Previous research studies defined the upper and lower bound values of ankle stiffness in quiet standing [1] [2]. While freely standing on footplates, subjects were submitted to a series of small disturbances that simulated the ankle movement common to this task. In this study, for a better understanding of the muscle thixotropy property – one of the short range passive phenomena in quiet standing [4] -, in addition to the sequence of small disturbances, we applied a slow and continuous large sway to reduce muscle thixotropy’s influence, and correlating it with static ankle stiffness. The experiment was approved by the local human ethics committee and conducted in ten participants that gave a written informed consent. A servo tube motor was connected to two footplates and programmed to apply different types of stimulus to the foot, summing up to eight different conditions. Fast, small and randomly positive or negative cosine-wave type disturbances (0.2 and 0.8 deg amplitude, 140ms duration) were followed by inter stimulus intervals of 2-4 seconds of stillness, or added to a randomized continuous slow sway of a higher amplitude (2-3 deg amplitude). Subjects were asked to stand freely on top of the footplates, with eyes open or closed – assuming that without a visual reference they would sway more. Types of conditions were determined by the differences of ankle sway size that each condition would incite. Torque was measured with miniature load cells attached to the footplates. For the ankle and body sway measurements, two laser-reflex sensors were placed at the umbilicus and mid-tibia levels. The accelerometer (attached to the bottom of the left footplate), left and right torque and relative angle data (captured by a potentiometer) were used for the Savitzky-Golay filter analsysis to calculate muscle stiffness. Despite the natural large disparities between subjects, the data suggests that ankle stiffness is inversely related to the stimulus size and body sway, indicating the decreasing effect that muscle thixotropy has on static ankle stiffness as the body sway increases.