-Decades of research about stress have shown that it could be source of performance but also of cognitive deficit. The studies have led to highlight occupational stress variables that researchers have characterized by physiological measurements, data treatments and protocols becoming more and more complex with time. If these devices are gaining in precision, they are now too complex to allow non-specialist users to produce a quick interpretation of results. Yet for vocational training, specifically on simulators, trainers need to know in real time whether or not what they implement allows the trainees to learn in good conditions, i.e. by favoring the behavior produced by the positive effect of stress on performance. The present paper addresses the performance versus occupational stress during training sessions of anesthetists on simulator. We studied the performance and stress with or without physical effort using a simple protocol based on the use of basic heart parameters in order to obtain a quasi-instantaneous interpretation of the data. We identified cognitive deficit zone during training according to the Yerkes & Dodson (1908) relationship between performance and stress. We showed that performance versus stress during simulation training with or without physical efforts could be successfully analyzed for immediate assessment of stress influencing performance. Suggestions have been made for improving training sessions and avoid trainees' behavior induced by cognitive deficit. Limits of the protocol are exposed.