Kipping Pullups? Part 2: An Anatomical Review
From an anatomical standpoint, this blog will dig into why we, Athletic Lab, believe a strength base through strict pullups should be established before kipping pullups are added to the mix. Bypassing the ability to do strict pullups and veering directly toward kipping pullups opens the door for serious injuries.
Across the board, kipping pullups are widely utilized by CrossFit (CF). It doesn’t take much searching to realize the CF injury message boards are overwhelmingly filled with reports of SLAP tears (Superior Labral Tear from Anterior to Posterior) and rotator cuff injuries that have come as a result of the excessive use of kipping pullups. There’s a reason for this and in order to further explore the cause for these injuries, it will require us to brush up on the anatomy of the shoulder.
Moving in nearly every direction, the shoulder joint is the most mobile joint in the human body. For this very reason, the joint is extremely unstable, especially while the arm is overhead. The shoulder joint is considered a “ball and socket” joint, but there’s an issue when it comes to this joint. The ball (the head of the upper arm’s humerus bone) is only partially covered by the socket [the glenoid fossa of the scapula (shoulder blade)] because the socket is very shallow. The ball is bigger than the socket is deep. In fact, only about one third of the head of the humerus is covered by the glenoid fossa. To make up for the loss of this coverage, there’s a rim of cartilage, the glenoid labrum, that lines the socket. From this point, we’ll refer to this cartilage as the labrum. The labrum has multiple functions. It attempts to make the joint more stable by providing a rim around the socket. With this rim, the labrum adds about 50% more depth to the glenoid fossa to allow more room for the head of the humerus. It also acts as an attachment point for the tendon (attach muscle to bone) of the biceps bracii (the same arm muscle you watch yourself flex in the mirror).
A SLAP tear occurs when there is damage at the point where the tendon of the bicep inserts the labrum. At this location, there is very little vascularity (blood flow) and it’s very unlikely to heal on its own. Other injuries may inflict the labrum but they’re more likely to heal on their own due to ample blood supply to the area. It is extremely rare for someone with a SLAP tear to return to full capacity without undergoing surgery.
When hanging by your hands, as pullups require, if muscles are not fully engaged throughout the entire range of motion, the load (weight of your body) is transferred to non-contractile tissues (such as ligaments, tendons and fascia)- including the biceps tendon that directly attaches to the labrum at the point where SLAP tears occur- which greatly increases the likelihood of injury.
Kipping relies on momentum and this allows the freedom to hang from the already unstable shoulder joint instead of engaging the muscles around it. Strict pullups engage muscles that take the load away from non-contractile tissues. In addition, they add strength to allow for a more controlled kip when it is used.