By: The Duluth RunnerPosted on

Guest post by Dr. Joey DeVlieger

Just over 50% of runners will experience Achilles tendon pain in their running career according to the National Institute of Health.  If we have not been derailed in our training with Achilles tendon pain, we likely know someone who has.  And yet, it is the strongest tendon in our bodies designed to take forces up to 1,100lb!  (Cleveland clinic).  

What is it and what can happen if it is injured?  What preventative measures should we be doing right now? And, what do we do if we start to experience pain?  

Anatomy 

Let’s start with an overview of the anatomy.  Two primary muscles (commonly referred to as the calf muscle) called the Gastrocnemius and Soleus combine towards the musculotendinous junction and form the Achilles Tendon, inserting into the heel bone (calcaneus).  The Plantaris muscle is not found in everyone, is quite small, and blends into the inside of the Achilles tendon.   What is important to appreciate is the Gastrocnemius crosses both the knee and ankle joint, whereas the Soleus, the primary deeper endurance muscle, does not.  Training plans with strength and stretching that account for this difference are simply better.   

Both muscles will transmit force into the calcaneus through the midfoot structures, including the plantar fascia, creating a lever arm as the forefoot pushes into the ground (plantar flexion) propelling the runner up and forward. For our forefoot runners, the Achilles tendon takes cumulatively greater load because these runners are not only pushing up and forward (concentric muscle contraction), but also accepting and decelerating their body’s mass at initial contact (eccentric muscle contraction).  

Pathology & Types

Nearly 70% of all running related injuries can be traced back to training error (Nielsen et. Al, 2012).  Like other tendons, the Achilles tendon can become inflamed because of inadequate load tolerance to the stress or tensile demands placed on it. A simple way to think about it is inadequate tendon durability.  The earliest phase of injury is referred to as the acute phase, covering the first approximate 3 months.  Runners may feel intermittent or constant pain during this time, fortunately the damage sustained to the tendon for the most part is reversible with proper care and/or rehabilitation.  

After 3 months of ongoing pain, however, the tendon’s structural integrity and composition begin to change.  This is around the time Achilles tendinosis can set in.  Degenerative products begin to collect between the dense collogen fibers of the tendon.  These products make the tendon appear thicker, weaken the tendon decreasing force generation, and create an environment susceptible for micro tearing.   See diagram below.

https://doi.org/10.3389/fresc.2021.726313

B) is normal.  C) is abnormal (less white collogen fibers, more fluid with degenerative products that shows up darker in appearance) 

A less common injury to the Achilles tendon is called tenosynovitis; inflammation within the lining of the tendon.  It is often thought of as part of the tendon degrading process. 

Differences:

Achilles tendinitis: Pain tends to be sharper and progressively worse with continued running. In the morning, the tendon is tight and sore. 

Achilles Tendinosis: Pain tends to dull and achy, can “warm up” after a mile or running and be tolerable, but then becomes more sore the longer the run.  In the morning, the tendon generally feels better, sometimes tight.  

Location of Injury

Mid-substance:  Location spans approximation 1-2 inches in the longitudinal direction of the tendon.  

Characteristics: It is usually point-tender when you push on it. It may or may not have local swelling.  It feels stiff, particularly in the morning.  

Insertional: Location is directly at the back of calcaneus where the Achilles tendon inserts, approximately the size of a fingertip, but possibly spanning the entire calcaneus. 

Characteristics:  It is point-tender when you push on it. It may or may not have local swelling.  Pain is typically sharper and provoked with end range stretching and/or any pressure on it, such as the back of a dress shoe.   

A contributing factor could be a heel spur, which is a boney protrusion off of back of calcaneus.  It is usually related to cumulative load at the Achilles tendon without adequate flexibility or range of motion of the foot and ankle.  Heel spurs are not necessarily painful, are typically slow growing, and require diagnostic imaging to confirm. 

Prevention 

  • Strength Training: Increase Load Tolerance of the tendon (Durability) 

Heavy slow resistance (HSR) strength training is one good option.  The key benefit is tension under time to stimulate your body’s response to build a stronger, more durable tendon (collogen synthesis).  In turn, the tendon will have a greater cumulative load tolerance and capacity for longer and more intense running bouts.     

Here is a helpful diagram that shows how best to use reps/sets/loads for different purposes. Note; you do not need more endurance strengthening as you are already getting this stimulus with running.    

Important Reminder: As discussed earlier, it is important to include calf strengthening/Achilles tendon loading with both the knee straight and the knee bent.  A strong calf muscle can perform 20 single leg heel raises throughout the full range of motion; a difficult measure to achieve for most.  

Research Plug: Strength Training programs reduced sports injury on average 66% and overuse injuries by almost 50%. Lauersen et. al (2013) & (2018) 

Bonus: Strengthen also the Tibialis Posterior, Gluteus Maximus, Gluteus Medius, and piriformis muscles to collectively help distribute force throughout the leg. 

  • Stretching: Improve Flexibility & Range of Motion  

Adequate ankle range of motion is critical, both with you knee straight and knee bent.  If you have any pinch- pain in the front of the ankle during stretching, consider seeing a health professional to further assess the cause. 

A helpful test you can perform on your own is linked here in the first minute of the video: https://youtu.be/dCwLYUjzslY?si=gk6bSUsCd9WkXCDI This test will address you deeper calf muscle the Soleus.

Great toe extension: The ability of your big toe to bend backwards takes undue stress off the midfoot and can enable greater performance out of your calf muscle and less stress into the Achilles tendon. 

Here are a couple stretching options: 

Go to: https://www.medbridgego.com/

Access Code: LV8DRJCV

Tip: It is widely accepted that pro-long stretching (static) before running is detrimental to performance and has a higher incident rate of injury than a general warm up or dynamic (movement based, short gentle holds) before running.    Pro-long stretching after running or a workout is best.  

  • Sleep:  

Sounds simple, yet many do not pay attention to this enough.  Your body needs time to recover and rebuild.  Do not skip this. 

Research plug:The American Academy of Cardiovascular Sleep Medicine has found that sleeping less than 7 hours has a 50% association with new injury risk in endurance athletes.

  • Shoe setup / Change in footwear:  If you are planning to reduce the stack height of your shoe (heel being closer to the ground / less slope towards the forefoot) by moving into a more neutral based shoe type, do it slowly over a 2-3 month period. This will allow time for your Achilles tendon to adaptively change to newer ranges of motion demands. This is not as important if you are a forefoot runner.  

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Injury Guideline: What do I do if I have pain? 

First Step:  1-4 weeks 

  • Do not ignore it or pretend it’s not there, but also do not panic either.  
  • Do not self-diagnosis.  There are many differential diagnosis and other structures that could be involved.  The location of the pain does not necessarily mean that is where the problem is.  
  • Do Follow the Soreness Guideline for Runners:

SORENESS GUIDELINES for RUNNERS

New soreness that is not expected in your training plan:

– Soreness during warm-up that continues – take two days off

– Soreness during warm-up that goes away – continue as planned

– Soreness during warm-up that goes away but comes back as session continues – take two days off 

– Soreness the day after – take one day off

– Soreness the day after – take one day off

– If excessive soreness (longer than 24 hours and/or does not improve with warm up), need to modify plan

– Soreness during warm-up that goes away – continue as planned

  Adopted from RunDNA™

  • Consider your Running History:  If you have experienced this before, consider seeking professional medical advice if your symptoms do no resolve in 7-10 days of activity modification and decrease in volume and/or intensity or running.  This is especially the case if you find yourself limping.  If the pain continues with a familiar history, there is likely an underlying, multifactorial cause, and may best be intervened professionally sooner than later.  
  • Anti-Inflammatories: All inflammation is not bad. It is a necessary part for healing.  While cold packs and ice baths will usually temporarily decrease pain, there is mixed reviews in the literature about the efficacy in tissue healing.   Consult your pharmacist and/or Primary care provider if starting any topical or oral medication.  
  • Tapping: Save yourself time and money and don’t bother unless you are being instructed by a health care professional or you are days away from a race and are desperate for any form of relief.  Here is an example: https://youtu.be/gGwHZDjktUU?si=lZyNRv31M6Kw9TVl
  • Use heel lifts temporarily in both shoes for walking and running.  An example is the original adjust a lift heel lift. This will help temporarily shorten the Achilles tendon and take undue stress off of it while it heals.  These lifts are designed to peel off a layer at a time decreasing the stack height week by week as the Achilles tendon is healing.  They are typically used over the course of 3-4wks. 
  • Begin Isometric calf strengthening ~ 3 days after the onset of pain daily If: The pain during the exercise is less than a 3-4/10 on a pain scale (10 being the worse) AND with more repetitions the pain decreases. Shoot for 4-6 reps, holding 20-30 second each depending on your level of conditioning. 
  • Avoid end range of motion stretching; This only aggravates the tendon at this stage.  Additionally, be mindful of uphill/incline walking as this also places the tendon in a compromised end range position. 
  • Use a foam roller, theragun, or similar on the calf muscles (not the tendon) to decrease any myofascial restriction, tightness, and/or hypertonicity in the muscle which will reduce tension going to the Achilles tendon.  
  • Adjust your training plan.  This may look like reducing total weekly millage, reducing the distance of your long run, avoiding back to back running days, running on relatively even terrain, or a combination of these.  The point is something will need to be modified temporarily in order to allow healing.  Consider in place cross training: biking or swimming if symptom-free.  

Second step: Injury Past 4 weeks 

If you are not seeing a gradual, consistent improvement in your Achilles tendon symptoms, it is likely time to seek out a healthcare professional who can help.  Stay positive and work around the injury during the interim. 

Wrapping it up. 

Managing the health of your Achilles Tendon has to be intentional if you are going to optimize injury prevention.  There are self-tests & exercises outlined in this document you can begin today to ensure a healthy, durable tendon for future running.  If you get into trouble, don’t panic, use the Injury Guideline as a starting point.  Connect with other runners, a running coach, or health care professionals specializing in treating runners.  Stay healthy. Run strong!    

Authored by: 

Dr. Joey DeVlieger, DPT, CIMT, CMP, CSCS

Physical Therapist

  Certified Running Analyst

  Certified IDN

Certified Exos Strength and Conditioning Specialist

Essentia Health Therapy & Performance Center

1600 Miller Trunk Hwy

Duluth, MN 55811

Joey.Devlieger@EssentiaHealth.org

Medical Disclaimer: 

The information provided in this document is for educational and informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the advice of a physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read in this paper. Reliance on any information provided in this paper is solely at your own risk.

References: 

Wang, Y., Zhou, H., Nie, Z., & Cui, S. (2022). Prevalence of Achilles tendinopathy in physical exercise: A systematic review and meta-analysis. Sports Medicine and Health Science, 4(3), 152–159. https://doi.org/10.1016/j.smhs.2022.03.003

Cleveland Clinic. (2026). Achilles tendon (calcaneal tendon). https://my.clevelandclinic.org/health/body/achilles-tendon-calcaneal-tendon

Lalumiere, M., et al. (2021). To what extent do musculoskeletal ultrasound biomarkers relate to pain, flexibility, strength, and function in individuals with chronic symptomatic Achilles tendinopathy? Frontiers in Rehabilitation Science. https://doi.org/10.3389/fresc.2021.726313

Nielsen, R. O., et al. (2012). Training errors and running-related injuries: A systematic review. International Journal of Sports Physical Therapy, 7(1), 58–75.

Lauersen, J. B., Andersen, T. E., & Andersen, L. B. (2018). Strength training as superior, dose-dependent and safe prevention of acute and overuse sports injuries: A systematic review, qualitative analysis and meta-analysis. British Journal of Sports Medicine, 52(24), 1557–1563. https://doi.org/10.1136/bjsports-2018-099078

Lauersen, J. B., Bertelsen, D. M., & Andersen, L. B. (2014). The effectiveness of exercise interventions to prevent sports injuries: A systematic review and meta-analysis of randomized controlled trials. British Journal of Sports Medicine, 48(11), 871–877. https://doi.org/10.1136/bjsports-2013-092538

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