Stiff knee after sitting, running, and exercising: Causes and treatments

stiff kneeKnee joint stiffness can plague us at any age. It may be caused by a recent injury, an acute infection, or even chronic disease such as arthritis. Knee stiffness often restricts our range of motion, limiting our performance and our quality of life. To better understand how a stiff knee can develop, we will have to take an in-depth look at the anatomy of the knee joint itself.

The knee is stabilized by two pairs of ligaments, they are the:

  • Anterior and posterior cruciate ligaments
  • Medial and lateral collateral ligaments


The knee joint also sits on two pieces of cartilage, which permit the bones of the knee to move smoothly against one another. They are known as the menisci.

These various parts of the knee may suffer from an injury, leading to restricted movement, with each presenting differently on diagnosis. However, not all knee stiffness is caused by direct injury to these structures, as fractures to the bone, inflammation of tendons or bursae, and damage to the cartilage knee caps may all produce restricted range of motion due to knee stiffness.

Stiff Knee after Running and Exercising

Stiff knee due to prolonged running or exercising is a common occurrence in both young and old. The knees are not isolated entities—they are part of a connected system of bones, muscles, and ligaments in the legs and they all work together to create smooth extension and range of motion. Cartilage provides much-needed cushion between the bones in the form of a smooth membrane that lines the inner surface of the knee joint. This inner lining of the membrane is filled with synovial fluid that helps the structures in your knees easily slide across one another during motion.

Damage or injury to any of these structures can cause pain and stiffness in your knees after exercise. They commonly occur during sports that require you to pivot quickly, such as tennis or basketball, but can also occur during strenuous exercise that involves a lot of complex movements.

Why Does the Knee Get Stiff after Sitting?

There are circumstances where limiting knee joint movement, as is often the case with seniors, may precipitate knee stiffness. Individuals with osteoarthritis often experience a stiff knee in the morning or after sitting for prolonged periods of time. This is primarily due to the joint already having experienced long-term bone stiffness and swelling, restricting flexibility. Patients with moderate to advanced knee osteoarthritis often find it difficult to straighten out their knee altogether.

Symptoms of Stiff Knee Pain

As previously mentioned, a stiff knee can be the result of many different causes. The following are a list of symptoms you may experience, categorized in terms of severity.

Common symptoms

  • Sharp, burning, stabbing, or aching pain
  • Redness, warmth, swelling

Moderate symptoms (consider medical consult)

  • Fever
  • Muscle weakness
  • Pain or swelling in other joints

Serious symptoms (seek immediate care)

  • Coldness of the feet with weak or absent pulse
  • High fever (greater than 101F)
  • Loss of sensation in the lower leg
  • Obvious breakage or deformity of the bones
  • Paralysis or inability to move a body part
  • Severe bleeding
  • Uncontrollable pain

What Causes Aching Knee Pain?

There are many causes of knee stiffness, all of which cause some degree of discomfort and pain. Considering we use our legs every day, it will be apparent that something is not right with how your knee feels and how it moves, hopefully prompting you to seek the advice of a medical expert. The following are a list of the various causes of knee pain and stiffness.

Knee injuries

Meniscus injury: Damage to the cartilage that lines the knee joint can cause knee stiffness and prevent of smooth motion of the knee. Sometimes, fragments of damaged cartilage can get stuck in the joint, restricting movement (called locking). This may also cause a stiff knee after running.

Sprain: Results from overstretching a ligament, leading to knee stiffness. Swelling may also play a part in reducing the range of motion. This may cause a stiff knee after exercise.

Fracture: Breaking any bone in the knee can cause knee stiffness due to pain, instability, and misalignment.

Ligament injury: Damage to particular ligaments involved in the stability of the joint may cause bleeding into it. This can be seen due to the injury of anterior cruciate and the posterior cruciate ligaments.

Arthrofibrosis: A rare condition that can occur following an injury or surgery and is due to excessive scar tissue adherence, which causes pain to restrict movement.

Tendonitis: Commonly affecting the patellar tendon at the front knee, irritation or degradation of the tendon can affect the pull on the joint, causing weakness and ineffectiveness and limiting the range of motion. The knee feels tight and swollen.

Medical Conditions

Rheumatoid arthritis: A chronic systemic disorder that results in inflammation and fibrosis of joints. It may result in damage to bones and cartilage found within a joint, causing stiffness. It is often seen with redness, warmth, and swelling, with symptoms coming and going. This disorder can affect multiple joints including the hands, feet, and knees. This may also cause a stiff knee when bending.

Osteoarthritis: Occurs due to the breakdown of cartilage and bone over time, giving it the more common name of “wear-and-tear arthritis.” The joint loses its smooth surface and the space between the bones decreases, causing knee stiffness. Typically, knee stiffness is worse in the mornings or after prolonged rest and becomes better the more you move the joint.

Bursitis: Swelling in one of the bursae (small fluid sacs that contain synovial fluid) due to excessive friction or a sudden blow that results in their compression.

Gout: A type of inflammatory arthritis caused by a buildup of uric acid, resulting in the development of uric acid crystals that have a tendency to become deposited in the knees and feet. Symptoms can come on suddenly over a few hours bringing along with it knee stiffness, redness, agonizing pain and joint warmth. Gout has a tendency for reoccurrence.

Serious but less common causes of stiff knee

Tumor: An abnormal growth in the knee joint seldom ever occurs.

Infection: Examples include osteomyelitis (infection of the bone) or septic arthritis (infectious arthritis).

Potential Complications of a Stiff Knee

If your knee stiffness is improperly treated or neglected, it may put you at risk for developing one or more of the following complications:

  • Absenteeism from work or school
  • Decreased athletic performance
  • Disability
  • Joint deformity and destruction
  • Nerve problems that cause pain, numbness, or tingling
  • Paralysis
  • Permanent joint immobility
  • Permeant or chronic pain

Treatment Tips for Knee Stiffness

Depending on the cause of your knee stiffness, your treatment will vary. The following will all most likely be implemented in some way.

PRICE: For early symptoms of knee stiffness, the PRICE principals can help speed up recovery.

  • Protect the joint from further damage with the use of a brace or padding.
  • Rest from aggravating activities that may worsen the .
  • Ice on the affected joint can reduce swelling and knee stiffness.
  • Compression bandages may help support the injured or damaged knee.
  • Elevation of the leg helps excess fluid in the joint drain away.

Avoid prolonged postures: Stiffness as result of sitting for long stretches of time should be avoided by periodically doing some joint movements. Gently bending the knee backward and forwards or getting up to move around helps lubricate the knee and can prevent knee stiffness from settling in.

Supplements: Many supplements claims to reduce the symptoms of knee stiffness. It is important to do your research on these products to see if they are right for you. Speaking to your doctor may also shed more light on the topic.

Exercises for Stiff Knee

These exercises can be useful for improving your stiff knee.

Straight Leg Lifts: This exercise helps strengthen the muscles which support the knee. To perform this exercise, lay flat on the ground on your back and lift one leg upward as straight as possible and as high as you can go. Hold this pose for about 10 seconds, slowly return the leg down, and repeat with the other leg. Repeat this move ten times each leg.

Half Squat: Stand with your feet shoulder-width apart and slowly begin to bend your knees to lower yourself down, as if you were to sit in a chair. Only bend as much as you can while being comfortable – if you experience pain you have gone too far. Once down, return slowly back up. Repeat this half-squat motion as much as you can.

Hamstring Stretch: Sit on the floor, upright nice and tall. Straighten your legs out in front and relax your feet. Place your palms down by your side and hold – essentially your body should be in the letter L position. You should feel a gentle pull on your hamstrings.

When to See Your Doctor?

If you are concerned that your particular cause of knee stiffness may be due to a more serious complication, speak to your doctor if you experience any of the following conditions

  • You cannot bear weight on your knee at all.
  • You have severe pain even when you’re not putting weight on it, such as during sleep at night.
  • Your knee locks or produces a painful click (painless clicks are okay).
  • Your knees keep giving way.
  • You’re unable to fully bend or straighten your knee.
  • Your knee looks deformed.
  • You are experiencing a fever, redness, or tingling of the calf beneath your affected knee.
  • The pain doesn’t start to improve within a few weeks or you have pain that’s still severe after a few days of caring for your knee at home.


When in doubt, seeing your doctor to get expert medical advice is always a good idea. Your doctor has access to advanced medical tests and procedures that, once done, can put your mind at ease.

A stiff knee isn’t a life sentence, and with proper exercise and other remedies, you can work passed your stiff knee to regain mobility.

Also read: Knee pain at night, causes and home remedies


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