The Achilles Heel of Runners

Runners focus on counting miles, better times, and improving endurance… but there is an essential component of performance and injury prevention that many neglect – tendon health! The Achilles tendon is a band of tissue that connects the calf muscles to your heel, and it plays a critical role in impact absorption, energy storage, and force production. But, unfortunately, Achilles tendon pain and injuries are very common in runners.

If you’ve ever felt discomfort, stiffness, or Achilles tendon pain – you are not alone. Research suggests that up to 22% of recreational runners experience Achilles tendon pain. Once it develops, it can be very frustrating and persistent. But we have good news – the research shows that intelligent resistance training can help reduce pain, build strength, and reduce injury risk, all while improving performance.

We are going to discuss why tendon specific training is essential for runners, and what the research suggests for incorporating these strategies into your routine.

Why Is the Achilles Tendon So Important?

Even though it is the strongest and largest tendon in the human body, the Achilles tendon is not indestructible. Every step you take places a tremendous force through your Achilles tendon – six times your bodyweight! That’s a ton of accumulative load considering how many steps you take during a single run. 

An easy way to conceptualize the function of the Achilles tendon is comparing it to a spring. It stretches to store energy and contracts to release it. In the case of the Achilles, this function helps to propel you forward while running. The more elastic the spring is, the healthier and more efficient your stride will be. Even though it’s extremely strong, we need to be careful to not overtrain it with excessive training volume and poor load management. If you are experiencing Achilles tendon pain, odds are you need to strengthen your Achilles. 

Another challenge when it comes to Achilles tendon pain and injuries is that it has a poor blood supply, meaning that it will heal relatively slowly. This is why prevention is key and these strategies should be a priority for every runner.  

Tendons Adapt to Loading

The research is very clear – tendons require consistent and progressive load to adapt. However, unlike muscles, it takes a long time for them to adapt. The research shows that in order to induce meaningful changes in tendon strength and stiffness, your program needs to include high loads and must be followed for at least 12 weeks. This is important to take into account when considering a time frame for your Achilles tendon pain and how you will adjust your programming. 

Not all forms of loading yield the same tendon adaptations. There are some key differences when considering different training styles and how tendons will respond. First, let’s discuss a few different kinds of exercises that are beneficial pertaining to tendon training – specifically for Achilles tendon pain and dysfunction; isometrics, plyometrics, and eccentrics. 

Isometric exercises don’t require any movement. You are applying tension with a fixed joint position. Some examples are holding a weight without moving it or trying to push something that is immovable – either way there is no actual movement occurring. Isometric exercises will contribute to increases in tendon stiffness which will make the tendon more stable under load. Because isometrics don’t require any movement they are also extremely safe. And they even have a pain relieving effect! 

Next we will discuss plyometric exercises – jumping. Whether it be light hopping or jumping off of high platforms, plyometric exercises are a key element to any Achilles tendon pain program. Running is basically thousands of mini plyometrics! These exercises contribute to the tendon’s elasticity – its efficiency with energy storage and release.

Finally, eccentric exercises are extremely beneficial because of their ability to drive damage repair and tendon remodeling (making the tendon stronger). The eccentric phase of an exercise is the lowering part of the motion. With a heel raise, it’s the portion of the movement when you are slowly lowering your heel towards the ground. 

When the goal is to build strong and resilient Achilles tendons, or recover from Achilles tendon pain, all three of these exercises should be part of your program. 

Load Management Is Key

Before we jump into some examples for each type of exercise and how to program them for Achilles tendon pain, we need to talk about something a lot of runners take for granted – rest!  As we spoke about before, tendons are very slow to adapt, meaning introducing too much load too quickly raises our risk of injury. It is vital that we increase our training volume and intensity gradually. This is absolutely essential for preventing overuse injuries.

And what about runners who are recovering from Achilles tendon pain or injuries? The research supports the same strategies – high load resistance training – as an extremely effective intervention. But as you can imagine, when dealing with injuries (acute or chronic) it is important to listen to your body and even more important to avoid overtraining. So once again – load management is key! 

How to Train Your Achilles Tendon

Isometrics 

Because of their safety and pain relieving properties, isometrics are especially  beneficial for runners who currently experience Achilles tendon pain or early stages of Achilles tendinopathy. 

Exercise example: Calf Raise Hold

• Stand on one leg and lift your heel up as high as you can
• Hold this position for 30 seconds to 1 minute
• Perform 3-4 sets per leg 
• Progression: Hold a weight or something heavy 
• Regression: Do both legs at the same time  

If you are currently dealing with Achilles tendon pain and the end range of a heel raise hurts, find a range where your pain is manageable. 

Eccentrics

Eccentrics are extremely effective for rehabilitating Achilles tendon pain and tendinopathy while preventing future injuries. 

Exercise example: Eccentric Heel Raises 

• Stand on the edge of a step with your heels hanging off the edge
• Push up onto your toes with two feet
• Pick up one of your feet and slowly lower one heel (3-5 seconds) 
• Repeat for 3 sets of 12 repetitions per leg 
• Perform these barefoot if you want to improve your foot strength as well!

Plyometrics

Exercise example: Double leg pogo hops

• Stand with your feet shoulder width apart 
• Keep your knees slightly bent while you hop up and down 
• Focus on quiet and quick ground contact 
• Do this for 3 sets of 20-30 seconds
• If you’re new to plyometrics or you are currently in the acute stage of Achilles tendon pain or injury, start with smaller hops and slowly build up the volume and intensity. If you are more advanced, try them on one leg! 

Some considerations and common mistakes

Now that we have gone over example exercises that will help with Achilles tendon pain, let’s discuss frequency and some common mistakes. The research suggests that we should be loading our Achilles tendons 2-3 times per week. There are many different ways to organize your training. You can do a smaller amount of each loading type in one workout, or have specific days for each specific loading type. A frequency of 2-3 times per week allows for adequate recovery time for your tendons and the muscles that attach to.

New runners aren’t the only ones prone to making mistakes. When it comes to training for Achilles tendon pain and injury, it can be tricky to get it right. The first mistake many runners make is choosing bodyweight exercises over heavy loading. After the initial adaptations from starting an Achilles training program take place, body weight calf raises are not enough. Especially if you are an advanced runner, it is important to use strategies to add additional resistance. Looking at the research, we see that tendons need high resistance activities (>70% 1RM) to force adaptation. 

Another common mistake runners make is doing too much plyometric work while neglecting strength. As we discussed, plyometrics are very important for increasing tendon elasticity, but tendon strength (how much force a tendon can handle before it tears) is just as important. An unbalanced amount of plyometric work can lead to microtrauma instead of adaptation.

Manage Training Load to Prevent Overuse

As we spoke about earlier it is important to give your body time to adapt. Increasing mileage or intensity too fast or too soon is one of the most common triggers for Achilles tendon pain and injury. This is why following a well structured progression scheme is key. Here are a few tips we recommend following to ensure you aren’t making this mistake. 

The 10% rule: don’t increase your weekly mileage or intensity by more than 10%. The purpose of this rule is to ensure that you are not increasing your running volume more quickly than your body can adapt. While the research shows that this rule is overly conservative, it can be a good reference to make sure you are not pushing too hard while you learn what your body is able to tolerate. Monitor how you feel with increases in weekly mileage and use that to dictate your progression scheme. If you are currently experiencing Achilles tendon pain, a great strategy you can use is cross-training. Cross training is utilizing different modes of physical activities that mimic an athlete’s main sport. For runners, cross training examples may be cycling, swimming, or rowing. We can use this to reduce the stress on your tendons while still maintaining or even improving your fitness. When performing these other activities, train a similar number of times per week and at a similar intensity to maximize the carryover to running.

Summary

A robust and resilient Achilles tendon separates runners who progress pain-free from those who deal with nagging injuries and setbacks. If you take one thing away from this blog, it is the importance of not relying solely on running. Your tendons love being loaded and they require consistent training over 12+ weeks to adapt.  If you’re serious about running long term and pain-free, then be serious about your Achilles tendon training. It’s non-negotiable! 

When to Seek Professional Guidance

If you are currently dealing with nagging Achilles tendon pain or chronic stiffness it may be worth consulting a physical therapist. 

At Perfect Stride PT, we specialize in helping runners recover faster and perform better. If you’re struggling with Achilles tendon pain, we can provide hands on treatment, gait analysis, and personalized tendon training plans to help you run pain-free.

Call us at (917) 494-4284 to start your recovery journey today!

References

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Fokkema, Tryntsje, et al. “Prognosis and Prognostic Factors of Running-Related Injuries in Novice Runners: A Prospective Cohort Study.” Journal of Science and Medicine in Sport, vol. 22, no. 3, 2019, pp. 259-263. doi:10.1016/j.jsams.2018.09.001.

Lagas, Iris F., et al. “Incidence of Achilles Tendinopathy and Associated Risk Factors in Recreational Runners: A Large Prospective Cohort Study.” Journal of Science and Medicine in Sport, vol. 23, no. 5, 2020, pp. 448-452. doi:10.1016/j.jsams.2019.12.013.

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O’Neill, Seth, et al. “Why Are Eccentric Exercises Effective for Achilles Tendinopathy?” International Journal of Sports Physical Therapy, vol. 10, no. 4, 2015, pp. 552-62.

Magnusson, S. P., Langberg, H., and Kjaer, M. “The Pathogenesis of Tendinopathy: Balancing the Response to Loading.” Nature Reviews Rheumatology, vol. 6, no. 5, 2010, pp. 262-268. doi:10.1038/nrrheum.2010.43.

Kubo, K., Ishigaki, T., and Ikebukuro, T. “Effects of Plyometric and Isometric Training on Muscle and Tendon Stiffness in Vivo.” Physiological Reports, vol. 5, no. 15, 2017, e13374. doi:10.14814/phy2.13374.

Radovanović, G., et al. “Evidence-Based High-Loading Tendon Exercise for 12 Weeks Leads to Increased Tendon Stiffness and Cross-Sectional Area in Achilles Tendinopathy: A Controlled Clinical Trial.” Sports Medicine-Open, vol. 8, no. 1, 2022, 149. doi:10.1186/s40798-022-00545-5.