Written by: James Stone L.A.T, A.T.,C, C.S.C.S & Dwayne Peterson C.S.C.S, R.S.C.C, Kansas City Royals
Oblique, what is it?
It’s a pair of muscles along with the pelvic and hip musculature that make up the core (External Oblique, Internal Oblique, Transvers Abdominis, Rectus Abdominis and Intercostals). (7,8) For a baseball player an oblique injury puts the breaks on a season very quickly, as most of these injuries require an extensive shut down (in most cases 4 weeks, but up to 8 weeks). This article focuses more on the External and Internal Oblique but note sound core strength is required to produce the forces needed to complete the complex nature of movements in use by professional baseball players.
The External Oblique originates on the sternum, external surfaces and inferior boarders of the lower 8 ribs. It inserts on the pubis and iliac crest of the hips. It is responsible for compression of the abdomen, flexion of the trunk/ spine, same sided lateral flexion of the trunk and opposite sided rotation of the trunk. (7,8)
The Internal Oblique originates on the lateral half of the inguinal ligament and middle lip of the iliac crest. It inserts on the pubis, inferior boarder of the lower 3-4 ribs and fuses with the External Oblique to form the rectus sheath. Like the External Oblique the Internal Oblique is responsible for compression of the abdomen & flexion of the trunk/ spine along with same sided lateral flexion but, where they differ is that the Internal Oblique controls same sided rotational contractions of the trunk. (7,8)
Baseball & Oblique Injuries
It seems like every time we turn around another one of baseball’s super star players is down with an oblique injury. I could only find a single study that looked at the Major League Baseball (MLB) injury data on this topic, but the study did range from 1991 to 2010. During that time oblique strains accounted for 5% of all injuries in MLB. (5) This injury slowed position players & pitchers alike. Hitters suffered this injury at a rate of 46%, pitchers 35% & non-pitching throwers 6%. (5) The time of year when these injuries occurred is not surprising with 54% happening during spring training & early season (March to May), likely due to a sharp increase in volume & intensity. The other 46% happening in-season (June to August) one would infer due to fatigue over the course of the season. (5)
While age usually plays a role in a person’s predisposal to getting injured, I was surprised to see that in a study done on cricket bowlers (similar to baseball pitchers) players 24 years or younger had a 2 times higher rate of injury compared to those that were 25-29 years old and had a 3 times higher rate of injury compared to bowlers that were 30 years of age or older. (9)
Like nearly all injuries there is an increased chance of reinjury with an oblique strain. In 12% of the cases a reinjury occurred and of those 1/3 happened in the same (37.8%) or following season (61.2%). (4) To break that out a little bit further a starting pitcher had a recurrence rate of 4.9% of the time, as opposed to a relief pitcher which had a recurrence rate of 9.57% of the time. (4)
So, what are some of the potential mechanisms of injury? The simple answer is a lack of range of motion (ROM) at the hips & thoracic spine. Some say, “traditional core work” (crunches/ sit-ups) can contribute negatively to the ROM at the hips & rotational ability. With an attachment point of the rectus abdominis, rib cage & pelvis, these exercises pull the rib cage down & over time can limit one’s thoracic rotation.1
In both pitchers and position players alike the majority (77%) of the time this injury tended to occur contralateral to the throwing shoulder side (excluding switch hitters). (4,6) Pitchers report feeling discomfort during the late cocking/ early acceleration transition of the throwing motion. Hitters traditionally occur on what would be the lead/ pull side, while accelerating to contact the ball. Baseball places extreme physical demands onto the body in order to perform effectively. Both pitching and hitting requires one or a combination of the following: maximum shoulder and arm segment rotation velocities, thoracic rotation, hip internal rotation, hip external rotation, shoulder ROM, and the ability to decelerate.
The exam for this injury in most cases is somewhat straight forward. On visual inspection you might see a player wince then grab, pinch or rub the lateral aspect of the trunk after a pitch or swing. On clinical exam you may find acute pain over the anterolateral or posterolateral thoracic wall (Over 1 or more of the 4 lowest ribs). Stiffness and pain in the mid to lower trunk may be present, this pain may also be present with deep breathing, laughing, sneezing and coughing depending on the severity. The pain and stiffness may be coupled with swelling or visible edema. Once the clinical exam is completed most teams will opt to get imaging (Usually MRI) to further assess the degree of severity and help determine a return to play timetable. Though, I must note the MRI is just a tool and should not be the sole determining factor in that timetable. The data showed that on average pitchers required 35 days to recover from an oblique injury and position players took on average 26 days to return. Though, it should be noted that variance was due to a pitcher’s build up being different to return to the mound. (4,6) The bad news is that if you were part of the 7.9% of players that received a cortisone or Platelet-rich Plasma (PRP) injection, it set you back another 11 days on average. (4)
The Process to Return
So, you have had the injury diagnosed now what? Oblique injuries are very unique in that the re-injury rate is around 12% with about a third of them being in the same or following year4. This makes it vital that the return to play protocol is designed with a slow progression and return to on field activities are not rushed in any way. Athletes can re-injure themselves with something as simple as the stationary bike. In order to progress them into on field activities it is important that they demonstrate the ability to stabilize both statically and throughout a full ROM, furthermore they need to demonstrate the ability to rotate powerfully and decelerate effectively all without any restriction of any kind.
Return to play programs can vary from individual to individual based on several factors, however the following basic guidelines are recommended:
Begin with basic non loaded stabilization exercises and progress slowly into more difficult variants. Example exercises would be band palloff presses, walkouts and holds. Once the athlete has demonstrated competency in this area without any restrictions or setbacks you can progress them into some single leg stability drills to ensure they can stabilize on one limb similar to the requirements of their sport. Unilateral upper body pressing can be introduced in their weight room activities to further progress the stabilization demands onto the body. Finally, once they have demonstrated they can perform these exercises efficiently, progressing them into more difficult stabilization exercises such as plank variations and farmer/waiter carries is recommended. If at this point there is no setbacks and athlete reports no discomfort, it is recommended to introduce rotational movements into their program, again starting basic with light band resistance and progressing slowly into more difficult weighted variants utilizing cables and medicine balls. The final stage of their RTP progression involves more ballistic rotational movements that mimic more of the physical demands of their sport. Chops, throws and tosses utilizing medicine balls along with some anti rotation exercises are all recommended to ensure they can powerfully rotate and effectively decelerate.
Keys to Prevention
What are some ways to help prevent any oblique injury occurrences in the first place? There are a number of key areas to look at when it comes to the prevention of this injury. Firstly, building a strong foundation in one’s lower body through resistance training will help prevent any compensatory movement patterns from developing. If one doesn’t have an efficient level of lower body strength, the body will utilize other muscles or muscle groups to be able to perform the movement demands required. The majority of power and velocity generated in order to hit a baseball comes from the lower body.2, 3 Optimizing a player’s hip and ankle mobility will help them be able to get their body into hitting and throwing positions much more effectively and ultimately safely.1 Athletes need to be able to internally rotate and extend their hips efficiently in order to throw and hit at the velocities and intensities required of them.2, 3 This is all to say that improving an athletes lower half both from a strength and mobility standpoint will go a long way in preventing unwanted compensatory movement and potentially any oblique injury occurrences. Other areas that may have a positive effect are thoracic ROM and limiting traditional core work for the same reasons outlined previously.
- Eric Cressey. (2008). Oblique Strains and Rotational Power. Retrieved from https://ericcressey.com/newsletter117html
- Shaffer B, Jobe FW, Pink M, Perry J. Baseball batting. An electromyographic study. Clin Orthop Relat Res. 1993;(292):285‐293.
- Welch CM, Banks SA, Cook FF, Draovitch P. Hitting a baseball: a biomechanical description. J Orthop Sports Phys Ther. 1995;22(5):193‐201. doi:10.2519/jospt.19126.96.36.199
- Camp, C. L., Conte, S., Cohen, S. B., Thompson, M., D’ Angelo, J., Nguyen, J. T., & Dines, J. S. (2017). Epidemiology and Impact of Abdominal Oblique Injuries in Major and Minor League Baseball. Orthopaedic journal of sports medicine, 5(3), 2325967117694025. https://doi.org/10.1177/2325967117694025
- Conte SA, Thompson MM, Marks MA, Dines JS. Abdominal muscle strains in professional baseball: 1991-2010. Am J Sports Med. 2012;40:650–656.
- Gamble, Eric. Abdominal Oblique Injuries in Rotational Sports (2018) https://www.bsrphysicaltherapy.com/2018/04/03/abdominal-oblique-injuries-sports/
- Sinnatamby C S. (ed) Last’s anatomy. 10th ed. Edinburgh: Churchill Livingstone, 1999215–220.
- Davies D V. Gray’s anatomy: descriptive and applied. 33rd ed. London: Longman’s, Green & Co, 1982621–625.
- Simth, Adam. A Clinicians Guide to Side Strains in Cricket Fast Bowlers. (2016)