We present a model to predict and represent human fatigue in a 3D interactive system. A fatigue model has been developed for the fatigue assessment of several joints of the human body within the static case hypothesis. The model incorporates normalized torques, joint strength and maximum holding time as parameters. Fatigue evolution is predicted taking into account how these variables evolve over time. The fatigue model is embedded within an Inverse Kinematics engine that tries to achieve user-defined goals. During the animation, the predicted fatigue level is given to the graphical system in order to visualize it around its associated joint. The current fatigue value is exploited by the fatigue model to perform a new iteration towards the goal. The traditional joint model is broken down into two half-joints that better represents the anatomic organization of motion production through two independent muscle groups. Based on this organization, we can calculate and visualize independent fatigue variables for each antagonist muscle group. This type of visualization gives an intuitive and clear feedback. Each half-joint maintains its own fatigue model and variable. The two fatigue variables are represented by means of dynamic semicircles. Visual guides as semicircle's length and gradual color indicates fatigue evolution along time