So you had a good run, but the second you stop, here comes that gnawing pain beneath your kneecap.

Or maybe it came on during your run.

What IS this and what can be done about it?

Or maybe you awaken the day after running to feel unbearable pain in the knee upon standing?

Or perhaps after sitting a while and then standing, your knee pain is hollering at you?

Causes of Running Related Pain Under Your Kneecap

I asked Dr. Kevin D. Plancher, MD, MS, FACS, FAAOS, a leading NY orthopaedic surgeon and sports medicine expert, questions about what causes knee pain in runners, and solutions to the aggravating knee pain and aching behind the kneecap, that runners often experience.

This kind of knee discomfort is called patellofemoral pain, and is also known as patellofemoral pain syndrome.

It’s also commonly referred to as chondromalacia, but you’ll soon see why these two terms are not interchangeable.

How can a person self-diagnose chondromalacia/patellar-femoral syndrome? (Some people have a large medical insurance deductible!)

Dr. Plancher explains, “Patellofemoral pain syndrome and chondromalacia patella are two separate entities, and should not be confused with one another.

“Patellofemoral pain syndrome is pain from behind the patella, and chondromalacia patella is fraying and/or damage to the articular cartilage of the patella. Chondromalacia is a surgical finding and not a diagnosis.

“Patellofemoral pain is commonly found in adolescents, especially young females, and has been estimated to account for up to 30% of all injuries seen in sports medicine clinics.

“Patellofemoral pain syndrome is a multifactorial condition, and mechanisms which cause this condition can be overuse or overloading, abnormal patellar tracking, or direct trauma.

“Other factors which may predispose an individual include muscle dysfunction, pes planus foot type, malalignment, muscle and soft-tissue tightness, congenital abnormalities of the patella or patellar groove, etc.”


Dr. Plancher explains, “Symptoms individuals commonly report are pain during and/or after activity, pain after prolonged sitting, crepitus (grinding), stiffness, and a sensation of giving way while ascending/descending or walking on an incline.

“The pain is usually described as a dull or achy sensation and arises from behind the kneecap.”   

(This particular knee discomfort syndrome has also been described as a “fullness” sensation in the knee, or a tightness.)

Will a person with this knee problem necessarily have every single symptom?

Individuals with patellofemoral pain syndrome may experience one or all of the previously listed symptoms,” says Dr. Plancher.

Can a person have knee pain just from running but be free of knee discomfort when climbing stairs or using the gym’s revolving staircase?

Dr. Plancher says, “Patellofemoral pain syndrome is the most common injury in runners, and running on a crowned road (repetitively in the same direction) increases the risk due to the altered biomechanics placed on the foot and ankle.

“Descending stairs typically causes more pain than ascending. This is because when descending, the contact area between the patella and femoral articulation is small, placing a great deal of stress over that small area.

“When ascending, the contact area is larger, therefore distributing the forces over a greater area.

“Patellofemoral joint reaction forces have been calculated at 3-4 times the individual’s body weight while ascending or descending.

“Patellofemoral pain syndrome is also different from jumper’s knee. Jumper’s knee is a layman’s term for patellar tendonitis.

“Patellar tendonitis is an overuse injury to the patellar tendon, which is frequently seen in jumping athletes such as basketball and volleyball players.

“The location of the pain in patellar tendonitis is typically located along the patellar tendon and not from beneath the patella.

“However, patellofemoral pain syndrome can occur in individuals who perform a great deal of jumping.”

Why is it that a person with patellar-femoral syndrome can feel minimal knee pain while running, and barely any knee pain the rest of the day after the running, but then next morning awaken with searing knee pain?

Increased amounts of endorphins are released during moderate to strenuous continuous exercise, which may mask the symptoms during such activities,” says Dr. Plancher.

“This phenomenon can cause more harm than good, as an individual may exceed their physical limit.

“Once the effects of the endorphins wear off, the individual may start to experience pain that they did not during their run.”

Why is it that someone with chondromalacia/patellar-femoral syndrome suffers notably more knee pain after sitting for long periods, but then the knee pain dissipates somewhat after walking around?

“Individuals with patellofemoral pain have an increase in symptoms during prolonged sitting due to the increased pressure from the articulating surfaces over a period of time,” explains Dr. Plancher.

“This often dissipates somewhat after walking a short period, due to the varying forces across the knee during gait.”

The motion of squatting is strongly advised against in someone with chondromalacia/patellar-femoral syndrome, yet the very act of squatting with the thighs parallel to the floor may alleviate the knee pain in some individuals.

In fact, for some this alleviates the discomfort after an entire leg workout session at the gym consisting of squats and leg presses. Why?

Squatting is strongly advised against in individuals with patellofemoral pain syndrome due to the increased stress being placed through the articulation of the patella and patellar groove with active knee flexion,” says Dr. Plancher.

“However, as flexion increases, the surface area of the patella articulating with the patellar groove increases, thus decreasing the overall force placed on the joint, which may be the cause for the decrease in symptoms.”

What would cause the patella to “float” or be wobbly or loose upon lightly pressing on it, while the leg is outstretched on the floor?

Although joint effusion is not commonly associated with isolated patellofemoral pain syndrome, an effusion may occur.

“The increased fluid in the joint may cause the patella to appear to ‘float’ compared to the uninvolved side.

“If a large effusion is present you should seek out care from a qualified sports medicine professional to evaluate if there are other pathologies present.”

At what point can a patient know he’s good to go for all-out exercise, if after the knee is feeling great for a week, he has a relapse? Is this a timeline thing? 

It’s not recommended that an individual return to their normal exercise routine immediately after their pain has resolved,” notes Dr. Plancher.

“It is recommended that the individual gradually progress their training back up to their normal exercise regimen, typically increasing their time and/or distance by 10% each week.”

This may help decrease the chance of recurrence as well as become more confident with her knee.

Gradual increases in training will also help build endurance and may help decrease other musculoskeletal injuries.

Dr. Plancher is founder of Plancher Orthopaedics & Sports Medicine, and lectures globally on issues related to orthopedic procedures and sports injury management.
Lorra Garrick has been covering medical, health and cybersecurity topics for many years, having written thousands of feature articles for a variety of print magazines and websites. She is also a former ACE-certified personal trainer.  


Top image: Shutterstock/Lopolo