Abstract
To examine the relations between driver's muscular activities and driving tasks while lane-changing, the examination was carried out with different four characteristics of vehicle dynamics by the combination of the two kinds of different tire in a closed proving ground. Driver's muscular activities of deltoid muscle anterior and masseter muscle were measured by using surface EMG. In, addition, driver's ECG, driving operations and vehicle dynamics were measured. As a result the activity of masseter was obviously non-related to driving operations and posture supportings; This activity level increased on the vehicle with lower stability and too much stability. In addition, activity level of masseter shows negative co rrelation with subjective evaluation of handling and driveability.