If you’ve ever experienced a prolonged bout of pain right behind or around the knee cap, you could have what’s called patellofemoral pain syndrome. One of the most common injuries in runners and other athletes, it’s better known as “runner’s knee” thanks to its prevalence among runners.
“This injury is usually due to movements that load the knee joint on a flexed position,” says Kim Kaiser, M.D., an assistant professor of orthopaedic surgery and sports medicine at the University Kentucky and team physician for UK athletics.
Any time you hit your stride, you add impact to a bent knee as you take that leap forward, and this is what can cause the pain, especially if your mechanics are off. Running stairs and doing squats can cause the same reaction. In fact, a telltale sign of runner’s knee is more pain when you’re running downstairs or descending steep hills, Kaiser says.
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The good news: Runner’s knee isn’t a structural problem, meaning your ligaments and cartilage are okay, Kaiser says. The problem lies in how your muscles function through the repeated movement of a run.
“Patellofemoral pain is most often a result of abnormal mechanics caused by problems up- or downstream from the knee, forcing the patella to bump against the femoral groove,” says William Roberts, M.D., professor of family medicine and community health at the University of Minnesota and a past president of the American College of Sports Medicine. Think of it like a train car: The patella is like a train on the femoral groove railroad track, says Roberts. When the train and track don’t run smoothly against one another, pain occurs.
The most common culprit of this uncomfortable rubbing is muscle weakness and tightness around the legs and core. Here, we outline where those issues occur, plus what you can do to treat runner’s knee.
Cause: Weak Hips and Inner Quads
“Runners have strong hip flexors and usually weaker posterior hip muscles, like the gluteus medius,” Kaiser says. With weakness in this area, the femur tends to rotate inward, making the patella strike the edge of the femoral groove, causing pressure and pain, Roberts explains. “But by building these muscles you can keep the femur from rotating inward during the weight-bearing phase of your running gait,” he says.
Treatment: Strength Exercises
Kaiser offers these exercises for a mini strength routine that targets all the right muscles to keep your knee and hip in proper alignment. Do them as bodyweight-only or use a resistance band around your thigh, right above the knee joint. Aim for three sets of 15 reps each.
Clamshell: Start lying on one side, propped up on your forearm, shoulder over elbow and hips stacked. Externally rotate top hip while lifting top knee toward the ceiling, keep feet glued together. Lower back down and repeat.
Donkey Kick: Start on all fours, shoulders over wrists and knees right under hips. Extend one leg up and back, foot flexed. Press heel toward the ceiling, making sure back stays flat and knee points straight down. Lower back toward floor and repeat.
Fire Hydrant: Start on all fours, shoulders over wrists and knees right under hips. Keeping knee bent 90 degrees, lift it out to the side and up toward the ceiling. Make sure you don’t drop into the opposite hip. Lower back down to the floor and repeat.
Straight Leg Raise: Sit or lie faceup, legs straight out. Lock out leg as you lift it straight up toward the ceiling. Hold for three to four seconds, then lower back down and repeat. The key is to keep the leg totally straight. You can make sure you’re working the vastus medialis oblique (VMO)—that inner thigh muscle you’re targeting—by placing your hand on the muscle above the knee, slightly toward your midline. It should activate while you lift and hold your leg.
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Cause: Tight Hamstrings or Hips
While weak muscles can cause a misalignment in running form that leads to knee pain, so can tight muscles. Typically, runners will find this limited range of motion in their hamstrings or hips, Kaiser says.
Treatment: Stretch and Foam Roll
The best way to avoid and treat tightness is by working on overall flexibility—in other words, stretching and foam rolling every day, Kaiser says. To stretch your hamstrings, simply lie on your back and pull one leg gently back toward your chest. For your hips, perform a running lunge: With one foot in front, place the opposite knee on the ground and press your hips forward, engaging your back glute to release the hip.
To get into your piriformis—the small muscle under the glute max that helps with hip rotation and can also cause tightness—do a figure four stretch. Lying on your back, cross left ankle over right knee, grab the back of the right thigh and pull it toward your chest.
Using a lacrosse ball or tennis ball to roll out the posterior glute muscle, IT bands, quads, and hamstrings is also a good idea, Kaiser says.
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When to See a Doctor
If there’s any swelling at the knee joint, get it checked out by a doc, Kaiser suggests. They can pinpoint exactly what’s causing the issue and rule out any structural damage, as well as provide a gait analysis to help improve your run mechanics. Also, if you experience the pain and start doing the above-mentioned strengthening and stretching work, and it doesn’t improve in a few weeks, then it’s time to see a pro to figure out the best treatment for your runner’s knee.
“If you have a big race coming up, we can also help speed up recovery,” Kaiser says. It’s not a bad idea if you’re looking to push your pace and don’t want to worry about discomfort.
Other Risk Factors
Women tend to be more prone to runner’s knee, thanks to wider set hips, Kaiser says. Working on hip and quad strength should reduce risk of pain.
Also, those with flat feet are more likely feel discomfort in the knee cap, which is why footwear is super important, Kaiser adds. In this case, you want more rigid arch support and a custom shoe or orthotics will help. A sports medicine doctor or physical therapist can set that up.
One final way to avoid any overuse injury is simply switching up your activity more often, Kaiser says. Do some extra yoga sessions or strength workouts on weeks you’re feeling discomfort, knowing it’s okay to take a rest day too.
Additional Runner’s Knee Treatments
A physical therapist or sports medicine doctor can easily help with more advanced treatments for knee pain, including more aggressive strength programs, taping the knee cap in a certain direction, or using a brace to help keep the knee in place as you get stronger and master pain-free form.
If you develop arthritis behind the knee cap—more common in older individuals—then there are even more solutions that go beyond the typical physical-based treatments. For instance, a glucosamine supplement can assist in strengthening the joints, but only if you have cartilage damage (not your typical runner’s knee). Also, turmeric can also help reduce inflammation in the body, which can help those with joint problems. But again, that only applies to those with more structural issues, not the average runner with poor mechanics.
The Bottom Line
While lots of runners do get knee pain, that doesn’t mean it’s just something you have to deal with on the daily. “Don’t feel like you have to run through it,” Kaiser says. “There’s more advanced things we can do.”
Roberts agrees. “I would suggest keeping your mileage below the pain threshold and meet with a physical therapist who can make sure your pelvis is properly aligned and guide you through a strengthening program to improve the mechanics of your patellofemoral joint,” he says. “This investment in kinetic chain evaluation and core strengthening will pay off with long term dividends of pain-free running.”
Mallory Creveling, an ACE-certified personal trainer and RRCA-certified run coach, joined the Runner's World and Bicycling team in August 2021. She has more than a decade of experience covering fitness, health, and nutrition. As a freelance writer, her work appeared in Women's Health, Self, Men's Journal, Reader's Digest, and more. She has also held staff editorial positions at Family Circle and Shape magazines, as well as DailyBurn.com. A former New Yorker/Brooklynite, she's now based in Easton, PA.
