Iliotibial band syndrome, also known as iliotibial band friction syndrome (ITBFS), is a condition most commonly seen in runners and cyclists or other athletes that require frequent bending and straightening of the knee. This movement can lead to friction of the iliotibial band over the side of the femur as the heel strikes the ground during running or at about 30 degrees of flexion. Symptoms usually consist of a burning pain on the outside of the knee that can radiate into the calf. Often pain will occur during activity but can persist for extended periods following.


References
Athletico. (2018). IT Band Syndrome: The Top 5 Causes and Solutions – Athletico. [online] Available at: https://www.athletico.com/2012/06/05/it-band-syndrome-the-top-5-causes-and-solutions/ [Accessed 3 Jun. 2018].
Lee Boyce, T. (2018). What’s Your Weak Link? | T Nation. [online] T NATION. Available at: https://www.t-nation.com/training/whats-your-weak-link [Accessed 3 Jun. 2018].
Physiopedia. (2018). Iliotibial Band Syndrome. [online] Available at: https://www.physio-pedia.com/Iliotibial_Band_Syndrome [Accessed 3 Jun. 2018].
van der Worp, M., van der Horst, N., de Wijer, A., Backx, F. and Nijhuis-van der Sanden, M. (2012). Iliotibial Band Syndrome in Runners. Sports Medicine, 42(11), pp.969-992.