Thursday, April 22, 2010

Eccentric Exercise - some cool ideas as to why it seems to heal certain tendinopathies (ps, ditch -itis and -osis)

ResearchBlogging.orgHave you been suffering with some kind of sore tendon/jointy pain? Rotator cuff area, achiles, elbow, forearm, rsi etc etc? Guess what? First we're not alone, but second, just about anything that's been tried to address it has no real evidence to support it working, especially over time. Indeed, as the authors of a 2009 review study put it, "Tendinopathy is common although pathology of this condition is poorly understood." In other words, we don't really know how this dis-ease works. The point of this article is to consider why, as these authors see it, Eccentric Exercise (EE) which has seemed to have some good, some neutral results in research, may actually be successfully addressing the effects of that pathology. So much so, that it gets rated as a good "conservative" therapy for these kinds of common, awful and sometimes career ending, painful problems.

By way of context, in 2008, the year before these authors proposed why EE might be useful, another group reviewed pretty much everything under the sun applied to tendinopathies, from NSAIDS to shock wave therapy (and anything else one's GP may recommend). THe paper has the remarkably useful title "Treatment of Tendinopathy: What Works, What Does Not, and What is on the Horizon"

They write of these therapies:
Tendinopathy is a broad term encompassing painful conditions occurring in and around tendons in response to overuse. Recent basic science research suggests little or no inflammation is present in these conditions. Thus, traditional treatment modalities aimed at controlling inflammation such as corticosteroid injections and nonsteroidal antiinflammatory medications (NSAIDS) may not be the most effective options. We performed a systematic review of the literature to determine the best treatment options for tendinopathy. We evaluated the effectiveness of NSAIDS, corticosteroid injections, exercise-based physical therapy, physical therapy modalities, shock wave therapy, sclerotherapy, nitric oxide patches, surgery, growth factors, and stem cell treatment. NSAIDS and corticosteroids appear to provide pain relief in the short term, but their effectiveness in the long term has not been demonstrated. We identified inconsistent results with shock wave therapy and physical therapy modalities such as ultrasound, iontophoresis and low-level laser therapy. Current data support the use of eccentric strengthening protocols, sclerotherapy, and nitric oxide patches, but larger, multicenter trials are needed to confirm the early results with these treatments. Preliminary work with growth factors and stem cells is promising, but further study is required in these fields. Surgery remains the last option due to the morbidity and inconsistent outcomes. The ideal treatment for tendinopathy remains unclear.

It's almost as bad as the common cold: ubiquitous and no idea how to cure it.
Aside: And if you have a type of rotator cuff tendinopathy, and your doctor is suggesting a steroid shot? I'm motivated here as this is me. You may want to point that caregiver to this 2007 review of the lack of proven efficacy of this approach.
This systematic review of the available literature indicates that there is little reproducible evidence to support the efficacy of subacromial corticosteroid injection in managing rotator cuff disease.
It's interesting that from that mix of "current data" strategies that look promising in the 2008 survey quoted above, the authors of the 2009 BJMS article are interested in eccentric exercises. In 2007, another group of researchers concluded a literature survey about Eccentric Exercise and chronic tendinopathy with the sad claim that
the dearth of high‐quality research in support of the clinical effectiveness of EE over other treatments in the management of tendinopathies.
In other words, good quality studies that would be taken as being say clinically significant are thin on the ground. They're not as rigerous as these scientists would like to see in the presciption of a protocol to treat something.

By 2009, however, the UK group of scientists seems ready to say that EE is a good "conservative" treatment for tendinopathy. What's quite remarkable is why they're making this claim, and that's at the heart of this article.

But first things first, just to be sure we're all on the same page, what is tendinopathy? Tendinopathy is the umbrella term that includes, among other considerations, tendinosis and tendinitis. As for the differences between these two, on a functional level, Mike Nelson puts it nicely:
TendonITIS is normally from inflammation (itis). TendonOSIS is normally from messed up connective tissue.
To get into a bit more detail, the intro to the 2008 survey is very helpful
Traditionally, pain in and around tendons associated with activity has been termed tendonitis. This terminology implies the pain associated with these conditions results from an inflammatory process. Not surprisingly, treatment modalities have mainly been aimed at controlling this inflammation. The mainstays of treatment have included rest, nonsteroidal antiinflammatory medications (NSAIDs), and periodic local corticosteroid injections.

There are two problems with this approach. First, several studies demonstrate little or no inflammation is actually present in tendons exposed to overuse [83, 96, 163]. Second, traditional treatment modalities aimed at modulating inflammation have had limited success in treating chronic, painful conditions arising from overuse of tendons. More recently, the term tendinopathy has been advocated to describe the variety of painful conditions that develop in and around tendons in response to overuse. Histopathologic changes associated with tendinopathy include degeneration and disorganization of collagen fibers, increased cellularity, and minimal inflammation [83, 163]. Macroscopic changes include tendon thickening, loss of mechanical properties, and pain [163]. Recent work demonstrates several changes occur in response to overuse including the production of matrix metalloproteinases (MMPs), tendon cell apoptosis, chondroid metaplasia of the tendon, and expression of protective factors such as insulin-like growth factor 1 (IGF-1) and nitric oxide synthetase (NOS) [10, 76, 93, 99, 154, 155, 174, 199]. Although many of these biochemical changes are pathologic and result in tendon degeneration, others appear beneficial or protective. Tendinopathy appears to result from an imbalance between the protective/regenerative changes and the pathologic responses that result from tendon overuse. The net result is tendon degeneration, weakness, tearing, and pain.
So for practitioners in the know, it seems the once-frequent diagnosis of "tendinitis" has gone down quite a bit - because inflammation may or may not be present, and when it is, may or may not be the main cause of pain. Also, there is an "imbalance" of protective/regenerative responses to overuse and pathological (diseease) responses. This is Mike's "messed up connective tissue."

Hence we circle back to the term tendinopathy to cover this not unusually mixed condition of perhaps some inflammation but in particular, "degeneration, weakness, tearing, and pain" Hence both osis (tears) and itis (inflammation) may neither be particularly pathologically accurate or diagnostically helpful. And so, tendinopathy is the new and more robust term for these conditions.

With that note in mind, let me also add that the following discussion is not meant to be a prescription of any course of action. Get yourself checked with your doctor before starting anything. In my own case i have been disappointed by the fact that the thing that has actually helped the most immediately has been taking NSAIDS - some inflammation, or -itis maybe?

After a month of other non-drug interventions, day one after finally breaking down and seeing the doc: bam - immediate reduction in the pain that was making putting on a jacket a painful experience. bugger. But ah ha, it ain't all better that's for sure. What to do next? My hope is that the following research may offer some insight into WHAT to do if not exactly how and when to do it.  

Eccentric Exercise and Tendinopathy
The authors of "Eccentric exercises; why do they work, what are the problems and how can we improve them?" J D Rees, R L Wolman, A Wilson write in the abstract:
Eccentric exercises (EE) have proved successful in the management of chronic tendinopathy, particularly of the Achilles and patellar tendons, where they have been shown to be effective in controlled trials. However, numerous questions regarding EE remain. The standard protocols are time-consuming and require very motivated patients. EE are effective in some tendinopathies but not others. Furthermore, the location of the lesion can have a profound effect on efficacy; for example, standard EE in insertional lesions of the Achilles are ineffective.

Until recently little was known of the effect of EE on tendinopathic tendons, although a greater understanding of this process is emerging. Additionally, recent in vivo evidence directly comparing eccentric and concentric exercises provides a possible explanation for the therapeutic benefit of EE. The challenge now is to make EE more effective. Suggestions on areas of future research are made.
So, the researchers are sitting with the 2007 surveyview that while there's some hints of promising evidence in the past about EE, it hasn't been super. They think that now, however, they have a better sense of what might be making it effective.

The body of the article focuses on Achilles tendinopathy (mid back of the leg - base of the calf muscles), Insertional Achilles tendinopathy (where the tendon inserts away from the calf muscles, down by the ankle where it attaches to the bone) , Patellar tendon (either side of the knee cap) in particular.

The authors' insight has been to look at where in the tendon the lesion is occuring. Is it where the tendon attaches to the bone or where it attaches to the muscle? The effects of EE in the small number of studies are all over the map, so it's hard to draw any conclusion except, it seems, that where the lesion is on the tendon seems to have a correlation between the degree to which EE will be successful. For insertional achilles, as opposed to "the main body" of the tendon, EE's not showing up as so great. With the paterllar tendons, while some studies have shown benefit, especially over CE or concentric, whether there's a difference around proximal or insertional hasn't been the focus of research in such a way as it's possible to make a distinction.

With respect to other tendinopathies - like forearms (RSI kinda stuff) and elbows, the authors write:
A small number of studies have examined the use of eccentric exercises in the management of tendinopathy of the lateral extensors of the forearms.26–28 There is some evidence suggestive of an increase in function using EE compared with ultrasound in the treatment of lateral extensor tendons,29 and a recent study adopted an isokinetic eccentric protocol in the management of lateral elbow tendinosis and reported promising results.30 No randomised study on the effectiveness of EE on the rotator cuff has been published, although a small uncontrolled pilot study of nine patients did suggest a significant benefit of EE (patients with arthritis of the acromioclavicular joint or significant calcification were, however, excluded).31 Further trials on both tendinopathy of the rotator cuff and lateral extensor forearm tendons are required in order to evaluate EE more fully.
Just my luck: shoulders with EE haven't been evaluated. Time to become an experiment of one.

What are Eccentrics Doing?
Despite this rather promising but still arid, partial research landscape for EE and tendinopathy, the authors have some ideas about the mechanisms that may be at play in eccentric efforts
The pathophysiology of tendon injury and healing is incompletely understood. It does appear, however, that in established tendinosis the tendon often does not progress into an active (or at least successful) healing cycle. EE may work by providing a mechanical stimulus to the quiescent tendon cells
The authors propose several interesting ways in which this "mechanical stimulus" may work. The first is on that all important building block for tissue, collagen
Physical training in general has been shown to increase both the synthesis and degradation of collagen,39 and in the longer term this may lead to a net increase in collagen. Recently it has been recently elegantly demonstrated by Langberg and coworkers, by use of the microdialysis technique, that a chronically injured Achilles tendon responds to a 12 week EE programme by increasing the rate of collagen synthesis.40 In this study 12 patients (six with Achilles tendinosis and six normal controls) performed EE over a 12 week period. The EE group had increased collagen synthesis (peritendinous type I collagen) without a corresponding increase in collagen degradation. There was also a corresponding drop in pain levels (in line with other studies).
That collagen production - to repair tendon degredation - is a huge and good deal. Especially that the exercise is not causing breakdown, but actual rebuilding.

Another factor the authors consider is blood flow. When we see tendons illustrated in anatomy texts, they're usually white-ish. That's the lack of a whole lot of blood going through them. This limit is in no small part why tendons can take longer than just about anything else to heal. So improving blood flow to tendons - blood being a nutrient carrier - could seemingly be a big plus. The authors write
The effect of EE on Achilles tendon microcirculation has also been studied. Achilles tendon oxygenation was not impaired by an EE programme but was accompanied by a decrease in postcapillary venous filling pressures, the authors suggesting that this reflects improved blood flow. Again this study looked only at eccentric exercise so it is not possible to determine whether this is a specific effect of EE.
In other words, concentric exercise may have the same benefit on blood flow as eccentric exercise - we don't know - but what we do seem to know is that exercise (in the studied case, eccentric) keeps the blood moving, circulating rather than sitting somewhere. The anti pump? in a good way?

Where using the Force Mayn't Matter. All this is cool, but it doesn't explain WHY these effects are occuring from EE. In particular, something the scientists can conclude rather strongly from the work that's been carried out is that the magnitude of the force has nothing to do with it. So lifting a big weight, or lifting a lighter weight faster (F=M*A) isn't what's getting the job done.

The key question the authors ask is:
If the efficacy of EE cannot be explained by the magnitude of force, then what is responsible?
Great Question. They have one very intersting finding about eccentric exercise - the shape of control of the muscle when it's lengthening and contracting at the same time:
Intriguingly, we observed a pattern of sinusoidal loading and unloading in EE which was not demonstrated in CE. The fluctuations in force probably reflect the difficulty in controlling a dynamic movement with a lengthening muscle; similar to the experience that it is easier to lift a heavy weight under precise control than to lower the same weight. We propose that these fluctuations in force may provide an important stimulus for the remodelling of tendon. Certainly in the remodelling of bone it is known that bone responds to high-frequency loading and appropriate mechanical signals can lead to a dramatic increase in bone density.

Frequency rather than Force. This is so cool - it sounds great too: that the sort of cycling on and off of the muscle (the sinusoidal loading and unloading) during the eccentric may be the biggie in stimulating that good collagen rebuilding in particular associated with EE and maybe the blood flow too. The other interesting part is that there is a possible parallel to bone remodelling here (and Woolf's law).

That is, as force is applied to a bone it will get bigger (the outer shell gets pushed out it seems, as the inner lace work architecture increases) and so stronger to respond to that demand. Davis's law on tissue seems a wee bit similar: "If soft tissue is placed under unremitting tension, the tissue will elongate by adding more material. "

Bottom line: the particular type of muscular demands to maintain control of a load in extension (force fluctuations not force magnitude) may play a particular role in remodeling tendons in these various opathies.

Whither, Voyager for Futuer EE / Tendinopathy Research?
The authors are now happy to say EE seems to have sufficient basis to be considered viable. Time to figure out how to optimize it. THey write in the Future Work section:
Little is known of the optimal protocol for EE. Indeed, fundamental questions remain unanswered, such as how fast the exercises should be performed and progressed. This is certainly an area worthy of future research. The specific location of the pathology within a tendon has increasingly been shown to have an effect on the efficacy of EE, and further study in this area is also suggested. Other potential areas of research include studying the effect of periodisation of training, a technique currently perhaps more familiar to athletes and their coaches than to sports medicine physicians.
Goodness, that's interesting. Periodization combined with frequency may be the sweet spot for rehab. Why not? It's excellent for anti-fatigue strength building; why not repair?

As an example of eccentric exercises that have been tried out among at least a small population of elbow-opathies,  Mike T Nelson's developed some nice eccentrics work with a kettlebell. Well worth a look and a go.

What i've been working lately for my shoulder/painful arc thing:

 put a wee kettelbell or light db in the hand of the sore side. bring hand up to chest (with weight in it), then lift elbow so it's parallel or close to shoulder height WITH NO PAIN - only go as high as you can with no pain
- slowly abduct the hand away from the chest, and potentially rotate wrist down (like pouring a jug) - if the load feels too heavy - brings on pain - bring hand in a bit; reduce turn in wrist; then lower the whole arm (not just the elbow but this L shape you're holding) so you're working the shoulder.

that lets one do the concentric pretty much unloaded and focus on a safe eccentric.
if you give that a go for a while let me know how that feels - just don't move into pain.

Perhaps the main take away from this summary of recent research reviews and primary work is that tendinitis vs osis is largely a non-starter; tendinopathy is where it's at. And saying that, the pathology or dis-ease of tendinopathy is not well understood, which may also explain why treatements - in particular long term ones - don't have much evidence to support their efficacy. There are some prospective treatements on the horizon, however, with eccentric exercise amongthem. This latest study on EE and tendinopathy seems to propose the best hypothesis so far as to why eccentric exercises is showing up as particularly effective for at least main body tendinopathy.

Rees, J., Wolman, R., & Wilson, A. (2009). Eccentric exercises; why do they work, what are the problems and how can we improve them? British Journal of Sports Medicine, 43 (4), 242-246 DOI: 10.1136/bjsm.2008.052910

Andres, B., & Murrell, G. (2008). Treatment of Tendinopathy: What Works, What Does Not, and What is on the Horizon Clinical Orthopaedics and Related Research, 466 (7), 1539-1554 DOI: 10.1007/s11999-008-0260-1

Woodley, B., Newsham-West, R., Baxter, G., Kjaer, M., & Koehle, M. (2007). Chronic tendinopathy: effectiveness of eccentric exercise * COMMENTARY 1 * COMMENTARY 2 British Journal of Sports Medicine, 41 (4), 188-198 DOI: 10.1136/bjsm.2006.029769

Koester MC, Dunn WR, Kuhn JE, & Spindler KP (2007). The efficacy of subacromial corticosteroid injection in the treatment of rotator cuff disease: A systematic review. The Journal of the American Academy of Orthopaedic Surgeons, 15 (1), 3-11 PMID: 17213378

Related Resources


eshlow said...

It may be interesting to note that anecdotally the people who come into the clinic with tendonopathies usually have very poor eccentric control of their muscles, and their muscles of the affected tendon are usually very tight/hypertonic.

From what I've seen (and done although I'm not a PT yet) loosening up the muscles connected to the tendon provides the most immediate relief and long term benefit in most cases of chronic tendonopathy. (Aka releasing tension on the muscles so they can function properly). Add that to eccentric exercise and that should be a good core of a program.

I also believe (albeit with no proof) that the modulating force on the tendon during eccentric exercise may be able to force nutrients into the tendon itself. Much like spinal loading and movement help to force in nutrients into the intervertebral discs. I think that in conjunction with Davis' law is probably what is helping the tendon a lot. Also, the eccentric exercise will help add more sarcomeres which should lengthen the muscle releasing some of the constant tension on the tendon as well.

Regardless, ice, massage, etc. IF they are helping should be continued. Research shows they are ineffective, but they really do help some people (including myself). I see no reason to exclude it.

dr. m.c. said...

fabulous comments - thank you -
really great to get clinical practice experience/insight.
like the thoughts on the tension side.
as for ice - likewise the work seems to be a big old "inconclusive" - but what's being tested? if it helps quiet down a threat response - soothes a person to get more work done - great.

likewise cool observation about the eccentric control from folks with difficulty. neat.

Thanks for stopping by, and all the best with the rest of your studies.


Anonymous said...

In my search for useful information about tendopathy I found two good resources. The one who had an idea about the reasons why you get it in the first place is Josua Tucker, massage therapist. Interesting stuff on his website.

Second is Doug Kelsey, physiotherapist in Austin, Texas, who heals injured athletes and weekend warriors with exercise. I printed out tons of pages from his blog.

Unknown said...

There are various therapies that do not include surgery and hospitalization. One of such therapies is shock wave therapy. These therapies have ability to cure pain without any surgery.

dr. m.c. said...

Hi Adiran
thanks for writing
have you had rehab with this technique?
the jury seems out on shockwave therapy. great if you've had success with it - the literature hasn't shown consistent results at this point. Me i prefer active strategies when and wherever possible.



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