The Rotator Cuff… Too fatigue or not too fatigue?

So the final blog for 2014, and I take a quick look at the question of should we be asking our patients with shoulder issues to exercise their rotator cuffs to fatigue. Enjoy and have a Happy New Year
This debate was triggered after I had a discussion around an old blog of Mike Reinold’s here. Now I really like Mike’s work and have a lot of respect and time for what he has to say. Mikes an incredibly smart guy, has a wealth of knowledge and experience, and does some great work on his website and has produced some interesting research. However, in this blog he argues that you should ‘never’ exercise the rotator cuff to fatigue, and when I questioned him on it recently he still stands by this statement.

I disagree

I actually think the exact opposite. The cuff needs to be worked to fatigue, or very close to fatigue when its in rehab or recovery from injury! Let me explain why…
First I simply disagree with Mike’s use of the word NEVER. One thing I have learned over these last few years is nothing is absolute and there are always exceptions to EVERY rule.
However, semantics aside, I believe exercising to, or very close to fatigue is far superior for developing, strength, endurance, and hypertrophy. There is however, some conflict in the S&C research on this topic with some studies showing fatigue is not always essential. However in general there is a trend for most studies to show that exercising to fatigue is superior for strengthening gains. For more on this see Chris Beardsley review here, and regardless of the research you just don’t argue with the Austrain Oak…

The last three or four reps is what makes the muscle grow. This area of pain divides the champion from someone else who is not a champion. That’s what most people lack, having the guts to go on and just say they’ll go through the pain no matter what happens.Arnold Schwarzenegger

Now exercising to fatigue in the injury rehab world is a little bit different than what Arnold was referring to during bodybuilding, with it having different goals and different priorities! But I aruge that exercising to fatigue is vitally important for any muscle/tendon lacking strength or endurance, and the rotator cuff certainly experiences its fair share of these problems.
In Mike’s blog he uses a study here done in 2008 to support his reasoning of never fatiguing a rotator cuff. They measured the humeral head movement in 20 males with normal healthy shoulders before and after a fatiguing exercise. They found that when they fatigued the cuff, the sub acromial space was reduced significantly when elevating the arm. They attribute this to the cuff being unable to control the humeral head against the upward force of the deltoid allowing an increase in its upward translation. This could potentially mean for those already with sub acromial issues that fatiguing cuff exercises could cause further compression, impingement and therefore pain.
However, there are a couple of major flaws with this study, and so issues when using it to support a belief that we can not exercise the cuff to fatigue. The first and most obvious limitation is that this study was only conducted on healthy males, so we can’t reliably say if the same things happen in those with shoulder pain or with cuff pathology, or even females? It probably does as some other studies have shown that when the cuff is artificially inhibited humeral head translation does increase significantly (ref, ref, ref)

So what!

The next question we have to ask is, so what if the humeral head moves up more! Does this matter? 
For example there are many studies that show that humeral head superior translation is perfectly normal, and highly variable from person to person! Some studies have shown that in normal pain free subjects the humeral head can move up to 12mm off the centre of the glenoid (ref).
Next, are we really that surprised when the cuff is fatigued it doesnt do its job well? This study used by Mike found on average an extra 0.79mm humeral head movement after fatigue, which in context of how much the humeral head can move for some, I really don’t think its that much to worry about.
We also know that many people have torn and deficient rotator cuffs with no pain or issues (ref, ref). Do they have more or less superior humeral head translation than those that have pain? Well, we simply don’t know, but I’d hazard a guess its more.
So can we say increased humeral head translation is solely to blame for sub acromial issues and shoulder pain? Of course we cant! There are many other factors that contribute to sub acromial pain, occupation, BMI, genetics etc etc its not just about the mechanical compressive forces, maybe even they may have little to do with it at all (ref ref)
So why are we so focused and concerned about the mechanical compression, and not all the other factors? Why should we worry about possibly creating a little more excessive humeral head movement, and ignore the many other more positive effects exercising to fatigue has?
Rotator cuff strengthening

Other flaws

This study also choose to fatigue the cuff with an exercise that in my opinion doesn’t represent what most therapists use or consider as a cuff exercise. In fact this exercise, the prone horizontal raise (shown above) heavily targets other key shoulder and scapula muscles such as the Deltoid, Rhomboids and Trapezius.
So how can the researchers differentiate fatigue of the cuff causing humeral head translation, to fatigue of the other scapula muscles causing the cuff to reduce its activity or maybe leading to more scapula downward rotation or altering scapulo-humeral kinematics that could also reduce the sub acromial space?
The simple answer is, they can’t.
However, the biggest flaw in this study is they only observed this extra humeral head movement for only 30 seconds AFTER fatigue!
This means we only know this increased humeral head movement occurs briefly after fatiguing exercise. Why they didn’t look at it for longer, checking humeral head translation at regular time intervals to see when it returned to normal is beyond me. This would have been so much more useful, knowing when the cuff recovers after fatiguing exercise to restore humeral head control.
This I very much suspect would have been after a shortish rest period, I’d guess around 2-5 minutes.

Making sense

Yes, of course it makes sense that when the cuff is fatigued it will be unable to stabilise the humeral head, just like when you have performed squats to fatigue, you cant walk for a while. However, this is only a temporary effect, all muscles when exercised to fatigue don’t function well for a short period of time.
However, that doesn’t mean the exercise induced discomfort of exercising to fatigue will go quickly! It may still ache for quite a while longer, maybe a few days after, which Mike suggested in our brief conversation means the humeral head is still being poorly controlled. But there is no evidence of that. I would simply suggest that this post exercise soreness, this being nothing more than some temporary increase in interstitial tissue oedema increasing the tendon thickness and so maybe increasing pressure in the sub acromial space (ref). This maybe an issue as it could increase the compressive forces on the tendon, but it could also be perfectly fine. 
Yes ok exercising to fatigue hurts, that doesn’t automatically mean its harmful or dangerous.

And what does exercising to fatigue really mean?

For most its a perception or feeling of not being able to do any more exercise, but that doesn’t mean the musclotendinous unit has truly worked to its maximal capacity.
The bit of reading I have done around the subject of fatigue is that the central neural system will always stop the body from exercising to the point of damage by giving signals of distress and discomfort long before actual adverse structural or biochemical harm is done (ref). It seems to take years of training to over ride this neural safety switch, sometimes referred to as the ‘central governor’ to reach true fatigue, most of us mere mortals stop well before!


Exercising to ‘perceived’ fatigue over multiple sets has a host of positives that in my opinion far outweigh any negatives.
Exercising to fatigue although as I mentioned has some controversy around it, is well known and well accepted by most to produce significant stimulus needed for increases in musculotendionous strength and endurance, and has research and literature to support it, check PubMed if you don’t believe me (hey its New Years eve give me a break).
Exercising to fatigue is also known to produce many beneficial therapeutic effects for myotendinous problems as well as producing pain relieving analgesic effects, again check PubMed if you don’t trust me…

Recognising when it is best to fatigue the rotator cuff is better than NEVER doing it.

For example you simply wouldn’t fatigue the cuff just prior to going swimming, or playing tennis, nor would you fatigue the cuff before going to the gym to throw some iron around! You also wouldn’t fatigue your cuff first thing in the morning when you need it to work during the rest of the day, especially if you have a manual or over head job, this is all common sense.
How you choose to fatigue the cuff, which exercise you choose, how much load to use, the amount of sets and reps depends on a whole host of other variables and really is for another blog or even for you to ask on one of my courses, shameless plug right here.


So I hope I have made my case that you can exercise a rotator cuff to fatigue!
In my opinion, mediocre, half arsed exercises, have never helped anyone or anything, especially in a rehab setting.
Now, of course there will be exceptions, as I said at the beginning, exercising to fatigue isn’t suitable for all. Also exercising to fatigue doesn’t suddenly mean you can start being all ‘gung ho’ or hardcore and macho with your patients with a “go hard or go home bro” attitude.
It simply means using your judgement, clinical reasoning and most importantly your exercise physiology knowledge to get the most out of any exercise, and that more often than not means working them to or very close to fatigue, and the rotator cuff is no exception.
As always thanks for reading
Heres to a healthy, happy 2015 to you all



  1. The study nearly lost me at the choice of exercise…it definitely lost me at; ‘only looked for and observed this increase of superior humeral head translation for the first 30 seconds AFTER fatigue’. No shit! Most things don’t do their job well when they’re knackered!
    Capacity is my main takeaway from the above. Just like McGill stresses the importance capacity and muscular endurance being protective in lower backs, the same could be said with most muscles.
    Is there a link between the fibre type composition of the rotator cuff and injury prevalence with athletes? e.g. do athletes with predominately fast twitch cuffs get injured more easily?

    • Hi Kirsty
      No link at all between fibre type and injury. All the reading I’ve done around fibre type and cuff is that its pretty much a 50/50 split between fast and slow twitch in everybodys cuff, and despite current belief training, sport etc has very little significant impact on fibre type regulation.
      It seems we are pretty much set with the amount/number of fast slow twitch fibres give or take some minor changes, all training, sport activity seems to do is improve their ability, capacity etc

  2. Can we fairly even claim rehab is successfully complete before the recovering subject is able to train to fatigue without it causing problems?
    Curious choice of exercise in the study too – its ok as one early stage exercise mode but unless full natural motion is included the assessment is certain to be skewed – for example if you get people to train front delts but not rear and the assess them their posture will surely be out of whack – that doesn’t mean that training delts is a bad idea – just that this is an incomplete training program.

    • As with all things mate, a balanced approach is needed, no different in exercise prescription.
      Im currently playing around with a more mixed approach in my set/rep prescription I give. I now use pretty much a 50/50 split with high rep, low load and low rep, high load work for all exercises per session, seems to be much more effective than one or the other, I think it hits all motor units nicely in one session, key for adaptation and gainzzzz ???

      • Seems sensible in respect of both theory and experience – best way to be sure you’re getting them to engage and train all fibre types, I like to start with simple high rep low resistance exercise with lots of concentration on form to make sure the mechanicals are good then progress it from there into compound movements and high resistance.

  3. Another great post, agree with much you have written. I think sometimes it is easy to forget that physiological improvement in muscle and tendon tissue is essentially a survival mechanism that has evolved over a very very long time to enable us to cope with a given environment. Therefore in order for the body to use its precious resources to build and maintain tissue it needs sufficient stimulus. Doing bicep curls with a can of beans 100 times when you could easily do 300 is not going to do much other than burn of a few calories!
    As for the best way or method to deliver this stimulus, well I am still reading about that, lots and lots of different opinions! There does seem to be a general consensus in the research that so long as you work hard (to failure or near) weather 50 reps or 10 or even cycle sprint (maybe not for the shoulder!) then it can produce hypertrophy in the muscle worked (James Steele from just done a interesting review of this area ‘’ if you have not seen already.
    I find how you apply this to improve muscle and tendon tissue with someone who has a painful shoulder can be a challenge at times. I find its always a balance between trying to give sufficient stimulus but at the same time not coursing there pain to increase to much.
    Thanks for the time you put into this blog, been interesting reading and look forward to further posts.

    • Thanks Dave, i will give the link you posted a read!
      I agree that hypertrophy and strength gains can be achieved regardless of load or resisitance, this was shown nicely in this small study by Mitchell as you say working to fatigue is key to improvements.
      However it is far easier, not to mention quicker to achieve total fatigue with bigger loads and resistances and so it makes sense to still use this strategy where possible and safe to do so, and if we do look at all the research combined it does seem that higher loads and resistances work slightly better as shown here by Chris Beadsley at S&C Research
      However it is handy knowing we can still get the same gains with lighter loads especially in a rehab settings

  4. As usual Adam… Excellent
    Could you comment on the usefulness of weightbearing exercises for cuff work, I like these in various guises and find them anecdotally useful.
    I realise that question is slightly off topic…

    • Hi Jack
      Thanks for your comments
      Closed kinetic chain body weight exercises are great for cuff rehab, but especially for management of the unstable shoulder. They produce high levels of co-contraction essential for stability and reduce any adverse joint shear forces, not to mention the added proprioceptive afferent information, its win win all round.
      I do a whole section of these type of exercises on my shoulder workshops, if you’re interested, free space going as well if you haven’t noticed ?

      • Thanks a lot Adam!
        A fair chunk of my caseload is hypermobility syndrome (and related) so that reassures me I am doing something sensible!
        I am v v v keen to come to one of your courses but unfortunately finance is a barrier. I am hoping I win your Twitter comp….

      • Sorry mate but grovelling wont help, its all down to a draw from a hat by my fair wife, only way to increase chance of success is to keeping retweeting the daily competition messages
        Wish you luck though

  5. Interesting Blog Adam. I agree we can not make an assumption of not exercising the RC to fatigue from one study especially in light of the exercise that was used which would have brought other muscles into the equation. Fatigue may not be so much the factor as over recruitment of deltoid causing the translation.

    • Hi Anju
      Thats a really good point, but surely the fatigue effects will have affected the deltoid just as much as the cuff with this horizontal abd exercise? It would be better to look at an exercise such as supported ER to target post/sup cuff and minimise deltoid, but I suspect we will still see increased superior HH translation immediately afterward fatigue, and really I am more interested in how long the poor HH control lasts for and if it causes any significant negative detriment to those with sub acromial issues
      As we both know ‘its tough being a cuff’ ?
      Happy New Year

    • Hi Martin
      Thanks for the paper, an interesting read. Blows more holes in the notion that tendinopathy of the cuff is solely due to mechanical compression by the acromion, and also could be argued that fatiguing exercise is good for ‘impingement’ type issues.
      I read this paper showing the stronger the external rotators are the less sub acromial pressure there is, again highlighting the need for strengthening.

    • Ah the kipping pull up.
      Kipping pull ups are a type of pull up and Im not a fan of saying one exercise is better than another.
      Kippings are obviously not as strict in form as other forms of pull ups, and ballistic in motion and so will have higher forces. This means that different muscles will be working more or less than other types of pull up.
      Also the high forces will mean the tissues will have to withstand more and so they need to be able to. Will they cause more injury than other pull ups, potentially yes…
      But if people train Kippings like anything else, gradually and sensibly then the risk will be lower and the tissues will adapt to endure the forces. It will just take longer.

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