mismatch tendon versus muscle growth rates


Original Post
kenr · · Unknown Hometown · Joined Oct 2010 · Points: 9,034

Found a new data source for this, the book, "One Move Too Many ...", by Volker Schoeffl, Thomas Hochholzer, and Sam Lightner Jr. (Sharp End Publishing) - (in either new or old edition)

The book first gives the "old lore" that generally muscles grow faster than tendons, mainly because of less blood supply of nutrients to tendons. So climbers need to be careful when training finger strength.

I note two concerns that are not addressed in the book:

? Is it true that availability of nutrients (amino acids) is the main factor limiting growth of tendon (as opposed to say effective area of substrate)?

? If the two "normal" tendons are usually way stronger than their attached muscle, then why should we worry that the ratio is temporarily somewhat tighter?

But then a few pages later the book reports that

  • veteran climbers show (in MRI scans) rather large hypertrophy of "normal" finger tendons.
  • veteran climbers show substantial hypertrophy of blood vessels in the fingers - (and since there are virtually no muscles in the fingers, presumably some of these blood vessels are helping supply nutrients to "normal" tendons).
  • climbers' fingers usually are just bigger than non-climbers.

Interpretation I'm coming to is that we need to modify the "old lore" to say that ...
Muscles grow faster than tendons, except for some tendons of great interest to climbers.

Finally the authors observe that most finger tendon injuries they treat for climbers are not to the "normal" tendons but rather to the ligaments and pulleys.

So in actual practice, the "muscle overpowering tendon" problem isn't happening.

Ken

P.S. Still the actionable advice I think remains:
Be careful when training finger strength.
Mark E Dixon · · Sprezzatura, Someday · Joined Nov 2007 · Points: 234
kenr wrote:Found a new data source for this, the book, "One Move Too Many ...", by Volker Schoeffl, Thomas Hochholzer, and Sam Lightner Jr. (Sharp End Publishing) - (in either new or old edition) But then a few pages later the book reports that * veteran climbers show (in MRI scans) rather large hypertrophy of "normal" finger tendons. * veteran climbers show substantial hypertrophy of blood vessels in the fingers - (and since there are virtually no muscles in the fingers, presumably some of these blood vessels are helping supply nutrients to "normal" tendons). * climbers' fingers usually are just bigger than non-climbers.
Ken, can you cite the specific pages in the 1st Ed where these statements can be found? I haven't bought the 2nd Ed. Or cite the original references?

kenr wrote:Interpretation I'm coming to is that we need to modify the "old lore" to say that ... Muscles grow faster than tendons, except for some tendons of great interest to climbers.
Maybe I'm missing something, but I don't see how this follows. Presumably the muscles attached to those 'normal' tendons have hypertrophied also, quite possibly faster than the tendons themselves. And what's a 'normal' tendon anyway?

kenr wrote:So in actual practice, the "muscle overpowering tendon" problem isn't happening.
Maybe. Seems like most injuries are to pulleys rather than tendons. You could hypothesize that pulleys are even slower to hypertrophy, since their blood supply is likely worse than that of tendons. So maybe the muscles are overpowering the pulleys. Lots of maybes here.

kenr wrote:Still the actionable advice I think remains: Be careful when training finger strength.
I believe it's an accepted bit of training lore that to avoid injury, one should begin a new training regime slowly and increase the intensity of an established regime gradually.
I don't see any reason that training finger strength would be any different.
kenr · · Unknown Hometown · Joined Oct 2010 · Points: 9,034

In response to me saying that
"normal" finger flexor tendons of climbers aren't so much subject to the problem of having their muscles overmatch them due to faster growth

Mark E Dixon wrote:I don't see how this follows.
What seems to follow for me is ...
The main reason given in the book for why tendons generally grow slower is less blood supply. But then the book says that specifically the finger tendons of climbers are likely getting more blood supply than most people. Therefore the finger flexor tendons of climbers are more likely to grow faster, and so do better at "keeping up with" the growth of the finger flexor muscles.

By "normal" tendons I mean the ones that attach muscle to bone. So each muscle has two "normal" tendons, one at each end. Non-normal "tendons" (if they are actually tendons at all) are pulleys and ligaments. Some climbers sometimes refer to finger pulley injuries as a kind of "tendon" injury.

I am open to the idea that finger pulleys might be over-matched by the strength of the finger flexor muscles and/or by the strength of the "normal" finger flexor tendons, after rapid growth of the finger flexors due to training.

Because the training stress from the types of exercises most climbers use to train finger strength might not be appropriately stressing the pulleys for the sudden unexpected peak forces that can be imposed on them (like when a foot blows off its hold).

Ken
Brent Apgar · · Out of the Loop · Joined Oct 2007 · Points: 35

So before things get any more confusing, instead of using "normal" tendon (since a tendon is a tendon) if you want to specify the tendon running from the two flexor digitorum muscles to the fingertips just use distal tendon.

Yes, many climbers incorrectly refer to pulley (ie ligament) injuries as a tendon injury. The defining characteristic of a tendon is that it's a muscle to bone interface whereas a ligament is a bone to bone interface. Tendons and ligaments are virtually identical with respect to structure.

Probably the main reason that muscles adapt faster than tendons and ligaments is that a muscle is a cell, whereas ligaments and tendons are not a cellular structure... so they have very different responses to stress/damage from training. The fascia/connective tissue of the body adapts and remodels more similarly to bone.

I've run across probably 5 or less true acute flexor digitorum tendon injuries in my career in healthcare. Definitely not scientific but from what I run across most often I'd say that problems with the forearm/hand are in order:

1) Some kind of nebulous chronic elbow tweak
2) Chronic and Acute tweaks to the PIP joint
3) Everything else (wrist pain, acute strains to muscles, the weird and random)

I'd agree w/ Mark. I haven't seen anything in the literature or anecdotally that makes me think the fingers and forearms of climbers would need to be trained any different than what our current understanding of strength development would indicate.

If anything due to the more delicate nature of the structures in the hands my guess would be that the development of "finger" strength in climbers would take longer and it would be easier to overdo it with respect to other structures in the body.

Brent Apgar · · Out of the Loop · Joined Oct 2007 · Points: 35
kenr wrote:Because the training stress from the types of exercises most climbers use to train finger strength might not be appropriately stressing the pulleys for the sudden unexpected peak forces that can be imposed on them (like when a foot blows off its hold). Ken
I doubt it's a failure of training modality. The physiology and the biomechanics of the tendon/pulley system dictate that the pulley is simply the weakest link and therefore most likely to go first.
kenr · · Unknown Hometown · Joined Oct 2010 · Points: 9,034
Brent Apgar wrote:The physiology and the biomechanics of the tendon/pulley system dictate that the pulley is simply the weakest link and therefore most likely to go first.
Building on this, perhaps it's the weakest link not so much in normal use as in special situations.
A key property of a mechanical pulley is it's frictional properties under different intensities of loading. Perhaps the finger pulleys are well designed for frequent transmission of low-lever loads for precise controlled motions, like say typing, or playing the flute.

But perhaps not designed for sudden-onset high-tension loads (like when a supporting foot blows off). So the finger pulley has non-linearly high friction then, and fails to transmit as much of the load quickly to the flexor muscle and proximal tendon. So a higher proportion of that sudden tension load must be handled by the pulley and the proximal tendon.

Ken
kenr · · Unknown Hometown · Joined Oct 2010 · Points: 9,034
Brent Apgar wrote:Probably the main reason that muscles adapt faster than tendons and ligaments is that a muscle is a cell, whereas ligaments and tendons are not a cellular structure
Makes sense, though for some reason the German experts who wrote that classic injury book explained it in terms of blood flow, not the obvious structure difference.

On the other hand, from an engineering perspective the tendon a simpler structure than muscle, so arguably it ought to easier (and quicker) to build.

As for fingers being more delicate than the structures trained in most other sports, well obviously they're just smaller. Not sure if that difference is critical at the "macro" level we're dealing with -- but it surely doesn't help anything.

Perhaps a more important factor is that's it can be tricky to control the alignment of finger joints in the kinds of training (and performance) moves for climbing.
Like I recall at least one expert warning against training single-finger grips for this reason (whereas two-finger "team" grips are more stable).

Also a possible injury mode for the crimp grip is if it collapses into an open grip -- though each grip is OK in itself, but the transition is harmful.
Whereas when an open grip fails, you just fall off.

Ken
kenr · · Unknown Hometown · Joined Oct 2010 · Points: 9,034
Mark E Dixon wrote:I believe it's an accepted bit of training lore that to avoid injury, one should begin a new training regime slowly and increase the intensity of an established regime gradually. I don't see any reason that training finger strength would be any different.
Building on that, perhaps another reason to go slow on training finger strength at first is that while veteran climbers already have hypertrophy of the blood vessels in the fingers to support faster growth of tendons, new climbers do not.

Ken
Brent Apgar · · Out of the Loop · Joined Oct 2007 · Points: 35
kenr wrote: Building on this, perhaps it's the weakest link not so much in normal use as in special situations. A key property of a mechanical pulley is it's frictional properties under different intensities of loading. Perhaps the finger pulleys are well designed for frequent transmission of low-lever loads for precise controlled motions, like say typing, or playing the flute. But perhaps not designed for sudden-onset high-tension loads (like when a supporting foot blows off). So the finger pulley has non-linearly high friction then, and fails to transmit as much of the load quickly to the flexor muscle and proximal tendon. So a higher proportion of that sudden tension load must be handled by the pulley and the proximal tendon. Ken
I have no idea on how the loading speed affects the the properties of the function of the ligamentous pulleys in the fingers but...
I definitely agree w/ you in the fact that the whole upper limb in general (if you want to go with a biological evolution theory) has been adapting more to manipulating tools since 'we' started walking on two legs and stopped using our arms for locomotion. So activities like climbing that place an unusually high load on the arms and hands are going to cause problems.

Just to be clear I wasn't suggesting that zee Germans were incorrect. Just that another reason (besides having a poor blood supply) that the connective tissue structures take longer to adapt is due to their physiology.

I would also agree that tendons and ligaments are a simpler structure than a muscle cell, however, the cell has an advantage in the repair process due to the fact that everything it needs to repair itself is readily available in a more contained area. And there's also the way that each structure gets repaired.
The fascia has to go through a repair and remodeling process to regain its' full strength and function.

I guess that I sidetracked some and never really answered the original questions directly. The explanation of available blood supply and also the way in which fascia adapts to stress to become stronger may be the answer to the first question.

And as far as the second goes: since we've pretty much agreed that climbers are much more likely to injure the ligaments that support the tendons (at least in finger injuries) there probably isn't any reason to worry about the tendons themselves, just how hard we're pushing the whole system w/ whatever finger specific training we're applying.
Guideline #1: Don't be a jerk.

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