Achilles Tendonitis: A Common Runners Injury Explained

Before I get started just a disclaimer, if you do think you are suffering from Achilles Tendonitis, it is best to get it checked out by your local physician.

Every Runner Knows Achilles Tendonitis

Achilles tendonitis. Everyone has heard of it. And runners are even more familiar with it. In 2019 Largas et al, found 1/20 runners suffered from Achilles tendonitis.[1].

It starts just soreness at the beginning of your run and progresses to lasting your whole run, eventually affecting your everyday life.

With this write-up I want you to understand what causes Achilles tendonitis, and the two different types.

I genuinely believe the best way to treat an injury is to understand what the condition is.

The Definition of Achilles Tendonitis

So what is Achilles tendonitis?

Ask Mayo Clinic, and they say (Check that out, they even sounded it out for you):

Achilles tendinitis is an overuse injury of the Achilles (uh-KILL-eez) tendon, the band of tissue that connects calf muscles at the back of the lower leg to your heel bone.

This definition is pretty basic and just scratches the surface, but it does the job for now.

When you start to peel back Achilles tendinitis's layers, you will begin to understand the complexities of the injury and will better understand how to:

1. Treat it
2. Prevent it

Basic Anatomy of Achilles Tendonitis

So to get started, I need you to understand some basic anatomy of the calf.

In the back of the leg, you have two muscles, the soleus, and the gastroc. In the medical world, the "tricep surae." They are two separate muscles starting in the back of the knee. They run down the back of the leg, and they both combine, forming the Achilles tendon that attaches to the heel of the foot.

When the calf contracts, it points your foot down, propelling you forward when you run.

The Types of Achilles Tendonitis

Okay, so back to the injury itself...

Believe it or not, there are two distinct subgroups of Achilles tendonitis. It is essential to recognize this because you will need to treat each subgroup separately (Don't worry, I'll get into that later).

The two different types are based on where on the Achilles tendon the pain is located.

1. Mid-Portion

• Isolated pain at the mid portion of the Achilles about 2-6 cm up from the heel bone

     2.Insertional

• Pain located at the base of the heel

Causes of Achilles Tendonitis

So both types of Achilles tendonitis are overuse injuries, right?

Well, kind of.

Cause of Mid-Portion Achilles Tendonitis

Non-insertional tendonitis (or mid-portion achilles tendonitis) is, in fact, indeed an overuse injury.

What exactly is an overuse injury?

In short, the tendon is being overworked. This can be for two reasons:

1. The tendon is too weak to withstand the forces you are putting through it
2. You are putting too much stress on the tendon

Have you ever felt muscle soreness the day after a long run? It's completely normal, your muscles are breaking down (this is the pain you feel), and building back stronger. This process usually peaks at around 48 hours and lasts 72-96 hours.

Just like your muscles grow back stronger after a good workout, so do your tendons. The only thing is our tendons can get stuck in a constant "rebuilding" phase.

Let's say you've spent your whole life off and on running. Finally, you decide it's time to train for a marathon. You have your training plan, new shoes, workout watch, and you are ready to run. You go for a good run after good run.

These runs constantly stress the Achilles tendon to where it is trying to rebuild itself stronger.

The only problem is you're stressing the tendon too much. As it is rebuilding, you're stacking another tough run on top of it. The tendon is in a constant state of rebuilding mode, except it never finished rebuilding in the first place.

It's like that saying, "one step forward, two steps back."

The body is smart. Your Achilles tendon realizes it can not rebuild itself fast enough. So it goes through a process called neovascularization (AKA growing blood vessels that aren't usually there).

Great! Problem solved, increased blood vessels mean increased blood flow, increased blood flow means increased nutrients, and nutrients mean healing.

WRONG.

Where there are blood vessels, there are nerves. So now, newly formed nerves begin sending pain signals to your brain.

At this time, runners usually start to notice something is wrong but will most likely continue to run through the pain.

About two weeks later, the swelling starts to form.

The other thing new blood vessels bring is increased fluid to the area, AKA swelling or that little nodule typical in many cases of non-insertional Achilles tendonitis.

BOOM, thats it, that is how non-insertional Achilles tendonitis forms.

Treatment for Mid-Portion Achilles Tendonitis

Now that process will continue until you do something about it, and you have some options (I recommend a combination of all of them).

1. Strengthening. As I mentioned, the tendon responds to strength-building exercises by rebuilding stronger. A strong tendon can handle more force which means the Achilles is less breakdown from the stress of running. You can snag my exercise program specifically designed for runners here.
2. Adjust your training volume. The nature of non-insertional Achilles tendonitis is cyclical. You need to break up the cycle and adjust your running volume. I recommend patients leave their training the same for two weeks. If symptoms do not improve, we start looking into cross-training.
3. Eccentric exercises. So a funny story here. Once, a researcher was so sick of his Achilles tendonitis that he decided he was just going to rupture it. So he started doing eccentric calf raises off the edge of a step. He was pleasantly surprised when his Achilles tendonitis went away. This same protocol has shown to be up to 90% effective in those with non-insertional Achilles tendonitis.
4. Extracorporeal shockwave therapy. This is a newer treatment, it has a big intimidating name. But basically, it works to signal healing cells to the Achilles to promote healing. You can google "extracorporeal shockwave therapy" to find more info.
5. Deep friction massage. Deep friction massage has been advocated for tendinopathies. Friction increases the output of tendon cells helping to promote healing. I suggest YouTubing "deep friction massage Achilles tendonitis." You can do it by yourself.

Cause of Insertional Achilles Tendonitis

Sooo now we get to the big bad wolf, insertional Achilles tendonitis. This one is trickier because it's commonly thought to be an overuse injury, and people are not wrong to believe that, but there is a little more to it.

Let me put you through the same scenario with some minor twists. Once again, you are gungho about your new goal to run a marathon.

You are a heel striker, always have been, always will be. It's what feels comfortable to you.

Because you are a heel striker, you put tensile stress through the Achilles tendon every stride. Your body reacts to this by growing more bone on your heel, commonly known as a heel spur. You don't notice your newly formed spur, though, because it doesn't hurt.

Two weeks down the road, you notice you are starting to have some pain where your Achilles meets your heel. You also notice the bump there.

You still keep running because the pain isn't bad enough to stop, and hell, you've already signed up for your marathon and started telling friends about it.

Your heel spur continues to grow.

Throughout our bodies, we have bursae. I'm sure you have heard of them. Their purpose is to lessen muscle friction in places that otherwise cause fraying. You have two bursae to prevent fraying of the Achilles tendon, the retrocalcaneal bursa, and the subcutaneous calcaneal bursa.

Because your heel spur is growing, it changes the angle your Achilles is pulled when you heel strike. As a result, the Achilles presses harder on the bursae.

The bursae don't like this and become inflamed signaling pain.

With your now inflamed bursae, your pain has begun to ramp up. You start to have pain whenever you put on a pair of shoes.

And there you have it. Insertional Achilles Tendonitis.

Treatment of Insertional Achilles Tendonitis

With insertional Achilles tendonitis, your once overuse injury (growing of the bone spur) becomes an impingement injury (the Achilles pinching on the bursae).

Unlike the mid-portion Achilles tendonitis, you can't just attack insertional tendonitis with eccentric strengthening. It doesn't make sense. You will just be aggravating the bursae. The literature backs this up as well. It has proven eccentric strengthening is only 30% effective.

So the first step is to calm down the bursa. A few strategies you can try:

1. Try to become a forefoot runner.
2. Don't wear shoes that cause pain.
3. Avoid uphill walking and running

After we have bursitis calmed down now, you can start to strengthen. Once again, unlike the mid-portion Achilles tendonitis, you can't just put your head down and hammer out a bunch of eccentric calf raises. Do this, and you'll likely find yourself with once again inflamed bursae.

The strengthening needs to be more precise. This is too much for us to cover here for another article, but a general rule of thumb is to stay pain-free by limiting your motion.

Summary:

There are two different types of Achilles tendonitis, insertional and mid-portion. Mid-portion eccentrics exercises are excellent (my program here), and insertional treatment is a little more nuanced (my program here).

Like I said, if you are suffering from an Achilles injury, please do yourself a favor and get it checked out by a local physician.

Anyways hope you enjoyed!