The Sideline: Brian Wilson’s Abdominal Muscle Strain

by Steve Hole, MD 2012

Though he’s under a 2-year, $15 million contract with the World Series champion San Francisco Giants, Brian Wilson wears several hats: tattoo canvas, captivating interview star, and closer extraordinaire. The relief pitcher led the majors with 48 saves in 2010 and pitched his best in the biggest moments, striking out Ryan Howard in Game 6 of the NLCS to send the Giants to the World Series, and striking out Nelson Cruz to clinch the team’s first title since leaving New York in 1958.

Despite his obsessive year-round workout program, odds were “less than 50-50” that Mr. Wilson would be ready to play on Opening Day 2011. In a Spring Training game against the LA Angels on March 17, he strained an abdominal muscle during an otherwise routine 7th inning appearance. Pitch counts are an essential part of baseball at all levels, and Mr. Wilson was not beyond his expected workload for this point of the preseason. The injury was undeniably a result of the pitching motion; Mr. Wilson might have felt the strain emerge during one single throw, or emerge gradually over hours or days.

According to Giants manager, Bruce Bochy, an MRI taken after the game showed a “mild strain of the left oblique muscle” but did not show any tears. Fans might remember Mr. Wilson missed time earlier in the spring with a sore back; this injury appears to be unrelated.

THE INJURY

What’s it called?

Commonly known as “side strain”, the stretching or tearing of the abdominal wall muscles — especially the internal oblique muscle — is a rather uncommon sports medicine injury seen more in javelin throwing, cricket, wrestling, and ice hockey than other major sports. As such, side strain was a poorly-described injury for many years and was only recently described as a tear of the internal oblique muscle from its origin on the rib or costal cartilage (1).


Where is this?

The internal oblique muscles are on both sides of the abdomen. They connect ligaments, part of the pelvis, and other tissue in the bottom of the abdomen with the top of the abdomen — the inferior (bottom) edge of the lower four ribs and their respective cartilage — without crossing the midline of the body. The muscle fibers are continuous with other muscles between the ribs, and are oriented in linear bundles approximately parallel to an imaginary line drawn from each hip joint to its opposite shoulder. They are just deeper in the body than the similarly-paired external oblique muscles, the fibers of which run perpendicular to their more internal counterparts. Together, these muscle groups flex and rotate the back to help a person touch the opposite toe, row a boat, or follow-through a baseball pitch.

What makes it a side strain?

Side strain is diagnosed clinically by the sudden onset of pain in the appropriate place and tenderness to touch over the site. The pain may be reproducible with movements similar to those which caused the injury, or with taking a deep breath.

How did it happen?

A proposed mechanism of the injury is that the muscle is lengthened by repetitive movements and then subjected to superimposed contraction. When Mr. Wilson brings his right arm back before releasing the ball, the internal oblique is lengthened; when the arm moves forward, then down and across the body during follow-through, it is rapidly and forcefully contracting. Muscles on either side of the abdomen can be strained by this motion. As seen in the images below, Mr. Wilson goes from peak back extension and rightward rotation to extreme flexion and leftward rotation in a fraction of a second.


How is it diagnosed?

MRI (magnetic resonance imaging) is the most accurate imaging study for suspected side strains. MRIs are likely to show a tear if one exists, and allow the tear to be measured. In side strains, the length of the tear correlates with the severity of the injury and may roughly guide treatment or predict recovery time. Bleeding within the muscle is common but rarely worrisome; tears of the external oblique muscle and rib fractures are less common.

PREVENTION

Because of the low frequency of side strains, preventive measures don’t extend beyond appropriate strength training and stretching. Those participating in activities that stress the muscles in the ways described previously should gradually increase the intensity of their workouts.

TREATMENT

With few exceptions, the treatment for side strain and other abdominal muscle injuries is non-operative. Side strains merit pain relief, gradual return to play, and change in activity to accommodate pain. When symptoms permit, abdominal strengthening is vital for the active treatment of the injured muscles. The images below provide a number of examples of abdominal strengthening exercises to prevent injury.

RETURN TO PLAY

Essentially, pain is what guides rehabilitation schedules and return to play decisions. For a professional athlete like Mr. Wilson, the decision is one shared between player, coach, physician, and trainer. One study puts the typical recovery time between 6 and 10 weeks but professional athletes often return to play quicker than amateurs (1). Those injured usually do not experience impairment of function or significant loss of strength after rehabilitation is complete.

IMPACT ON TEAM / CAREER

Teams competing without star players rarely play as well, but this injury comes at as good of a time as any for the Giants. Given the expected timeline for his return to pitching, most of the games Mr. Wilson misses will be Spring Training games (though the importance of preseason games to major league players is perhaps greater than to athletes in any of the other major professional sports). An offseason rather than preseason injury might have meant a healthy Mr. Wilson throughout Spring Training, but either time is preferable to dreaded in-season ailments. Given his magical performances in the playoffs a season ago, a late-season injury would be far more devastating to the club. Though missed preparation time must now be recovered while facing top talent in games that count, the impact from this single oblique strain is likely to be minimal barring a repeat or related injury. Most favor the Giants to win the NL West again and make another deep playoff run.

WORRY FACTOR

How much should you worry about straining an oblique?  Accordingly to our Sports Player Injury Talk Scale (SPIT, for short), you don’t have much to worry about.  For the recreational athlete, side strains aren’t a common problem. Though data is limited, one study finds it would take a college athlete who practiced basketball for 2 hours at a time 25,000 practices to suffer one side strain (2). That’s a lot of worry-free layups.

REFERENCES

1. Connell DA, Jhamb A, James T. Side Strain: A Tear of Internal Oblique Musculature. AJR. June 2003;181:1511-1517.

2. Johnson, R. Abdominal Wall Injuries: Rectus Abdominis Strains, Oblique Strains, Rectus Sheath Hematoma. Current Sports Medicine Reports. 2006;5:99-103.

3. Schulman, Henry. “UPDATE: Giants closer Wilson injures oblique, Opening Day in doubt, now with Wilson comment.” sfgate.com, “The Splash” blog. 19 March 2011. Available here.

4. Schulman, Henry. “Brian Wilson set back by strained oblique muscle.” San Francisco Chronicle. 20 March 2011.

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