What Happens When Pitchers Get Tired?

Effect of Fatigue on Medial Elbow Torque in Baseball Pitchers: A Simulated Game Analysis

The American Journal of Sports Medicine, June 4th, 2018

Okoroha Et. Al   

Department of Orthopaedic Surgery, Henry Ford Hospital, Detroit, Michigan, USA

If you’ve ever played baseball, an overhead sport, or even just thrown a ball over and over then you know that at some point your arm’s going to start tiring out. What exactly happens at the elbow when a pitcher arm begins to fatigue throughout the course of a game? We know UCL injury is a huge issue in baseball, but how exactly does fatigue play a role in stresses to the medial elbow?

The authors in this study wanted to have a specific understanding of what happens, biomechanically, at the medial elbow as pitch count increases throughout the course of a game (simulated in this case).

If we assume fatigue increases throughout the course of a game and pitch velocity decreases along with it, then does stress to the medial elbow:

A) Increase due to pitch biomechanics changing from fatigue?


B) Decrease due to the body being able to generate less overall force from fatigue?

If we can get a clear understanding of how torque to the medial elbow is affected in the context of fatigue then perhaps it could help influence future preventative guidelines in baseball.


What Happened During The Study


11 pitchers (5 high schools, 6 division II collegiate) participated in this study and pitched a simulated game in a lab environment. The Motus Compression Sleeve Sensor was used to assess torque in the medial elbow during pitching. The pitchers filled out a 0-10 VAS for fatigue between each inning, a radar gun was used for peak velocity of each pitch, and data for medial elbow torque, arm speed, arm slot position, and shoulder rotation was collected. Warm-up, rest time and innings pitched were simulated to what could be expected during a game.

Interesting Findings:

  • Fatigue increased on average by 0.72/10 per inning pitched
  • Beyond inning 3, medial elbow torque increased significantly each inning (0.84 N*m per inning)
  • Beyond inning 3, ball velocity decreased each inning (0.28 mph per inning)
  • Arm slot decreased overall throughout the simulated game

What Was Not Found:

  • No observed relationship was seen between innings pitched and either arm speed or shoulder rotation

Types of Pitches:

  • Fastballs produced the highest medial elbow torque
  • Fastballs and changeups produced significantly higher medial elbow torque than curveballs
  • Fastballs and curveballs had higher arm slot position than changeups
  • Fastballs had higher velocity and arm speed than changeups and curveballs, duh.
  • No difference in shoulder rotation was noticed between pitches


Consider Fatigue After Inning 3

  • As the the pitchers progressed throughout the game, especially after inning 3, they began to fatigue and have decreased pitch velocity. Consequently, despite the decrease in pitch speed, medial elbow torque began to increase as fatigue set in.
  • This echoes another study where ball velocity dipped as pitcher fatigue increased throughout the course of throwing.

Consider Arm Slot Position

  • With regards to type of pitch and it’s impact upon medial elbow stress, although fastballs had the most medial elbow torque, it was interesting to see this in context with other research studies. For example, one study demonstrated an association of increased medial elbow torque with maximum shoulder external rotation and elbow flexion, such as throwing from a lower slot, side arm position.
  • In this study, fastballs and curveballs had the highest arm slot positions with changeups having the lowest.  Furthermore, a 1 -n*m increase in medial elbow torque has previously been associated with a 13 degree decrease in arm slot, a 116 deg/sec increase in arm speed and an 8 degree incease in arm rotation.
  • With all of this said, the authors suggest that arm slot may be a potential modifiable factor to decrease medial elbow torque and can be targed in pitch training.


Overall, a small, but applicable and clinically relevant study to add to the body of evidence towards overhead throwers. Now go enjoy the rest of your Sunday watching some baseball, Orthohub Followers!


Tyler Cope

Forever Disclaimers:

1): Readers –  If any of these articles peak your interest, please click the link to the original source to read the full text! It’s important to interpret research for yourself and as it pertains to you and your practice. Not to mention, we should support our journals and authors that provide this content.
2): Journals and authors – I do my best job to help promote the message from the research you provide to help clinicians improve. This is not a platform to try and promote my own individual views. I can promise you that I will not always have everything right, so please, if you have any feedback for me or if I misinterpreted anything then let me know!

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s