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The Tendon Injury Process Article three of five by Debbie Cameron

There are three main phases of the tendon injury process:

1. Reactive tendinopathy

2. Tendon disrepair

3. Degenerative tendinopathy

In the first phase the enlargement of the tendon surface can decrease stress and increase stiffness. If there is enough time between loads or the overload is reverted, the tendon structure can return to normal.

The second stage is defined as tendon disrepair, because of the appearance of fibrillar dis-organisation in the tendon. Closer inspection shows that the tendon has changed in the following way: there is an ingrowth of nerves into the tendon, increased water content and hypervascularisation of the tendon. These changes cause the tendon to thicken, and the increased width of a tendon is palpable.

In the third phase, a variety of changes can be observed within cells and surrounding protein matrix. There are areas where the fibroblastic cells die and so cause the development of large zones with an absence of cells. In these zones blood vessels spread throughout the disordered zones of the protein matrix. The possibility of recovery of the tendon decreases at this stage.

Pain or dysfunction of a tendon may be observed in clinical testing but may not correlate with imaging tests findings and a diagnosis is made on clinical findings.

Research has shown that there is a discrepancy with MRI and Ultra-Sound findings and the severity or even existence of an injury. Neither do these reports have any prediction value for the recovery of a tendon. Therefore, tendinopathy is currently diagnosed as a ‘clinical hypothesis based on the patient symptoms and physical context’. (Lorena Canosa-Carro et al 2021).

Diagnosis criteria for a tendinopathy:

  • Pain is related to overload.

  • Pain increases with loading and immediately lessens when the load is removed.

  • Pain is very localised to the tendon.

  • Pain should increase when the load applied to the tendon increases (dose-dependent loading), e.g., a shallow squat would be less painful than a deep squat in patella tendinopathy.

  • Pain should stay localised during loading activities (an exception is gluteal tendinopathy which may refer down the leg).

  • Pain tends to improve during activity (warm-up phenomenon) but may be worse the day after high loading activities.

  • Isometric exercises often decrease pain originating from a tendon (if isometrics aggravate the pain consider a different diagnosis).

  • Area specific signs, e.g., morning stiffness for Achilles’ tendinopathy and discomfort with sitting for hamstring tendinopathy.[5]

Healthy habits for tendons

1. Increase load carefully.

2. Progressive tendon loading seems to be crucial in the management of tendinopathy. The rule of a 10% increase per week is a guideline for progression of exercise or activity used by most clinicians.

3. Allow 36 hours of rest between exercising an area of the body.

4. Add slower resistance training such as 6 seconds to complete the movement.

5. Increased times for isometric-holds to 45 seconds. Aim for 70% of maximin voluntary contraction of 45 seconds hold and repeated 5 times.

6. Do not take anti-inflammatories when exercising because anti-inflammatories taken during exercise prevent any collagen synthesis from being made and the benefit of tendon adaption to exercise is lost. A surge of inflammatory mediators is needed for collagen turnover (Magnuson et al 2019).

7. Pain is protective in a tendinopathy to prevent rupture, so respect the pain from a tendinopathy and ease off when necessary.

8. Keep active so that the tendon has sufficient stimulation for cellular integrity and good function.

According to @ProfJillCook on Twitter “only Achilles tendons with pathology, rupture during activity. It is impossible to rupture a normal tendon.”


1. Breda SJ et al (2021) Effectiveness of progressive tendon-loading exercise therapy in patients with patellar tendinopathy: a randomised clinical trial. J Sports Med, Vol 55, 501–509.

2. Bullock GS et al (2021) Clinical Prediction Models in Sports Medicine: A Guide for Clinicians and Researchers J Ortho & Sports Physical Therapy, Vol 51, No 10, 517- 526.

3. Canosa-Carro L et al (2021) Current understanding of the diagnosis and management of the tendinopathy: An update from the lab to the clinical practice Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license ( Accessed 28/03/2023.

4. Clifford C et al (2020) Effectiveness of isometric exercise in the management of tendinopathy: a systematic review and meta-analysis of randomised trials.

5. BMJ Open Sp Ex Med 5:e000760. doi:10.1136/bmjsem-2020-000760 file:///C:/Users/User/Documents/OMTPG/Tendonopathy/Tendinopathy%20article%201.pdf Accessed 28/03/2023.

6. Cook J et al (2009) Is tendon pathology a continuum? A pathology model to explain the clinical presentation of load-induced tendinopathy. Br J Sports Med 43:409-416.

7. Cook et al (2016) Revisiting the continuum model of tendon pathology: what is its merit in clinical practice. Br J Sports Med 50:1187-1191.

8. Cook J et al (2019) Managing Difficult In -Season Tendinopathies. Aspetar Sports Medicine and Science in Athletes Targeted Topic pg 268-271 Accessed 28/03/2023.

9. De Vos et al (2021) Dutch multidiscipline guideline on Achilles tendinopathy Br J Sports Med 55,1125-1134 accessed 24/06/2023.

10. Hanlon S L et al (2021) Beyond the Diagnosis: Using Patient Characteristics and Domains of Tendon Health to Identify Latent Subgroups of Achilles Tendinopathy J Ortho & Sports Physical Therapy, Vol 51, No 9, 440-448.

11. Jones LE et al (2014) The Pain and Movement Reasoning Model: Introduction to a simple tool for integrated pain assessment Manual Therapy Vol 19, Issue 3, Pages 270-276.

12. Magnusson SP et al (2019) The impact of loading, unloading, ageing and injury on the human tendon J Physiol 597.5, 1283-1298.

13. Masci L (2023) Tendon Neuroplastic Training: More effective rehab for tendonitis Accessed 22/04/23.

14. Masci L (2020) How to treat tendonitis from a tendonitis specialist Accessed 22/04/23.

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