In my last blog, I probed your knowledge of the rotator cuff. I asked 3 main questions and will reveal the answers here!
1) Why does the shoulder joint sacrifice stability for mobility?
2) What are the 4 rotator cuff muscles? (Hint: Use the acronym SITS)
3) How does each rotator cuff muscle move the shoulder joint?
1) The shoulder joint sacrifices stability for mobility because the head of the humerus sits in a very shallow glenoid fossa (glenoid cavity of the scapula). See more on this topic below.
2) The Rotator cuff muscles connect the head of the humerus to the scapula. They provide the stability across the joint. Namely, they are: Supraspinatus, Infraspinatus, Teres Minor, and Subscapularis.
3) Supraspinatus: participates in abduction of the arm.
Infraspinatus: externally rotates the arm.
Teres Minor: also participates in external rotation of the arm.
Subscapularis: participates in internal rotation of the arm.
A joint has two main functions:
- allow for movement/mobility
- while holding itself together (stability)
These are competing ideas, and neither extreme is desirable. For example, you don’t want to be super flexible because super flexible means you have likely stretched your tendons and/or ligaments to the point where they cannot provide adequate stability and therefore, you are more prone to injury. In the case of a shoulder, overstretching without backing it up with proper strength may lead to a situation where the head of humerus is removed from its proper location leading to dislocation or a tear in a rotator cuff, etc. Therefore, it is desirable to have an adequate amount of strength that is proportional to the level of flexibility so that the strength provides tightness which holds the shoulder in place. The other extreme –the joint holding itself together too zealously– is not desirable because too much tightness means that you will have very little motion. That’s no fun and also leads to pain or injury.
Hip sockets are nice and deep, providing a ton of stability. This makes sense when you consider that they are designed to be carrying heavy loads. The shoulder sockets, on the other hand, are often compared to a golf ball on a tee. The very shallow socket also makes sense when you consider the fact that the shoulders are not designed to carry huge loads. Then aerialists come along and change the name of the game. This is all well and good as long as you learn how to properly manage and care for your shoulders.
As a new aerialist, one of the best things you can do for proper shoulder care is to work your external rotators. If you live like a normal human being, your protractors are already relatively strong. You drive, eat, type at a computer, give hugs, and all the other fun things in life that bring our arms forwards. Rarely do we recruit our external rotators in daily living. It is important to exercise and learn to recruit the external rotators for the health of your aerial career (even if you are just a recreational aerialist).
As you grow in your aerial journey, understand that exercising your internal rotators and protractors certainly are not a bad thing. In fact, if you being an extreme aerialist, you just may swing so far in one director, you’ll need to maintain some balance by coming back to push ups. Balance is the key. Variety is an important training element. Variety will help you balance out. Do a little bit of everything. Do some internal rotating, some external, some protracting, some retracting, etc. Work your weak areas. Stretch out your tight areas. Go get professional help if you hurt. And happy flying!