Simultaneous measurement of the grip/load force and the finger EMG: Effects of the grasping condition

Human has efficient grasping strategies, such as the anticipatory force programming, using the somatic sensation of the various properties of the object. However, it is not clear how the object's weight and grasping condition affect the motor outputs during the grasping motion. In this paper, the grip/load force and the surface electromyography (EMG) of abductor pollicis brevis muscle (AbPB) and adductor pollicis muscle (AdP) are measured simultaneously to investigate the relation between the object's weight and the motor outputs. The experimental results show that the changes of the weight affect the initial peak grip force. However, the grasping condition affects the motor outputs in the precontact phase measured by the AbPB EMG. These results suggest that the anticipatory force programming largely depends on not only the object's properties but also the grasping condition.