Oblique injuries strike at the WBC. Or do they?

When is an abdominal injury not just an abdominal injury?

Why, when it's the dreaded abdominal oblique strain, of course.

It had seemed as if an oblique injury trifecta knocked out the stars of the Stars and Stripes the past two days. Team USA saw Atlanta Braves third baseman Chipper Jones, Milwaukee Brewers outfielder Ryan Braun and Boston Red Sox second baseman and American League MVP Dustin Pedroia all removed from competition this past weekend as a result of pains in their side.

We know how debilitating oblique injuries can be, one of the few injuries that seem to impact both hitters and pitchers. A muscle strain of this variety can keep a player out of competition for six to eight weeks, depending on its severity. Setbacks during rehab sometimes extend that period.

We can see how concerning these injuries are to organizations simply by observing the reaction of Red Sox general manager Theo Epstein to the news that Pedroia does not have an oblique injury as originally thought. According to the Boston Herald, Epstein was relieved that the Red Sox "dodged a bullet" with Pedroia, who has been diagnosed with a lower abdominal strain and is expected to miss only "days, not weeks" if all goes as planned.

It turns out Braun has been diagnosed with a right intercostal (rib muscle) strain, according to the Milwaukee Journal Sentinel. That's a relief to the Brewers because Braun's injury is not an oblique strain, but it's a concern because a similar injury caused him trouble near the end of last season.

Meanwhile, Jones, who injured his right side, described the sensation as "cutting off my swing" pain. And we know Jones has had his share of injuries. If anyone is in a position to compare muscular aches, pains and strains, it's Jones.

So what exactly is an oblique strain? And why does it seem more problematic than a generic abdominal strain or an intercostal strain? Most importantly, are we really seeing more of these injuries lately, or do we just know what to "name" it now?

To answer these questions, you first have to endure an oversimplified crash course in the functional relationship of the abdominal muscles. First and foremost, it's important to know that all abs are not created equal. Some are small, some are large, most are not as well developed in each of us as we would like and all contribute something to both flexibility and strength of the trunk (torso) as it moves on the pelvis. Together with some of the spine stabilizers and hip muscles, they form what is commonly referred to as the "core," the critical center of stability for the body.

It is best to think of viewing the abdominal wall three-dimensionally. There are deep muscles (transverse abdominals) that wrap in a horizontal direction around either side of the trunk, like bands of a corset. They are very small but critical to stability of the spine.

The most superficial layer of abdominals, the rectus abdominis, also are known as the "six-pack" abs because, well, when not covered by excessive fat, they form the chiseled, sculpted abdominals that countless numbers among us aspire to daily. Their primarily role is to flex the trunk on the pelvis, or vice versa, but they play a less significant role when it comes to stability.

Overlying the transverse muscles but deep to the rectus are two layers of diagonally oriented abdominal muscles. These are the internal (deeper layer) and the external obliques. The internal and external obliques work together to produce controlled trunk rotation. They also help to flex the trunk on the pelvis, provide stability through the pelvis and counter the forces that the hip flexors exert on the pelvis.

The obliques are unique because they span the entire trunk and are so specifically oriented toward rotation, yet their function is critical for trunk-on-pelvis stability. Because rotation is such a critical component of both pitching and hitting, as is stability of the trunk on the pelvis while weight is being transferred, oblique function is key to performing both activities. Any muscle strain can be painful, and pain, in turn, inhibits muscle performance. Attempts to contract an injured oblique muscle can trigger pain that immediately inhibits the other trunk muscles from functioning normally, which explains why batters cannot complete their swing and pitchers cannot deliver the ball.

Proper trunk function is essential to maximize both upper and lower extremity function. Continued attempts to push through an oblique injury lead to compensations by other, often weaker muscle groups, which then can lead to other problems. Hence the importance of not returning a player to action too soon.

So what is going on with this rash of oblique injuries? The answer is not as simple as it might seem. For perspective, I spoke with Stan Conte, director of medical services for the Los Angeles Dodgers, who is both a physical therapist and athletic trainer and has been at the forefront of efforts to gather and analyze injury data on baseball players. Conte says that between 2002 and 2007, an annual average of 20 professional baseball players were sent to the disabled list during the season because of oblique injuries. Of those, approximately half were pitchers and half were position players.

Interestingly, in 2008, there were a similar number of trips to the disabled list, but there was a shift: Only four pitchers suffered the injury, and the remaining 13 were position players. Now, here we are in Spring 2009, and already, three position players have been sidelined with abdominal injuries, with one of those reportedly to the oblique abdominal muscles. Conte says it's too early to call it a trend but adds, "We may be seeing an indicator of a trend."

Conte notes that in pitchers, the injury has been studied a little more closely and seems to be very consistent in terms of location. MRI studies show that the internal oblique muscle seems to be the most commonly injured in pitchers, and specifically at the attachment on the 11th rib, on the contralateral (opposite) side. The theory, Conte says, is that there is a massive contraction of the internal oblique during a hard throw and the muscle tears, often pulling with it a little piece of bone (also called an avulsion fracture). There is some speculation that evolution of pitching mechanics may contribute to the hard pull that results in such an oblique contraction and potentially leads to injury in some cases.

Hitters, however, have not benefited from the same close study. It is unknown whether any patterns or trends could explain where within the oblique musculature a player typically suffers the injury or what factors might be contributing. Are injured players swinging differently? Are they training differently? There certainly has been more emphasis in all aspects of health, fitness, wellness and rehabilitation on core strengthening. Does this correlate with the injury patterns that are occurring?

It is interesting to note that Pedroia dedicated himself to an intensive offseason conditioning program. As he told the Boston Herald, "It's frustrating. Obviously, I trained real hard in the offseason to get ready and try to prevent something like this from happening. But maybe I pushed it a little too hard, too fast to get this going."

Burning questions abound, but as of yet, there are more questions than answers. It will be interesting to see how the season plays out and whether we continue to see more oblique injuries in hitters this season. In the meantime, it will be worth watching the return timetable for the 36-year-old Jones and his oblique injury compared to the 25-year-old Braun (intercostal strain) and the 25-year-old Pedroia (lower abdominal strain).
Braun is staying with Team USA, according to the Journal Sentinel, suggesting his strain is indeed very mild. Pedroia is resting for a few days but is confident he'll be ready for the Red Sox's opener.

Jones, on the other hand, is hopeful he'll be ready but told the Atlanta Journal-Constitution that this injury is "a lot worse than it was [the] first time around in Canada," referring to the injury which had him miss Team USA's third WBC game in Toronto. The Braves have to hope that pulling Jones to rest him now will help speed up his recovery and that he will not be the first official hitter-on-the-DL-with-oblique-injury statistic of the 2009 season.