Abstract: The present invention is a device for effectively isolating the shoulder joints and surrounding musculature to provide a strength and conditioning effect while maintaining flexibility about the joint. More specifically, the instantly disclosed apparatus is a butterfly exercise device useful for isolating the pectoral and deltoid muscle groups while rotating the shoulder joint and forearm areas of the user. In its most basic form the device includes first and second members which are constructed and arranged to accept the user's forearm and hand. These members are hingedly engaged and are maintained in a first position by variable resistance means. A force, exerted by the user's forearms in opposition to the variable resistance means, moves the first and second members to a second position, followed by completion of the repetition by returning to the initial position.