Abdominal Muscle Strain Injury in Professional Baseball Players 1991-2010

Abdominal muscle strains can result in substantial loss of playing time for athletes. The occurrence and frequency of abdominal muscle strains has never been reported in baseball literature but the incidence of these types of injuries in Major League Baseball (MLB) players has been rising over the past 20 years. Abdominal muscular strains are fairly common and require much time for recovery to regain active playing status. Because of these factors abdominal muscle strain is a major concern in this profession.

Strain injuries to baseball players typically occur on the side opposite of the dominant throwing arm or batting side. Tremendous force is generated in the opposite side abdominal muscles while throwing a baseball or swinging a bat because speed is crucial for generating optimal baseball and/or bat velocity.

Researchers Stan A. Conte, Matthew M. Thompson, Matthew A. Marks, and Joshua S. Dines used retrospective review of the Major League Baseball disabled list from 1991 to 2010 and determined that abdominal core muscles (internal and external oblique, rectus and transversus abdominis muscles) play an important role in the baseball activities of pitching and hitting.

Player age, position they play on the baseball field, dominant throwing hand and batting side as well as the recovery time from abdominal muscle strains was recorded in the MLB disabled list during the 1991 to 2010 time period. The researchers found there were a total of 393 abdominal muscle strains in Major League Baseball from 1991 to 2010 which comprised approximately 5% of all baseball related injuries that placed players on the disabled list. At least 92% of these injuries were internal/external oblique or intercostal muscle strains with 44% of injuries being sustained by pitchers. These players reinjured these muscles at a rate of 12.1%.

An upward trend in abdominal muscle strains was seen from 1991 to 2010 with many such injuries occurring in the early baseball season with an overall injury rate that was 22% higher in the 2000s than in the 1990s.

With abdominal muscle strains, pitchers averaged 35.4 days on the disabled list compared with 26.7 days for position players. 78.1% of pitcher injuries were contralateral (on the side opposite) to their dominant arm and 70.3% of position player injuries were contralateral to their dominant batting side. These figures excluded switch hitters. 

As can be seen from these statistics, injuries involving abdominal muscle strains most commonly occur contralateral to the dominant arm or batting side. However, the recovery time differed between pitchers and position players depending upon the side of injury. Position players missed more time for contralateral than for ipsilateral (same side) injuries (28.9 vs 21.2 days of disability) whereas pitchers missed more time for ipsilateral injuries (44.5 vs 32.8 days of disability).

 
The conclusion was that the incidence of abdominal muscle strains in baseball has been increasing over the past 20 years, especially early in the season, and there is a relatively high rate of injury recurrence. This upward trend is occurring in spite of new and more advanced diagnostic procedures, preventive core strengthening exercise programs, and rehabilitation techniques.