Surreal illustration of a baseball pitcher's arm transforming into a flexible river, symbolizing range of motion and injury prevention.

Dodging Injury: How Shoulder Flexibility Can Save Your Game

Mira Elwood monogram
Mira Elwood in Health & Wellness October 2026 • 5 min read.

"New research highlights the crucial role of shoulder external rotation and flexion in preventing baseball injuries, offering insights for athletes and trainers."


In the high-stakes world of professional baseball, staying healthy is as crucial as mastering the perfect pitch or swing. Injuries can sideline even the most talented players, turning potential triumphs into frustrating setbacks. While many factors contribute to on-field performance, a growing body of research emphasizes the importance of understanding and addressing modifiable risk factors, particularly those related to shoulder and elbow health.

One area of increasing focus is the assessment of shoulder range of motion (ROM) and its impact on injury prevention. Traditional attention has been heavily focused on Glenohumeral Internal Rotation Deficits (GIRD). However, recent studies suggest that deficits in other ROM areas, especially shoulder external rotation and flexion, may be even more critical in predicting injury risk.

A groundbreaking study published in The Orthopaedic Journal of Sports Medicine sheds light on this topic. It highlights the importance of preseason ROM assessments in identifying pitchers at higher risk of shoulder and elbow injuries. The study, which analyzed data from 132 pitcher-seasons, reveals that specific ROM parameters are independent risk factors for injury development, providing valuable insights for trainers, coaches, and athletes alike.

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Shoulder Injury Burden in Batters

A study of professional baseball batters reported 3,414 shoulder injuries over an eight-year period. Those injuries accounted for 68,808 days missed, averaging 22 days per injury. These figures describe the burden in that study population, rather than all baseball players.

Common Prevention Measures

Prevention guidance for baseball and softball includes warm-up tips and pitch-count guidelines. Another baseball-focused guide lists pitch limits, arm-care strength, mobility checks, workload warning signs, and evaluation as prevention measures. These source descriptions outline commonly recommended tools but do not report comparative results showing which approach works best.

Why Shoulder Flexibility Matters: Key Findings from the Study

Surreal illustration of a baseball pitcher's arm transforming into a flexible river, symbolizing range of motion and injury prevention.

The study, conducted over six seasons (2010-2015), involved a comprehensive preseason assessment of ROM in pitchers invited to Major League Baseball (MLB) Spring Training Camp for a single MLB organization. Researchers meticulously tracked total range of motion (TROM) and deficits, correlating these measurements with subsequent shoulder and elbow injuries that resulted in at least one day out of play. Using advanced statistical analysis, they identified key factors associated with increased injury risk.

The results revealed that 53 shoulder (n=25) and elbow (n=28) injuries occurred during the 132 pitcher-seasons analyzed. Several significant risk factors emerged, underscoring the importance of specific ROM parameters:

  • Shoulder ER Deficit: A shoulder external rotation (ER) deficit greater than 5° was associated with increased elbow injury rates (OR 2.40; p=0.069).
  • Shoulder Flexion Deficit: Similarly, a shoulder flexion deficit greater than 5° was also a significant risk factor (OR 2.83; p=0.042).
  • Continuous Variables: Increasing shoulder ER deficit (OR 1.07, p=0.030), decreased shoulder flexion (OR 1.09, p=0.017), increased IR deficit (OR 1.04, p=0.068), weight (OR 1.10, p=0.012), and decreased shoulder ER (OR 1.06; p=0.076) were also identified as important factors.
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Bone Adaptation and Shoulder Rotation

Research on injured baseball players reports that humeral retrotorsion (HRT), a bony adaptation, may explain up to 65% of glenohumeral internal rotation range of motion (GIR ROM). The source emphasizes considering osseous adaptations when interpreting shoulder rotational motion. This finding suggests that measured rotation should not be interpreted without accounting for bone structure.

Limits of ROM Screening Evidence

A systematic review and meta-analysis states that a potentially protective ideal external-rotation range of motion in swimmers needs confirmation in a second independent cohort before strong recommendations for screening are made. Separately, a high-school baseball stretching study did not measure shoulder range of motion or acromiohumeral distance during the season. It reports a previously observed association between dominant-shoulder internal rotation and shoulder injury, with an adjusted odds ratio of 0.951, but these sources do not establish a universal screening rule.

Strength Training Versus Stretching

A non-inferiority study in high-school baseball pitchers investigated whether external-rotation strength training was inferior to sleeper stretching for preventing shoulder and elbow injuries. The study reports that external-rotation muscle-strength training was not inferior to sleeper stretching in high-school baseball players. A separate review says multimodal injury-prevention programs addressing multiple musculoskeletal impairments may be more comprehensive and may reduce injuries better than programs targeting one impairment.

These findings emphasize that shoulder ER and flexion deficits are critical indicators of potential injury risk. While prior research has highlighted the importance of addressing GIRD, this study suggests that focusing on shoulder ER and flexion may provide even more significant predictive value.

Protecting Your Arm: Practical Steps for Injury Prevention

The insights from this study offer actionable strategies for athletes, trainers, and healthcare professionals. By incorporating preseason ROM assessments and addressing identified deficits, it's possible to reduce the risk of shoulder and elbow injuries in baseball pitchers. Emphasizing targeted exercises and training programs that improve shoulder ER and flexion can help players maintain optimal flexibility and strength, ultimately keeping them healthy and on the field. While GIRD remains an important consideration, a more comprehensive approach that prioritizes shoulder ER and flexion may offer a more effective path to injury prevention and long-term athletic success. Early detection of ROM deficits provides a vital window of opportunity to intervene and prevent injuries before they occur, safeguarding the careers and well-being of athletes at all levels.

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Prevention Research and Prediction

A 2024 review identifies prospective studies evaluating stretching to increase posterior shoulder flexibility and strengthening the external rotator muscles as prevention strategies for throwing injuries in baseball players. Another 2024 study describes a novel game theory–based approach to develop a machine-learning model for predicting next-season shoulder and elbow injuries in MLB pitchers. Its stated purpose also includes examining interactions among important risk factors; the source description does not report model performance or establish its effectiveness.

Programs Studied in Baseball Players

A 2017 study prospectively evaluated a prevention program’s effects on shoulder and elbow injury incidence in high-school baseball pitchers. A separate study assessed a standardized exercise program during the fall season in collegiate baseball players, focusing on shoulder range of motion and rotational strength. These descriptions identify the players and outcomes studied, but do not provide results that would establish how much either program changed injury risk or physical measures.

How other pitcher and player findings compare

Among professional pitchers, insufficient throwing-shoulder external rotation was associated with greater likelihood of shoulder-related disability-list placement and surgery. That outcome differs from injury-rate comparisons between prevention groups, so the findings address related but distinct questions.[1]

In adolescent pitchers, side-to-side motion differences were reported as possible discriminators of injury risk, whereas other ROM research has focused on motion in the throwing arm. The different measurement approaches make direct comparison difficult.[2] [3]

A review combining professional pitchers with high-school players, including position players, cautioned that differences among those groups matter when interpreting pooled screening results. Its populations are not interchangeable, which limits how broadly a single estimate can be applied.[4]

A biomechanics review describes how force moves through the body during pitching and links mechanics to shoulder and elbow loading. It also notes that fatigue has been associated with pain, placing range of motion among several relevant dimensions rather than a complete account of injury risk.[5] [6] [7]

What remains uncertain about shoulder motion

  • Could differences in total shoulder rotation provide a clearer injury-risk picture than internal-rotation loss considered alone? The cited definition of pathologic GIRD combines internal-rotation loss with reduced total rotation, so an isolated measure may not capture the full pattern.[8]
  • How much of the reported effect of stretching might reflect changes in internal rotation, posterior flexibility, or shoulder spacing? These are proposed explanations, not mechanisms established by the reported comparison.[9]
  • Could throwing speed alone explain differences in shoulder and elbow loading? A comparison reported different ball speeds without significant force or torque differences, leaving that relationship unresolved by those measures.[6]

Shoulder motion and pitching mechanics

Why might external rotation matter during pitching?

Insufficient or excessive external rotation at foot contact may leave the throwing arm out of position or lagging, potentially adding stress to the shoulder or elbow.[6]

Terms used in shoulder-motion research

Glenohumeral internal rotation deficit (GIRD)
A loss of internal rotation combined with a loss of total rotational motion.[8]
Kinetic chain
The linked transfer of force through body regions during a movement.[5]

Sources

  1. Deficits in Glenohumeral Passive Range of Motion Increase Risk of Shoulder Injury in Professional Baseball Pitchers: A Prospective Study. (pubmed.ncbi.nlm.nih.gov)
  2. Preseason shoulder range of motion screening as a predictor of injury among youth and adolescent baseball pitchers. (pubmed.ncbi.nlm.nih.gov)
  3. Risk Factors for Baseball-Related Arm Injuries: A Systematic Review (pmc.ncbi.nlm.nih.gov)
  4. Preseason shoulder range of motion screening and in-season risk of shoulder and elbow injuries in overhead athletes: systematic review and meta-analysis (pmc.ncbi.nlm.nih.gov)
  5. The Relationship Between Pitching Mechanics and Injury: A Review of Current Concepts (pmc.ncbi.nlm.nih.gov)
  6. Baseball Pitching Biomechanics in Relation to Injury Risk and Performance (pmc.ncbi.nlm.nih.gov)
  7. Evaluation and Treatment of Baseball Pitchers: There’s More to Assess than the Arm (pmc.ncbi.nlm.nih.gov)
  8. Glenohumeral internal rotation deficit in throwing athletes: current perspectives (pmc.ncbi.nlm.nih.gov)
  9. Shoulder Stretching Intervention Reduces the Incidence of Shoulder and Elbow Injuries in High School Baseball Players: a Time-to-Event Analysis (pmc.ncbi.nlm.nih.gov)

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

Everything You Need To Know

1

Why is shoulder flexibility so important for baseball players?

Shoulder flexibility, specifically shoulder external rotation and flexion, is crucial for baseball players because deficits in these areas can significantly increase the risk of shoulder and elbow injuries. Addressing these deficits through targeted exercises and training programs can help maintain optimal flexibility and strength, reducing the likelihood of injury and keeping players on the field. Early detection using preseason ROM assessments offers a vital opportunity to intervene and prevent injuries.

2

What is a Shoulder External Rotation (ER) Deficit and why is it a problem?

Shoulder External Rotation (ER) Deficit refers to a limitation in the ability to rotate the arm away from the body at the shoulder joint. A deficit greater than 5° has been linked to increased elbow injury rates. Shoulder ER is important because it is a key component of throwing motions, and limitations can alter mechanics, leading to increased stress on the elbow.

3

What does it mean to have a Shoulder Flexion Deficit?

Shoulder Flexion Deficit indicates a restriction in the ability to raise the arm forward and overhead. Similar to ER deficits, a flexion deficit greater than 5° is a significant risk factor for injuries. Adequate shoulder flexion is essential for achieving the proper arm slot and generating power during the pitching motion. Restrictions can lead to compensatory movements that increase injury risk.

4

What are Glenohumeral Internal Rotation Deficits (GIRD), and are they still important?

Glenohumeral Internal Rotation Deficits (GIRD) refers to a loss of internal rotation in the throwing shoulder compared to the non-throwing shoulder. While GIRD has been traditionally emphasized, recent studies suggest that deficits in shoulder external rotation and flexion may be even more critical in predicting injury risk. It's still an important consideration, but a comprehensive approach that prioritizes shoulder ER and flexion may offer a more effective path to injury prevention.

5

What are Preseason Range of Motion (ROM) assessments and why are they used?

Preseason Range of Motion (ROM) assessments involve evaluating a player's shoulder flexibility before the start of the season. These assessments measure various ROM parameters, including shoulder external rotation, flexion, and internal rotation. By identifying deficits in these areas, trainers and healthcare professionals can implement targeted interventions to improve flexibility and reduce the risk of injury.

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