TESTIMONIAL: “The stretches and exercises he shows to avoid and/or recover from the jumper’s knee are the best. I had a really bad jumper’s knee, but 1 month later I didn’t feel anything of it anymore. It now is 4 months later, and I haven’t had problems with my knees since.”

Tendon problems are caused by too much physical stress on a tendon. The body is designed to adapt to physical stress, but recovery abilities have limits. In particular, tendons and ligaments have relatively slow adaptation processes, which is why tendinitis is a common problem. The suffix “itis” means inflammation, so tendinitis simply means tendon inflammation. Tennis elbow is a common example of tendinitis. The repeated violent arm action in tennis places stress on the tendons of the forearm and triceps muscles. Too much of this results in an overworked tendon that becomes inflamed and causes pain.

Jumper’s knee is a term given to tendinitis in the quadriceps tendon, which connects the quadriceps muscle group to the front of the tibia (shin bone). The knee cap (patella) is embedded within the quadriceps tendon, so it is also referred to as the patellar tendon. Jumper’s knee is common among athletes in sports that involve a lot of jumping, landing, stopping, and cutting, movements that require a lot of work from the quadriceps muscles and put stress on the knee joint. For example, with two-hour practices and games all week long, it is easy for the quadriceps tendon of an in-season basketball player to get overworked, resulting in inflammation and pain. It’s important to understand that inflammation is not the actual problem. The problem is that physical stress has caused a lack of structural strength in the tendon. At a microscopic level, the tendon matrix is not properly knit together. There is typically not much visible swelling associated with what most people call tendinitis. I prefer the term tendinosis. The suffix “-osis” just means “a condition.” If you have jumper’s knee, your tendon is in an unhealthy condition. Developing strong healthy tendons requires finding the right amount of stress that will stimulate positive adaptation rather than just break the tendon down.

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Jumper’s knee is a problem I ran into my sophomore year of high school. I had added 6 inches to my vertical in the two months before the season, meaning that all my movements suddenly had significantly more force behind them. So looking back, it makes sense that I developed the tendinosis at that time. In my particular case, the pain flared up badly enough to sideline me for a couple of days during the season and then lasted for several months after.

I went through a process to overcome my jumper’s knee, guided by an athletic trainer at my school. My first responsibility was to rest and ice as much as possible. This meant no extra work at the end of practice and taking off days completely off. I iced whenever I got a chance, especially after any activity. The method the trainer preferred for icing was to rub a block of ice directly on the tendon. I also wore a knee strap to help get me through the rest of the season. The strap can take some pressure off the tendon to prevent further injury, but it has no rehabilitative effects in itself.

In order to actually rehab the patellar tendon, I did two exercises. The first was basic body squats. The goal of these is to put a light, controlled stress on the quadriceps tendon to provide stimulus for strengthening.  The second exercise I did was seated leg raises with the hip externally rotated (foot pointed out). What the leg raises do is place the responsibility of holding up the lower leg entirely on the inner quad muscle, the vastus medialis, which tends to be weak. That weakness is one of the most common causes of problems related to the patella. These exercises are very easy and do not demand a lot of recovery. I used to do numerous sets of 10 each day. I just made a habit of it, and was able to limit the pain enough to make it through a few months of my season.

I was able to manage that first bout with tendinosis, but I dealt with the problem again on and off for the next several years. It turns out the approach given to me by my athletic trainer was far from ideal for a few reasons.
1. Icing is worthless.
2. Flexibility was not addressed.
3. Squat mechanics were not addressed.
Through my experience and education, I have learned a lot about how to effectively prevent and eliminate jumper’s knee. The following info has helped a lot of people.

There are a few common causes of jumper’s knee. Identifying your particular cause(s) is important.

Problem: Poor Flexibility

Tight muscles experience more stress than loose muscles. The same can be said of the tendons attached to those muscles. Poor quadriceps flexibility increases the amount of stress on the quadriceps tendon. The solution is simple: stretch the quad. Most people are familiar with a basic quad stretch. You should be able to touch your heel to your butt. Most people can do that. However, that stretch neglects one of the quad muscles, the rectus femoris. Most people are not aware of this muscle, so it’s commonly very tight. For some people, simply stretching the rectus femoris completely eliminates jumper’s knee. Watch the video below.

An inflexible quad muscle directly contributes to quad tendon pain. But at the same time, poor all-around flexibility can indirectly cause problems by causing poor biomechanics. For example, the hips are the most powerful joint in the body. Athletic movement should be largely driven by the hips, AKA hip-dominant. A person with tight hips and hamstrings may not be able to properly load the hips. The consequence is greater knee stress and higher risk of things like tendinosis. It is very important to not just address quad flexibility but to have good all-around flexibility to allow proper mechanics and prevent all sorts of problems including jumper’s knee.

Problem: Lack of Strength

Weak muscles mean weak tendons. Getting strong is one of the best ways to prevent tendon problems as well as all kinds of injuries. Specifically for jumper’s knee, strengthening the quads with squats is highly effective. But once again, we have to consider the rectus femoris. Because it crosses the hip joint, it is not lengthened like the other quad muscles during squats and many other common strength exercises. So it is very easy to neglect rectus femoris strength. Fortunately the solution is simple. Do lunges. More on that here: Pain Above the Knee Cap? So doing squats and lunges will help develop strong, healthy quad tendons. But it is important to understand that these exercises make the tendon strong, because they place a lot of stress on it. If the tendon is in an unhealthy condition, the stress of squats and lunges will likely make things worse. You will most likely have to use gentler exercises and address other issues in order to work your way toward using squats and lunges safely.

Problem: Knee Valgus

This is a quite common and quite problematic mechanical flaw. Knee valgus is a term for inward bowing of the knees. We’ll be talking about knee valgus, the movement, not valgus deformity where the knees are permanently bent inwards. Knee valgus is a common cause of patellar tendinosis. During knee loading and extension, the quadriceps should pull the patellar tendon in a straight line. But if the knees bow inward, the tendon gets slightly curved and twisted. That creates stress in multiple directions. The structure of tendons is designed to provide tensile strength in one straight line. Multi-directional stress is not something a tendon can effectively adapt to. An appropriate amount of stress makes tendons stronger, but knee valgus places unhealthy stress on the patellar tendon. It also creates improper tracking of the patella through the femoral groove. This can cause patello-femoral pain, which is similar to patellar tendinosis pain but located in different spots surrounding the patella. Knee valgus also increases risk of injury to the menisci and the ligaments (LCL, MCL, ACL, PCL) of the knee. On top of all the injury risk, knee valgus reduces athleticism. This is a problem that needs to be fixed.

Biomechanical flaws generally have a variety of possible causes. Often times the source of the problem is tight and/or weak muscles. Thus the general solution is stretching and proper lifting that develop all-around flexibility and strength. You can correct a lot of issues with basic stretching and strengthening. Let’s consider some specific factors influencing knee valgus.

1. WEAK HIP MUSCLES? The generic source of knee valgus identified by a lot of physical therapists is weak hip abductor muscles. The logic here is simple. Knee valgus includes hip ADDuction, the femur moving toward the midline of the body. In theory, this occurs because the ABductors, the muscles that pull the femur away from the mid-line of the body, are weak. The prescription then is to do hip abduction exercises. This may be useful for certain populations that have been inactive, but if you’re an athlete, why would your abductors be weak? If they are, is strengthening them in isolation effective? In spite of what many think, weak abductors are most often not the cause of knee valgus. If they do need to be strengthened, it should not be done in isolation, but within the context of compound movements like squats and lunges.

Hip abduction exercise, not likely to correct knee valgus or help patellar tendinosis.

2. WEAK VMO. VMO stands for vastus medialis obliquus. This is the inner quadriceps muscle, known for it’s teardrop shape. The VMO is commonly underdeveloped compared to it’s counterpart, the vastus lateralis. This imbalance is commonly cited as the source of patellar tracking problems; the stronger VL pulls the patella laterally. But the quad imbalance is generally not thought to contribute to knee valgus. While the quads do extend the knee, they do not control it’s location in space. That is done by the hip muscles as mentioned above. So again, the widespread belief is that knee valgus is corrected with hip exercises.

In my early training days, I saw on video that I displayed some knee valgus while jumping off two feet. I also knew that my knees had a tendency to collapse during squatting. Following the generic prescription, I decided to use hip abduction exercises. But I had a hard time believing that my abductors were weak. Playing basketball and lifting all the time didn’t make my hip muscles strong? But laying on my side and lifting my leg up in the air would? Really? Sure enough, I found that I was already good at abduction exercises, and doing them regularly did not help me prevent knee valgus during a jump or a squat.

Watching depth jumps is what taught me that abductor strength was definitely not the issue. I saw in myself and some other people a tendency to turn the feet in before hitting the ground in a depth jump. With the feet turned in, the knees go in on landing. Since the internal rotation was happening in the air, it obviously was not the result of valgus force overcoming the strength of the abductors. My body wanted to internally rotate in order to perform the jump. Why? Quad imbalance. Internal rotation allows you to take advantage of an overdeveloped VL and hide the weak VMO. Internal rotation when the foot rotates along with the rest of the leg is actually not a problem. The foot, shin, and femur can still line up together. But when the feet are straight and the thigh and shin turn inwards, we get valgus collapse. You can see that in my jumping in the videos below.

With a weak VMO, you actually get stronger knee extension by going into valgus. During high effort knee extension like a squat or a jump, the knees always go in, because that’s where you get the most strength. It does not matter how strong your abductors are. To correct knee valgus, you have to strengthen the VMO and correct the quad imbalance. This is done by squatting deep with good mechanics. In the long run, good squatting is the key to eliminating jumper’s knee forever. But again, if you are starting out with unhealthy tendons, you may not be able to jump right into squatting. There are some gentle rehab type exercises in the video below and some more options further down the page.

Again, I have to admit that some of my claims contradict the beliefs of many physical therapists. In college, I took a class with the PT graduate students. The professor taught that the quadriceps muscles activate together, so it is impossible to target the VMO specifically. This was based on EMG testing done during a reverse pulling exercise. My response? Maybe the activation is not different between the VMO and the VL. Maybe it is. (I question the research methods.) But something is certainly different between the two muscles during certain movements, or we could never end up with an imbalance in the first place. Ask any basketball player where his or her thighs are burning after playing 30 seconds of defense. It’s the lateral quad. Look at that same player’s leg and note the lack of a VMO. Have that player pull a heavy sled backward with the feet turned out for 60 seconds and ask where the burn is now. It’s right in that nonexistent VMO. Get that player squatting deep with perfect mechanics for a couple months and watch that VMO tear drop appear. It doesn’t matter whether or not we can measure a difference with EMG. Some movements clearly offer more development to one quad muscle or the other.

In these two videos I show the type of squat that will correct knee valgus over time. In the first one I show some easy VMO exercises. In the second one I did the politically correct thing and talked about strengthening the hip abductors. But honestly it’s all about the squats.

3. BAD FEET. Feet that like to turn out and/or roll in always bring knee valgus along with them. In this case, changing foot habits is necessary, starting with habitually pointing the feet straight forward whenever possible. Proper squats are still key as well. Squatting well with bad feet is a challenge, but it can be done by elevating the heels. (See video below.) If you have really bad feet, you may never be able to perfectly line up your foot and shin during explosive movements. But over time proper squatting can still stabilize your mechanics, meaning instead of collapsing in, your knees can hold a stable position, even if that position is not perfect.

Problem: Too Much Stress

This problem is simple. Even with good mechanics, strength, and flexibility, you can still wear your tendons out by doing too much activity that puts physical stress on them. In my experience, this is a rare scenario. Everyone with patellar tendinosis that I have come across has had a mechanical source of the problem. A high volume of stressful activity may have contributed as well, but that by itself is usually not enough. Again, this in my experience. In this rare case, the solution should be simple. Reduce physical stress, and the tendons should heal up.

Problem: Too Little Stress

This one might surprise you. It’s important to understand that stress makes your tendons strong. Too little stress allows them to get weak. Two situations come to mind where this scenario can cause problems.
1. Injury. Someone is forced to rest due to an injury. When they return to sports or training, tendinosis shows up because their tendons got weak from the inactivity. When coming off total rest, be sure to start with a low amount of activity and work your way back up.
2. Exclusive jump training. Some people just train to jump higher and don’t play a sport. When doing this, it is easy to fall into the trap of doing all low volume, high intensity training. It’s the explosion principle. Jumping is all about power and not endurance, right? The problem with this is that connective tissue like tendons and ligaments responds to volume, not intensity. A few sets of depth jumps, cleans, and squats is a great workout for the nervous system, but it is not enough to make the tendons strong. Be sure to get some volume in your training somehow, whether it be playing a sport casually, doing more practice jumps, or running some sprints.

So What’s the Plan?

To sum things up, here’s a list of things you need to do to get rid of jumper’s knee.
1. Stop doing stuff that hurts.
2. Get flexible, particularly in the rectus femoris muscle.
3. Perfect your squat and lunge with body weight.
4. Get strong in the squat and lunge.
5. Use a reasonable volume of activity.

If you have bad feet, step three will involve working on that. If your tendons are starting out in pretty bad condition, you may have to insert another step before number three. If body weight squats and lunges hurt your knees, you need to work up to that level of stress. This is where those VMO exercises are useful as well as some other options listed below.

I have a few rules for effective quad tendon strengthening during rehab.

  1. Avoid deep knee flexion if it hurts. In deep knee flexion, a lot of quad muscle tension is required to extend the knee. Because of this, even a simple deep body weight squat can be more painful than full effort jumps.
  2. Limit high effort eccentric quad contraction. Muscles can generate the highest tension during eccentric (lengthening) contractions. In running and jumping movements, peak muscle/tendon tension occurs during eccentric loading. Many strength training exercises like squats involve a muscle tension peak at the bottom of the movement where the weight is stopped and turned around. Modifying exercises to eliminate those moments of high tension is useful for rehab.
  3. Use long sets and go for a burn. There are two reasons for this. First, as mentioned before, tendons respond to volume. Second, getting a good burn in the quad muscles indicates lactic acid buildup. Lactic acid provokes the release of an enzyme that stimulates collagen synthesis in tendons.

With those guidelines in mind, the following exercises may be useful in the battle against jumper’s knee.

  • Reverse Sled Drags. This exercise features little to no eccentric muscle action, and you can control the amount of knee flexion. Do the sled drags with your feet pointed out to focus on the VMO. Do 3-5 sets that are long enough to give you a really good burn.  I have received several reports of dramatic improvement in jumper’s knee pain after doing this exercise.
  • Box Squats. This is a modification to regular squats that accommodates unhealthy quad tendons. Sitting on the box eliminates the muscle tension peak at the bottom of the movement. And you can use the height of the box to control the amount of knee flexion. Be sure to practice good mechanics with the foot, shin, and femur all lined up. If necessary, this may start out as just sitting down and standing up with no additional weight. Do several sets of 10 reps.
  • Car or Sled Push. Pushing something heavy directly targets the quads without  high force eccentric muscle contraction. Again, you can control how much knee flexion is involved. Be sure to keep your feet pointed straight forward. If they turn out, you will be practicing bad mechanics. Do 3-5 sets long enough to make you burn.
  • Hill or Stair Sprints. Sprinting on flat ground involves a high-speed, high-force eccentric phase. But in a sprint up a hill or up stairs, each step is up to a higher elevation, so the eccentric phase is minimal. Again, be sure to keep your feet straight. I used a hill in a local park that took 6-7 seconds to sprint up. I did 10 trips up the hill using the walk down as my only rest, so I could get a quad burn. This is an exercise that gave me next day improvement.
    You may find that walking down a hill or down stairs hurts your knees, because it involves the exact eccentric action in the quad muscle that you want to avoid. Walking down backward will eliminate that problem.

It can be tricky to find the appropriate amount of physical stress that will promote repair in the quad tendons and not just break them down more. It will likely require some trial and error. Use pain as your guide. With tendinosis, if an exercise hurts it’s probably putting more stress on the tendon than you want. Try out some of these exercises and find a couple that allow you to get some good work in on your quads without hurting your knees. Do one of these exercises every day with stretching. Once your patellar tendons are healthy enough to allow deep body squats, start repping those out with perfect mechanics, and you will be well on your way to healthy knees!