A spacing member can be positioned between teeth of the athlete to obtain a desired position between the upper and lower jaw. At least one bite registration can be recorded while the lower jaw is in the desired position. The desired position can range from the physiological resting position, to a performance position, in which the lower jaw is positioned anteriorly in relation to the physiological resting position. The mouthpiece can be formed to include a pair of bite portions configured to substantially space apart and position the jaws generally according to the desired position, and a connecting portion can connect the bite portions within the mouth. The connecting portion may extend labially along the anterior teeth and associated gum region of the lower jaw, and may be sized and shaped to substantially lie out of the way so as to not impede speech of the athlete.