Robotic assisted locomotion systems are recently gaining appreciation and diffusion as useful methods to rehabilitate individuals with lost sensorimotor function. Our aim was to evaluate potential changes in the autonomic nervous system activity (by ECG and spectral analysis), due to the experimental protocol, which include suspension of the subject to be instrumented on the system. A group of 10 normal subjects was studied during the rehabilitation protocol. Results showed a significant tachycardia and a reduced variance, during orthostatic stress induced by the suspension phase in comparison with sitting baseline condition but no significant increase of LF normalized power as it would be expected during a sympathetic activation.