Driving posture is important to determine the comfortability of the driver. The purpose of this study is to investigate the muscle response in car pedal operation. To evaluate this response, 11 volunteers involved in simulated driving experiment using an electrical impedance myography to detect the muscle contraction of the lower leg, particularly at Gastrocnemius medial (GM). The driver requires to perform different pedal actions. The results depict that GM muscle shows different reaction according to pedal actions. According to these results, different degree of ankle angle lead to different muscle response. These findings help us to understand the effect of physical attribute related to muscle response and joint angle on driver during monotonous driving task.