcome. Investigators will introduce novel evaluation metrics based on the kinematics and kinetics variables recorded by the NEEM and compared them with MAS values.