The Truth About Shoulder Impingement: Part 1
Written on November 11, 2008 at 4:27 pm, by Eric Cressey
Shoulder Impingement….Yes, We Get It.
Roughly 10-15 times per week, I get emails from folks who claim that they have “shoulder impingement.” Honestly, I roll my eyes the second I read these emails.
Don’t get me wrong: I’m not making light of their pain. It’s just that it drives me crazy when doctors throw this blanket statement out there. I will be completely and 100% clear with the following statement:
Shoulder impingement is a physiological norm. Everyone – regardless of age, activity level, sport of choice, acromion type, gender, you name it – has it.
Don’t reach up to touch that mouse on your computer; you’ll aggravate your impingement and your supraspinatus will explode!
And, don’t scratch that itch on the back of your neck; your impingement will go crazy and your labrum will disintegrate!
Don’t believe me? Check out research from Flatow et al. from 1994.
Yes, this has been out for 17 years now.
So, the next logical question is: why do some people have pain with impingement while others don’t?
In reality, there are several factors that dictate whether or not someone is in pain, including:
1. Tissue quality – the most “impinged” structures are more likely to break down in older age than they are in earlier years. Younger individuals can regenerate faster even when overall stress on the tissues is held constant, so how you handle a 50-year-old with “impingement” is going to be somewhat different from how you handle a 15-year-old with “impingement.”
2. Degree of elevation – the more one abducts or flexes the humerus, the greater the degree of impingement. This is why folks need to start in a more adducted (arm at side) position early on in rehab. Those that impinge early in their arc tend to be dealing with subacromial impingement, whereas those who hit it at the absolute top tend to be more AC joint impingement.
3. Acromion type – flat acromions have significantly less contact area with the rotator cuff tendons than hooked or beaked acromions. These structures may change over time due to…
4. Bone Spurs – bone spurs on the underside of the acromion will increase the amount of impingement.
5. Strength of the rotator cuff – the stronger the cuff, the better its ability to depress the humeral head and minimize this impingement
6. Scapular stability – the more stable the scapula, the more likely it is to posteriorly tilt and upwardly rotate effectively when the humerus is raised into the zones of greater impingement. This scapular stability includes adequate length of the downward rotators (pec minor, levator scapulae, and rhomboids) with adequate strength of the upward rotators (lower traps, serratus anterior, upper traps).
7. Thoracic spine mobility – the posture of the thoracic spine dictates the position of the scapulae, which in turn affects impingement as noted in #6. Assess and Correct is an awesome product for improving thoracic spine mobility – and you can also find some good drills in my recent post, Shoulder Hurts? Start Here.
8. Increased internal rotation – Certain movements that lock the humeral head in internal rotation increase the degree of impingement during dynamic activities. It’s why some people can’t bench press early-on in their rehabilitation programs, yet they can do dumbbell bench presses with a neutral grip pain-free. It’s also the reason why upright rows are a stupid exercise, in my opinion.
9. Breathing patterns – think about what happens when someone has poor diaphragmatic function and becomes a “chest breather:” the shoulders shrug up, and you get extra tightness in the levator scapulae, scalenes, pec minor, and sternocleidomastoid (among other supplemental respiratory muscles). In the process, the degree of impingement can increase.
10. Other issues further down the kinetic chain – I could go on and on about a variety of issues in this regard, but it’s impossible to be exhaustive – so I’ll just give an example. If someone has poor core stability in the sagittal plane that is manifested in an inability to resist the effects of gravity during a push-up, the hips will “sag” to the floor. As this happens, and the upper body remains strong, the scapulae are shifted into an anterior tilt –which increases the amount of impingement on the rotator cuff. So, weakness and/or immobility in other areas can certainly predispose an individual to shoulder problems.
This can also be carried forward to pitchers. We know that shoulder problems are more likely to occur in throwers who have poor lead leg hip internal rotation, as it causes the stride leg to open up early, leaving the arm “trailing behind” where it should be.
Speaking of pitchers, a phrase that has been coined with respect to the “unique” kind of impingement you see in them is “internal impingement.” In next week’s newsletter, I’ll discuss the different kinds of impingement – and why it’s still a cop-out diagnosis for any health care professional to just say you have one or the other rather than tell you explicitly what dysfunctions need to be addressed.
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