Internal Rotation Range of Motion

Why it matters, how it’s analyzed and what the research says

Internal Rotation Range of Motion

Why it matters, how it’s analyzed and what the research says

Why it matters

The internal rotation range of motion of the shoulders is often asymmetrical, with less internal rotation occurring on the throwing arm. These changes are often normal adaptations of throwing, but may also be a sign of restrictions developing in the arm.

A loss of internal shoulder rotation is commonly called GIRD (Glenohumeral Internal Rotation Deficit) and currently defined as a loss of more than 20° of internal rotation on the throwing arm compared to the non-throwing arm.

However, the presence of GIRD is not always a bad thing and usually considered normal for a baseball player as long as the total range of motion between shoulders is symmetrical.

Research shows a significant loss in internal shoulder rotation after pitching, which can accumulate throughout a season if it’s not caught or left unaddressed. These changes can alter the biomechanics of the shoulder and increase the risk of injuries like labrum and rotator cuff tears.

Analyzing Internal

Range of Motion

There are two ways that we look
at internal rotation ROM:

1. Symmetry

Symmetry compares your throwing arm internal rotation range against your non-throwing shoulder. Most players have less internal rotation range in their throwing arm than their non-throwing arm.

2. Trend

Trend looks at how your range changes when compared to previous tests. Players range will fluctuate throughout the season, but if there is a loss of 10% or more, the app will optimize the arm care to a more recovery based program that focuses on mobility.

2. Trend

Trend looks at how your range changes when compared to previous tests. Players range will fluctuate throughout the season, but if there is a loss of 10% or more, the app will optimize the arm care to a more recovery based program that focuses on mobility.

Summary of Research
    • Players lost 9.5 degrees of internal rotation and 10.7 degrees of total motion immediately after pitching, which remained unchanged 24 hours after pitching (Reinold 2007).
    • College pitchers lost up to 17 degrees of total range of motion between the preseason to postseason (Case, 2015)
    • A study of 39 professional pitchers over a single season found that 60% of the pitchers with a GIRD of 35° during spring training experienced shoulder problems that caused them to miss playing time during the season (Amin, 2015)
    •  

    • Pitchers with a total range of motion difference more than 5 degrees between the throwing and non-throwing arm had 2.5 times greater risk of shoulder injury (Wilk, 2002)
Research
Research
Rose MB, Noonan T. Glenohumeral internal rotation deficit in throwing athletes: current perspectives. Open Access J Sports Med. 2018;9:69–78. Published 2018 Mar 19.
Reinold MM, Wilk KE, Macrina LC, et al. Changes in shoulder and elbow passive range of motion after pitching in professional baseball players. Am J Sports Med. 2008;36(3):523–527.

Case JM, Mannava S, Fallin JH, Stone AV, Freehill MT. Acute changes in glenohumeral range-of-motion following in-season minor league pitching starts. Phys Sportsmed. 2015;43(4):360–365.

Amin NH, Ryan J, Fening SD, Soloff L, Schickendantz MS, Jones M. The Relationship Between Glenohumeral Internal Rotational Deficits, Total Range of Motion, and Shoulder Strength in Professional Baseball Pitchers. J Am Acad Orthop Surg. 2015;23(12):789–796.

Wilk KE, Meister K, Andrews JR. Current concepts in the rehabilitation of the overhead throwing athlete. Am J Sports Med. 2002;30(1):136–151.