A load and stress of a tensioner may be determined from the change in the strain of the tensioner. The strain of the tensioner may be detected by an optical device having a Fiber Bragg Grating (FBG) that is attached to the tensioner. An electrical signal may be generated in response to the detected change in the mechanical strain of the tensioner by processing the light reflected from an optical fiber coupled to the optical device. The electrical signal may be processed to calculate a load on the tensioner. The calculated load may be stored and analyzed, along with previously-stored values for the load, to determine the condition of the tensioner system, and whether the tensioner system requires maintenance.