Tendon-injuries are extremely common, with the top 3 being tears of the rotator cuff, Achilles, and wrist flexor tendon. Conservative therapy has been able to produce excellent outcomes in 75% of cases, with exercise being a key component, but why? To answer that let’s first go over a few other questions:
- What are tendons?
- Tendons are a form of connective tissue that transmit muscle forces to bone. They have the highest tensile strength of all connective tissue, because of their high proportion of collagen in their fibers that are in a closely packed arrangement along the direction of force.
- **Understanding this collagenous makeup is important, as it’s what makes them as strong as they are**
- What does a healthy tendon look like?
- A healthy tendon has a high expression of mature Type I collagen, which is very strong. Further, healthy tendons have an organized and highly cross-linked array of these collagen fibers.
- What does an injured tendon look like?
- An injured or healing tendon basically has the opposite. It has high levels of immature type III collagen that’s weak and much less organized.
So, it’s this high proportion of organized type I collagen that’s the key factor of healthy tendons. Now, why is exercise important?
- Well, studies show that immobilization leads to the formation of irregular and uneven collagen fibers. Further, it decreases the total weight of the tendon, its stiffness, and tensile strength.
- Exercise on the other hand, helps provide the necessary force to orient the collagen along the direction of force. Tendons exhibit greater cross-sectional area, greater tensile strength, and an increased production of type I collagen in response to physical training.
Is there ever “too much” physical training?
- Yes, tendons are known for their slow healing due to them being hypovascular and hypocellular. It takes some time for the type I collagen to take precedence over the type III, and the tendon is much weaker up to that point. Even a year after a tear, the healed tissue shows inferior mechanical and biochemical properties compared to the original. Due to this, too much physical training too soon can be detrimental.
WANT MORE?! Do you want a deeper understanding of how tendons heal and ways to maximize it? Check out our other blog “How Tendons Heal”!
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Written by Dr. Brandon Buchla, DC, CSCS
Check us out at www.atpplusct.com