IT band
noun [ C ] anatomy specialized uk/aɪˈtiː ˌbænd/ us/aɪˈtiː ˌbænd/
髂胫束（iliotibial band 的简称）
a thick piece of tissue in the body that is on the outside of the leg from the top to just below the knee. IT is short for "iliotibial".
Many runners are familiar with the sharp pain associated with IT band syndrome. 很多跑友对髂胫束综合征带来的剧烈疼痛都很熟悉。