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New thinking about Tendons Article one of five by Debbie Cameron



The injury known as a ‘tendinopathy’ has a reputation of being troublesome in the sports’ medical world. With the understanding of the nature of the tendon, it need not be. To speed up recovery from a tendinopathy, knowledge of the tendon structure is important for an exercise programme to make sense. Perseverance and compliance with a recovery programme for tendinopathy can be increased with an understanding as to how and why the exercises work, including a realistic view of the time frame needed for the recovery needed.


The word ‘tendinopathy’ is description is an accepted term which is used to indicate a variety of tissue conditions that appear in injured tendons. It means an injury which has not yet torn the tendon but there is damage in the tendon or paratendon, i.e., tissue around the tendon.


The pain from the injury in the tendon is intensified with mechanical loading (Lorena Canosa-Carro et al 2021). Mechanical loading consists of any force that increases the load on the tendon. There are three different ways that the tendon is subjected to force: a compression force, a shear force, or a torsion force. These forces are natural forces that occur during sport, training and in everyday activities. The tendon’s chief role is to manage and transmit force received by muscle to the bone, thereafter the force is dissipated through the body.


The structure of the tendon can be visualised as a flat, sinewy band. The tendon is made up of elongated cells called ‘fibroblasts’ that lie with collagen fibrils and have a rich mixed of proteins throughout the structure. It is believed that this protein matrix is responsible for the mechanical abilities of a tendon: strength, stiffness, elasticity, and energy storage.


The tendon transmits force through the chemical reactions of the cells in its protein matrix. If the protein matrix is altered this decreases the ability of the tendon to perform its role of contributing to strength, stiffness, elasticity and jumping ability, all components that are vital for good movement of the body part (Magnusson et al 2019). You can feel the weakness in a muscle when you have a tendon injury, for example, people suffering with an injury to the wrist extensor tendon commonly called a “tennis elbow’, lifting a teacup can be near impossible and painful too.


What is interesting about the quality of a tendon’s structure is that it is mostly developed in childhood and adolescence. The tendon condition is topped up daily in response to the work that a body has done during that day. This adjustment mechanisms gives the tendon the ability to adapt to changes in forces exerted on the body. Conversely, if no work is put through a tendon, it’s condition and functionally ability will deteriorate. Scientists believe that deterioration in a tendon is due to the lack of the daily maintenance and does not affect what has developed in childhood (Magnusson et al 2019).


The principle that is important for athletes to bear in mind is that the health and ability of the tendon is dependent on regular exercise. The tendon needs regular mechanical stimulation for maintenance of the matrix protein synthesis of the tendon. At a cellular level, stimulation causes a cell response in the tendon and the tendon’s fibroblastic cells produce collagen (collagen type I). This type of collagen is a vital component required for a healthy tendon structure and its ability to perform force management.


So, what is meant by force, mechanical loading, or stimulation? Any movement that the body makes. Muscle movements that are isometric, concentric, and eccentric will stimulate a tendon and provide a mechanical load to the tendon. Even when a muscle contraction is induced via electrical stimulation, there is mechanical loading applied to the tendon and the positive increase in collagen synthesis.


The tendon has a slightly higher capacity of force management than its trained ability. The second principle that is important to understand is that as the ability of the tendon increases, its capacity increases too. If the tendon is not trained, its ability decreases and with this so does its capacity.


So how does injury or damage to a tendon occur:


There is a state of flux that a tendon is in, between loading, localised cell response, and collagen produced. Just as we need air to survive, the tendon needs load to thrive. Load on the tendon contributes to and is essential for the maintenance of the protein matrix. It is this protein mix inside the tendon that is responsible for the tendon’s abilities. However, if the load on the tendon is too great and the tendon is overloaded beyond its capacity to bear load, the damage to the tendon structure is called “disrepair’. The integrity or health of the tendon structure can go in two directions; healing and return to the initial state of flux (called the reactive phase) or the tendon can degenerate to a state where it can be torn. This concept is known as the Continuum model theory of tendon health and performance (Cook et al 2009).


The take home message is that: the mechanical stimulation of work, whether through activity or training, applied to a tendon will promote the development of a stronger structure of the tendon, has a more effective performance ability and one that is safer from injury.


References

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 (http://creativecommons.org/licenses/by-nc-nd/4.0/) 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

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8. 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

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

10. De Vos et al (2021) Dutch multidiscipline guideline on Achilles tendinopathy Br J Sports Med 55,1125-1134 https://bjsm.bmj.com/content/55/20/ accessed 24/06/2023

11. 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

12. 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

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

14. Masci L (2023) Tendon Neuroplastic Training: More effective rehab for tendonitis https://sportdoctorlondon.com/tendon-neuroplastic-training-more-effective-rehab-for-tendonitis/ Accessed 22/04/23

15. Masci L (2020) How to treat tendonitis from a tendonitis specialist https://sportdoctorlondon.com/tendonitis-specialist/ Accessed 22/04/23

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