Because of the enormous number of neurons and reflex pathways involved in the control of human motion, a comprehensive identification of the structure of the feedback control circuitry is a formidable experimental task. A theoretical approach based on a carefully developed model could shed light on its likely general structure, thereby providing guidance to experimenters. This paper presents a fuzzy logic based control strategy for modeling the human postural dynamics. In particular, we develop a fuzzy controller to coordinate the movement of a three segment sagittal human model to achieve upright posture. The actuation mechanism of the system consists of six muscle like actuators which are co-activated to modulate the stiffness at the joints. Simulation results are presented to illustrate the underlying principles.