Patellofemoral Pain: Why Your Knees Hurt During Running
Patellofemoral pain, often called runner's knee, is one of the most common reasons runners end up modifying their training mid-season.
It shows up as a dull, aching pain around or behind the kneecap, usually worse with downhill running, stairs, or after sitting for a while with the knee bent.
It develops when the kneecap doesn't track smoothly against the thigh bone during repeated loading, often related to how the hips, quads, and running mechanics distribute force through the knee.
At Summit Physical Therapy and Performance, we see this pattern often in runners and trail runners training on Vermont's hilly terrain. This article explains what's actually happening in the knee, why downhill running plays such a specific role, and which patellofemoral pain syndrome treatments have the best track record.
What Is Patellofemoral Pain Syndrome?
Patellofemoral pain syndrome refers to pain at the front of the knee, around or behind the kneecap, that develops from how the kneecap interacts with the groove at the end of the thigh bone. This joint is under real load every time a runner's foot strikes the ground.
The kneecap acts as a pulley for the quadriceps, helping transmit force from the thigh to the lower leg with each stride. For that system to work smoothly, the kneecap needs to glide within its groove without excessive tilting or shifting.
In most cases, there's no structural damage to see on imaging. The tissue around the kneecap is simply reacting to a mismatch between how much load it's being asked to handle and how much it's currently prepared for.
Why Front Knee Pain Develops During Running
Running is a repetitive, single-leg activity. Every stride asks one leg to briefly support the entire body's weight while absorbing impact and controlling the knee's position. A few factors tend to drive patellofemoral pain.
Quad strength and eccentric control. The quads control knee flexion as the leg absorbs impact, which depends heavily on eccentric strength, meaning the muscle's ability to generate force while lengthening. When eccentric quad capacity falls behind the demand placed on it, the patellofemoral joint absorbs more of that load directly.
Hip and glute strength. The hips have more influence over knee alignment than most runners expect. When hip control is limited, the thigh can rotate inward with each step, pulling the knee slightly out of alignment.
Training load and volume changes. Tissues adapt to load gradually. When mileage, hill repeats, or race-specific workouts increase faster than the knee's current capacity can handle, symptoms tend to show up. This is especially common in early and mid-season training.
Running mechanics. Stride length, cadence, and foot strike all influence how much force reaches the knee. Overstriding tends to increase impact loading. Mechanics aren't something to overhaul on your own, but they're a real piece of the puzzle for recurring front knee pain.
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Why Vermont's Hills Add a Unique Demand
Downhill running requires the quads to work eccentrically at a much higher intensity than flat or uphill running. With every downhill stride, the quads lengthen to control the knee and decelerate the body against gravity, and that demand increases sharply as the grade steepens.
A runner who has built solid mileage on relatively flat roads may find that a long descent on Vermont's trail network creates a level of loading their training hasn't prepared them for. Repeated exposure to steep descents without matching eccentric strength is a common contributor to patellofemoral pain during trail race season.
This doesn't mean Vermont's terrain is something to avoid. It means the eccentric demands of local hills are a real training variable, and preparing for them deliberately makes a real difference in how the knee tolerates a hilly season.
Signs of Patellofemoral Pain
Aching or dull pain around or behind the kneecap
Pain that increases with downhill running, stairs, or squatting
Discomfort after sitting for a while with the knee bent
A sense of the knee feeling achy or fatigued during longer runs
Mild swelling or a grinding sensation, though not present in every case
These patterns are common with patellofemoral pain, but front knee pain can also stem from the patellar tendon, IT band, or meniscus, so they aren't a substitute for an individual evaluation.
Patellofemoral Pain Syndrome Treatments That Address the Cause
Effective treatment focuses on rebuilding the capacity of the tissue around the knee, not just resting until pain fades. Rest alone often provides temporary relief but doesn't address why the joint became overloaded, which is part of why symptoms tend to return once training resumes.
Building eccentric quad capacity through slow tempo squats, step-downs, and controlled lunges directly addresses the demand that downhill running places on the knee. Step-downs translate especially well to running because they load one leg at a time and emphasize the lowering phase.
Hip and glute strengthening, through exercises like side-lying hip abduction and single-leg bridges, targets the muscles responsible for keeping the thigh and knee aligned during single-leg stance.
Training load adjustments matter too, which might mean temporarily reducing downhill mileage or building volume more gradually. A running assessment can help identify whether mechanics, strength deficits, or training load are the bigger factor for a given runner, since these variables often overlap.
Exercise selection should always be individualized. What works for one runner recovering from a mild flare-up may be too aggressive, or not enough, for another.
When to See a Physical Therapist
Many mild cases of patellofemoral pain improve with adjusted training load and consistent strengthening. An evaluation is worth considering when:
Pain persists more than a couple of weeks despite reducing volume
Symptoms return predictably as training volume or hill work increases
Pain doesn't meaningfully improve with rest and basic strength work
There's noticeable asymmetry between how the two legs feel or perform
Symptoms are new heading into a demanding training block
This isn't a sign something has gone seriously wrong. It simply means a closer look at strength, mechanics, and training load, tailored to you, may identify factors that aren't obvious from the outside.
Keep Front Knee Pain From Derailing Your Season
Patellofemoral pain is common among runners, but common doesn't mean it has to be accepted. The pain is usually a signal that the patellofemoral joint is handling more load than its current capacity allows, whether from a training spike, limited eccentric strength, hip control deficits, or Vermont's downhill terrain.
At Summit Physical Therapy and Performance, we help runners and trail runners build the strength and load tolerance to handle a full season of Northern Vermont racing. If front knee pain has been showing up on your runs, especially on the descents, get in touch to schedule a running assessment and build a plan suited to your training and goals.
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Frequently Asked Questions
What is patellofemoral pain syndrome?
Patellofemoral pain syndrome is pain around or behind the kneecap caused by how the kneecap tracks and loads against the thigh bone during movement. It's commonly triggered by activities that bend the knee under load, like running, squatting, or stairs, and is usually related to a combination of quad and hip strength, training load, and running mechanics.
Is patellofemoral pain the same as runner's knee?
Yes, runner's knee is a common name for patellofemoral pain syndrome, though the condition can also affect cyclists and hikers. The name reflects how frequently this pattern shows up in runners due to the repetitive, single-leg loading involved in the sport.
Can I keep running with patellofemoral pain?
Many runners can continue some training, but this usually requires adjusting volume, intensity, or terrain rather than running through pain unchanged. Modifying training while building strength tends to produce better results than either stopping completely or pushing through.
Why does downhill running make patellofemoral pain worse?
Downhill running increases the eccentric demand on the quadriceps, since the muscle has to lengthen under greater force to control the knee against gravity. If quad strength hasn't caught up to that demand, the patellofemoral joint absorbs more of the load directly.
How long does it take to recover from patellofemoral pain?
Recovery timelines vary based on how long symptoms have been present, current training load, strength deficits, and how consistently a rehab plan is followed. Most runners see gradual improvement as strength and load tolerance build, which is why an individualized evaluation is more useful than a generic timeline.