Knee pain is common in middle-aged and elderly patients, mostly with degenerative disease knee osteoarthritis, however, young adult patients with knee pain, especially in the lateral knee, and who run frequently need to pay attention to iliotibial fascia friction syndrome. Due to long-term repetitive activities, the knee joint is the main site of running-induced injuries that can cause serious symptoms. The iliotibial bundle is one of them. ITBS is the leading cause of lateral knee pain in runners, accounting for almost 12% of all running-induced injuries, and can occur for a variety of reasons, such as increased running distance, movement on uneven surfaces, excessive pronation, and inadequate hip abduction. The main purpose of this article is to review the underlying causes of ITBS and in turn provide stretching and strength techniques to rehabilitation and fitness coaches to aid in the prevention and rehabilitation of ITBS. Anatomic factors: The broad fascial tensor begins at the proximal iliac crest and connects to the posterior gluteus maximus to form the iliotibial bundle (ITB), a fibrous, hypertrophic bundle that extends from the lateral aspect of the hip to the lateral aspect of the knee and is stimulated by friction of the bundle across the femoral epicondyle when in a 30° flexion position. The ITB has the function of abducting the hip joint and stabilizing the pelvis in a single-leg position. It also plays a role in stabilizing the hip by balancing internal retraction and internal rotation during centrifugal loading of the knee joint. The gluteus medius and the vastus lateralis tensor muscles work together to abduct the hip, but the gluteus medius abducts the hip superficially while the vastus lateralis tensor abducts the hip deeply. The vastus lateralis also acts to flex the hip joint. Causes of ITBS: Muscle imbalance is the main cause of ITB tightness and ITBS. This imbalance is caused by the frequent contraction of the quadriceps and N cord muscles during running, while the gluteus medius becomes relatively weak. Because running is a sagittal movement, the muscles that work primarily in the frontal plane (hip abduction) are not strengthened during normal running. This causes the muscles to be unable to withstand hip abduction during running. In order to counteract the movement of the pelvis and maintain level, the gluteus medius must have the ability to withstand three times the body weight. The movement of the ITB over the femoral condyles is another major cause of ITBS. As the knee extends and flexes, the ITB moves anteriorly and posteriorly over the surface of the femoral epicondyle. Running requires constant flexion and extension, and when the ITB is constantly sliding over the femoral epicondyle, it may lead to irritation of the ITBS. Miller et al. found increased knee flexion in patients with ITBS, which correlated with the height of ITB impingement during heel landing. When landing on the foot during running, the femur is in an inward position relative to the pelvis. In this position, the gluteus medius and broad-fascia tensor contract centrifugally, while contracting centripetally in the support phase. Athletes with weak gluteus medius are more prone to inversion and internal rotation during the mid-stance phase of running gait analysis. Further, because the distal attachment point is located at the femoral epicondyle, weak hip abductors result in greater ITB valgus forces. The valgus force increases friction between the ITB and the femoral epicondyle. Strength Exercises Description Hip hikes Hip hikes strengthen the gluteus medius helping to keep the hip in proper position. The athlete stands on the edge of a box with a height of 4 to 6 inches and places most of the weight on the healthy side. The athlete lowers the affected hip and returns to the starting position. Start with 10 reps/set*2 sets and gradually increase to 15 reps/set*3 sets. Clams with the athlete in the lateral position with the knee flexed at 90°. The athlete adducts and abducts the hip joint (the movement is similar to the opening and closing process of a clam). Start with 15 reps/set * 2 sets and gradually increase to 20 reps/set 3 sets. The use of an elastic band provides greater resistance to the lateral aspect of the knee. Step downs The main purpose of this exercise is to maintain sagittal motion and limit the external rotation force of the affected knee. The athlete stands on a 6-foot step and walks down the step on the healthy knee, keeping the affected knee in front of the 2nd toe. Start with 10 reps/set * 2 sets and gradually increase to 15 reps/set * 3 sets. Lateral monster walks Tie an elastic band to the lateral position of both ankles and flex the knee and hip for lateral movement. When the glutes become fatigued, still keep both knees and hips flexed and avoid extension. Start with 10~15 yards/set*2 sets. Elastic band (45° angle) Place the elastic band on the ankle joint. Begin by extending the affected lower extremity in a 45° direction (i.e., at half the degree of full hip abduction and extension action). Start with 15 reps/set*2 sets and gradually increase to 15 reps/set*3 sets. Conclusion: With these exercises, rehabilitation and fitness coaches can play an active role in reducing the likelihood of ITBS in athletes. These exercises can help athletes recover more quickly and are easy to perform.