Why don't football quarterbacks and tennis players sustain UCL injuries at the same rate as baseball players?
Recently, there has been much discussion about the difference in UCL and overuse injuries in baseball pitchers compared to tennis players or football quarterbacks, and a lot of smart people have chimed in. As with any injury, there is often a plethora of factors that can contribute to occurrence. For the purpose of this post, were going to steer clear of analyzing body mechanics, strength, overhand motion, and other outstanding variables and solely look at why tennis players and football quarterbacks are not suffering the UCL tears at nearly the same rate that baseball pitchers are.
The weight of a tennis racquet can range anywhere from 9 ounces to more than 11 ounces, a professional football weighs about 14 ounces – 15 ounces. First I want to address the common thought that holding onto the racquet could be the reason for the decreased likelihood of a UCL tear in tennis players. Holding onto the racquet certainly doesn’t increase your chance of injury, because it doesn’t play much of a factor in UCL tears considering that most UCL tears occur at the point of max external rotation where there is the most elbow varus torque. The UCL is the primary passive stabilizers against elbow varus torque. Also, as Dr. Glen Fleisig and his team noted in their 2017 study published in Journal of Sports Health that flat ground ‘holds’ produced significantly decreased elbow varus torque throughout the arm cocking phase, even with 14ounce and 32 ounce balls.
That same study showed that pitching from a mound with a 5ounce ball produced significantly increased varus torque on the elbow compared to balls of greater weight. Here Is a chart from the study that shows the trajectory of varus stress on the elbow with differently weighted balls.
As you can see the elbow varus torque will continue to downwardly trend as the weight of the object thrown increases. We could expect this trend to continue with an 11-ounce tennis racquet and 15-ounce football. As referenced in this study, Newton’s second law requires the force to move a ball be equal to the mass of the ball multiplied by its acceleration. Although the heavier balls have more mass, there is less arm acceleration.
I was not able to find any specific data on internal rotation speed of the arm when throwing a football or during a tennis serve but this same study provided another graphic to show that as the weight of the external object increases the speed of the arm itself decreases.
Note: This is not the speed of the object as it travels through the air, rather the internal rotation speed of the arm as it moves through the throwing motion.
Could this mean that maybe 5 ounces balls are the MOST dangerous to throw? Or have we just become accustomed to moving a 5 ounce ball faster than any other weighted ball? hmm... For another day...