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The knee has a lot of moving parts that adjust constantly as we shift our weight from one leg to the other, and flex as we retract and swing through each step. All this mobility allows tremendous freedom, vital for the unpredictable world of trail running. But it also provides ample opportunity for the knee to become over-stretched and twisted in stressful and painful ways.
In simple terms, the knee joint is a middleman between our body (the trunk and pelvis) and the ground (our feet). Muscles of the feet and lower leg help control the knee joint from the below, while muscles from the hip and trunk help control it from above. A healthy, stable knee joint depends on landing stress (or lack thereof) initiated in the lower body, and on central hip and core stability to keep things aligned between landing and push-off.
The three most common areas of knee pain
The knee joint
The primary knee joint, known more technically as the tibiofemoral joint,
joins the tibia (lower-leg bone) and the femur (upper -eg bone). It connects them with a combination of ligaments, thick strands of tough collagen fiber, horseshoe-shaped pads called menisci, a shiny shield of protective tissue called cartilage and the joint capsule (synovium), which is like a leathery balloon filled with fluid that lubricates and provides nutrients for the bones and connective tissue.
Depending on how force is distributed through the joint, any number of these tissues can become irritated, strained or torn. Strains and tears in the joint tissue strike fear into most runners, but generalized irritation is far more common than outright strains or tears.
The kneecap (patella)
The patella is a separate bone that sits in a groove in the lower femur, which is called the patellofemoral joint. The patella protects the front of the knee joint, and connects the quadriceps with the patellar tendon. Various other tissues also tether into the kneecap from various directions,
like a series of stretchy tie-down straps. By design, the patella is more mobile than the primary knee joint. However it is just as prone to irritation.
The lateral knee
The outside of the knee is an important junction for several stabilizing tissues, including ligaments, quad muscles and a fibrous connective tissue
called the iliotibial band (IT band). The IT band inserts across the lateral knee, to the outside of the tibia and helps prevent the knee from collapsing inward.
The lateral knee (and IT band, in particular) tends to absorb a lot of landing stress, which is exacerbated from landing with your foot too far in front of the body or from inward collapse of the knee.
A Four Dimensional Treatment Approach
You should be able to fully flex and extend your knee, and slide your kneecap at least a half centimeter in all four directions, without pain.
However, general overuse and poor knee alignment can cause the joint tissue to tighten, limiting full mobility.
If the pain is significant, consult a sports medicine professional. If you have full mobility, but your knee feels tight, try these stretches.
Quadriceps (knee-flexion) stretch
Stand and pull your knee straight back toward your buttocks, holding onto the top of your foot (right hand/right leg and vice versa). Maintain some abdominal stability to avoid over-arching your back and to accentuate the stretch. Stretch with the goal of having equal flexibility on both sides. Most healthy runners should be able to touch heel to butt.
Lateral knee and IT band active self massage
Find the stiff or sore spot with a finger. Hold firm pressure on the area, and apply cross-friction massage by gently and slowly flexing and extending the knee. For chronic cases of tight IT bands, this is an effective technique for restoring mobility.
Very often, knee pain is due to a deficit in hip mobility. A simple runner’s lunge stretch is an effective way to improve hip flexion, extension and abduction. Place a foot up on a knee-high object, then place both hands to the inside of the knee. Take the leg that is still on the ground and carefully extend it backward, keeping the foot pointed straight ahead. Be sure both sides are equally flexible.
Most knee pain is caused by a combination of excessive landing forces and a loss of neutral knee-joint alignment. Neutral alignment places the center of the knee over the second or third toe. The most common misalignment, called knee valgus, is where the knee joint collapses inward.
What kind of injuries can result from a misaligned knee? They sky’s the limit. Misalignment can cause strain and pain anywhere inside, outside or in the middle of the knee joint—from diagnostic tissue trauma like full tears and fractures, to generalized irritation. Knee valgus, in particular, can cause the muscles and connective tissue around the knee to become overstretched and painful.
Strengthening the muscles above and below the knee can improve landing and push-off stability. Classic hip-strengthening exercises include hip abduction (e.g. side leg raises), clamshells (lie on your side with your knees bent and stacked, and raise the top leg up and back down) and fire hydrants (kneel on all fours and lift one leg out to the side, keeping the bent angle of the knee and maintaining a straight back).
Putting it all together: The Ice Skater
This exercise is one of my favorites, because it closely mimics the specific demands of efficient running alignment. Stand on one leg with your knee aligned over the second or third toe. Extend the opposite leg backwards and to the side at a 30-to-45-degree angle. Repeat the motion slowly for active strength, or hold it like a pose to improve stability endurance.
Avoiding excess stress to the knee is crucial in recovery from and prevention of knee pain. When landing and pushing off, focus on rotating your knee outward. This helps prevent inward collapse, and increases push-off power.
Over-striding can also cause knee pain. Avoid over-striding by maintaining a trunk-forward stride and extending the hip backward. Avoid landing with any part of the foot in front of the body. In this position, your core, hip and thigh muscles control the impact, allowing the knee to land more cushioned and with less stress.
Improving mobility, stability and efficiency can potentially result in rapid improvement in symptoms and running tolerance. However, return to running gradually, making sure not to exceed what your irritated joint tissue can tolerate. More severe and chronic knee pain may require a medical professional to screen for serious pathology and guide the recovery process.
Knee pain doesn’t have to end your running career. Give the joint what it needs—full motion, stability and efficiency—and then gradually progress toward healthier and happier running.
Joe Uhan is a physical therapist, coach and ultramarathon runner. He has a Master’s Degree in Kinesiology and a Doctorate in Physical Therapy, and is a USATF Level II Certified Coach. He ran his first ultra at Autumn Leaves 50 Mile in 2010, and since has placed 4th at the 2015 USATF 100K Trail Championships (and 3rd in 2012), second at the 2014 Waldo 100K and finished M9 at the 2012 Western States 100. He owns and operates Uhan Performance Physiotherapy in Eugene, Oregon, and offers online coaching and running analysis at Uhanperformance.com.