Jumper's Knee Rehab

Link to the Jumper's Knee Rehab Program

Perhaps the most common injury I see here at FIS Athletics is Jumper’s Knee (JK). JK, also known as patellar tendinopathy, is usually the result of overtraining of the knee extensor muscles and causes pain below the knee cap with activity. Factors leading to JK include: repeated jumping, sprinting, and rapid changes of direction, sudden increase in training intensity or volume, inadequate recovery between high-load sessions and weakness or imbalance in the quadriceps, glutes, or hamstring muscles.

To understand what JK is, first we have to understand the basics of tendons and tendinopathy. Tendons are bundles of connective tissues, made up mostly of collagen type 1 fibers, that connect muscles to bone. Tendons allow the muscles to exert their forces on the bone, enabling us to move or hold a position. Compared to muscles, tendons are very stiff and do not change their length much, typically less than 5%. They also store and release elastic energy - think explosive movements like plyometrics. Tendons also adapt, becoming more or less load tolerant, depending on what mechanical forces are applied on a regular basis. This adaption is slow and takes place over a longer period of time. For this reason, a gradual and progressive build up in training is recommended. But what happens if the forces applied to those collagen fibers quickly and consistently exceed their loading capacity? Well, simply put, you get tendinopathy - degeneration from overuse of the tendon with a loss of stiffness. At a cellular level the overloaded collagen type 1 fibers begin to degenerate and break down. These are often replaced by weaker collagen type 3 fibers. Other changes happen at the cellular level affecting the tendon matrix, causing more fluid to be present and a thickening of the tendon. Along with the type 3 fibers, new blood vessels form, bring new sensory nerve fibers along with them. All of this leads to pain when seemingly normal loads are placed upon the weakened tendon. Suddenly, normal activities like walking down stairs or jumping become painful.

But why does this occur? One theory for why degeneration of unhealthy fibers happens is stress shielding. With a healthy tendon, mechanical forces are distributed equally along all fibers of the tendon. In cases of tendinopathy, on the other hand, unhealthy fibers are protected or shielded from mechanical loads by the healthy fibers directly surrounding them. This actually causes the unhealthy fibers to degenerate further, becoming even weaker and more sensitive to load. It's a vicious cycle - fibers become overloaded, degenerate and weaken, physiological changes to the tendon cause pain with loading, healthy fibers protect the unhealthy fiber from mechanical loads, causing the unhealthy fibers to further weaken and degenerate, causing more pain with activity, repeating and repeating.  

So how do we break this cycle and treat JK? It's extremely difficult, especially during the season, but there is hope. The simplest way to treat JK is to rest or avoid aggravating activities as soon as the pain starts and to slowly return to sport. Some experts recommend up to 6 months of rest before returning to sports. But that isn't really realistic for most athletes, except in extreme cases, especially with our sports season lasting roughly 3 months. Additionally, rest may help the pain but it doesn't really make the tendons stronger. So we also need to strengthen tendons so that they can handle the demands placed on them during sports. 

Here's where it gets tricky... as I explained earlier, with tendinopathy seemingly normal activities become painful - walking, running, jumping and even strength training. That means we can't simply perform barbell squats and expect the patella tendon to adapt and become healthy again. Actually, that would likely worsen JK. What we need to do is find exercises that can provide appropriate levels of loading, using pain as our guide. On a pain scale of 0-10, I recommend training at levels of 3 or below. Anything above is likely worsening the symptoms and the condition. The easiest way to do this is performing isometric exercises - meaning no change in the joint angle. Simply put - we use the leg extension machine with a weight so heavy we can't move it, to press against the leg pad as hard as possible for >30 seconds while keeping pain at  <3/10 on the pain scale. See this video for a demonstration. Earlier I mentioned stress shielding, the healthy fibers protecting the unhealthy fibers. This is important because studies show that with an isometric contraction 30 seconds or longer, the healthy fibers relax, causing the unhealthy fibers to take up the slack to hold the load. We then progress to eccentric leg extension, only the lower phase of the exercise, and eventually full range of motion leg extensions as pain and strength improves. 

We may also need to look at other measures to reduce pain, including a reduction of training, patella compression bands, icing for pain and pain medication.

I’ve developed a progressive rehab program to help students with JK for the Fitness Center or your favorite gym. Ideally, the exercises are performed before practice, in order to warm the tendon for training 2-3 times per week. 

Exercises labeled either A or B.  A1, A2, A3 etc. is a progression of exercises - starting with the simplest (for more severe cases of JK) to more complex (for less severe or healing cases). If you can perform A1 with minimal pain for multiple sessions, move to A2. Same with A2 to A3. Usually, only the most advanced possible of the A exercises will be performed per training session. Regressing from A2 to A1 may also be necessary if symptoms increase. B exercises may be done in addition to the A exercises. Each exercise is also linked to a video to demonstrate proper technique.

Again, it is important to keep pain to a minimum while training and doing these exercises. I recommend no more than 3 on a scale of 0 (no pain) to 10 (maximum imaginable pain). 

See Mr. Scott for more tips for Jumper's Knee, including how to use a compression wrap during practice and games.