An apparatus for strengthening hand, wrist, forearm, and shoulder muscles, thereby increasing performance and reducing the risk of injury in sports that utilize a swinging motion, such as golf, tennis, or baseball. The apparatus is also used to rehabilitate injured muscles and connective tissue in the wrist, forearm, and shoulder.The apparatus consists of two cam assemblies connected to a extensible support that has an adjustable height. The cam assemblies are adjustable relative to the coronal plane of the player's body and each comprises a support, a rotatable cam, a handle, and a resistive band. Each handle is adjustable relative to the sagittal plane of the player's body. The ability to adjust the apparatus in three planes means that a player is able to focus on the development of sport-specific muscles by adjusting the apparatus to mimic the swing used for a particular sport.