Runner's knee, clinically known as Iliotibial Band Syndrome (ITBS), is a common injury in endurance sports, especially running. The condition involves irritation and inflammation of the iliotibial band, a long tendon running along the outer thigh from the pelvis to just below the knee. The iliotibial band helps stabilize the knee during movement, but repetitive motion or poor biomechanics can cause it to rub against the outer knee joint, leading to pain and swelling. This injury is common in long-distance runners but also affects cyclists and other athletes who perform repetitive leg movements.

Overuse is the most frequent cause of runner's knee. Athletes who run long distances or engage in sports involving continuous motion, like cycling and soccer, are at risk. Additionally, biomechanical issues such as abnormal foot alignment (flat feet or high arches), poor running technique, or weakness in the hip or thigh muscles can increase the likelihood of developing this condition. The pain is typically located on the outer side of the knee, often becoming more intense with activity and subsiding with rest. It may initially present as a mild discomfort, but as the inflammation worsens, the pain can become sharp and disabling.

For targeted support while running, the UD Runner's Knee/Thermal Zone Tights feature graduated compression zones developed specifically for this injury — available for men and women.