Rest Betrayed: The Subtle Threat to Achilles Tendon

The Achilles tendon is the largest and strongest tendon in the human body constituted predominantly of collagen fibres and helps in movement such as running and jumping. Achilles tendinopathy is an inflammatory in the Achilles tendon that cripples a lot of athletes and sometimes the general population. For years, overuse was thought to be the root of the problem but how this tendon gradually breaks down at a molecular level, has largely been a mystery. What happens to these fibres after intense physical activity?

This study examined the impacts of running on the Achilles of rats, revealing something new about collagen damage. Surprisingly, the researchers found that this tendon did not deteriorate straight after exercise, even when the tendons were under a lot of strain and stress from running. However, the damage is gradual and is referred to as collagen denaturation which occurs when muscles are at rest.

This study highlights that degradation is not due to mechanical stress, collagen denatures through inflammation and protein degradation. The reported findings indicated that collagen fibres associated with tendons and ligaments have denaturation at about twelve hours post-running and regain their ‘normal’ state in seven days of rest. However, when running continues uninterrupted for weeks and months with no rest, collagen can be compromised leading to the basis for Achilles tendinopathy.

This study utilizes in vivo magnetic resonance imaging to examine Achilles tendon injuries induced by collagenase, employing a contrast agent that specifically targets denatured collagen. This creates a new possible application for identifying tendon problems at an earlier stage and providing treatment.

The results of the present study have implications for both athletes and clinicians by acquiring insights from molecular reactions underlying tendinopathy, better strategies to prevent injury and diagnostic techniques can be developed, potentially transforming the management of overuse injuries expected in the future.

Reference:

Fang Y, Zhu D, Wei J, Qian L, Qiu R, Jia T, Huang K, Zhao S, Ouyang J, Li M, Li S. Collagen denaturation in post-run Achilles tendons and Achilles tendinopathy: In vivo mechanophysiology and magnetic resonance imaging. Science Advances. 2024 Oct 2;10(40):eado2015. https://doi.org/10.1126/sciadv.ado2015

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