Augmented Reality (AR) uses computer-generated virtual information to enhance the user’s information access. While numerous previous studies have demonstrated the large potential of AR to improve industrial processes by enhancing product quality and reducing production times it is still unclear if and how long term usage of such AR technology produces stress and strain. This paper presents an approach to use the analysis of Heart Rate Variability to objectively measure current user strain during different work tasks. Results of a user study comparing strain during an AR supported and a non-AR supported work task in a laboratory setting are presented and discussed.