Tendon health

MrRippedZilla

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The topic of injuries, specifically relating to joints & tendons, has gathered a decent amount of interest across the board to the point where it would be silly for me not to try and add something to the discussion. Building on the excellent work posted by Mythos here, I thought I'd share this amazing paper by Kjaer:
Role of Extracellular Matrix in Adaptation of Tendon and Skeletal Muscle to Mechanical Loading


This paper challenges some of the commonly accepted forms of recovery and coincides nicely with my experience helping clients work around/through injuries. It is 49 very technical pages so I think it's safe to say 99% of you will never read it but I'll do my best to provide a simplified overview here focusing on:
1) Why injuries happen
2) What can we do about them


A short physiology lesson

When a muscle contracts it has the same type of viscoelasticity (the ability to change its physical property based on length) as a rubber band. It's a stretchy, elastic material that when stretched out tightens and quickly snaps back into place when you let go of it.
Muscle can contract under its own power to cause active tension (shortening, rather than lengthening, the muscle). This active tension of the muscle pulls the bone along with it and causes movement around the joint. Simple biomechanics.

Now, our muscles & bones are exposed to extremely high forces from life in general. Something like going for a jog easily generates greater peak forces than anything you'll be doing in the gym. Even basic things that we did as kids like jumping/running around generates high, albeit brief, forces. So with all this force ging on it takes a lot of work to keep our muscles anchored to our bones.

Muscle tissue is surrounded by a network of collagen (making up 25% of the total protein in your body) & support cells known as an extracellular matrix (ECM). An ECM is basically a ladder for cells to to hold on to and produces growth factors along with a bunch of other cool stuff that helps keep these tissues together. So when muscle meets bone, the ECM thickens into a tough band of fibres known as a tendon.
It's down to our tendons to absorb & trasmit the forces of life and they have a pretty impressive range of strength & stretching ability in order to do this.


Tendon talk

In the past, people assumed that tendons and other connective tissues were just useless lumps of meat. The last few decades have taught us that they're actually active biological systems that are involved in signalling alongside hormones, growth factors, etc.

We all know that muscle responds to tension. It exists in a constant state of protein turnover with the damaged proteins being replaced with newly synthesized ones. Normally this is a balanced process but lifting sets off a cascade of chemical signals within the muscle fiber (in response to protein breakdown) that generates protein synthesis. This is how our muscles grow - a positive, rather than neutral, protein balance.
Why am I telling you all this? Well, our tendons respond in exactly the same way. A positive protein balance (collagen) to help make it better able to handle higher loads in the future.

This tendon adaptation is vital. I don't give a shit how much weight your muscles are capable of lifting if your tendons remain unchanged (zero adaptation), it is going to end very, very badly. If tendons along with other connective tissues grow & adapt alongside your muscles, could that alone explain the higher rate of injury that occurs with enhanced lifters? In other words, your muscles can now lift a lot heavier but if the tendons haven't adapted to this new high load...

Back when people thought tendons were useless, they were assumed to be avascular tissues (lacking blood supply). Now we know that they do receive blood but the amount is tiny compared to muscle. Kjaer mentions that, during exercise, a tendon gets only a fraction of the blood flow of nearby muscle:
"It has been possible to demonstrate in human models that blood flow within and around tendon connective tissue increases up to sevenfold during exercise, both in young, middle-aged, and elderly individuals...This increase is by far smaller than the 20-fold increase in adjacent skeletal muscle blood flow under similar exercise conditions."
F2.large.jpg
The blood flow that reaches our tendons is regulated by an entirely different system (I'm not going into it) and our tendons have a relatively low metabolic activity so this tiny amount of blood flow is probably sufficient under normal circumstances but maybe not during training.

As we get older, collagen accumulates advanced glycation end products (AGEs, fascinating separate topic). These stiffer, "glycated" tendons can withstand higher stresses (good) but this comes with a price:
"...the accumulation of AGEs with aging thus indicates a stiffer and more load-resistant tendon and intramuscular ECM structure, but on the other hand reduces the ability to adapt to altered loading, as the turnover rate of collagen is markedly reduced."
Aging, and injuries to the tendons that accumulate AGEs, make your tendons stiffer/more resistant to higher loads but also reduces their ability to adapt to any damage. That is the issue here - the inability to adapt.

To make sure everyone is keeping up:
- Tendon adaptation is vital and may be compromised during AAS use due to muscle overtaking tendon in the rate of growth.
- Blood flow to our tendons is relatively poor, important point to address for recovery from injuries.
- Injuries increase with age due to reduced tendon adaptation and, as a result, reduced collagen turnover.


Overuse injuries

The harder you train, the more often you train hard, the higher the risk of injury. Tendons, like muscle, have a threshold for activity that once you go beyond it, you're risking tendinitis or a lot worse.
Kjaer mentions that though we use the word "overuse" to describe injuries from repetitive loading, we don't actually know if this is the cause. Some injuries occur due to changes in the collagen structure, tendon rubbing over bone and becoming worn out, etc. Overuse may be an issue but we don't know if loading per se is the cause.
He mentions other causes of overuse injuries like tissue inflammation and the regulation of blood flow & metabolism within the tissues that are worth exploring in greater detail.

Inflammation is a localized immune response involving chemical messengers, known as cytokines, that play a role in tendon pain & overuse injuries (also play a part in depression and other conditions). Two cytokines in particular, TNF-alpha & IL-1beta, directly act against collagen synthesis. Since heavy training, especially the kind you're unfamiliar with, elevates these cytokines, I think it's safe to assume that they may contribute to tendon injuries by hampering the process of tissue regeneration.
The inflammatory pathway COX-2 also negatively impacts tendon healing with data (mostly on rats) showing anti-inflammatory drugs to be helpful in this regard. We don't know if a solid dose of NSAIDs helps with overuse injuries but prostaglandins - inflammatory mediators made by COX-2 - seem to be bad for tendons. Kjaer thinks that anti-inflammatories, by blocking the synthesis of prostaglandins, might have a protective effect.
This is interesting since NSAIDs themselves may negatively impact protein synthesis in muscle depending on the data set in question. Whether this negative extends to actual hypertrophy is debatable with studies providing mixed results. Plus AAS use should negate this mostly. Hmm. My interpretation would be that at a normal dose, say below 1g, the positives of NSAIDs would outweigh the negative since being able to train pain free, even with the aid of NSAIDs, would be better for muscle growth than not being able to train at all.

Lack of blood flow is another common feature for tendon injuries. Hypoxia (lack of oxygen) triggers degenerative changes in tendons (think of the reduced capillary density you see in shoulder injuries, same type of thing). Less blood flow + decrease in muscle metabolic rate = broken down tendons. An obvious solution comes to mind here - mobility. By keeping things moving you'd be able to increase blood flow & the metabolic rate of muscle = higher collagen turnover.

Pain itself is cause by the release of nociceptive (pain causing) substances during both overuse & mechanical loading. Pain may actually have nothing to do with the injury (discussed a bit here) itself so something like tendonitis may not be an issue even if its aggravating. This too traces back to the inflammatory signals (COX-2 & prostaglandin in particular).

Another piece added to the puzzle:
- Tendon adaptation is vital and may be compromised during AAS use due to muscle overtaking tendon in the rate of growth.
- Blood flow to our tendons is relatively poor, important point to address for recovery from injuries.
- Injuries increase with age due to reduced tendon adaptation and, as a result, reduced collagen turnover.
- Inflammation plays a role but addressing it through pharmaceutical options may cause more problems than it solves.


Practical advice

Kjaer says:
"...several conservative treatments such as immobilization, physical therapy, stretching, and pharmacological treatment with NSAIDs as well as surgical procedures have by no means produced impressive results."
This goes hand in hand with my experience re the accepted treatments are only slightly better than nothing at all. The pain is eventually controlled but you never fix the issue. It can start all over again with the slightest aggravation and while the "if it hurts, don't do it" strategy is fine for some, for athletes, competitive bbers, etc it simply isn't an option.

Instead, Kjaer suggests trying out some alternatives.
Resistance training has been shown to improve overuse injuries in average folks (not us). Loading "of a certain magnitude" combined with stretching the area "induces increased reorganization of the collagen structures" which may strengthen the tendon. Eccentric loading does this a lot better than concentric and is an excellent method to adopt for certain forms of tendinitis. Plenty of studies available on this (as well as anecdotes) but one example was a case of tennis elbow a client had that went away with eccentric only work, 2-3xweek for a few weeks. Similar approach works for the knee.
The main point of this paper is this - keep the hurt area mobile irrespective of loading. Tendons get a terrible amount of blood at rest, which leads to a reduced metabolic rate and degenerative changes. Rest may feel good but does little to help the tendon. This extra blood flow may encourage healing through increased collagen synthesis.

The findings of this paper fit well with my experience re keeping active with regular loading to help with tendon injuries. The difference between, say, squatting 1-2xweek vs 5-6x week is pretty dramatic. The increased frequency leads to quicker healing, less chance of re-injury, etc - sounds counterintuitive but it's true.
Note that I'm not saying you should all start training with injuries under heavy weight every day. It's just to consider some type of loading as often as you can. Let the area feel a little stretch, some tension and pump a bit of blood in there. Even simple conditioning work like dragging a sled would do. As Kjaer says, healing from tendon overuse injuries "requires adjusted loading rather than absence of loading in the form of immobilization".

The anti-inflammatory suggestion is a controversial one. Ibuprofen at 800mg-1g does work for soft tissue pain and appears to possibly accelerate the process of healing but taking into account the big picture, I'm not sure if chronic use is a good idea. Especially at high doses. A moderate dose with occasional use is fine. I don't have much experience with other anti-inflammatories so cannot add much there.

So, if you've got a pain that won't leave you alone, it might be better to work through it rather than resting and making the problem worse :)


Speculating beyond this paper

The 4 key areas that this paper tells us to address in order to avoid/treat tendon injuries are 1) allowing time for tendon adaptation, 2) encouraging blood flow into the inflicted area, 3) increasing collagen synthesis and 4) controlling inflammation. Kjaer addressed 2 & 4 so I'll add my thoughts on 1 & 3.

1) - This is the main reason why we see an increase rate of injury among the enhanced population and, IMO, the best way to address it is with better programming when it comes to your training.
Everyone should know that going heavy all the time in the gym is a bad idea but we also know that higher frequency is good for our tendons. Therefore, a moderate intensity, high frequency approach with added eccentric only work during blasts/cycles makes a lot of sense to me if injury prevention is a major priority. You will still generate plenty of growth from the volume & AAS in your system and it allows you to save the high intensity work for the "off" periods where weight progression on the bar is going to be a lot slower anyway (therefore your tendons will have plenty of time to adapt).

3) I honestly don't think this should be the focus for enhanced lifters because the only way to noticeably increase collagen synthesis is through PEDs that most cannot access. Specifically, GH & IGF-1. Localized. Good luck with that.
The impact of AAS on collagen turnover is mixed with the data trending negative but honestly, I wouldn't be too focused on what specific AAS to use (some are better than others here but meh) since the common feature of them all is compromised endothelial function = worse off blood flow/more inflammation = bad for tendons anyway. Note that I'm talking about superphysiological doses, TRT is absolutely beneficial for injury prevention/recovery.

Then you have other pharmaceutical options that may/may not help that I won't go into too much detail on. Bupropion is an awesome fat loss aid and inhibits TNF-alpha, a key cytokine involved with inflammation, so that may be a cool addition in general. You have prostaglandin inhibitors and other more exotic options that will probably do more harm than good considering the end goal (get stronger, bigger, etc) so...TBC.

Excellent paper. Gives everyone plenty to think about.
 
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snake

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Another good read Zilla!

When they are speaking about age being a factor, what age are they talking about? I am sure they have data on this but without time (age) we can not develop enough to handle the weights we use. For arguments sake, I'm assuming all this without any AAS use. So is it the years that it takes for us to reach our genetic potential that is the problem or just the fact that we are handling those heavy weights? Is it to say a 20 y.o. benching 300 lbs would be running less of a risk to an acute tendon rupture then a 60 y.o. doing the same weight?
 

MrRippedZilla

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Another good read Zilla!

When they are speaking about age being a factor, what age are they talking about? I am sure they have data on this but without time (age) we can not develop enough to handle the weights we use. For arguments sake, I'm assuming all this without any AAS use. So is it the years that it takes for us to reach our genetic potential that is the problem or just the fact that we are handling those heavy weights? Is it to say a 20 y.o. benching 300 lbs would be running less of a risk to an acute tendon rupture then a 60 y.o. doing the same weight?
The data they cite suggests that once you move past 50, it becomes more of an issue. Your tendons stiffen up to take daily abuse, since your more fragile in general as you age, and sacrifice adaptability (ie collagen turnover). That means progression without injury at that age is going to be a major stumbling block for advanced trainees.

The problem isn't the weights, it's getting old.
Weight training in and of itself has a positive effect on tendons. Getting old in and of itself has a negative effect once you get past a certain progression point. For example, 55yr old Tom who has just started lifting will 100% benefit from the impact of training on his tendons (overall net positive collagen turnover). 55yr old Duncan, who has been lifting for 30 years and wants to continue progressing, might suffer if he doesn't proactively adjust how he trains (in terms of cycling intensity, etc).
To answer your question, yes, the 20yo benching 300lb is at less risk than the 60yo.
 
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stonetag

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The data they cite suggests that once you move past 50, it becomes more of an issue. Your tendons stiffen up to take daily abuse, since your more fragile in general as you age, and sacrifice adaptability (ie collagen turnover). That means progression without injury at that age is going to be a major stumbling block for advanced trainees.

The problem isn't the weights, it's getting old.
Weight training in and of itself has a positive effect on tendons. Getting old in and of itself has a negative effect once you get past a certain progression point. For example, 55yr old Tom who has just started lifting will 100% benefit from the impact of training on his tendons (overall net positive collagen synthesis). 55yr old Duncan, who has been lifting for 30 years and wants to continue progressing, might suffer if he doesn't proactively adjust how he trains (in terms of cycling intensity, etc).
To answer your question, yes, the 20yo benching 300lb is at less risk than the 60yo.
Shit, figures I would be Duncan is this story.
 

JuiceTrain

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Mythos

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Finally got some time to look at this, great post, well put together and some very interesting stuff I had not been aware of. The AGE thing is really interesting! And thanks for the compliment on my thread!



It looks like we are coming to the same conclusions here from the available data, I think #1 being that science is telling us that without a doubt, controlled load is essential for tendon health and repair.



The way I’m starting to see it is like this: We all know the term ‘sweet spot’ around here in reference to finding balance in our blood chemistry, etc. through trial and error within rough guidelines, and I think that’s a good way to think about tendon recovery too. You have to figure out the right amount of load to put on your injury to keep it healing without putting so much that you re-injure it and start moving backwards.

Along those same lines, maybe figuring out NSAID timing and dosing is another personal sweet spot to find, although this will probably take a lot of trial and error. Like you alluded to, the NSAID issue is seriously complicated, contradictory and getting in to the chemistry of it is a little beyond what my attention span can handle, but from what I’ve gathered I’ve decided to use minimal doses of NSAIDs, especially being conservative with them immediately after an injury. My idea is to slow down any runaway inflammation without interfering too much with the complex chemical process of healing that is taking place, and so far that’s been working pretty well for me.



That’s a really good observation about mobility possibly enhancing blood flow to the injury site, and that may be a part of the puzzle as to why loading is so essential for tendon health. The low blood flow thing with tendons was something that I thought was really interesting when I found out about it.. especially the fact that the body compensates for this lack of flow after a tendon injury by forming a bunch of new vessels, which later actually recede or ‘die back’ once the tissue is healed. I think that if there’s ever going to be a PED that enhances tendon repair, it’s probably going to be something that enhances this neo-vascularization in the early stages of healing…( I guess that’s the theory on the mechanism of why BPC-157 has been effective in healing rat tendons.)



Some food for thought from my recent experiences: after doing a lot of reading, I started working on my own protocol for my elbow tendon and it’s really improved the recovery process. Later, I had an overload (at work and out of my control) on the tendon that set me back quite a bit, but this gave me a great opportunity to see the difference in recovery from my new approach. In my experience, without question there is an improvement with progressive loading.



Basically, the first time around, I did what many us do when we have a tendon injury, blast through it and try to ignore it, propping it up with NSAIDS and constant compression, and not lowering weight until it’s so bad that you start to have to lower weight. Then, when that approach became a nightmare, I did some WebMD style browsing and got some general medical advice and just tried to put as little load as possible on that tendon. This was not doing me any favors either.



Bottom line is, I think a lot of us are falling in to this trap of first ignoring the injury, making it worse to the point where we’re seriously screwed, powering through it instead of initially decreasing load then progressively increasing it. Then, following less-than-up-to-date medical advice, we don’t load enough and end up prolonging our misery. What makes it worse is that these kinds of injures are by nature so goddamn frustrating that we either want to power through them or we get to that point where we just fuken give up all together and take a bunch of time off.



When it comes to my issue, I think I have found the sweet spot. Basically, I load the tendon to the point where it maybe aches a little after a workout, backing off when pain starts to interfere with the lifts and keeping controlled movements. I found that when I do this, the next day I have a little dull ache in the tendon, nothing major, then later I can feel some quality strength increases and overall pain improvement.



Anyway, again, great post and nice analysis Zilla, thanks
 
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BRICKS

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Thanks for the research, excellent stuff. I will add to this from my experience and what I observed in a recent thread about shoulder stuff. After toasting my shoulder a month ago, I did a lot of retrospection and that shoulder had been bothering me for a long time. Sore in the morning, sore to train but could train through it fine, so chalked it up to chronic aches and pains. Untill that shoulder said FTS. Now in Docs shoulder thread it seems a lot of guys are having similar issues. Heed the warning fellas. Not saying that my shoulder wasn't going to crap out eventually, but perhaps if I had listened better to what it was telling me I could have mitigated a lot or at least some of the damage. How I've rehabbed and adjusted training this last month is dead on consistent with what Zilla reports here. And I'm actually getting a better response from my body, I feel better, and training is much more enjoyable. My take home is check the ego at the door and train smarter. It doesnt do any good to train with X amount of weight today if you can't come back and train tomorrow.
 

Beezy

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When it comes to my issue, I think I have found the sweet spot. Basically, I load the tendon to the point where it maybe aches a little after a workout, backing off when pain starts to interfere with the lifts and keeping controlled movements. I found that when I do this, the next day I have a little dull ache in the tendon, nothing major, then later I can feel some quality strength increases and overall pain

Some of you guys never cease to blow my mind.

I'm definitely starting this tomorrow. Even picking up a baby will make me cringe some days and the dr said, "Ice it, wrap it, take some Motrin and probably a good idea to take a couple months off the weights and just go for a run."
Probably a good idea to find a doc who even lifts.
 

MrRippedZilla

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Along those same lines, maybe figuring out NSAID timing and dosing is another personal sweet spot to find, although this will probably take a lot of trial and error. Like you alluded to, the NSAID issue is seriously complicated, contradictory and getting in to the chemistry of it is a little beyond what my attention span can handle, but from what I’ve gathered I’ve decided to use minimal doses of NSAIDs, especially being conservative with them immediately after an injury. My idea is to slow down any runaway inflammation without interfering too much with the complex chemical process of healing that is taking place, and so far that’s been working pretty well for me.
The fundamental issue with the NSAID stuff is that it interferes with the natural adaptation process that makes us stronger, have bigger muscles, etc. The fact that you cannot use them in a specific manner (ie targeting the injury site to keep inflammation under control vs overall inflammation from a workout that is a good thing) is why I'm hesitant to recommend them. I still think a moderate dose, with non-chronic use, should be fine for those who need it (training with NSAIDS > not training/training with pain).

As far as timing, prewo makes sense since most of the adaptation stuff occurs post and by that time it should be out of your system (depending on the NSAID in question).

That’s a really good observation about mobility possibly enhancing blood flow to the injury site, and that may be a part of the puzzle as to why loading is so essential for tendon health. The low blood flow thing with tendons was something that I thought was really interesting when I found out about it.. especially the fact that the body compensates for this lack of flow after a tendon injury by forming a bunch of new vessels, which later actually recede or ‘die back’ once the tissue is healed. I think that if there’s ever going to be a PED that enhances tendon repair, it’s probably going to be something that enhances this neo-vascularization in the early stages of healing…( I guess that’s the theory on the mechanism of why BPC-157 has been effective in healing rat tendons.)
Valid addition :)

We do have pharma options to enhance blood flow in general but, ideally, you want it to be more localized. That's what prevented me from recommending anything in particular. As for BPC-157, I think it's safe to say that it's over-hyped right now considering, you know, we have zero human data on it.
 

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