The invention is directed to a muscle trainer for exercising opposing muscles of a person moving an implement, such as a golf club, wherein, if the opposing muscles were of appropriate strength, the opposing muscles would desirably apply forces in opposite directions to the implement to assist in maintaining an ideal movement of the implement. The contemplated muscle trainer of this invention includes a body and a force generator positioned at a prescribed location on the body for urging the body in a direction away from a force direction which a weaker set of the opposing muscles would normally apply to the implement in the movement of the implement by the person.