What Can Cause Knee Pain After Working Out?

Knee pain from exercise? Here are some causes—and what to do about them.

Knee pain is a common exercise complaint—about 25% of adults experience it, per StatPearls. Many physical activities—running, jumping, stretching, bending—can put strain, impact, or body weight directly on the knees, and in turn, cause pain while you work out.

The knee is an intricate joint, involving bones, menisci, muscles, tendons, and ligaments all supporting the joint. If there is damage or stress to any of these components, you may have achy knees. Here are some common causes of pain.

Runner's Knee

Runner's knee, also called patellofemoral pain syndrome (PFPS), is a type of injury to the knee joint. It's the most common type of injury brought on by musculoskeletal (referring to muscles and skeleton together) overuse, per an October 2019 paper published in the journal Annals of Translational Medicine. About 13–30% of runners experience this condition. People can also get runner's knee from trauma or surgery in the area.

PFPS is one of the most common causes of pain in the front of the knee. People also describe it as knee tenderness or a grating sensation, per the National Library of Medicine MedlinePlus resource. The pain can get worse after sitting for a while or getting out of a chair, as well as after squatting, running, or using the stairs, per StatPearls.

People often experience PFPS when they change running mileage or speed, or start doing more stair or hill training. Stress and poor nutrition or sleep can contribute to the injury, per the October 2019 paper.

People generally recover from runner's knee, but it may take a while: About 40% still experience symptoms after one year of treatment, per StatPearls.

Iliotibial Band Friction Syndrome

Iliotibial Band Friction Syndrome (ITBFS) is another type of knee joint injury caused by overuse. It's most frequently seen in long-distance runners, cyclists, skiers, and players of hockey, basketball, or soccer, per StatPearls. About 1.6–12% of these athletes can experience ITBFS.

People feel ITBFS pain in the outer (lateral) part of the knee. It occurs when the iliotibial band—a tendon along the outside of your leg—gets swollen and irritated from rubbing against the bone, typically when you bend, per MedlinePlus. You can get ITBFS if you don't warm up before exercising.

ITBFS symptoms first appear when you start exercising and get better after your warmup. As the condition progresses, you may start feeling pain after warming up as well. Bending the knee during sitting or running down a hill makes the pain worse, per MedlinePlus.

Jumper's Knee

Jumper's knee, also called patellar tendinopathy, patellar tendinitis, or patellar tendonitis, is knee joint injury that primarily affects athletes between ages 15–30, per the October 2019 review. As the name suggests, you can get it after strenuous jumping, often from participating in volleyball, track, and basketball. Long-distance running and skiing can also result in jumper's knee, per StatPearls.

People with jumper's knee typically experience pain below the kneecap, as well as knee stiffness while jumping, kneeling, or climbing stairs, per the American Academy of Family Physicians. Resting is typically painless, per StatPearls.


Knee osteoarthritis (OA) occurs when wear and tear break down some of the joint cartilage (connective tissue). It's the most common disease affecting the knee, and can happen due to injury or overuse. People typically develop it with age: About 3% of people between the ages of 45–54 experience OA, compared to 44% of people 80 years or older, per an October 2013 paper published in the Journal of Open Access Rheumatology.

Knee pain from OA typically gets worse with the following, per StatPearls:

  • Moving around for long periods of time
  • Repetitive bending
  • Using stairs
  • Inactivity
  • The longer you've had the condition

Knee swelling, stiffness, and changes that limit motion can also occur. You may hear a grinding or scraping noise when walking and experience buckling knees, per the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).

If you're worried you might have knee OA, schedule an appointment or ask your primary care provider for a referral to a rheumatologist—the type of healthcare provider who specializes in arthritis and other joint conditions.

Your rheumatologist may also diagnose you with knee pain from a different type of arthritis, such as rheumatoid arthritis, osteoarthritis, lupus, or gout. But OA is the most common type of arthritis—the general name for a condition that causes deterioration or inflammation in the joints—per MedlinePlus.


A bursa is "fluid-filled sac that acts as a cushion between muscles, tendons, and bones," per MedlinePlus. In bursitis, a bursa gets swollen and irritated and you may feel pain in the front of your knee.

The inflammation may occur because of overuse, injury, or repeated pressure (for example, from kneeling). Changes in activity level, such as training for a marathon, may also cause it, as can infection or some types of arthritis.

Symptoms of bursitis include, per MedlinePlus:

  • Pain and tenderness when you press on the knee
  • Stiffness when moving
  • Pain when moving and resting
  • Swelling, warmth, or redness
  • Pain in areas near the knee

Ligament and Cartilage Tears

Ligaments are tissues that connect bones to each other, per MedlinePlus. Two ligaments in particular—the anterior cruciate ligament (ACL) injury and medial collateral ligament (MCL)—can tear and cause knee pain, swelling, and instability, per MedlinePlus.

The ACL runs in the middle of the knee, per MedlinePlus. An ACL injury typically occurs in sports such as basketball, football, soccer, and skiing. You may tear your ACL if you get hit during a tackle, overextend your joint, or quickly stop moving and change direction.

The MCL is on the inside of the knee, preventing it from bending in. The same sports that are associated with ACL injuries can also tear your MCL.

Symptoms of ligament tears in the knee include, per MedlinePlus:

  • A loud popping sound at the time of injury
  • Swelling—within six hours in the case of an ACL tear
  • Pain
  • Feeling unstable—your knee may also shift from side to side in the case of an MCL tear

The meniscus is a "cushion" between the ends of bones in a joint and absorbs shock, per MedlinePlus. It can tear if you twist your knee, kneel, or squat while lifting something heavy. You may also tear it the same way as an ACL: by quickly stopping moving and changing direction or by getting hit.

Symptoms of meniscus tears in the knee include:

  • Pain that gets worse if you put pressure on the knee or walk
  • Swelling the day after the injury
  • Locking of the knee

ACL, MCL, and meniscus tears often occur together, per MedlinePlus.

Strains or Sprains

Strains are muscle tears, also known as pulled muscles, per MedlinePlus. Common strain causes include excessive physical activity, improper warmups before exercise, and poor flexibility.

Sprains are ligament injuries that can occur from tears or excessive stretching, per MedlinePlus. Both strains and sprains are caused by "sudden or unnatural twisting," per MedlinePlus.

Common symptoms of the two injuries are, per MedlinePlus:

  • Pain
  • Swelling
  • Joint stiffness in sprains and difficulty moving the muscle in strains
  • Discoloration or bruising of the skin

Both strains and sprains are considered minor injuries, per MedlinePlus. Warming up properly before exercise can help prevent them.


Home care is the first step to treating knee pain that is not severe. Here are some things you can do, per MedlinePlus:

  • Rest
  • Apply ice
  • Keep your knee raised
  • Wear an elastic bandage or elastic sleeve—you can buy one at a pharmacy
  • Take over-the-counter pain relievers—but talk to your healthcare provider if you take them for more than two days

After the symptoms are reduced, talk to your healthcare provider about customizing a physical therapy program to your condition. For example, people who've had runner's knee benefit from hamstring stretching, quadriceps strengthening, and hip exercises. For jumper's knee, eccentric exercise—a type of exercise that causes your muscles to lengthen—is most effective, per StatPearls.

Cardio may help with arthritis, per the October 2013 paper. Your provider can also prescribe braces or custom-molded shoe inserts, per the American Academy of Orthopaedic Surgeons.

When To See a Healthcare Provider Right Away

Occasionally, you may experience a more serious knee condition, such as a kneecap or bone fracture, or kneecap dislocation. If you experience severe pain, it's always a good idea to see a healthcare provider. Here are some other signs you should get your knee checked out, per MedlinePlus:

  • Buckling, clicking, or locking
  • Deformity or other change in shape
  • Trouble flexing or straightening your knee
  • Fever, redness, or warmth along with swelling
  • Pain after three days of at-home treatment

Treatments for severe knee pain can vary. For some conditions, your provider may give you a steroid injection to reduce pain and swelling. In many cases, they'll refer you for physical therapy. Occasionally, you may need surgery. If you're in a lot of pain, don't hesitate to contact your healthcare provider or head to the emergency room.

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