Any exercise results in musculoskeletal stress, damaging structures in the body. Every joint has static (i.e. ligaments) and dynamic (i.e. muscles) structures. Sporting stress causes adaptation for both of these structures. Swimming stresses the shoulders, increasing the range of motion of the shoulder, allowing range of motion of sport specific motions (i.e. the early vertical forearm). Unfortunately, this adaptation damages the cellular structures relaying positional awareness or proprioception. Damaging these structures increases one's risk of injury and ability for joint control and biomechanical adjustment/correction. Theoretically, improving the impaired positional awareness will prevent injuries and improve motor control for ideal swimming biomechanics.
Cut out a bullseye target and place it on a wall. Next, have the athlete hold a laser pointer, keep their eyes open, and internally and externally rotate their arm telling them to stop with the laser pointer in the bullseye. Once they master this with their eyes open, have the athlete perform this with their eyes closed. Closing the eyes further stresses the proprioception system, improving motor control.
Perform 10 repetitions on each arm.