The objectives of this study was to examine the effect of stimulation pulse shape on the recruitment selectivity of a novel combined interfascicular and cuff electrode (CICE) in an in vitro pig nerve model and secondly to examine if information extracted from intramuscular EMG (iEMG) recordings can provide reliable information on a functional movement and during development of muscle fatigue in a rat model. To investigate this, two experiments with a pig nerve model and a rat model was conducted. The first investigation was performed in vitro on a pig nerve model. The CICE was placed around and in the nerve, to give the most possible selectivity during Functional electrical stimulation. The results showed that a combination of the five pulses increased the selectivity also the CICE showed higher device selectivity compared to the cuff electrode alone. Besides this it was also observed that pulse 4 showed the highest selective activation of the fascicles. For the second part a rat was stimulated with longitudinal intrafascicular electrodes in the hindlimb. The results showed that the ankle angle and the iEMG amplitude decreased when the muscles fatigued also a higher correlation between the ankle angle and iEMG was present when stimulation frequencies above 40 Hz were applied. It also indicated that TA might be a more reliable source of feedback than the GM since the TA had a higher correlation.