Long-distance runners may experience pain on the inside of the knee from stress or irritation to the tendons. This pain can happen to anyone at any time during a run, but it's more likely to occur after several miles, especially if you've had knee injuries before. Many runners fix the pain by making a few simple adjustments. If your pain persists or worsens, visit your doctor.
Tendons
Your knee consists of the kneecap, and several tendons and ligaments that connect the bones and muscles of the legs at the knee. Your pain at the inside of the knee is likely due to irritation of at least one of these tendons. The popliteus tendon runs behind the knee and attaches to the tibia or shinbone. When it becomes irritated, it inflames, causing pain. If your knee pain is comorbid with foot pain, it may be inflammation of the extensor digitorum and extensor hallucius longus tendons, two tendons at the inside of the knee that also help flex the foot.
Rotation
While all joints bend and stretch — or flex and extend — the knee also rotates. The rotation of the knee is a delicate process. Its rotation allows a full range of movement and helps with shock absorption, but it isn't meant to twist. Running several miles may incline you to accidentally twisting or over-rotating the knee during your stride, exacerbating your condition.
Form
Run with correct form to avoid or mitigate pain at the inside of the knee. Align your posture so that your feet don't land in front of your center of gravity. This can lead to poor shock absorption, which irritates the tendons that are probably causing your pain. Keep your knees slightly bent at all stages of your stride. Hyperextension stresses the tendons and causes pain during and after your run.
Fatigue
Fatigue may play a large role in the specific knee pain you feel. If pain begins after several miles, you may be running sloppily because of fatigue. Run lightly. If your steps become heavy, you're probably fatigued. Fatigue makes it harder for your body to prevent inflammation, too, because your cells are focused on getting oxygen to your muscles.
Prescriptions
Some runners may be more prone to tendon inflammation or other knee pain because of prescription medications. If you're more susceptible to injury because of medication, running long distances increases your risk by adding overuse as a factor to your likelihood for injury. Some of the prescriptions that may be a problem include treatments for anti-anxiety, stomach acid or cholesterol. Talk to your doctor about this possibility.
