Injury Series: Eccentric exercise and tendon remodeling, part I: Achilles tendonitis

Attention readers: I have published a significantly revised and updated article on midpoint Achilles tendonitis.  I strongly recommend you read that instead! The information below is incomplete and out of date! Click here to go to the updated Achilles tendonitis article.

Note: if you are looking for information on insertional Achilles tendonitis, see this article

We're shifting gears a bit today.  As high school and college cross country seasons approach, lots of runners are hitting their peak mileage right about now.  At the same time, there's a lot of runners who wish they could be out there hitting the road every day, but are sidelined by injury.  This will the the first post in a series on injuries: their cause, prevention, and treatment.  In the past 10-20 years, there have been some very important changes in the way the medical community approaches and treats many common running injuries.  In a few cases, highly effective treatments have been discovered that were not known even a decade or two ago.  Unfortunately, many physicians and physical therapists don't stay on top of the injury research that's being published in several of the major medical journals, so the clinical implementation of these scientifically proven treatments is lagging.  At the same time, many treatments that enjoy wide acceptance have not withstood a scientifically rigorous examination.  While few are harmful, wasting time on ineffective treatments is something neither the patient nor the doctor wants.  At the same time, I realize that treatment based solely on scientifically proven methods is often limited.  I've also amassed a fairly large bag of "tricks" either through experimentation or advice from fellow runners.  In truth, it's usually a combination of "tricks" and "treatment" that get you healthy and running again.  I'll do my best to keep it clear what is scientifically rigorous and what is hocus-pocus-magic.  This is quite a large undertaking, so (much to your delight, I'm sure) I'm going to break with my usual long-winded posts and break this series up in to smaller and more numerous posts, each on a specific injury and its causes, prevention, and treatment.  Today's topic: Achilles tendonitis.

Introduction and Background

Injuries to the Achilles tendon are often cited as one of the "big five" most common running injuries (the others being plantar fasciitis, patellofemoral pain syndrome (runner's knee), medial tibial stress syndrome (shin splints), and iliotibial band syndrome).  Whether to label Achilles injuries as "tendonitis" is controversial.  The suffix -itis implies the main problem is inflammation, as is the case in conditions like appendicitis, gingavitis, etc.  But Achilles tendon issues often present without any signs of cellular inflammation, especially in chronic cases.  Some podiatrists prefer the label "tendonosis," which implies a more general dysfunction in the Achilles.   Some even differentiate between tendonitis and tendonosis when diagnosing Achilles tendon injuries.  Regardless, "tendonitis" is the most common term, and it's the term I'll be using in this post.  However, it is important to remember that the root problem behind Achilles injuries is not inflammation--it is real, physical damage to the fibers of the tendon.


Before we delve into Achilles tendonitis, I need to give a quick primer on concentric and eccentric muscle contractions.  Concentric contractions are simple.  It's when the joint movement is in the same direction as the muscle's contraction.  Using your biceps to curl a dumbbell up towards your shoulders is a concentric contraction.  In contrast, an eccentric contraction is when a muscle is working to oppose the motion of a joint.  Slowly lowering the dumbbell you've curled up to your shoulder is an eccentric motion.  If you were to completely relax your biceps, the weight would quickly slam down.  Your biceps work eccentrically to slow down the motion.  Most "down" motions are eccentric contractions working to oppose gravity: the down phase of a pushup, lowering a barbell down while doing a bench press, and the down phase of a squat all involve eccentric muscle contractions.  These contractions are stressful on muscles and are responsible for most injuries and muscle soreness--it's why running down a long hill several times will often make your quads more sore than if you'd ran up it. 


The Achilles tendon is the biggest and strongest of all the tendons in the body.  It connects the gastrocnemius and soleus muscles to the calcaneus, or heel bone, and allows them to perform their main task: plantar flexing the foot. Its role in running is essential--it allows the calf muscles (the gastrocnemius and soleus) to elastically store energy via the stretch-shortening cycle, which is released upon toe-off.  The tendon itself also stores energy by functioning as a very stiff spring.  And I do mean very stiff--upon loading with 120 pounds of force, it only lengthens by a few millimeters.  In fact, its stiffness tops that of suspension springs in high-end sports cars--it would take over 900 pounds of force to stretch your Achilles an inch!

The Achilles tendon connects the calf muscles--both the gastrocnemius and the soleus--to the heel.  Some doctors and researchers refer to both muscles as one unit: the triceps surae

 Like all tendons, the Achilles is made up of collagen, a long helix-shaped protein that makes up much of the tough, fiberous material in your body: skin, cartilage, ligaments, and tendons.  In a tendon, the collagen fibers are arranged in a wavy, linear, and quite orderly fashion, as shown to the left.  The wavy shape is likely what allows the tendon to have its spring-like behavior. 

Naturally, any activity that involves explosive upward or forward motion relies heavily on the Achilles.  A high jumper, a cross country runner, and a sprinter all require their Achilles to be ready to rapidly store and release loads many times the athlete's body weight.  Because of its ubiquitous nature, injuries to the Achilles tendon are quite common across many sports.  Though acute Achilles injuries, including ruptures, are often a concern in contact sports, runners usually deal with overuse injuries to the tendon.  These almost invariably occur in the last three inches of the tendon.  Due to the size and relatively poor blood supply to the tendon, Achilles injuries can seem quite intractable to the frustrated athlete.

In runners, the traditionally-blamed culprits for Achilles tendonitis are excessive speedwork, hillwork, or explosive strength training.  Runners who have a forefoot-striking style also seem more likely to suffer Achilles tendon injuries.  But even heel-striking runners doing all easy mileage on flat roads can suffer severe Achilles tendonitis.  So what's the research say about the causes of Achilles tendinitis in runners?


As we've seen before, epidemiological studies are not particularly useful in determining the cause of running injuries.  "Training errors" are cited in 60-70% of Achilles tendonitis cases, though this is not a helpful finding--presumably, something else caused the Achilles to be the weakest link.  Runners only rarely come down with two or more completely unrelated issues at the same time; although a training error may have provoked the injury, there still must be some underlying reason the Achilles tendon gave out first.  Among factors other than training errors that have been linked to Achilles tendonitis, the most relevant to our discussion include ankle range-of-motion limitations, weak calf muscles, and excessive pronation.  More rare causes like reactions to local cortisone injections in the ankle and reactions to fluoroquinolone antibiotics are important to be aware of, but aren't a factor in most cases.

More than a few studies (1, 2, 3) have shown excessive pronation to be associated with Achilles tendonitis.   All of these studies have a flaw, however--they are retrospective, meaning they look at athletes who already have Achilles tendonitis, instead of taking a healthy group of runners and seeing who gets injured.  A prospective study like that would be very difficult--in a typical year, somewhere in the neighborhood of 30-50% of runners report an injury, but of these injuries, only 10% or so would be Achilles tendonitis.  To get a workable study size, a very large group would need to be evaluated.  As a result, we're left to extrapolate from retrospective work.  The main problem with retrospective results is that they make it impossible to determine causal relationships--do runners with Achilles tendonitis pronate because their Achilles is injured, or did the pronation cause the Achilles injury? Unfortunately, this can't be answered yet.  Even if we assume pronation does increase strain on the Achilles, one of my earlier posts showed that common interventions like supportive shoes and orthotics do not reliably alter pronation, so approaching treatment from that angle seems to be a non-starter.

Weakness in the calf muscles is at least a possible causal factor with no evidence against it.  It makes intuitive sense--a weak gastrocnemius or soleus would require the Achilles to contribute a greater portion of energy return during toe-off, which would in turn increase the strain on the tendon.  There is also evidence that strengthening the calf muscles improves recovery from Achilles tendonitis; we'll go over this later.

On the same token, poor ankle range of motion (ROM) is another possible cause that makes intuitive sense.  When ROM at any joint is poor, the muscles must work harder to move the joint, much like it takes more force to twist a tight screw than it does to twist a loose one.  Poor ankle ROM can have several causes: an acute injury like an ankle sprain, tight shin muscles, and tight calf muscles.  It's easy to see how tight calf muscles or tight shins can reduce your ankle's range of motion and increase strain on the Achilles.  In the case of a tight shin muscle (tibialis anterior for the scientifically minded), the calf has to work harder when contracting to plantar flex the foot.  Likewise, if the calf muscles are tight, there is also increased strain on the Achilles because the baseline tension is greater.  So, for a given impact or push-off, the Achilles will experience a higher stress.


So, all these various causes, perhaps combined with some more run-of-the-mill methods of overloading the Achilles (overzealous hill running or a block of higher mileage, for example) can set off an Achilles tendon injury.  But what actually happens on the cellular level when the Achilles (or any tendon) is injured? This brings me to John's First Maxim of Injury: injury-related pain is the result of real, physical damage to the musculoskeletal system. It may seem like a silly maxim, but you'd be surprised how many people fool themselves into think that the only reason something hurts is because there's "inflammation in the area"-as if their chronically injured Achilles was perfectly intact and they'd be good to go if not for that pesky inflammation.  So they'll pop a few advil or ice a bit and head out the door.  This brings me to John's Second Maxim of Injury: Your recovery plan should be geared at repairing the damage and addressing the root cause of your injury.  This is not to say that tackling inflammation with icebaths or icecups is a bad idea.

Without getting too far off-track (because we know how often that can happen on this blog), inflammation is the body's response to an injury.  Anyone who's seen his or her ankle swell up to the size of a grapefruit following an ankle sprain can tell you that.  Inflammation rushes fluids to an injured area, and also prevents fluids from draining out of an injured area.  Inflammation is usually demonized as an out-of-control overreaction to an injury, but it does have some redeeming qualities: it stimulates nerve endings and increases the pain coming from an injury, strongly discourages you from doing additional damage from continuing to run (this is why avoiding painful activities while injured is usually a good idea).  Despite this, it is an overreaction, and should be dealt with accordingly.  I usually recommend icing 3-5 times a day (10 minutes each if using an ice cup, 20 minutes if using an ice bag) for 2-3 days following minor muscle and tendon injuries.  But this is just hocus-pocus magic.

Moving back to the Achilles tendon, let's take a hypothetical college runner, Sam.  He's running 10-12 miles a day during the summer, preparing for his sophomore college cross country season.  One day after finishing his long run, he notices his left Achilles tendon feels tight and sore.  The next day, it start to tighten up in the last mile or so of his easy run.  In the following days, the pain increases to the point where he feels an ache in his Achilles with virtually every step he takes.  Being the hard-headed type, Sam ices it a bit and goes ahead with his training, but after nearly a week of this, he feels pain even walking, and his Achilles tendon is sore to the touch.  Even with several days' rest, his Achilles aches if he tries to run.

If we could have looked at a sample of Sam's Achilles tendon before he got injured and put it under a microscope, it'd look like the pink sample above--with collagen fibers neatly arranged in a wave-like pattern (this is illustrated even more beautifully in the image to the left, which I couldn't resist including in this post.  It was created using a tendon from a rat and a non-linear optical microscope at Texas A&M).   However, if we took a sample of Sam's tendon one or two days after it had started to hurt, it'd look like a war zone--there would be frayed collagen fibers, inflammatory cells, swelling, and amino acids everywhere.  Why the difference? When Sam injured his Achilles, probably during his high-volume training in the past week or so, he actually caused a microsized rupture of the tendon.  While Sam is probably not in danger of a true Achilles tendon rupture, his body is responding to the damage nonetheless.  Gaping holes in the collagen structure in his Achilles are patched frantically as his body struggles to keep pace with the damage.  Every time Sam runs on his injury, he is tearing apart some of the new collagen that is attempting to shore up the tiny rupture in his Achilles, magnifying the problem.  Once Sam finally does take enough time off to allow his body to repair the damage by laying down new collagen, the result is nothing like what he started with.  If we took a biopsy of Sam's Achilles tendon after he's been cross training in the pool for a week or two, it'd look something like this:

Perhaps it wouldn't be quite this bad--this is from a woman who actually ruptured her Achilles tendon, but the same mechanism is at work in Sam's Achilles.  This looks more like a plate of spaghetti than the flowing waves of collagen we saw earlier.  The continual damage/repair/damage cycle that Sam has put his body through while trying to "run through" his injury has caused the new collagen to grow in a disorganized, random fashion, effectively forming scar tissue. This cycle of injury and repair does not necessarily have to take place in rapid succession; several injuries to the same Achilles tendon over a period of months or years can also bring about the disordered collagen arrangement characteristic of chronic Achilles tendonitis.  Either way, the consequence of this is that the disruption in the natural collagen orientation has altered the mechanical properties of the Achilles tendon.

In this study, runners with Achilles injuries had measurably less-flexible Achilles tendons compared to a group of healthy volunteers.  When the calves were isometrically contracted, an injured Achilles is pulled tighter than a healthy one.  Why? Because of the disrupted collagen arrangement.  In a healthy tendon, the orderly, wave-like pattern of collagen allows the proteins to stretch slightly, granting more "give" to the tendon.  But the disordered collagen pattern in a chronically injured tendon is not flexible.  Like pulling on a knotted rope, strain on a injured Achilles tendon disproportionally affects the injured (knotted) area.  The tighter you pull, the tighter the knot becomes.  This, along with the poor blood supply to large tendons like the Achilles which slows the recovery and rebuilding process, makes recovering from chronic tendon injuries difficult.

Traditional Treatment
We've established that Sam, our hypothetical runner, has done quite a number on the collagen fibers in his Achilles tendon.  All Sam cares is that his Achilles hurts and he can't run on it.  What should his rehabilitation program look like?  Most sports doctors and podiatrist would refer Sam to a physical therapist, who would give Sam a set of stretches and exercises to perform daily.  These programs vary from therapist to therapist, but mostly involve exercises similar to those in the graphic below:

Here's the logic behind these exercises:

  • Calf Stretches: if the calf muscle is tight, as covered earlier, it will increase strain on the Achilles.  Stretching the calf, both with a straight knee and bent knee, should loosen up the muscle and take some strain off the Achilles.
  • Calf strength (heel raises): strengthening the calves should also take some strain off the Achilles.
  • Upper-leg strength and balance: Improving overall strength and balance should reduce the total amount of strain the Achilles has to take during running--better balance and more coordination should create less of a shock on the Achilles during impact.

Unfortunately, few of these "theoretically sound" exercises actually have evidence-based proof supporting their claims.  I contend that fully half of the exercises above are inefficient and three of them--the calf stretches--might even be harmful.
Why do I think calf stretching a bad idea for Achilles tendonitis? I've already established that tight calves are bad and predispose you to Achilles problems, and stretching loosens tight muscles, so why not stretch them out? Because stretching increases strain on the Achilles.  Remember the knotted rope analogy? Every time you stretch, it's like tugging on both ends of that knotted rope.  Additionally, there is no substantial evidence supporting its useEspecially in the "acute" phase of an Achilles injury, I recommend avoiding stretching, because it will only tug on the Achilles more and disrupt the collagen healing process.  Once the collagen has healed (which probably takes anywhere from a few days to a few weeks depending on severity of the injury, but I'm just guessing here), gentle stretching can be helpful, but runners are far too eager to crank away, thinking stretching more forcefully is better.  Fortunately, there are ways to loosen up the calves in the acute phase without putting any strain on the Achilles.

Foam rolling and heat (applied to the CALVES, not the Achilles tendon!) can accomplish nearly the same thing as calf stretching without the drawbacks.  Foam rollers are an inexpensive and highly versatile recovery aid, and I would wager a large sum of money that you can find one underneath nearly every professional runner's bed.  You can get one at your local running shop.  You might find that a foam roller is too soft for some areas, including your calves.  In this case, you can move up to something harder--an 18" section of 3" PVC pipe from a hardware store is ideal.  A few minutes twice a day on the foam roller will go a long ways towards loosening your calves and is helpful for other injuries to.  Heating up your calves with a hot pack, especially before rolling, will loosen your calves too--just avoid applying heat to the Achilles tendon, unless you're about to leave for a run.

Sam might also receive a heel lift or a custom orthotic insert for his shoes from his doctor, though there is surprisingly scant evidence for their use.  One very small study (only three participants) found that a heel lift actually increased maximum Achilles tendon force, while a somewhat larger study (seven participants) found a highly variable effect with no statistically significant change overall.  In some individuals, peak Achilles tendon force decreased; in others, it increased.  This should not be surprising to regular readers of this blog, as we've seen the same effect with orthotic and shoe changes meant to control pronation.  This doesn't mean heel lifts or orthotics are to be avoided at all costs--you're probably just as likely to be helped as you are to be hurt by them.  However, there are concerns about the long-term effects of wearing heel lifts.  The deleterious effects of high-heeled women's shoes are well documented: a modified gait, increased pressure on the forefoot, and possibly shortening of the Achilles tendon itself.   A standard running shoe with a heel elevation of 12mm combined with a 10mm heel wedge to treat Achilles tendonitis brings the total heel-to-toe drop to 22mm--nearly an inch.  While most studies on the effects of high heels involve larger drops of 45 or 80 mm, it would not be outrageous to propose that even more moderate heel elevation would be harmful long-term.  Alas, this is another topic for another day.

Eccentric heel drops: a superior treatment method

In the past decade or so, using targeted eccentric exercise on injured areas has become a very important part of rehabilitation for several chronic overuse injuries.  Although there was evidence that eccentric calf strengthening was useful in Achilles tendonitis treatment since as early as 1992, it was not until this 1998 study by a top-notch team of Swedish doctors and therapists that the value of eccentric calf strengthening was realized.  The study used thirty recreational runners who had been suffering from chronic Achilles tendonitis for several years on average (one subject had been injured for over eight years!), all of whom had tried rest, nonsteroidal anti-inflammatory drugs, physical therapy, and footwear/orthotic intervention to no avail. Fifteen were assigned a rigorous eccentric calf strengthening routine and fifteen were assigned surgical debridement of the Achilles tendon.   

The eccentric strength protocol consisted of two exercises: straight-knee heel drops and bent-knee heel drops.  These exercises were performed twice a day, every day for twelve weeks, and done slowly.  Alfredson et al. describe the exercises as follows:

From an upright body position and standing with all body weight on the forefoot and the ankle joint in plantar flexion, the calf muscle was loaded by having the patient lower the heel beneath the forefoot (Fig. 1). They were only loading the calf muscle eccentrically, no following concentric loading was done. Instead, the noninjured leg was used to get back to the start position. The patients were told to go ahead with the exercise even if they experienced pain. However, they were told to stop the exercise if the pain became disabling. When they could perform the eccentric loading exercise without experiencing any minor pain or discomfort, they were instructed to increase the load by adding weight. This could easily be done by using a backpack that was successively loaded with weight.

A straight-knee heel drop, as the name suggests, involves keeping the knee locked throughout the exercise.  A bent-knee heel drop involves bending the knee upon descent (thereby strengthening the soleus muscle), as illustrated below.

Alfredson et al. also provide an oddly-humorous photo of a very Swedish-looking man with a very heavy-looking backpack to illustrate how weight can be added.

After 12 weeks of eccentric exercise, the results were astonishing.  Fully 100% of the subjects had been able to return to their pre-injury running level.  Their reported pain during activity, reported on a 100-point scale (the visual analogue scale, or VAS, for the medically-minded), decreased from 81.2 to 4.8!  They also showed a marked increase in strength on their injured side.  But perhaps even more impressive is how the eccentric exercise group compared to the control group who underwent surgery.  All 15 of the surgery group members were eventually allowed to return to running, but their VAS pain scores, which averaged 71.8 pre-surgery, only dropped to 21.2 ±11.4 after 24 weeks post-surgery (recall that the eccentric exercise group was scored after 12 weeks).  Thus, the eccentric exercise protocol was superior to surgery in every respect--it had better results in less time without any risks that surgery entail.
What is it about the eccentric exercise protocol that enabled such drastic improvements, even in subjects who had been injured for many years and not responded to any conventional treatment?  A later study by the same group ruled out a simple increase in strength--in that study, 44 subjects were assigned either a concentric (calf raise, going "up" only) or eccentric (heel drop, going "down" only) protocol.  18 of the 22 members in the eccentric exercise group were able to return to their previous activity level, while only 8 of the 22 members in the concentric strength group were able to do so.  So there is more at play than just muscular strength.

Three factors were crucial to the success of the Alfredson et. al 1998 rehabilitation program: the emphasis on eccentric strength, the progressive nature of the exercise (accomplished by adding weight), and the requirement to continue the exercise even when in moderate pain.  Eccentric overload on muscles and tendons is actually blamed for causing many injuries, so it seems odd that the same type of activity encourages recovery.

 Recall that the root cause of chronic Achilles tendonitis is the disproportionate strain on the disordered collagen at the injury site--the knot in the rope, per our analogy earlier.  Uncontrolled eccentric exercise does more damage, which causes more disordered collagen (scar tissue) to build up, magnifying the problem.  Additionally, eccentric movements in regular activity (like running) are paired with concentric movements, which don't damage a healthy tendon, but do put strain on an injured one.  But controlled and targeted eccentric exercises--like eccentric heel drops---actually reverses the problem.  Here's how:

  • A moderate amount of eccentric exercise (into moderate pain) damages and breaks down the disordered collagen at the injury site in the Achilles tendon
  • The body responds by increasing collagen synthesis and laying down new fibers
  • Because all of the exercise is eccentric, the disordered collagen fibers are disproportionately broken down.  If a new collagen fiber happens to be laid down in the proper direction (in line with the original, healthy fibers), it will not break down when exposed to additional eccentric exercise.  But if it is a coiled mess like many of the fibers in the microscope image above, it will be broken down again
  • Over time, as the eccentric load increases, more and more disordered fibers are broken down and replaced with properly-ordered fibers.  Eventually, the tendon has been repaired enough to handle a return to high-level training

Scientific evidence for the actual restructuring of the collagen fibers in the Achilles tendon is only circumstantial, probably because a tendon biopsy is the last thing on the mind of anyone who's just recovered from a multi-year bout with Achilles tendonitis.  But ultrasound imaging and studies of vascular flow in the Achilles have shown strong evidence that the mechanism by which eccentric exercise works is a fundamental rearrangement of the tendon's structure.  Additionally, microdialysis of the injured area has confirmed that eccentric exercise increases collagen synthesis.

Conclusion: treating and preventing Achilles tendonitis

Although I've broken my promise to keep this post short, I'll try to wrap things up briefly.  As you've seen, the focus on eccentric movements, progressive addition of weight, and exercising into moderate pain all contribute to the ability of eccentric heel drops to heal chronic Achilles tendonitis.  There are ancillary benefits too: the heel drops also stretch the calf muscles and strengthen the lower leg.  Obviously, a progressive rehab protocol of eccentric heel drops should be the central part of your recovery plan if you have Achilles tendonitis.  In short, the eccentric heel drop protocol is as follows:

  • 3 sets of 15 eccentric straight-knee heel drops and 3x15 bent-knee heel drops over a step or ledge, starting "up" on one leg, descending slowly, and returning to the "up" position uisng the uninjured leg.
  •  The two exercises are to be performed twice a day, every day for twelve weeks.
  • Continue the exercise even into moderate pain, but stop if the pain becomes debilitating.
  • When you are able to do all three sets without any pain, add weight using a backpack.
  • Once you have recovered, continue to do eccentric heel drops several times a week as a preventative measure.

As mentioned earlier, there are other things you can do to hasten your recovery from an Achilles injury: Stretching your shins, foam rolling your calves and shins, and applying heat to your upper calves (not the tendon itself) will loosen those muscles up and improve your ankle's range of motion.  A doctor, podiatrist, or physical therapist can get you orthotics or heel lifts, which may help your condition, and can also prescribe additional rehab exercises to improve general strength and balance.  Heat up the tendon with a heat pack or warm water bath before you run, and ice it afterwards.

If you're lucky enough to have never suffered Achilles tendonitis, you can still apply many of these same principles to prevent it.  Incorporating eccentric heel drops and calf and shin stretching & rolling into your daily or weekly routine might help prevent future problems.  Doing a moderate amount of running in low-heeled shoes like racing flats or spikes (or even running barefoot) will allow your calf and Achilles to work through their entire range of motion.  This will reduce the shock to the area at the beginning of the racing season.  Far too many runners go the entire summer without running a step in anything other than their trainers, which have a 10 or 12 mm heel-to-toe drop.  In the fall, they slip on racing spikes (which, because of the metal spikes in the forefoot, effectively have a negative heel-to-toe drop) for their first race and risk calf soreness and Achilles tendon injury due to the sudden overload on the lower leg.  Doing a few miles of barefoot running and a few strides in spikes every week will go a long ways towards preventing these sorts of injury.

Next time, we'll look at a similar eccentric rehab protocol for another common chronic injury: patellar tendonitis.

About the Author

John J Davis, PhD

I have been coaching runners and writing about training and injuries for over ten years. I've helped total novices, NXN-qualifying high schoolers, elite-field competitors at major marathons, and runners everywhere in between. I have a Ph.D. in Human Performance, and I do scientific research focused on the biomechanics of overuse injuries in runners. I published my first book, Modern Training and Physiology for Middle and Long-Distance Runners, in 2013.

65 thoughts on “Injury Series: Eccentric exercise and tendon remodeling, part I: Achilles tendonitis”

  1. In the original 1998 paper, Alfredson writes, "During the 12-week training regimen, running activity was allowed if it could be performed with only mild discomfort and no pain." Of course if you have a severe case of Achilles tendonitis it may take several weeks to get to the point where you can run without any pain. But you don't have to take 12 weeks completely off—the best advice is that running is okay once it doesn't hurt to do it.

  2. Hi John - I've been suffering from severe Achilles pain at the insertion point for over 6 years now. I've seen sports doctors, PTs, had dozens of tests, a PRP injection, surgery, name it, I've probably tried it. And nothing has worked.

    A question for you - do you think that these eccentric exercises will also work for an Achilles which is painful at the insertion point? I've read other studies which say that eccentrics ARE still beneficial for this type of pain, but a) not AS beneficial and b) only if the eccentric decent is to the horizontal plane, not below as is prescribed by your blog above. Do you have any knowledge on insertional achilles tendonitis?

    Thanks for any help that you can provide John!

  3. Hi John,

    I recently happened upon this blog entry, and what you have found and summarized so well matches my experience. My left Achilles has bothered me for over 4 years, and through the several PTs the alleged cause has been a functional leg length discrepancy with the course of treatment involving exercises to correct the length difference and different versions of the eccentric drop exercise. At first I was doing slow complete (concentric and eccentric) single-leg calf raises, up to 90 a day. And this helped, but I never returned to 100%. If I went more than a week or so without doing the calf raises at least 2-3 times a week, the tendon would act up again. Last year I injured it again after several months of a very gradual, conservative transition to running shoes with less of a heel drop--in the minimalist vein, but nothing barefoot aside from some strides now and then. This time I ended up with a red, bulging nodule on the tendon and of course plenty of pain. This time a PT recommended the eccentric drop by raising up on the leg and then dropping down quickly over the edge of the step to break up the disordered tissue and speed heeling. They were moderately painful, but I did 20 reps of this a day for a few weeks and then as recommended continued with traditional calf raises and core and other exercises to address the leg length discrepancy. And yet the Achilles problem has remained chronic. All this recommended treatment seems "old school" and counter to what you have found in your research.
    So I have been doing the treatment you summarized so well for about 10 days, although I have been able to manage doing the sets only once a day. I have been able to keep up with runs of up to 10 miles for a total about 22-25 miles per week, I have noticed improvement with the tendon, and I am optimistic. My question is this: Was there anything in your reading about introducing a strength imbalance by focusing exclusively on one leg? Last night after I finished the 3 sets my left leg was quivering with fatigue. That's a good sign of eventually strengthening, of course, but I don't want to end up making the left leg significantly stronger than the right. And yet, I can't do the same exercise with the uninjured right leg without potentially straining the left Achilles. Nor do I want to irritate the right Achilles tendon (which has always been fine) and take that time if it's not necessary. So I'm interested to see if you ran across this issue at all.

    This is a great blog you have, by the way. You summarize and translate the research well. I've already started looking at entries for the other running-related aches and pains. 🙂

  4. Hi PJL,

    Thanks for the feedback! You make a very good point about muscle imbalances. I haven't read anything about problems coming up from imbalances created in the calf muscles, but you are correct in why the scientists don't have the runners do the eccentric heel drops on both sides: going "up" on the bad leg is to be avoided at all costs. That point is also relevant for people who have Achilles tendonitis in BOTH legs!

    If you wanted to do the exercise on the right side without using the left calf muscles to get into the "up" position, what you can do is put you left foot FLAT on the NEXT step, then just use your quads to get up. Does that make sense?

    I talk about the same idea in the comments section of this article for insertional Achilles tendonitis:

    If you've only got the problems on one side, I wouldn't worry too much about doing the heel drops on both sides unless a doctor or PT is worried about a strength imbalance. But if you do want to do them on both sides, or if you are another reader who has Achilles tendonitis on BOTH sides, then you can use the next step up to get into the "up" position, placing your foot FLAT on it and using your quads instead of using your calves.

    Best of luck!

  5. Hi John,

    Thanks for this great summary of Achilles tendonitis. I've been following the Alfredson protocol with a good deal of, but not total, success. What I find after 6 weeks of the regimen is that I can now run without pain, but the next day my injured Achilles will be sore in the morning and stay that way until I do more of the heel drops.

    Any thoughts on whether this "next day" pain is acceptable within the healing process, or if I need to modify my routine to avoid it?

    Thanks again.

  6. Hi Kevin,

    That's a tough call--Generally if you are running without any pain, you aren't doing any damage to your Achilles. Soreness in the morning is a "caution" sign, usually: don't ramp up too quick, otherwise it'll be hurting WHILE you're running. If you continue to improve and your morning soreness gradually decreases, then you're probably in the clear. If not, try to find a good physical therapist who has experience working with runners; he or she might be able to identify exactly why it's hurting. Best of luck!


  7. Very excited I found your blog! Have a right Achilles tendon injury that developed while training for a 1/2 marathon. So far it is really only tender if I poke at the middle of the tendon, otherwise it is just a very mild discomfort. I can still run if I keep it under 10 km or so. I have been reading up on some other blogs about avoiding stretching as well so have not been doing much. How do you feel about stretching the night before a run? I was also thinking of progressing from my 4mm drop shoes to 0 drop. I guess I should wait until my tendon is better? Thanks!

  8. Hi Lisa,

    Be careful with an injury like that. It's often easy for something like that to flare up and get much worse. I'm not sold on stretching the Achilles in general, so unless you feel like it is really helping, I'd avoid it (you do get a stretching stimulus from the eccentric heel drops too, though). Also if I were you I'd avoid going into more minimal shoes right now--that'll just put more stress on the Achilles. Heck you might even consider going back UP to a shoe with a bit higher heel-toe drop temporarily. Best of luck!


  9. Good points. With the summer upon us, I have also switched my every day shoes to quite flat ballet flats and was wondering if that wasn't helping. Maybe I'll try switching my everyday shoes at least. I was reading what you wrote about excessive pronation...I was an orthotic wearer up until March of this year (transitioned over 3 months) and always had what I felt to be a "thicker" tendon on the right, tendency to a little metatarsalgia...I have been doing all kinds of foot strengthening exercises but had not done any gastroc/soleus strengthening. Have to say that after the set of soleus ex's my muscles were quivering! Hopefully this aspect of retraining will be part of my missing link! Thanks again!

  10. Really an awesome article and so very helpful as I am just into a bout with this Achilles thing that has lasted about 6 months. I like the scientific explanation that is thorough without being overwhelming. I am not a biomechanical scientist! But I need some details to get me where I want to be...which is back running and marathon training. So thank you!
    I had started doing the heel drops, and they seemed to be helping but did not realize the 2 x per day!! Nor the bent leg version, nor the use of the non-injured leg to return to the starting postion. I have really tight calves and all I have ever gotten from PT was stretch your calves which seemed to make everything worse (my foam roller was in the closet, not under the's out now). Until I realized that I couldn't stretch until I was somewhat warmed up. And that ice actually makes it worse. I also have very stiff ankles and fairly rigid feet. I can plantar flex really well (point my toes, I think I have this right) but I can't really dorsi flex. I actually under-pronate and everyone wants to put me in motion control shoes because obviously over-pronation causes this (and the plantar faciitis I had before this).
    Finally this makes sense!
    Anecdotally I have found that ultrasound seems to help as well...just the small handheld unit you can buy on Amazon. They aren't expensive and I wouldn't say they are a cure all, but worth a try as part of the arsenal. Every day, 15 minutes.

  11. Great article - thanks. I'm 1 yr into this injury and coming back around to eccentric exercises after trying it w/o success and then a bunch of other things (graston, a.r.t., ultrasound, RICE....) Found this blog while trying to find the most recommended way to actually do them (knee bent or not? loaded or not?). This article explains it all well, and with all the backup theory that helps - I like the 'knot in a rope' analogy, except have one question about it:

    If you think that stretching the calf could possibly make the achilles tendinosis worse (by further tightening the 'knotted'/injured portion of achilles), why is that factor not present or a concern when doing the repetitive eccentric 'heel drops'? Eccentric heel drops (at least the last 10-20 degrees of the motion) are stretching the calf and also most straining/stressing the knot/injured portion. Do you think its the static and long hold on the knotted portion when stretching vice a repetitive dynamic/kinetic movement with the heel drops that heats up and somewhat gently tugs at the 'knot'?

    Thanks again. I'm a week into this program and at this point I'm hopeful that I'll be back on the soccer pitch in a few months...!

  12. Terrific Article. OK- my story. 48yrs old, avid runner, pronator with lightly supportive shoes, had achilles issues all my life. Last year, the achilles didn't hurt much, was able to up my running (60-75mpw) and BQed in January (Yes!). They both hurt after that, but I kept running on them as long as the pain was low. While training for an uphill marathon (Mt. Lemmon) in April, where I was doing a lot of hill work, the pain got too much so I knew I had to stop. I haven't run in 3-1/2 months and cancelled my triathlons for this summer. Tried everything (stretching, rolling, chriro, ART, PT, acupuncture, sleeping in the boot, etc). I stopped the eccentric stretches as I was told those were better only after the tendon sufficiently healed. Since I'm addicted to exercise- I've been doing a lot of cycling. Much of it intense. It does seem to leave the achilles a little sore.

    After reading your article, I'll start back on a daily regiment of the eccentric heal stretches. Straight and bent knee, and continue the rolling. But- what about the cycling? any thoughs? I've always thought that it was a good idea to keep the blood flowing.

  13. Hi Morey,

    Sorry for the delay getting back to you! Sometimes things get lost in my inbox...anyhow, in general, my thoughts are that anything that doesn't hurt an injured area is OK, but if cycling hard is making your achilles sore, watch out. When rehabbing for a long time, I agree that it's good to get some blood flow to the area, but you want to avoid anything that irritates the injured spot. Maybe it's just standing up when you ride up a hill that irritates it, or something like that. But it's also possible that the tension from having your forefoot on the pedal alone is irritating the Achilles. In that case, I'd try something else, like aquajogging (as boring as that may be...)

    Best of luck!

  14. My thoughts exactly. Keeping up with riders much stronger than I was certainly hurting it. I stopped riding altogether 2 weeks ago- but still no change. Tried an easy high cadence spin on a spinning bike yesterday. still a little sore aftewards. I'm now just trying to be as easy on it as possible, short of walking with crutches. Might have to go to the crazy stuff like dry needling, prolotherapy, ugh. Swam today. didn't push off the walls. I really miss running. Plus- my dog just doesn't understand...and he's getting fat.

  15. Hi, I'm having achilles discomfort and only minor pain if any. I don't think it is serious tendonitis or tendoniosis as I have full range of motion and can dorsi/plantar flex no problem. I can even do the eccentric exercises with just my bodyweight no problem, so I'm adding weight now. I've cut down my miles by over 50%. I'm also staying on flat surfaces. I believe the cause of my injury is bad form going down steep hills throughout a speed workout. I'm doing the eccentric exercises. I am noticing some improvement, but not that much. I was running in a minimal shoe, but I was already fully transitioned. Now, I am running in a more traditional shoe. But I am going around the house barefoot half the time so my achilles isn't 'shortened' by footwear. I would like to get back to running with my regular minimal shoe. I am icing and massaging my calves to keep them loose. Do you have any advice for me?

  16. Some good questions in there. I don't functionall understand the benefit of icing, if inflammation isn't the problem- especially when blood flow is required for healing and the achilles is notorious for lack of blood flow. Secondly- is it better to walk around barefoot, as you suggested, or better to wear supportive shoes and heel lifts to take all the pressure off? I've heard it both ways. the heel lifts seem counter to doing exxentric heel drops. no?

  17. I'm in an experimental phase right now because if it was not for this article, I would be 100% clueless about my injury. About the ice, I'm just doing it whenever I feel pain/discomfort. I don't have any science to back it up, however. I am able to walk w/ no pain or discomfort in my achilles, so I'm going to do it because I don't want my achilles to shorten/tighten in footwear. (I got this idea from the 2nd comment on this article). However, when I'm running, I am not sure whether to use my traditional shoe along with heel lifts or my minimal shoe. I'll keep on posting updates about my injury.

  18. hi john--

    great blog; clear, well-written advice.

    i've been running for a little more than four decades; in nov. 2011 i felt something in my achilles, tried to run through it for a day or two and, of course, that didn't work out. i have achilles tendonitis and haven't really been able to run since then (i was doing about 40 miles/week when i got hurt). i've been to the doctor, had an mri, went to a physical therapist, stretched, wore special socks, etc., etc.

    i also did the eccentric exercises for about 12 weeks. they seemed to help but i can't use the weights on my back in any fashion. i tried a little but i have had back surgery and even a small amount of weights caused back pain.

    can these exercises be effective without adding the weight as recommended at the five, six week period? i tried adding the weights at week six before having to stop after a few days.

    after completing the 12 weeks of exercises i stopped--not for any reason other than the time period was over.

    thanks very much. this not running is driving me crazy.


  19. I read somewhere that the achilles tendon uses the gastrocnemius and soleus muscle pretty evenly. I never had pain when doing the straight leg heel drop, but felt a weird spasm feeling when I did it with the bent leg, which uses the soleus muscle. I am thinking I might not have AT or AT along with this soleus injury. Or maybe the pain has just migrated because my main concern was my achilles tendon, right until I started the bent heel drops. The achilles tendon hasn't bothered me as much as my soleus lately, so I'll see what happens when I run. Any thoughts? Thanks.

  20. "If a new collagen fiber happens to be laid down in the proper direction (in line with the original, healthy fibers), it will not break down when exposed to additional eccentric exercise."

    Does this mean I could do more than 3x15 bent/straight 2x a day? I won't go overboard with 1000, but could more be beneficial? Does running tighten the 'knots' on the new collagen fiber or just the bad tangled up one? After the eccentric exercises, is it normal to feel a little more discomfort as the collagen has been broken up? About how long does it take to repair? Thanks so much.

  21. After 4-1/2 months of no improvement, I started another therapy today. EPAT:
    3 sessions. 3 weeks. non-invasive. Seems like it just gets in there and irritates the tendon to get more blood flow. Nothing magic here. Perhaps it will help my body heal.

    I will continue with the sets of eccentric heel drops, stretching and boot. Am bringing back easy cycling and will keep you posted.

  22. Hi Bill,

    That's a toughone. You might be able to add more repeats (say 3x20 or 4x15) if you can't add weight. Perhaps you could also try using ankle weights? That way you'd still be loading up your body but it'd be below your back. With these kinds of things, it is nice to have a creative PT to work with, since he or she can think up new twists on exercises that adapt to whatever idiosyncrasy you've got.

  23. Anyonymous,

    Be careful with the exercises if your soleus is bothering you. The heel drops are designed to stress the calf muscles, so if something is messed up in there, pushing it with the exercises could be harmful. Of course, it could be soreness/irritation at the high end of the Achilles too. Have you seen a doc or PT?

    Also, with regards to adding more exercises, I have to recommend sticking to the literature-proven regimen of 2*3x15, using added weight to progress, not added repeats or sets. The goal of the eccentric heel drop program is PROGRESSIVE overload, so you don't want to stress your tendon at a level that outpaces its recovery ability--that's what caused the problem in the first place!

    The rate that the body can repair damaged tendons probably depends on a lot of factors. My hypothesis is that it's a fairly slow process, hence the several-week long program of eccentric heel drops. Every day, you strip away a little bit of damaged tendon and lay down some new collagen. Of course, the new-collagen-synthesis theory is not yet 100% proven—the evidence certainly points towards that as the reason why this rehab protocol works, but there probably needs to be more research on that. Anyhow, yes, per the research it's normal to feel a bit of discomfort during/right after the eccentric heel drops, but it should not be TOO painful.

  24. That's very interesting stuff. Best of luck! I think a lot of the future of chronic injury rehabilitation may be in external therapies (like shockwave) that progressively overload the tendon fibers in a similar way to the eccentric exercise protocols. However, there's scant research on those sorts of things, and indeed in the '80s they thought that e-stim was going to be the "big thing" for injury rehab in the future.

  25. Thank you for your reply. I don't think it is my soleus. I did some searching and I believe it is the upper part of my achilles tendon. I used to think the achilles tendon was only a few inches long. I am having less discomfort each day and I am able to run a little bit. I have been wearing heel lifts along with a shoe with more heel to toe drop. I used to be wearing my 4mm drop shoe. When do you think it is appropriate to start re-transitioning into them again? I don't want to use the heel lift and my shoe w/ a larger heel to become a crutch for me.

  26. Do you think these straight and bent leg heel drops will help with other tendons other than the Achilles? I believe that one of my superficial tendons that deal w/ plantarflextion (peroneus brevis?) is the source of my discomfort. Thanks.

  27. It's certainly possible, however, there's no scientific evidence for it. I also worry that a full body weight eccentric heel drop might be too much strain for a smaller tendon. Remember, the Achilles is one of the biggest and strongest tendons in your body. The smaller tendons in the foot and ankle are much smaller. Anecdotally, I've had luck with doing more rudimentary stuff like ankle circles, but I'd really recommend seeing a good PT who knows some more specialized exercises. Some day, if I go into research, I'd like to work on devising additional eccentric exercises for other injured areas too. Best of luck!

  28. my gym has a seated leg press machine that allows me to load up the weight and hang my heels over the edge of the platform. no load on the back- just legs. Seems to be good for increasing weight and providing a stable and controlled loading.

  29. John,
    have you researched or discovered any correlation with nutritional or hormonal deficiencies? or- I have an avid runner friend who is plagued with hamstring issues. His doctor gave him a blood test that revealed a very low testosterone level. Interesting. I'm a pescatarian (veggie, ovo-lacto, fish). I eat what I think is an excellent diet- but I could be missing something. Correlations?

  30. John
    I just wanted to say how much I have enjoyed reading through your blog articles over the past few days. Of particular note is how well you have managed to translate potentially biomechanical specific mumbo jumbo and broken it down to be understood by the general public.

    Thank you for sharing your expertise. Your blog posts are very much appreciated 🙂

  31. Update- after 6 months of no running. It has been 11 weeks since my EPAT treatments and 4 weeks post Prolotherapy injections. Started running again lightly 7 weeks ago slowly building. Up to over 20miles this week. Achilles still sore/tender, but much better than 2 months ago. No longer walking with a limp or feeling much pain in the mornings. Still hurts when running but only after 3-5 miles and not severely. Boston is 19 weeks away and I plan on being there. 😉 Feeling hopeful at continued recovery and will do another round of Prolotherapy next week perhaps.

  32. Oh- My sports med/prolotherapy doc suggested I take Vitamin C, as much as my GI tract can handle, up to a few grams a day. He noted that Vitamin C helps your body build collagen. I've only been doing 1000mg.

  33. Great Article. Thanks very much. I have just one question. You mention that using a heat pack on the calf (not the tendon) is beneficial. I understand the intention of this (to loosen the calf) which makes sense but I am wondering if heat applied to the tendon may actually be beneficial in that it could increase blood flow to the area and so help to speed up recovery? What d you think?

  34. The reason I'm hesitant to recommend heat applied directly to an injured area is because it can increase inflammation. This study:

    on ankle sprains (granted, an acute injury with a lot of inflammation) found that soaking a sprained ankle in hot water will lead to a 25% increase in ankle size (presumably because of swelling) a day later whereas soaking in cold water leads to only a 3% increase in ankle volume. As this article discusses, inflammation is not so much the main culprit, but it certainly plays a role in the initial injury process. Without any studies on the actual effects of heat on inflammation in the tendon, it's hard to say for sure, but in the case of heat it's best to be conservative. Icing something is not likely to cause any harm, but heating certainly can (as illustrated in the ankle sprain example).

    On the flip side, you are correct—heat does increase blood flow to an area. When returning from a tendon injury, I've found that applying heat for 10-20min before I go for a run helps loosen the area up and prevent it from feeling stiff at the beginning of the run.

    There's also the interesting topic of contrast baths, which involve alternating between hot and cold water in an attempt to "pump" body fluids in and out of an injured area. There isn't enough good research on that therapy to recommend it yet, but it's an interesting idea at the very least.

    Thanks for the comment!

  35. Thanks for writing this article, very informative and interesting. To do the exercises twice a day, I would have to wake up early in the morning to do the first set. Would I need to do a warm up before doing the exercises? And would I need to ice afterwards?

  36. A great article, thankyou. I've just started (a week into) eccentric exercises and am finding a definite improvement in mobility. The nodes behind my achilles have also diminished. In saying that, I have to wear my brooks running shoes all the time. It seems any other shoe (flat shoe) causes a significant ache, sharp pain in my lower calf muscle.. I thought about heel cups but after reading about them, they don't seem convincing.

    Thanks again for being so informative

  37. I forgot to mention that my physio suggested that I stretch before and after the eccentric exercises. After reading your article on stretching and the knot theory, I'm not too sure now..your piece on collagen makes sense. Like I said, the nodes have pretty much gone but I find I have to walk pretty slow, and right now the lower calf and tendon is sore when I walk to the point where I have to limp as to not put additional weight on the achilles/calf muscle..I just want to do the right thing. cheers Liza

  38. Great article John. Throughout the past years I have spent an incredibly amount of time looking for achilles tendon information and this is one of the best sources I've found. I have tried the eccentric exercises and they did help, although I was in my last season of cross country and I was definately running through the injury because I wanted to finish on a good note. I have now had almost a year off of training and I am beginning a 12 week eccentric program. After 2 weeks, my achilles continues to hurt in the morning and for the first couple sets of the straight leg exercise, but it seems to warm-up as I do the exercises and by the end it rarely hurts much at all. Is this normal? Also, though it is small, I have a nodule on my achilles (classic sign of chronic tendonosis). Will the eccentric exercises actually help diminish this small lump or will my achilles always be a little deformed without surgery? I went to doctor Dr. Robert Johnson at Tria in Minneapolis when I was sitting out track last spring and he said that with time these things do has been about 8 months. I have cross trained a little bit, but as time has gone on, I have been doing a lot less. Is there a point at which surgery is a necessity? It is hard to be patient...I'm 24 and would love to be competitive again before I'm too old to run another PR. On another note, I have learned some about treatments for the achilles. For me, Prolotherapy did not fact I'm convinced that it set me back (possibly back about 4-5 months in the healing process). Myopulse and Electro-acuscope therapy seemed to have promising results for me, however, I think that you need to be able to dedicate a lot of time to consistently treating with these twice a day...if you want real results. But my advice to anyone considering Prolotherapy, don't think of it as something that "can't hurt, might help" it has the potential to really set you back.

  39. Hi Tom,

    While I'm not sure whether soreness/tightness before or during the exercises is supposed to happen, it's certainly something I've received a lot of comments about because of this article. A lot of people find that the eccentric exercises do irritate their Achilles somewhat; unfortunately the scientific articles (though they do say it's okay for it to hurt DURING the exercise) don't really say whether that sort of tightness and stiffness is normal. As far as bumps on the Achilles, they are not discussed specifically in the literature, but I do know a friend of mine who had a pretty large marble-sized bump on his Achilles which did eventually go away.

    It's very hard to make a call on when to have surgery. That's something I went through with my hip last year. Something to think about would be to TALK to a doctor about it now, just to discuss your options and expectations, but stick with the eccentric program until you've seen it through. Even if you decided to have surgery today, you'd probably have to wait for several weeks at least to actually get in and have it because of scheduling stuff. The best advice I can give for now is to really stick with the eccentric program, doing the 3x15 sets with both the straight knee and bent knee twice every single day, and adding weight as they become easier/less painful. The encouraging part is that in the original studies, there were some people who had chronic Achilles tendonosis for many months (sometimes years) who benefited significantly from the program.

    I recently found some good new papers on emerging treatments in tendon injuries, and was thinking about doing a revision or update to this article. As you pointed out, there are a lot of new treatments which don't really have much evidence and don't seem to work well, though there are a few which /may/ show some promise, like extracorporeal shockwave therapy or a topical medication called glyceryl trinitrate. You might have a hard time even finding a doctor to ask about these upcoming treatments, which is tough too—you don't want some guy who's looking to make a quick buck by doing the latest experimental treatment with no forethought or caution.

  40. That is a very nice write-up! I wish all blogger would come up with such informative post like this one. Tendons or sinew really plays an important role in a human body. It’s the one that connects bones and muscles. Exercising alone is not advisable. It’s vital to ask a physician since they are the one who can provide the needs of a person: nutrition and proper training.

  41. My god, THANK YOU for critically engaging with existing evidence in a way no GP, sports med or physio I've encountered seems to have bothered with, and for offering an easy-to-understand explanation of how eccentric exercise might work.

    Got anything on peroneal tendinopathies? I haven't been able to find anything.. (Though neither I nor the various providers I've seen is 100% confident that's what I've got, after various inconclusive scans, but then, who cares, it's only an ankle. I've been told that theoretically, it's possible to figure this out with an ultrasound diagnosis, but am seeing cluelessness around this too.)

  42. Thank you for the fantastic information John.

    I am a Podiatrist as well as an avid runner who experiences bouts of AT. I agree with 99% of what has been discussed. Like many of you, I too have struggled to successfully treat my Achilles tendonitis/osis. I blame the initial cause of my AT from a training error of too much, too soon, and too hard. So I stopped running and I was wearing a Z-coil shoe for several months during my bout with AT. Initially, it helped relieve the pain in the mid-substance of the Achilles. After 3-4 months or wearing this shoe, I realized that it was actually hurting my recovery for the exact reason that has been mentioned previously, and that is that my Achilles tendon was healing in a shortened position. What I believe got me 80% better (I still have to work at foam rolling every day) is cross-training (exercise bike- made the Achilles a little sore, swimming- sore when kicking off the wall and even with freestyle kicking), I also began wearing a minimalistic running shoe, which I believe really helped gain length and flexibility back to my Achilles. Although I am much better than I was 2 years ago I still have occasions when it tightens up. I have just realized I have to incorporate a daily ritual of stretching, foam rolling, stick, running compression socks, and cross training in order to maintain the active lifestyle that I want. Do these acute Achilles tendon injuries that turn chronic ever truly become 100% better? As much as I would like to believe that they do, I wonder if they may become 80-90% at best and occasional flare-ups down the road are to be expected.

  43. That's a very good point. While these eccentric exercises and other therapies for chronic tendinopathies can do a world of good, it may be that you can't get back to 100% if you've had a bad case for a very long time. I've still got scars on my skin from scrapes and cuts I got years ago, and maybe something similar happens in the tendons. While you might have to pay extra attention to your Achilles even after you've "recovered," the good news is that the eccentric training protocols have been demonstrated to help even in people with extremely long-lasting cases of tendon problems. I'm always encouraged by the individual in Alfredson's study who had Achilles tendonitis for eight years, but was able to return to athletic activity after the rehab protocol.

  44. John, Great blog! I had what I think was a "calf heartattack" over 4 years ago and it became chronic and eventually turned into both calf and achilles tenodonitis. I spent almost an entire year resting and stretching without improvement. I started doing the eccentric calf drops about a month ago and have built up to 60 pounds of extra weight. I have pain in my calves right below the Gastronemeus but nothing in the achilles. I have recently started doing some light running and between a quarter and a half mile I start to feel pain in my achilles but nothing in my calf. If I do the heel drops after I run then I feel pain in both the calf and achilles. I am not sure where to go from here and if this technique is hurting or helping.

  45. This article provides the best advice and exercise regime I have found or been given for an Achilles injury
    After really struggling with an Achilles injury for six months I have stuck rigidly to the exercise regime and found my Achilles injury to have improved way beyond what I thought would be possible.

    If I could give any advice for Achilles injuries it would be.

    1. Stop Running as soon as you get any problems or tweaks on the Achilles tendon. In my experience trying to keep going can really end up giving you major problems, better a few weeks out than months of continuing problems.

    2. Ice as much as you possibly can. Make it as cold as you can stand it and for as long as you can stand it. I use a mop bucket filled with cold water and ice. Immersing my foot and ankle into the torture chamber, sorry mop bucket until I can no longer stand it.

    3. If you can manage it use a foam exercise roller on your calf muscles and Achilles tendon there is plenty information on line. Ive started using a stone rolling pin on the Achilles which along with the recommended exercises helps remove the thickening of the tendon.

    4. Try to keep exercising in some shape or form theres plenty of info on line. I bought the following exercise bike which I would thoroughly recommend for price, build, and the simple info screen "Ultrasport Exercise Bike F-Bike" £79 @ amazon an absolute bargain for the price.

    4. Do the exercises recommended on this page as many times as possible.

    5. Be extremely disciplined in your approach and Im sure you will see the benefits.

  46. My injury is not from running, but from walking on a treadmill. It is a pretty old treadmill too. I am sure it stems from my uneven legs. The tibia and fibula in my right leg are noticably longer than in my left. This causes an uneven gait and causes pain in my right knee (aggrivates an old injury - ruptured bursae) and causes the tendonitis in my left leg. I walk on a treadmill to get back into shape and lose weight. So far it's been working really well for me, I've lost around 20lbs in under 8 weeks. That is coupled with some weight training and core toner exercises as well as changing the way I eat - what I eat and how much. I have now gotten to doing 1.5 hours on the treadmill twice a day. I don't want to stop, but don't want to aggrivate the injuries. I did fasion my own heel lift type of thing by shaving down an insert from an old pair of shoes and putting it under the insert in my left shoe. It doesn't bring my knees to even, but it does seem to help. The tightness returned because that pair of shoes was wet from having been worn doing some outside work, so I wore a pair of sneakers. The other shoes are high tops.

  47. Have been suffering from AT since the past two years. Am fifty years old and was very active with running,playing squash and hiking. Can barely walk over twenty minutes without pain and have a nodule mid Achilles on both sides. Is age a big factor for a woman for recovery. Going to start eccentric calf drops.

  48. Thanks for your post John. I think its finally convinced me to be a grown up and do a disciplined program for my achilles pain rather than just pushing through the pain and doing a few heel raises once or twice a week. Now I need to sit down and work out a plan for my cardio for the next few months in the absence of running!

  49. Anon- if you're still around here. The doc I've got that does Prolotherapy on me told me that his treatments seem to work best on those who have developed a nodule on the tendon. Guess the injection helps break up that scar tissue.

  50. Hello John,

    I have recently (as of 7/18/2013) been diagnosed with Achilles Tendonitis. I also have slight Plantar Faciitis in the same foot. After I performed one set with a straight leg I felt pain in my calf and there was a burning sensation that went along with it. Should I continue to do the eccentric drop of should I wait longer? Also, typically how long does it take before you don't feel anymore pain?

    Thanks much!


  51. Bent knee heal drop completely changed my achilles. After one day...achilles hurt...after two days...achilles hurt like hell...after three hurt even more. I did one more day...and then backed off thinking I'd totally screwed up my achilles. Guess what after few days of rest and ice. Significant increase in ROM in achilles...pain gone......morning achilles pain gone...running achilles pain gone.

    So....don't get too freaked if the pain increases from doing the eccentric heel drop....remodeling may result in some sensation.

    Now I just do the heel drops every other day as a preventive exercise. Achilles issues have not returned.

    That's how it went for me.

  52. Just wanted to add my anecdote to encourage people who are dealing with this. My achilles recently began to hurt like hell, and fortunately I stopped all exercise and didn't try to push through it till I figured out what was going on.

    Found out that it was probably achilles tendinosis, and after doing tons of research on the internet, I read about eccentric exercises where you do these heel drops even if its painful to do. Since this treatment seemed to be endorsed by many different reliable sources, I started doing it. The first day I had to quit after just one set, it just hurt too much to go on. The second day I was able to get through all the sets. I didn't see much improvement for a while, but after about 6 days I could tell it began to feel better. Its now about 2 weeks, I'm not fully recovered yet, but I've gotten to the point where I now have to add weight according to the protocol. Its still slightly uncomfortable but now a lot better.

    These results (doing this well after only 2 weeks) might be quicker than most cases, since I probably only had a minor injury and stopped stressing my achilles at the first sign of pain, so I probably didn't have as much damage to repair, but this definitely worked for me.

  53. Hi John,
    I am 70 years old .I suffer for about 2 months from Achilles tendon partial rupture (MRI diagnos).
    Do you recommend eccentric exercises ? and/or Shockwaves therapy? Last 2 weeks I feel much better with only cooling ice .

    Thank you for the wonderfull work.
    Edna Zamonski.

  54. You may want to look into the effects of statin medications. In my own experience, I continued to have significant problems with my Achilles despite having undergone the eccentric heel drop. As a result, I had PRP/fat injections done. During this time the regenerative medicine physician who was treating me suffered from a similar Achilles injury. Although not evidence-based, he went through his patients and found that most of running patients (including himself) who presented with unresolved Achilles problems were also on a statin medication. After searching the medical literature, both he and I (in conjunction with our primary care provider's approval) reached the conclusion to stop taking the statin medication. Finally my Achilles has improved.

  55. Hi. I've been doing heel drops for a few days and only recently (2 days ago) introduced bent knee drops to straight leg drops. I've added 5kg's because I hardly feel anything while I do them. It's not painful when I do them but it hurts during the day. It's not unbearable but it's irritated and sensitive until I do the evening session.
    I've entered the Paris marathon in April 2014 and I'll be devastated if I'm not healed by then 🙁

    * Just a few questions:
    1. can I ice during the day?
    2. Is it normal to experience pain during the day?
    3. Is there any other leg cardio exercise I can do that wont be harmful? I.e. walking and gym apparatus.
    4. Is it advisable to include shockwave therapy once a week?

    Please help.

  56. Good article. Similar to what my physio said and, for me, the general advice works.
    I have some questions on the precise nature of the technique. Your pictures from the side give a good idea of the movement. However
    1. Looking down when bending the knee, should the knee be bent as far as possible forwards obscuring the view of the big toe?
    2. Again looking down. what if the knee comes in (ie right leg moves to the left). That is probably ITB weakness but should the correct form (that the knee should bend and move forwards) be followed
    3. Exactly what part of the foot is left on the step? ball of foot or does the ball hang over slightly?
    4. When raising a straightened leg, how far up should you go? Going up so that the foot goes 'over the ball' to maximum physical extension makes the exercise considerably more difficult.
    5. when raising a straightened leg, the movement on the foot tends to be up and OUT following where the smaller toes point ie moving from the knuckles of the smaller toes. Should correct form be to try to go straight forwards over the big toe using the 'knuckle' of the big toe as the main pivot?

    I guess some of these questions and points might not matter. However some of these (probably incorrect) micro movements might be partly symptomatic of why the biomechanics caused the problem in the first place (pronation, collapsed arch, etc). So, surely, doing the exercise 'wrongly' might be reinforcing one or more of the causative factors?

  57. Thank you for the great article John! My issue is posterior tib tendonosis, I have been doing the flat heel drop for several weeks without results. Should I try the drop heel exercises? Best explanation of tendonosis that I've seen, thanks, Terri

  58. Hello John,

    I am an avid runner for 10 years now. During peak season, I run on avg 8 miles a day. Long runs on weekend of 15 miles at most. I first came down with insertional Achilles tendonpathy last year. Nieve at the time, I ened up running through it, which ultimately gave me a really bad case of the point where I couldnt even walk to work. AT the time, I pursues a couple of recovery options and didnt start anything until the swelling and pain went down. I was off my feet for a good month and no running for another 2 months. I started the alfredson protocol and dint finish, since my orthopedic surgeon did not believe in it and recommended I just start back up running again gradually. Thats what I did, for 3 months. I endded up competing in IronMna Maryland and ran the marathon virtually pain free. All this being said, I did not take any time off after IM Maryland and contuned running 8 miles aday, etc About 2 months ago after running, I started to fee a slight pain in my achilles again, nothing close to when I initially had the issues last year, but I became a little concenred, as I did not want it to come back again. I am now going back to the Alfredson in hopes that this will squash it for good. I am at 50 days now. I do not have any sharp pain, but I feel aching around my heel and sometimes a few inches up ont he achilles. is this normal? Also, when I sit at the computer, I feel a very minor vibration in the tendon...almost like a shockwave is going up this the tendon healing?


    BTW There are many articles on this subject around, but yours is the best.

  59. Hello John,

    I am an avid runner for 10 years now. During peak season, I run on avg 8 miles a day. Long runs on weekend of 15 miles at most. I first came down with insertional Achilles tendonpathy last year. Nieve at the time, I ened up running through it, which ultimately gave me a really bad case of the point where I couldnt even walk to work. AT the time, I pursues a couple of recovery options and didnt start anything until the swelling and pain went down. I was off my feet for a good month and no running for another 2 months. I started the alfredson protocol and dint finish, since my orthopedic surgeon did not believe in it and recommended I just start back up running again gradually. Thats what I did, for 3 months. I endded up competing in IronMna Maryland and ran the marathon virtually pain free. All this being said, I did not take any time off after IM Maryland and contuned running 8 miles aday, etc About 2 months ago after running, I started to fee a slight pain in my achilles again, nothing close to when I initially had the issues last year, but I became a little concenred, as I did not want it to come back again. I am now going back to the Alfredson in hopes that this will squash it for good. I am at 50 days now. I do not have any sharp pain, but I feel aching around my heel and sometimes a few inches up ont he achilles. is this normal? Also, when I sit at the computer, I feel a very minor vibration in the tendon...almost like a shockwave is going up this the tendon healing?


    BTW There are many articles on this subject around, but yours is the best.


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