The Thrower's Arm 101

The throwing arm of a baseball player has one of the toughest jobs in the world. It gets asked to create tremendous torque and then gets asked to slow it back down and control that torque. In fact the humeral head has been reported to internally rotate several thousand degrees per second in elite throwers. Imagine something spinning REALLY fast, and then having to come to a halt.

#Rapidfam member Zach Wheeler generates some of the highest arm speed in MLB as his average fastball is nearly 97 mph.

#Rapidfam member Zach Wheeler generates some of the highest arm speed in MLB as his average fastball is nearly 97 mph.

However, just as everything else in life, such demand can come at quite a cost, especially without proper strength and stability. The baseball player must have a strong rotator cuff and adequate scapulo-humeral rhythm (fancy talk for the shoulder blade working in sync with the arm bone) in order to avoid injury.  The rotator cuff contrary to popular belief, is not simply one structure and is made up of a team of 4 tiny muscles. These muscles act together with the deltoid (big shoulder muscle) to both stabilize and move the arm bone in the socket. While the rotator cuff team is busy doing its job, the shoulder blade’s team of muscles also is hard at work. There are about 17 muscles that attach to the shoulder blade, as it is surprisingly capable of 6 different types of movements. It can rotate up, down, tilt back and forth, and glide on the rib cage. If the baseball player’s shoulder blade does not move properly with the arm bone, things such as pain or loss of range of motion can occur, which in turn can cause decreased velocity, decreased command, or both.  

In consideration of all these characters in the story of the throw, it is extremely important to train the shoulder and scapula with optimal positioning and proper technique. This is one of the integral parts of our assessment process as we look at the following (among many other things) :

  • Can the athlete flex the arm without rib cage extension compensation? (Full range of motion over head)

  • Can the athlete adequately internally and externally rotate the humerus?

  • Can the athlete adequately rotate to each side?

  • Does the athlete rely heavily on larger muscles like pectorals or latissimus?

  • Can the athlete achieve full range of motion with scapular (shoulder blade) motions?

Some baseball players need to work on overhead mobility and movement quality, while others need to build protective strength around the joint itself. All of these questions paint a picture that helps the coach make the best decisions for each athlete whether it be strength, mobility, stability or all of the above. While it’s true that baseball players generally need the same thing in terms of strength and power, it doesn’t necessarily mean they should take the same paths to achieve these adaptations. 

Additionally, the athlete must have enough motor control and strength to generate power from the ground through the legs, through the core, and ultimately to the arm. This is why general strength training and motor competency are SO important. The more physically prepared an athlete is, the more physical (and mental) stress they are able to withstand. It’s about more than banded external rotation drills and speed ladders. Good training is multi-faceted!

We believe strongly in managing the stress of the throwing arm and giving each athlete exercises tailored to their needs. I like to think of arm care akin to maintaining the basics in a car. Changing the oil, gauging tire pressures, and rotating tires can seem tedious and not always impactful, but doing so can tremendously increase the life and value of your car. If these things are ignored all together however, you’ll certainly find yourself in need of a repair. In much the same way, maintaining the health of the throwing arm through consistent, properly executed exercise can make a huge difference on the health and longevity of a career.

We hope this is helpful! Have a question or comment? Let us know what you think, and be sure to follow us on social media!