This paper proposes maneuverability indexes for a control stick that are based on considerations of muscle characteristics. The indexes are defined on the basis of muscle forces: stiffness of the musculoskeletal system and torque for accelerating the stick. Measuring muscle forces with electromyography, we examine the effectiveness of the proposed indexes experimentally. In a slow tracking operation, the index based on stiffness conforms to the subjective evaluation, but the index based on the torque is inadequate as an index of maneuverability; we therefore use the index based on stiffness as the maneuverability index. In experiments on a step operation, we divided the operation into two phases: moving and holding. The index in the holding operation is in good agreement with the subjective evaluation. In both tracking and step operations the characteristics of the index are appropriate whether or not the controlled object has a first-order lag element. As a result, it is shown that the index can indicate the maneuverability in the low-frequency tracking operation of the stick.