The Ultimate Guide to the Most Misunderstood Exercise for Knee Pain

If you’ve had knee pain and seen a physical therapist, orthopedist, or personal trainer for help, there’s a good chance that you’ve been issued this exercise – the “Quad Set”.

And as ubiquitous as a Quad Set is for knee pain, it’s also the most misunderstood exercise for knee pain.

The Quad Set is an isometric exercise of the four muscles of the thigh – the quadriceps muscles: “Quad” for quadriceps and “Set” for “setting” or contracting the muscles.

One of the reasons that the Quad Set is recommended as a solution for knee pain is for a presumed or observed mal-tracking patella or, in other words, your kneecap doesn’t travel in a straight line.

When the quadriceps contracts and pulls on the patella (knee cap), most people assume that the knee cap should travel up the leg in a straight line so if it looks like it doesn’t, that must be why your knee hurts.

The thinking is that one of the quadriceps muscles – the Vastus Medialis Oblique – the one on the inside of the thigh – is weak which then allows your patella (kneecap) to drift or move the wrong way when the muscle tightens.

The incorrect patella motion then causes pain from an increase in pressure between the kneecap and thigh bone.

However, the patella doesn’t move in a straight line when you tighten the thigh muscles normally and, in fact, people who have a mal-tracking patella don’t have any more knee pain than people who don’t.

In one study, 50 people who had kneecap pain were compared with 47 people who had never had kneecap pain. The painful group had better kneecap position and motion than the non-painful group as revealed by MRI.^[1]O’Donnell P, Johnstone C, Watson M, McNally E, Ostlere S. Evaluation of patellar tracking in symptomatic and asymptomatic individuals by magnetic resonance imaging. Skeletal Radiol. 2005 … Continue reading

And, even if this were true, the idea that you can isolate one of the quadriceps muscles and selectively strengthen it, is a myth.

But, strengthening your leg muscles is a good thing to do and, while the Quad Set can get you started down that path, it has an even greater benefit to your knee.

The quad set is an isometric exercise.

An isometric exercise is one in which no movement of a joint occurs. Isometric comes from the Greek words ISOS – same – and METRIA – measuring.

In addition to isometric exercise, muscles can be strengthened by concentric (a shortening of the muscle), eccentric (the muscle lengthens while also contracting) and something I call a variable isometric where the tension in the muscle varies from low to high by the movement of the body while the targeted joint doesn’t move.

With an isometric exercise, the exercised muscle remains the same length. So, in the case of the knee, the knee joint, where the femur (thigh bone) connects to the tibia (shin bone), remains fixed, usually straight.

You can perform the exercise in a variety of positions – lying down, sitting, standing –  but most often it’s done in “long sitting” (as pictured).

One of the main reasons your quadriceps can be weak is the presence of fluid in your knee joint. You might argue that because your knee doesn’t look swollen that it’s not but even a small amount of extra fluid in the joint, small enough you can’t see it, will inhibit or reduce the muscle’s ability to contract ^[3]Spencer, J. D., et al. (1984). “Knee joint effusion and quadriceps reflex inhibition in man.” Arch Phys Med Rehabil 65(4): 171-177.] [Rice, D. A., & McNair, P. J. (2009). Quadriceps … Continue reading

You can try all you want to strengthen your muscles but until the swelling decreases, quad sets will fail to deliver on strengthening the muscles.

While a quad set seems like a simple enough exercise to do, there are a few details that can make a big difference in the effectiveness.

The most common instruction is to push the back of the knee down into the table or floor but sometimes doing this while tightening the muscles as much as possible can create knee pain most often around or under the knee cap.

There are a couple of tweaks to try.

The first one is to think of pulling the kneecap upward toward the thigh like you’re sliding the kneecap up the leg. In fact, in one study, this was shown to work better than the standard method.^[6]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4211772/

The second thing to try is to place a small towel roll under your knee. As you press the knee down into the towel, tighten your hamstring muscles at the same time as you tighten the quadriceps. This reduces the travel of the joint and tends to also reduce focal pressure under the knee cap.

A third option is to lie face down with your toes of the involved leg contacting the floor or table. Your knee will naturally be flexed a few degrees from the positioning of the toes.

Now tighten the quadriceps which will cause the knee to straighten.

Finally, a fourth option is to add tightening of all the leg muscles including the opposite leg. We call this a “sizzler”. The technical term is hyperirradiation. By tightening the other muscles, you increase the neural output to the quadriceps muscle (my colleague Laurie Kertz Kelly explains in her video a few of her tips on performing a quad set).

You can tighten your quadriceps while standing in line at the grocery store, sitting in traffic, on a plane or train. Just about anywhere. And since the goal is not primarily muscle strengthening, the more reps you do, the better.

The Quad Set can help your knee pain a lot but it’s something that takes time to do and time to reveal the benefits.

In that way, it’s a lot like a weight loss plan.

You can’t expect to execute the strategy for weight loss for a couple of weeks and reach your goal.

You have to keep at it, day after day, week after week, and eventually, all of that effort translates into something tangible.

Same thing with Quad Sets for knee pain. Do it every day, day after day and in about two months, you’ll likely notice that your knee feels better.

Thanks for reading.