In spring training 2001, researchers from Philadelphia’s Jefferson Medical College used high-resolution sonography to examine the anterior band of the ulnar collateral ligaments of 26 major-league pitchers.

The ultra-sound tests revealed micro-tears in 69 percent of the pitching arm UCLs of these 26 pitchers, who were between the ages of 21 and 39. Calcifications, which often accompany ligament injuries, appeared in 35 percent.

“The image quality produced by sonography has dramatically improved to the point that the wear and tear that occurs in a pitcher’s arm is now visible on an ultrasound well before he experiences symptoms,” says Dr. Levon N. Nazarian, the lead author of the study.  “Our results showed that when the pitching arms of these professional baseball players were stressed, the anterior band of the UCL was thicker, was more likely to have micro-tears and calcifications, and had a greater laxity or looseness in the joint when pressure was applied.”  The extent of ligament degeneration strongly correlated with years in professional baseball.

The study, published in the journal Radiology in April 2009, provides a significant piece in the puzzle of the UCL anterior band, the troublesome piece of sinew the size of a stubby pencil that often defines the success and duration of pitching careers.

The study not only demonstrates a remarkable diagnostic tool for seeing changes in the UCL before the onset of pain or disabling injury, often resulting in Tommy John Surgery.  It also provides evidence that degradation occurs to this critical component of the throwing arm gradually over the course of a pitching career.

Ligaments and tendons are cable-like bundles of collagen fibers.  As with any cable, breaking one strand will make it imperceptibly weaker.  It is not until a significant portion of the strands break that the ligament becomes significantly weaker, more compliant, more susceptible to complete failure.

There is anecdotal evidence that this weakened condition results in a diminished maximum velocity of the fastball. The UCL anterior band is the cable that transmits the torque of internal rotation from the humerus bone in the upper arm to the ulna bone in the forearm. The 5-m.p.h. fall-off in fastball velocity that typically occurs at the end of a career or before a UCL injury becomes acute is the likely result of weakening of this ligament.

An indication of this condition is instability of the elbow joint.  The Jefferson College study showed that when stress was applied, the joint space in the pitching elbows of the 26 subjects measured 4.2 mm on average, significantly greater than that of the pitcher’s non-pitching arm, which averaged 3 mm.

A compliant tendon, one that stretches more easily, is like a slipping clutch on a dragster.  The rotational acceleration of the arm is indeed dragster-like.  In the internal-rotation phase of the pitch, the forearm’s angular velocity exceeds 7,000 degrees/second, the equivalent of 1,200 rpm.  It accelerates to this velocity in just 0.03 second, placing huge stress on the UCL.

Ligaments and tendons are elastic.  For example, biomechanical studies have shown that the elasticity of the Achilles tendon in humans and similar tendons in animals provides storage and return of energy with each stride while running. Like all elastic materials, ligaments and tendons have a strain limit. Once a collagen fiber stretches beyond 105% of its normal length, it is likely to break.

The science of how ligaments and tendons heal indicates that the damage of broken fibers is not completely reversible. Though the human body produces new connective tissue for repair, it does not organize the tissue of tendons and ligaments into the original structure of long bundles of fibers.  The healing rarely creates a structure that is equal to its original strength and elasticity.

One implication of the irreversibility of ligament damage is that that there is only a finite number of strain-limit pitches in an arm.  That number may vary with the thickness of the ligament the pitcher has been given by the genetic dice-roll; with individual differences in pitching mechanics, strength, and flexibility; and with the cumulative number of maximal-effort pitches thrown. Pitchers who exceed this strain limit too frequently eventually suffer the cumulative result of broken fibers that leads to Tommy John surgery.

Though the sonography study brings good news — that UCL degeneration can now be measured before it becomes critical, the bad news remains: there are few practical options for preventing the degeneration, short of not pitching.  Here are some possibilities:

Proper wrist extension. Some pitchers begin the acceleration phase with the wrist locked at zero degrees of flexion.  This produces greater stress on the UCL than does extending the wrist during acceleration.  By extending the wrist 30 to 40 degrees (angled toward the back of the hand, as shown in the photo above), as most pitchers do, the ball is about 5% percent closer to the elbow on a fastball grip, reducing the resistance to acceleration by the same percentage.  The wrist flexes later, transferring momentum just before release.

Light- and heavy-ball training protocols.  Throwing a 6-ounce baseball places 20 percent more stress on the UCL than the standard 5-ounce baseball.  If maximal effort is applied with the heavy ball in this light-then-heavy routine, the additional stress could hasten degeneration of the UCL.

Lighter baseballs for young players. This concept has been presented in scientific papers by Dr. Glenn Fleisig of the American Sports Medicine Institute, a prominent research scientist.  Throwing a 4-ounce baseball would reduce the stress on young elbows by 20 percent.  There is precedent for this lighter-for-younger approach in another throwing sport.  The men’s shot put increases from 8 to 12 to 16 pounds from middle school to high school to college.

Fewer maximal-effort fastballs.  This may be the least practical path to UCL preservation, because the gatekeepers to professional baseball are armed with radar guns.  No one is likely to ascend to the majors by pitching the way they did a century ago — by throwing high heat only when there were base runners.  There are many major leaguers who have succeeded, however, by dialing back on fastball velocity.

*Bill Blewett is writing a book exploring pitching velocity including its history, how it is produced, and what we can do to manage, increase and further understand it.  The book will analyze the latest research to gain a better understanding of the elusive act of throwing 90+ mph and the implications that throwing hard has on the human body.*