In-Season Changes in Pitchers Upper Body: Mitigating the Damage

In-Season Changes in Pitchers Upper Body: Mitigating the Damage

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Kansas City Royals Athletic Trainers Gavin Grosh and Yannick Plante share their research and thoughts on in-season changes in pitchers’ upper bodies. In this article, you’ll find information on range of motion, strength and conditioning and much more. 

Written by: Gavin Grosh, LAT, ATC & Yannick Plante, MKin, CSCS, RSCC | Kansas City Royals

Injuries can be debilitating to a players’ career both in the short and long term as a loss in time can impact their development, their potential opportunities, and their future financial earnings. As a player development staff, one of our biggest challenges is ensuring that every player maximizes its opportunity for success by mitigating the risk of injury. Shoulder injuries account for 8 of the top 20 injuries that account for the most time out of play (1). This is especially true for pitchers who are twice as likely to suffer from a shoulder injury compared to a position player (2). This article will look at acute and chronic changes to the throwing shoulder as well as potential strategies to maintain range of motion and strength across a pitcher’s season and career.

During spring training, most teams employ testing to evaluate where a player is at physically before the season starts. Testing such as goniometer readings of shoulder range of motion, Microfet shoulder strength testing, movement screens and assessments, and isolated stability and strength testing are just some of the tools that can be used to help assess the risk of injuries and future interventions required. Also, testing should be done periodically throughout the season to continue to monitor their changes and make changes where necessary in their exercise routines.

Before diving into the topic, it is imperative to know the consequences of throwing to a pitcher’s shoulder. In overhead athletes, it has been shown that when compared to the non-dominant side that there will be an increase in external rotation and a decrease in internal rotation range of motion (3). As far as strength levels, a decreased external rotation strength and increased internal rotation strength has been demonstrated in professional baseball 3. These alterations have been shown to remain that way 24 hours post-throwing activity before returning to baseline3.

Range of Motion

There are differing theories for the chronic changes in range of motion (ROM); whether it is bony changes (humeral retroversion) or soft tissue adaptation (posterior capsule tightness and muscle damage due to the eccentric forces of throwing overhead) (3) . Therefore, getting baseline testing on athletes can help bring clarity to the picture. It is recommended that to maintain range of motion a proper baseline must be established and an exercise routine to help mitigate the changes in range of motion needs to be dosed properly.

After taking baseline measurements and understanding usual changes in shoulder characteristics after throwing, it is important to understand the cumulative impact over the course of a season. A study conducted by McGraw, Vrla & Wang (2019) found that pitcher’s shoulder external rotation increased by 6.6 degrees and total arc (combined internal and external rotation) increased by 7.3 degrees.

In contrast, shoulder internal rotation as well as other shoulder ROMs did not change significantly and there was no correlation between innings pitched, number of pitches, or velocity (4) . Another study done by Freehill, Ebel & Archer (2011) showed no significant changes to shoulder ROM over the course of the season (5). Studies over the years have yielded inconsistent results, which is most likely due to varying level of the population (high school, college, and professional). Taking these studies together, it seems that high-level athletes have been implementing proper strategies at various levels to allow for minimal changes in range of motion.


Next, it is worthy to look at the implications of multiple months of throwing on strength levels of the shoulder. A study done on youth players showed a significant loss of glenohumeral internal rotational strength, as well as hip internal rotational strength which were correlated to pitch volume (2).

This study highlighted that careful consideration must be made in pitch volume and exercise selection to mitigate this loss. In the professional environment, this is especially true for pitchers who have just entered a new organization or who are embarking on their first full season of minor league baseball. Examples that come to mind are former high school pitchers who are not accustomed to the volume of throwing or college pitchers who have already reached a high innings count, sometimes with limited rest.

On the other hand, studies looking at Major League level players have shown that most pitchers were able to maintain similar level of strength from pre-season to post-season testing(4,5).

A number of factors could possibly contribute to this finding such as: a high level of technical proficiency, a heightened body awareness, a high level of expertise from the support staff and greater resources available for maintenance and overall recovery.

All studies demonstrating consistent levels of strength across the season emphasized proper training programs, maintenance routines and overall recovery modalities.

Theoretically, a proper strength and conditioning routine and arm care program considering the individual’s strength and limitations should help to maintain their strength throughout the season. Taking a long-term approach, identifying compensation patterns that lead to increased stress on the shoulder and finding the proper exercise selection to address those deficits can help achieve greater results. Some other factors to consider are their lower body strength, lower body mobility, core strength, and spinal rotation as these are all part of the kinetic chain involved with throwing a baseball and being able to do it safely and in the most efficient manner.

Final Thought 

In conclusion, a loss of shoulder ROM and strength can lead to injuries which can be debilitating not only physically, but also mentally.

Although there are limited studies on pitchers’ shoulder strength changes throughout the season, there are still ways to help maintain or gain strength. There is no cookie cutter method, so appropriate solutions are required to be individualized to the specific player and their needs. A consideration that was not discussed in this article that is equally, if not more important, is the crucial role that technique plays in reducing injuries and the involvement of pitching coaches and other staff in that regard.

Therefore, constant communication with other department and staff members are important to avoid redundancy and make sure you are both working towards the same goal: KEEPING THE PLAYERS ON THE FIELD!

As a final thought, it will be interesting to see what new practices are employed by organizations as new research on causes and injury prevention strategies surface.


  1. Camp, CL, Dines, JS, van der List, JP, et al. Summative report on time out of play for Major and Minor League Baseball: an analysis of 49,955 injuries from 2011 through 2016. Am J Sports Med. 2018;46(7):1727–1732.
  2. Harding, JL, Picha, KJ, Huxell Biven, KC. Pitch Volume and Glenohumeral and Hip Motion and Strength in Youth Baseball Pitchers. J Athletic Training. 2018;53(1): 60-65.
  3. Reinold, MM, Wilks, KE, Macrina, LC, et al. Changes in Shoulder and Elbow Passive Range of Motion After Pitching in Professional Baseball. Am J Sports Med. 2008;36(3):523-527.
  4. McGraw, MH, Vrla, M, Wang, D, et al. Shoulder and Elbow Range of Motion Can Be Maintained in Major League Pitchers Over the Course of the Season Regardless of Pitching Workload. Orthop J Sports Med. 2019 Feb 8;7(2):1-7.
  5. Freehill, MT, Ebel, BG, Archer, KA. Glenohumeral Range of Motion in Major League Pitchers: changes over the playing season. Sports Health. 2011 Jan;3(1):97-104.