When baseball coaches observe power pitchers who can throw hard, or position players who can gun down baserunners, they talk about players with great arms or strong arms. But when those same players develop arm problems, the term rotator cuff always seems to be part of the conversation. Those two words-rotator cuff-are often associated with serious injuries, major surgery, and threatened careers.
Athletes who throw as a major part of their performance place an inordinate amount of stress on the shoulder. A pitcher who throws a 90-mileper-hour (145-km-per-hour) fastball has an internal rotational velocity of the shoulder of between 6,000 and 10,000 degrees per second. If he could continue moving his arm in a complete circle and maintain that velocity (both of which are, of course, impossible), his arm would complete 17 to 28 circles during a period of one second. That kind of stress, exacerbated by age and overuse-especially in the absence of a strength training program for the rotator cuff-brings a high probability of injury. At least 50 percent of all professional baseball pitchers have missed one or more starts in their careers because of shoulder problems.
As a group, baseball players tend not to enjoy rotator cuff exercises. In fact, it is probably not an overstatement to say that they hate them. To many, these exercises are boring, and players may not understand the importance of the rotator cuff and what it does for their throwing motion. This attitude is common among players and is one that they have to overcome.
A related mistake is using the wrong lifts. Bench presses, for example, are popular among lifters but do not help develop rotator cuff muscles. The reason for the name "rotator cuff" is that the humerus (the long bone of the upper arm) rotates. Bench presses are performed in a single plane that does not involve the muscles needed for rotation-no rotation, no development of rotator cuff muscles.
The third mistake is a common one-poor technique. Once an athlete gets sloppy, using momentum instead of force, or recruiting the wrong muscles to lift the weight, the lift loses its effectiveness and the person risks injury.
If medicine balls are used, never use one that is too heavy. If its unclear what weight to use, it is better to err on the light side. If the ball is too heavy, technique will break down. A second mistake is to catch a medicine ball in the air. The receiver of medicine ball throws (with the exception of abdominal exercises), should always let the ball bounce or hit the floor before receiving it. Catching hard-thrown balls can cause elbow and shoulder injuries.
This is an excerpt from Complete Conditioning for Baseball.