Kinesiology of Exercise


The exercise that most effectively develops the supinator and pronator muscles is supination and pronation with the Strength Bar.

Major Muscles and Actions Involved

The supinator and biceps brachii are involved in supination, whereas the pronator quadratus and the pronator teres are involved in pronation. In supination the palm of the hand is turned upward while the elbow is kept bent, preferably at a 90-degree angle. In pronation the palm of the hand is turned downward while the elbow is kept bent at approximately a 90-degree angle.

Sports Uses

Of the two movements, pronation is more important in most sports actions. However, to keep the muscles in balance, the supinators must also be adequately developed. Pronation is used in almost all hitting and throwing wrist and hand actions, as for example, in baseball pitching, football throwing, baseball and softball batting, racquet sports forehands and overheads, and in the golf swing.

Exercise Analysis

  • Supination-pronation is often done with a dumbbell. However, it is not very effective when done this way because the resistance lever arm is too short. In essence, the closer the resistance to the hand, the easier it is to turn your hand and the less development that can occur. However, when you are using the Strength Bar, you can adjust the length of the lever by holding the weighted end closer or farther from your hand.
  • To isolate the supinators and pronators, you must maintain your elbow at a 90-degree angle when you execute supination and pronation. In this the forearm should remain level in a stable position at all times. This means you can also do it in other positions but only if you maintain a level forearm. Because of the difficulty in doing this,
    it is usually not ecommended. 
  • For an even greater ROM of the Strength Bar (up to 280 degrees), supination-pronation can be done with your arms held straight. The Strength Bar is held in front of you or out to the side in line with the shoulders. When done this way, the medial and lateral rotators of the shoulder joint are also involved, which produces the greater ROM.
  • For example, you can assume a standing position with your arm straight, parallel to the floor, in line with your shoulders, and then rotate the Strength Bar clockwise and counterclockwise. Be sure to hold your arm straight and stationary to develop the muscles in both joints. These are very good exercises for pitchers and tennis players, who often injure the rotator cuff muscles. 
  • The Strength Bar is very similar to the Thor's hammer. However, the Thor's hammer is limited in use. The Strength Bar has a collar for both two-inch and one-inch plates and has greater leverage so you do not have to use as much weight on the end. Because of its length, the Strength Bar is very suitable for a variety of players to develop the forearm muscles as needed in their respective sports. 
  • In addition, supination and pronation exercises are very important in preventing and treating various athletic injuries such as rotator cuff problems, tennis elbow, and golfer's elbow. Practical experiences have shown that this exercise is more suitable than many others in injury prevention and rehabilitation of elbow problems.
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