Supination, and especially pronation, are very important actions that occur in almost all hitting and throwing actions. Supination is the act of turning the palm upward and pronation is the act of turning the palm downward.
For example, in throwing (as in a fastball) pronation occurs to get the fingers behind the ball so that they can impart the force generated by the body into the ball. It is a natural action in the follow-through.
Supination is not used in throwing because the fingers end up getting in front of the ball just prior to release. As a result you will be able to apply only limited force as the hands move from behind the ball to in front of the ball.
More importantly, this action creates great force in the elbow which and lead to injury and in some cases, Tommy John surgery. Supination is seen quite often in young pitchers and football quarterbacks. It is usually seen when they try to throw a breaking ball, i.e., a ball that breaks to the left when thrown by a right-handed pitcher.
In execution of hitting actions as seen in baseball and golf, supination of one hand and pronation of the other hand, takes place in the wrist break. Because both hands are in contact with the hitting implement, they exert equal amounts of force. They are especially important in golf to bring the clubhead to the square-to-the-ball position prior to contact.
Supination-pronation are also used in common everyday activities as for example turning a doorknob or turning a screwdriver. If the muscles are not strong enough, or do not have sufficient endurance, these actions are usually responsible for all combined shiftcarpal tunnel syndrome.
Thus, development of the muscles involved in supination-pronation is very important for improved sports performance and injury prevention. Supination-pronation exercises can be done separately or at the same time.
For convenience, they are usually executed in one exercise by going through a full range of motion in supination and then pronation. I have found that the Strength Bar is best suited for strengthening these muscles. Using longer or shorter bars typically make the exercise too easy or too difficult.
The key to success in this exercise is to strengthen the muscles through the full range of motion with your forearm held stationary. Your forearm should rotate sufficiently to allow the bar to come to a position that is parallel to the floor. For some athletes, especially pitchers and tennis players, the range of motion can be even greater.
The exercise is usually done with a stationary forearm on a bench with the elbow bent at 90°. However, it is also possible to combine medial and lateral shoulder rotation with hand supination and pronation. This typically occurs when doing rotator cuff exercises with a straight arm held in front of the body.
For more information on exercise execution together with illustrations, see Biomechanics and Kinesiology of Exercise . For more information on the Strength Bar, see Products section.