I saw a post by Jeff Morton saying that it takes only 4% of maximal muscle strength to flex the elbow. That means 96% of strength is covered by muscle strength grade 4 and 5. Your hands are not that sensitive: Most people would dive right in here and say that this is untapped muscle strength that needs addressing and we need to do this by dynamometry.
But is more strength better or necessary for recovery? These devices measure torque, force, or power.
These are especially useful components in the biomechanical world of how these things interact with one another.
My point here is in acute injuries we are never sure how much biological damage has occurred if any, full rupture would appear obvious but for everything that lies below that threshold we really are just guessing with our grade 1 or 2 grades and even grade 3 sometimes.
The problem here is should we really be guessing? How much muscle force, torque or power is needed to perform a task? What would limit these factors? Should we just try the task, and see? There are many factors that limit these measurements such as pain, fear, swelling and tissue damage. Trial and error with weight and time frames is needed –What should guide our progressions? Is pain telling us it is just sensitive or irritated or damaged? Perhaps for many injuries, strains and tears, force production tends to return once pain has subsided so maybe loading could occur earlier in rehab rather than waiting for 12-14 days for the inflammatory phase of healing to settle. There is a lot of wiggle room here especially if we think less tissue structure damage and more nervous system sensitivity.
Even when we suspect tissue damage has occurred our bodies are very good at adapting new ways to get around these inconveniences. This even happens at a tissue level in the form of stress shielding. This is where the load and forces go around the injured areas and/or degenerative parts of the tissue and still gets the task done: Keith Barr is a researcher based out of California who does extensive tissue work: His theory to tendon recovery (I think and these are my words not his) is to load the tendon with long holds of 30-45 seconds x10-15 mins every 6-8 hours as the tissue has a refractory period of time before it can make collagen cross links again: Interesting the more cross links you have the stronger the ligament and tendon but for ligaments we want them to be as strong as possible at they attach bone to bone but for tendons we might want them less stiff on occasion: More cross links lead to more force production which lead to stiffer tissue structure but it that always a good thing?
Problems with manual muscle testing / handheld dynamometer:
We have no idea how much force production is being limited by pain, muscle guarding, fear, tissue capacity especially in the acute phases of healing. We can and we always should measure force output of the other limb and use that as a comparison but how useful is this to measuring soft tissue function? Maybe we are just measuring whole limb function at that point in time but in acute phases this is not very helpful as all these other factors are limiting the use of the limb as well.
Muscle atrophy has a steep decline after three weeks of inactivity especially immobilization or nerve damage type injuries.
Handheld dynamometry is probably more beneficial once pain settles but by that time, we may have missed potential rehab time if we take a wait and see approach. Also, tissue weakness is probably now present more from disuse rather than the extend of the damage of the injury in the first place. Too much rest is not good.
However, I would argue that we never truly experience our full-strength capabilities. We see lots of examples of this all the time when a mother lifts a car off her child’s body or a climber moving a rock off a pinned arm when the rock weighs some ridiculous figure, and they don’t get injured (context matters a lot). This is not imagined strength, its real just like pain is never imagined, it is real. Context plays a huge role here –would we run in to the water if we knew a great white shark was there—Of course not, however if you thought you could save a young child you probably would.
Now the main questions we need to ask ourselves ---
Do we always need to use dynamometry??
Are we just guessing if we do not use it?
Are there certain populations of people when dynamometry is necessary?
Is strength a mediating factor to recovery?
Can graded exposure to load occur without knowing exact force/power/torque production?
Why is no bruising or swelling observed with many shoulder, elbow, and back injuries?
When is movement variation a problem?
For example, let’s say a worker is working in a factory and his job is to lift 30-50lbs for 8 hours daily all different lifts and heights.
Can we rely on just reducing hours post acute injury (5-7 days) and have a starting point of 2 hours lifting without any dynamometry objective strength testing: The argument here is that some tissue damage may or may not have occurred at time of injury, if MMT testing is 4 or 5 out of 5 and it falls somewhere in the 96% range of strength gains, this may be all that is needed to carry out the job at hand and then build up the hours progressively. The fear here of course for both parties is reinjury.
The point here is that people should be able to continue their job at a reduced capacity and always scale the job activity—our body has in build stress shielding mechanisms to protect us. We may need to do slow sets to get some mechanical stress through the weakened part of the tendons and ligaments as stated above: Are we too fearful of reinjury as physiotherapists?
Now I still do believe for ACL reconstruction (which I do not see) we need objective measures, and they are great, and they are also good feedback for the client if strength gains are being made and in this case strength gains are needed for recovery in my opinion due to massive quadriceps atrophy and muscle disuse:
Dynamometry I think is more important with faster, agility plyometric activities and when returning sports personnel to the field. I do like the idea of small fields and less player numbers when truly getting someone back to sport (later stage rehab) after an ACL reconstruction.
Maybe all we need is a grade 4+/5 or 5/5 on manual muscle testing to perform warehouse work which is heavy repetitive lifting and build up the hours gradually over time, maybe make some minor modifiers temporarily and then slowly progress. We may not even have to play around with the weight after 5-7 days of relative desensitisation:
Psychological stressors may be more important when sending an athlete back to sport than tissue capacity and structure for many injuries unless there are major strength deficits.
Our bodies can adapt on a macro level like limping or a reduced squat temporarily and on a micro level like stress shielding: People use all sorts of adaptive ways to offload an area so maybe this is important when assessing as this is useful in early rehab but needs adjusting mid to later rehab to get loads through the injured areas for recovery of the tissue and for confidence and efficiency later. Get back to the task at hand first—better to do the task with modifiers rather than wait until efficient form and strength has returned would be the simple message here.
If we think about movement variability, we realize how resilient, adaptive, and clever we all are innately at recovery. Our job is to enhance this recovery. As Voltaire said, “The art of medicine consists in amusing the patient, while nature cures the disease.”
Once pain settles take modifiers away on a macro level and get load through injured areas possibly doing slow isometrics to get some load though the injured area to promote healing if we stay in the biomechanical, tissue is damaged world, but isotonic also work in relation to some research here, maybe is does not have to be isometric at all either.
This does get more complicated when trying to return athletes to the pitch after ACL surgeries and getting good reading from dynamometry and muscle bulk and other test are useful, but the real juice is playing the sport they love in a more controlled way before retuning them. This can be very difficult to achieve and measure. Compensatory patterns are useful in early rehab but getting load through the weak body part is a priority in sub acute and/or later rehab.
Pain levels tells us little of damage that has occurred or even at all in acute, sub acute or chronic stages.
Manual muscle testing will be reduced in all acute cases but perhaps less due to muscle damage or injury but rather sensitivity maybe but not always from inflammation. We do not even have to have inflammation for pain to occur, we do not even have to have nociception for pain to occur so relying on pain is not a good measure for progressions in relation to tissue structure but may be helpful in working with nervous system regulation. I am bias but we are working much more with nervous system regulation than with biomedical structures in rehabilitation.
Damage does occur at a tissue level, and we see this through swelling and bruising so we cannot rule out tissue capacity as not being present at all because it is a part of the issue, but I would argue a lot less part of the issue than once believed:
Maybe MSK injures are a symptom (not a diagnosis) of current ecosystem affairs and not isolated incidences.
Maybe entire system overload is the problem rather than weakness at point of injury –if I was to use a fuse analogy of electricity –MSK injuries might be the fuses of our bodies: We have a number of injury prone sites—(fuses) (BACK). They are our release valves allowing us to slow down our whole lives at that moment in time. They might be better seen as fail-safe mechanisms.
MSK Injuries may be more a systemic issue than a local issue.
They are the fuses of our bodies—MSK injuries are our protection system: they are a blessing not a curse?
Isolating dead tissue or an alive tissue structure in a petri dish can tell us some information on tissue capacity but really, we need to know more about systemic human capacity not just tissue capacity:
These methods still don’t account for all tissue tolerance/capacity as the tissue is not hooked to a live human being with thoughts, feeling and stressors on the system.
This is the debate on whether strength is necessary for recovery, and it is not in many instances.
There are of course caveats.
Maybe tissue capacity is a lot less of the problem than originally thought.
Maybe the tissue was never weak or compromised in the first place (injury prevention may be null and void here for tissue capacity), but the overall system was and just like fuses in an electrical system blowing the tissue blows to protect overall system meltdown.
We can replace the fuse (rehab the tissue) but we can’t prevent specific injury in many cases. We can try by treating globally, by muscle preparation, by trying to recover well, sleep well, eat well and train consistently and live well.
Final thoughts:
Survivorship Bias
We only see the damage (end result) not the things that were undamaged.
In WW2 American planes returned after taking heavy gun fire. A team was set up to try and protect the planes.
On inspection of these aircraft the researchers found many bullet holes in certain areas of the planes, and they concluded based of these visuals that these were the weak spots however another researcher said that these planes all returned, perhaps the places where no bullet holes were found are the more vulnerable spots as these planes returned safely. They decided to put more armor on the area of the planes that had no bullet holes in them as it was believed these were more vulnerable to attack as they did not return (it would be cool to see the shot down planes too).
Illustration of hypothetical damage pattern on a WW2 bomber. Based on a not-illustrated report by Abraham Wald (1943), picture concept by Cameron Moll (2005, claimed on Twitter and credited by Mother Jones), new version by McGeddon based on a Lockheed PV-1 Ventura drawing (2016), vector file by Martin Grandjean (2021).
This analogy can be likened to MSK injuries ---many episodes of acute lower back pain for example looks like someone has back trouble but maybe there back is strong and robust and a lot of our rehab is targeted at the wrong areas:
We should be building up our armor else where (psychologically and physically) and not just concentrating on the back.
We tend to make decisions on what we see but we need to step back a little and instead look at it from a systemic perspective. This way of thinking would cut out many false nocebic narratives about the back being weak and fragile. It is my belief our back is the strongest part of our bodies like the bullet holes in the planes above. It does not need protection. It needs movement variety, load, and exercise. Fun activities and the doing is the fixing is the key messages here.
This can apply to many bodily symptoms, headaches, shingles, irritable bowel syndrome, msk injuries, autoimmune issues are primarily, I think, psychosomatic or system wide overload at a particular moment in time. This would explain linear simplistic explanations (“my back went out when I was just tying my shoelace” or “I think I slept funny last night” “whatever way I turned the pain just happened”) comments. Homeostasis has been disturbed for too long and allostatic load ensues where the individual in unable to cope with life stressors and demands. These are what I call perfect storm situations which are also almost impossible to predict due to human complexity. Can an MSK injury happen in isolation (overload of tissue capacity only) maybe? but we will we ever know this and to what extend? —I don’t think so. Too little load and too little stress can also be problematic physically and mentally ironically. We must build a bigger buffer system to withstand the harder times, and this is where consistency comes in. Where can we be healthier.
Todd Hargroves used an analogy once –if you buy coffee with your credit card and you have insufficient funds in your bank account then coffee was not all the reason you went into debt or at least not the only reason. It got you into the red zone but anything at that point would have you into the red zone depending on amount of money left in your account and item/s purchased at that moment in time. The point being injury happens when we are globally, physically, spiritually, and mentally depleted or because shit just happens sometimes, nobody really knows.
Coffee may have been the straw that broke the camels back at one moment in time but that does not mean we can or should never buy coffee again due to getting into debt.
We waste so much time energy and resources trying to put that straw back on the camels back but maybe we need to keep the camel healthy not its back. We are I believe far too narrow minded to think we can control injury and to distill it to weak or fragile body parts. It is but one link in a long chain of events. Fun picture below of how we are blinded quite literally by our own ignorance and biases and lack of knowledge. The world appears flat because that is what we directly see however things are not always what they seem. Sorry if I just offended some flat earthers. It is time for reform in the physio world. What is it that we are really doing?
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