Humans are most sensitive to whole body vibration under low-frequency excitation in seated position. Biodynamics of seated human subjects has been a topic of interest over the years, and a number of mathematical models have been established. A simple model that captures the essential dynamics of a seated human exposed to whole body vibration is 4-DOF dynamic models of the human body developed by Wan and Schimmels. After introduction of the excitation we can analyze the response in particular segments of the model. As an example, the operator's head displacement was determined for the cultivation of the soil.