Why Do My Knees Hurt When I Run? 6 Reasons

Whether you're new to running or a veteran marathoner, you may wonder, "Why do my knees hurt when I run?" Causes of knee pain after running can range from runner's knee to having poor form while running to wearing the wrong shoe for your foot shape and stride.

Read on to learn more about why your knees may hurt after you run, how to prevent this, and possible treatment options.

1. Runner's Knee

Running is a high-impact exercise, which means your joints have to absorb and react to high levels of force—and repeatedly. Known clinically as "patellofemoral pain syndrome" (PFPS), runner's knee describes pain at the front of the knee or around the kneecap. It's usually caused by repetitive motions, poor knee-cap alignment from weak and/or tight leg muscles, and occasionally from poor running form.

What Are the Symptoms?

With runner's knee, you'll typically experience pain under your knee cap or at the front of your knee while running, said Sabrina Strickland, MD, a sports medicine doctor at Hospital for Special Surgery in New York City. Other symptoms include:

• Pain during activities when you have to bend your knee (climbing stairs, hiking, etc.)
• Pain in the front of your knee after sitting for a while
• Popping or crackling sound when you bend your knee

How To Treat It

Often, runner's knee is a sign of overuse, which means you'll want to rest it for at least two weeks, said Thanu Jey, DC, CSCS, clinic director at Yorkville Sports Medicine Clinic. Once you've done that, run on softer surfaces like grass or sand, and ice after every run as you get back in the game. If it's a persistent issue, you might want to consider working with a physical therapist to address any muscle weaknesses—particularly in your hips, added Dr. Strickland.

At home, you can treat runner's knee pain with the RICE method—rest, ice, compression, elevation. You can also take nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen and naproxen if these are safe medications for you.

How To Prevent It

First and foremost, increase your mileage slowly and strategically to minimize your risk of overuse injury, suggested Jey. Otherwise, Dr. Strickland recommended pairing your running with plenty of cross-training, stretching, and resistance training to support balanced muscles.

2. IT Band Syndrome

If you have weak hip muscles, your iliotibial band (IT band), a long strip of connective tissue that runs from the outside of your hip to the outside of your knee, may experience extra strain when you run. As a result, it can rub against your thigh bone or knee enough to cause irritation, swelling, and pain, known as IT band syndrome, or ITBS.

What Are the Symptoms?

You'll feel pain on the outside of your knee—and may even notice some popping or clicking sensations there. Pain typically appears when you finish running but can be present at any point in your workout. It may be more painful when you run up hills or increase your stride.

How To Treat It

As with a runner's knee, your best bet for easing ITBS pain is to rest it for at least a week to allow irritation to die down, suggested Jey. Foam rolling and stretching regularly is important, added Dr. Strickland.

A healthcare provider might explore physical therapy and corticosteroid injections as treatment.

How To Prevent It

"A good routine of stretching tight muscles and strengthening hip muscles will do wonders for keeping ITBS from affecting your workout routine," said Jey. Spend time stretching throughout the day and add hip-strengthening exercises like side-lying abductions and clamshells to your workout and warmup routines.

3. Patellar Tendinitis

Also referred to as "jumper's knee," patellar tendinitis is an overuse injury that typically crops up because of the impact of jumping and similar movements. In this case, the patellar tendon, which connects your knee cap to your shin bone) becomes inflamed—and even torn. According to Dr. Strickland, running in worn-out shoes that no longer offer proper support can also contribute.

What Are the Symptoms?

Patellar tendinitis typically presents as pain just below the kneecap, where your patellar tendon attaches to your shin bone. People with this issue might also notice pain when they first start running, get up from sitting down, or stretch, added Dr. Strickland. Other symptoms include:

• Bruising
• Cramping
• Difficulty walking
• An indentation at the bottom of your kneecap
• Kneecap movement toward your thigh
• Tenderness

How To Treat It

As with other overuse injuries, the RICE method can help alleviate pain. From there, Dr. Strickland recommended checking whether you need new running shoes, while Jey recommended considering wearing a knee brace that can lessen some of the force put on your patellar tendon.

If your tendinitis escalates to a potential tear, your healthcare provider may recommend imaging to decide further treatment. Note: Healthcare providers avoid treating jumper's knee with corticosteroid injections because they've been shown to further weaken the tendon.

How To Prevent It

For good measure, Dr. Strickland recommended changing your running shoes every 250 to 300 miles. In your actual training, adding quad-strengthening exercises to your routine (think squats and leg extensions) can help protect your patellar tendon from future trouble.

4. Arthritis

Arthritis is the inflammation of joint. The articular cartilage—a smooth, shiny covering on the bones of our joints—wears down. Your knee can experience osteoarthritis, rheumatoid arthritis, and/or posttraumatic arthritis.

What Are the Symptoms?

If you have any type of arthritis in your knee, your kneecap may feel painful and inflamed. Other symptoms include:

• Pain that's worse in the morning or after you've rested
• Pain that seems to change with the weather
• Locking, sticking, or buckling knees
• Stiff and swollen joint

How To Treat It

Arthritis has no cure but pain management is possible. The type and progression of your arthritis will determine the treatment. Treatments can include:

• Lifestyle changes like minimizing activity that triggers symptoms, adopting low-impact exercises, and managing your weight to reduce stress on joints. "Motion is lotion. When you have arthritis in the knee, it is important to keep active," Jey said. "Swimming is a great way to keep moving while putting less stress on your joints."
• Physical therapy to improve strength, flexibility, and mobility.
• Assisted devices like canes, walkers, and knee braces to alleviate pressure on your joints.
• Medications like over-the-counter pain relievers and oral and topical NSAIDs for pain management. Talk to a healthcare provider before trying a new medication.
• Alternative therapies like acupuncture and magnetic pulse therapy, though more research is needed to prove these methods' effectiveness.

How To Prevent It

While there's no guaranteed way to prevent arthritis, limiting the stress put on your knees is your biggest bet in avoiding the pain.

5. Poor Form

If you have imbalances in the muscles involved in running—whether strength imbalances or uneven levels of tightness—they can throw off your form and ultimately put extra stress on your knees, said Jey. Of course, exactly what these imbalances look like—and how they mess with your form and knee health—varies from runner to runner.

What Are the Symptoms?

Since there are so many flavors of poor form, knee pain caused by them is equally variable. "It can hurt anywhere in the knee joint," said Jey. "However, you'll usually feel it on the inside of the knees or within the knee cap."

How To Treat It

Good form is crucial if you want to run pain-free for life, so see a physical therapist who works with many runners, suggested Dr. Strickland. They'll analyze your gait to identify exactly what's going on and prescribe strengthening exercises to help you regain balance.

How To Prevent It

If you're just getting started with running or are planning to up your mileage, get ahead of the game by seeing a PT or running coach who can check your form and give you any necessary tips or corrective exercise suggestions before you ramp up.

6. The Wrong Shoes

Though there's plenty of variation here, knee pain resulting from wearing the wrong shoes often stems from a lack of arch support. In this case, your feet tend to overpronate or fall inward, which then causes your knees to bow inward, putting more stress not only on your knees but on your ankles and hips, too, explained Jey.

What Are the Symptoms?

Pain anywhere in your knee could indicate you need different shoes—but in the case of overpronation due to shoes that aren't supportive enough, you'll likely feel pain on the insides of your knees, said Jey.

How To Treat It

Head to your local running store or even a podiatrist for recommendations of running shoes that deliver on arch support. If you're struggling, consider custom orthotics, which will offer support exactly where you need it most, suggested Jey.

How To Prevent It

Sometimes finding the right running shoes for your feet takes trial and error, said Dr. Strickland. However, spending the time (and money) at a reputable running shoe store can help eliminate some of that.

When To Stop Running Because of Knee Pain

As tempting as it may be to push through discomfort, "any level of knee pain can be an indicator that you should stop and further examine the cause," Jey told Health. Otherwise, you put yourself at risk for more issues down the line.

"If you are sore for a day or two as you ramp up your running program, that is fine, but joint pain is not normal," said Dr. Strickland. So go ahead and drop that "no pain, no gain" mentality.

Do You Have Concerns About Your Knee Pain?

The health of your bones and joints can offer important insights about your overall well-being. If you're experiencing pain in your knees, take the quiz below for personalized tips on how to take care of your bones and joints.

Quiz medically reviewed by Soma Mandal, MD.

When To Contact a Healthcare Provider

If running is a significant part of your life (or you'd at least like it to be), safe is better than sorry when it comes to taking knee pain seriously. "If your pain does not go away after exercise or is persistent every time you perform an activity, it is worth getting the knee evaluated," said Jey. "This will also help prevent further damage, which could keep you out for extended periods of time."

Another key indicator that it's time to see a pro, according to Dr. Strickland, is swelling. Unexplained knee swelling can indicate a serious health concern, so don't let it go unchecked.

A Quick Review

No matter your running level, you may at one point notice your knees hurt when you run. Several possible causes could be behind this pain, including runner's knee, jumper's knee, the wrong shoes, or incorrect running form.

Depending on the cause, you may experience knee pain, tenderness, swelling, or more severe symptoms. You should rest and consider seeing a healthcare provider if your knee pain persists so you do not risk further injuring yourself.