Tendon Health & Performance
Tendon health can be tricky. They can be an asset or a liability. Let's break down some key concepts:
What are tendons?
Tendons are the tissues that connect your muscles to your bones. They are primarily made up of collagen, which is a connective tissue, with some elastic tissue called elastin as well. They do not contract, but are like an extremely firm bungee chord.
What do tendons do?
They transfer the force from your muscle to your skeleton, allowing your bones to move. They also help absorb shock and provide a type of quick recoil to help you move fast (think hopping or jumping).
How do tendons get damaged?
Overuse or "too much, too soon." Your connective tissues take longer to adapt to stress compared to bone or muscle. So when you begin a new training program, or increase your intensity, it is smart to ramp it up slowly in order to allow your tendon tissues to adapt properly and get strong!
When your muscles fatigue and don't absorb the shock like they should during running, jumping, or other activity, your tendons take a huge beating. They become your main shock absorbers, which they don't like. This can lead to overuse injuries called tendonitis. So it is essential to develop and maintain strong muscles that have the control and endurance for the demands of your sport or activity.
Tendons can also become damaged under acute loads where the tendon actually ruptures. This can lead to long term impairments and extended periods of time aw ay from your sport or activity. Ruptures of the achilles tendon, for example, typically occur in weekend warrior athletes who are not consistently training, but may participate in their specific activity a few times a month. When this happens in this population, the tendon has not been conditioned to be strong and withstand the demand and ultimately ruptures under high levels of force like jumping or sprinting. This can also be seen in degenerative tendons called tendinosis (see more below) where the tendon is weak due to inadequate recovery time and ultimately leads to the same result.
How do tendons heal?
1. Tendons don't have a great blood supply like muscles and bones, so they are quite a bit slower to heal and recover. When injured, the tendon tissues go through an inflammatory cycle (which is a good thing). White blood cells clean up the damaged tissue. Cells called fibroblasts create unorganized collagen fibers to patch up the injured area. Then, with gradual, progressive loading of the tendon, the fibers align and strengthen, becoming healthy tendon tissue again. BUT if the fibers keep getting damaged before undergoing full healing, they stay inflamed and the tendon will actually go through a degenerative process. This process results in your body creating weaker types of collagen fibers in your tendon, along with more nerve endings and blood vessels (to make the tendon more sensitive so that you stop doing the thing that is damaging it). We call this tendinosis. It is no longer tendinitis because the tissue is not going through an inflammatory process anymore, it is degenerating.
Good news though! You can regenerate and heal tendon tissue even when you have chronic tendinosis. But it won't just heal on it's own at this point. You need to stimulate growth of good collagen tissue. Doing manual therapy techniques, can help stimulate healing and reduce pain. But the real magic happens when you properly load the damaged tendon...
How can I develop strong, healthy tendons?
Well, I'm glad you asked. Some tendons, like your achilles and biceps long head, are wrapped in a sheath. Within the sheath is synovial fluid, which nourishes the tendon. High-volume exercises can help secrete this fluid. Isometric exercises can help reduce pain and reteach the body to activate the muscle attached to the painful tendon. So we usually recommend starting with isometrics and progressing into more high-volume work as tolerated.
Here's a link to a research study that showed how they healed achilles tendinopathy through specific exercises:
They prescribed eccentric heel raises twice a day, 7 days per week, 3 sets of 15 reps both with knee straight and bent. Those who completed this were able to resume running, while those who rested, iced, and did "physical therapy" went on to have surgery.
A novel way to strengthen tendons with less time commitment.
Some of the newer research is starting to show that heavy slow resistance (HSR) training can also reduce pain and strengthen tendons, possibly even better than eccentric strength training. HSR exercise is based off the principle of progressive overload where loading the tendon begins with lower intensity with higher repetitions, and progressively gets heavier with fewer repetitions over weeks and months. This allows the tendon time to adapt to these heavier loads over time to be able to withstand higher intensities and capacity in the future.
The prescribed method for this style of training starts with 3 sets of 15 repetitions and progresses to 4 sets of 6 by week 9 of training. 12 total weeks is the recommended length of the program.
Here is another link to a great article that compares the two previous methods listed above.
Now, your recovery may not be as simple as just doing a handful of progressive exercises. You may need to develop better movement mechanics in surrounding joints, strengthen other muscles to properly support your limb, and the list goes on. To find out what you need as an individual requires an individualized evaluation and treatment/training plan. That's what we are here for! But we do hope that this blog information has shown you that through intelligent loading, you can rebuild your tendons and improve your function without expensive injections, imaging, or surgery.
Go do some calf raises!
Written by Dr. Luke Phillips, PT, DPT, OCS
Find Your Weakness. Make it a Strength.