A recent research line investigates the motor control adaptation after the perturbation of the muscle pulling directions, simulated with myoelectric control of an isometric reaching task in virtual reality. Such perturbations rely on an estimation of the mapping between the electromyographic (EMG) signal of recorded muscles and the end-point forces. However, the consistency of this mapping across sessions performed in different days is not known. In this study we tested the consistency of the EMG-to-force mapping recorded on multiple sessions in different days. We also tested the consistency of the EMG-to-force mapping after subject posture changes and accidental EMG electrodes detachment. A good consistency was identified when all the EMG recordings are normalized to a unique value, even if incorrect electrode positioning remains one of the major issues for reliable use of myoelectric control.