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Expert Guest Blog by Michael Braccio DC, DACRB


Over the previous couple of decades, our understanding of tendon pathology has changed; from tendinitis to tendinosis, and then to tendinopathy. With Achilles tendinopathy being one of the most common injuries, it is essential to understand these changes to improve our management. This blog will discuss recent updates on tendon pathology as well as a rehabilitation protocol for Achilles tendinopathy.

Check out what ACA Rehab Council’s Dr. Michael Braccio recommends for rehabbing Achilles Tendinopathy.


Understanding Tendon Pathology


Pain related to the tendon has historically been attributed to inflammation, hence the diagnosis of tendinitis. However, there has been much debate about whether inflammation actually has a role in chronic tendon pathology.1,2 Despite this debate, the model for tendon pain has transitioned away from the inflammatory model towards a load-based model.

The current concept to describe tendon pathology is the continuum model purposed by Jill Cook and Craig Purdam.3,4 The continuum model is divided into three different stages:

(1) reactive tendinopathy

(2) tendon dysrepair

(3) degenerative tendinopathy

The reactive tendinopathy stage occurs following a spike in tendon load. In response, proteoglycans are produced which draw water into the tendon cells, causing separation of the tendon fibers. With sufficient rest, the proteoglycans are broken down and the tendon fibers return to their original state.

With continued loading, the pathology can progress to the tendon dysrepair stage. The fluid accumulation in the tendon causes more separation of the cells and matrix disorganization.

Finally, in the degenerative tendinopathy stage, there is extensive disorganization in the tendon cell, to the point of apoptosis. There can also be neovascularization in the tendon cell which has been implicated as a potential cause of chronic pain syndromes.5 These changes in tendon structure are likely to be permanent.


Management for Achilles Tendinopathy


A crucial aspect of Achilles tendon treatment involves managing the load. Continued overloading on the Achilles tendon can lead to structural changes and irritation of the tendon. Completely removing the load placed on the tendon can lead to stress-shielding and a reduction in the structural integrity of the tendon.6

The goal of load management is to find the balance between loading enough and not overloading the tendon. This can be achieved by modifying a combination of the intensity, frequency, and duration of the load placed on the Achilles tendon.

Compression of the tendon is another aspect that should be considered in management, particularly with an insertional Achilles tendinopathy. Compression of the Achilles tendon against the calcaneus has been suggested to cause similar changes to the tendon as overload.7 Therefore, stretching of the calf muscles may be ill-advised in the early stages of treatment.


Clinical Rehabilitation Progression


Isometric exercises should be considered as a starting point to load the tendon. Heavy isometric loading on the patellar tendon has been found to have a pain-relieving effect.8 However, this same response was not observed with the Achilles tendon.9 Despite the absence of analgesia, low-load isometrics exercises on the Achilles tendon can allow those with significant pain or fear-avoidance behaviors to begin rehab. An isometric heel raise can be held for 30-45 seconds with the knees straight or bent to emphasize the gastrocnemius and soleus muscles, respectively.6 Once the isometric calf exercise is tolerated, concentric and eccentric loading can begin via one of two protocols:


The Alfredson eccentric protocol has been the gold standard.10 This protocol consists of 3-second heel lowering movements performed for three sets of 15 reps. The leg lowering would be performed with both a straight knee and a bent knee to isolate the gastrocnemius and soleus, respectively. The program was to be performed twice per day, seven days a week for 12 weeks.


The heavy, slow resistance (HSR) protocol consists of three different exercises performed three days per week. The exercises included: (1) a seated calf raise, (2) a straight leg calf raises on a leg press, and (3) a standing straight leg calf raises. The HSR protocol performs both concentric and eccentric muscle contractions, each performed over three seconds.

A study performed by Rikke Beyer, et al compared a heavy, slow resistance protocol to the Alfredson eccentric protocol and found similar improvement for Achilles tendinopathy. 11 However, the patient-reported satisfaction for the HSR protocol was higher than with the Alfredson protocol.

The decision to use either the Alfredson eccentric protocol or the heavy, slow resistance protocol will depend on the patient’s preference. If the patient has access to the equipment and enjoys being in the gym, the HSR protocol may be better suited for them. If the patient does not like to do resistance training than the Alfredson eccentric protocol would be a better option.

Of note, it may not be necessary to isolate the eccentric muscle contractions from concentric movements. A systematic review found that there was no benefit in only performing the eccentric muscle contraction.12

Before returning to higher impact activities, it is important to prepare the Achilles tendon for these quick loads; thereby minimizing re-injury risk. When reintroducing plyometric exercises, the collagen in the tendon needs time to adapt to the load. Usually, it takes 48 hours for the tendon to respond.13 The selection of specific exercises will depend on the needs of the patient. For example, a patient returning to running should perform single leg hops to replicate the demands of running.

 Since the pathology model of tendinopathy has shifted from inflammation-driven to load-driven, the management should focus on initially reducing the tendon load. Subsequent rehabilitation should include a progressive loading program beginning with isometric exercises, then concentric-eccentric exercises, and finally plyometric exercises.

  1. Rees JD, Stride M, Scott A. Tendons – time to revisit inflammation. Br J Sports Med 2014;48:1553-1557.
  2. Khan KM, Cook JL, Kannus P, et al. Time to abandon the “tendinitis” myth. Painful, overuse tendon conditions have a non-inflammatory pathology. BMJ 2002;324:626.
  3. Cook JL, Purdam CR. Is tendon pathology a continuum? A pathology model to explain the clinical presentation of load-load-induced tendinopathy. Br J Sports Med 2009;43:409-416.
  4. Cook JL, Rio E, Purdam CR, et al. Revisiting the continuum model of tendon pathology: what is its merit in clinical practice and research? Br J Sports Med 2016;50:1187-1191.
  5. Knobloch K. The role of tendon microcirculation in Achilles and patellar tendinopathy. J Orthop Surg Res 2018;3:18.
  6. Cardoso TB, Pizzari T, Kinsella R, et al. Current trends in tendinopathy management. Best Pract Res Cl Rh 2019.
  7. Cook JL, Purdam CR. Is compressive load a factor in the development of tendinopathy? Br J Sports Med 2012;46:163-168.
  8. Rio E, Kidgell D, Purdam C, et al. Isometric exercise induces analgesia and reduces inhibition in patellar tendinopathy. Br J Sports Med 2015;49:1277-1283.
  9. O’Neill S, Radia J, Bird K, et al. Acute sensory and motor response to 45-s heavy isometric holds for the plantar flexors in patients with Achilles tendinopathy. Knee Surg Sports Traumatol Arthrosc 2018;1-9.
  10. Alfredson H, Pietila T, Jonsson P, Lorentzon R. Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis. Am J Sports Med 1998;26(3):360-366.
  11. Beyer R, Kongsgaard M, Kjaer BH, et al. Heavy slow resistance versus eccentric training as treatment for Achilles tendinopathy: a randomized controlled trial. Am J Sports Med 2015;43(7):1704-1711.
  12. Malliaras P, Barton CJ, Reeves ND, Achilles and patellar tendinopathy loading programmes. Sports Medicine 2013;43(4):267-286.
  13. Mascaro A, Cos MA, Morral A, et al. Load management in tendinopathy: clinical progression for Achilles and patellar tendinopathy. 2018;53(197):19-27.

A special thanks to Dr. Michael Braccio and the ACA Rehab Council for providing the cutting-edge information for this week’s blog. The ACA Rehab Council exists to provide its members with the best educational resources to improve our presence & care in the chiropractic & rehab structure. For more information joining the ACA Rehab Council visit their website today at www.acarehabcouncil.org!

About the Author

Dr. Michael Braccio

Dr. Michael Braccio


Dr. Michael Braccio is a graduate of Palmer Chiropractic College West. After graduating, he went on to earn a diplomate in chiropractic rehabilitation. Additionally, he is certified in FMS, SFMA, and RockTape. He is now in private practice at Velocity Sports Rehab in Seattle, WA. Dr. Braccio also serves as a council representative for the ACA Rehab Council.

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