What Are the Oblique Muscles and Why Are So Many Baseball Players Injuring Them?

The epidemic of oblique muscle injuries in Major League Baseball is indicative that something is wrong in the way that many ballplayers are training.  In years past an oblique injury was an extraordinarily uncommon occurrence, but over the past 4 or 5 years oblique injuries have put many guys on the disabled list.

Why?  It’s the training, stupid.

Read everything that you’ll need to know about the obliques and how improper training is bad for them…


Even if you aren’t a pro baseball player you have oblique muscles and they help you to perform vitally important actions.  These muscles are located on the sides and front of the abdomen and are the largest of the abdominal muscles.

The external obliques are located on either side of the rectus abdominus – the muscles that are responsible for that “6-pack” look – and among other functions allow the trunk to twist.  The externals originate at the 5th and 12th ribs connect at the pelvis. The left oblique contracts to allow the torso to twist to the right, and the right oblique contracts to allow the torso to turn to the left.

The internal obliques lie underneath the external obliques and are located inside the pelvis.  They originate at the pelvis, run up underneath the externals and insert at the 10th and 12th ribs and at various places underneath the rectus abdominus.  The internals work in conjunction with the external on the opposite side to produce torso rotation.  So when the torso rotates to the left the right external and left internal obiliques contract to produce movement.

The oblique muscles link the pelvis to the torso and are involved in almost every sports related movement. After this little primer, you can see why healthy obliques are very important for a baseball player and for any athlete who swings at anything.  Actually, all athletes need to have healthy and strong obliques, but baseball players are particularly reliant upon their proper function. To swing a baseball bat the muscles of the body have to move in a coordinated sequence that starts with hip, moves through the trunk and finishes with the arms. 

Electromyographic analysis of the abdominal muscles during a baseball swing reveals that in the obliques there is greater than 100% maximum activity through the swing and follow through phases. In laymen’s terms this means that the obliques are responsible for transferring the power generated by the hips (pelvis) to the arms to both produce the swing and to decelerated/control the body during the follow through.


Baseball players are experiencing oblique injuries and this is an indication that there is a problem with the way that they are training.  These problems include issues such as over training – doing too much – the obliques, training them in a manner that’s counter-productive to the act of swinging the bat or a combination of both. When you consider how much batting practice hitters engage in throughout the year, there is no reason to engage in an extensive abdominal training program. 

Certainly there is the need to perform basic strengthening exercises to ensure that the muscles of the trunk are strong and balanced.  However, by virtue of the number of swings a professional hitter takes during the course of the year, their abdominal muscles are more than strong enough to endure the rigors of the sport and shouldn’t be bombarded with a variety of exercises.

Over training can result from doing too many exercises for the obliques, regularly performing rotational exercises while lying down or sitting down or in a machine, performing these exercises with too much added weight and/or rotating/twisting at speeds slower than needed to swing a bat. Over training syndrome occurs when athletes – even recreational ones – train beyond their body’s ability to recover. 

In what little that we are able to see with regard to baseball players’ off-season preparation, over the past several years there has definitely been a trending up of the volume of exercises, sets and repetitions. This increased volume, in both batting practice and off-field exercises, diminishes the body’s ability to recover from training and competition and over time, this lack of recovery leads to over training. 

An increased incidence of injuries is one of the known effects of over training. Swinging a baseball bat 500 times per week, every week, places a ton of stress on all the muscles of the body, especially the obliques.  If you add to this mix a high-volume of twisting/rotating exercises performed in a variety of positions with various amounts of extra resistance and at speeds not similar to that experienced during competition, and understand that there are limits to the body’s ability to exercise and recover, you can see why oblique injuries are on the rise.


What is amazing is that there is apparently the widely held belief that a massive amount of “more” is better, when clearly there is no scientific evidence to support this position. To allow athletes to recover properly and reduce these oblique injuries, some of these variables needs to be drastically adjusted downward or eliminated; fewer swings, fewer off-field exercises, no machines, no seated or lying down exercises, no added resistance.

If there isn’t a change of philosophy in this matter, the avoidable kind of oblique injuries will continue to put guys on the disabled list.

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