The IT band: if you run, cycle, or do pretty much any exercise with your legs [1], chances are you've heard of it, and not because it was making your workout more comfortable. People typically only learn about their IT band when it's causing them pain [2]. So, what causes this otherwise elusive part of your body to feel tight and wreak havoc on your workouts? POPSUGAR asked two experts.

"The IT band, or iliotibial, is a thick bunch of fibres located on the side of the leg that runs from the top of your hip, along the outside of the thigh and knee, and connects to the shinbone," Jess King [3], an NASM-certified corrective exercise specialist and Peloton [4] instructor, told POPSUGAR. King added that when the IT band is irritated, you may feel pain in your hip, knee, or lower back, or up and down the side of your leg. You may also experience clicking or tenderness in the knee.

What exactly aggravates this band of fibres? King explained that the typical culprits are weak hips and glutes, as well as repetitive movements like running [5] or cycling. As the IT band is repeatedly activated, it causes friction at the top of the hip joint or the knee, resulting in the pain and discomfort you feel.

Though it can feel like the IT band is tight, Austin Martinez, MS, an NSCA-certified strength and conditioning specialist and the director of education for StretchLab [6], explained that this term is a bit misleading. The IT band consists of dense, connective tissues that can't contract like a muscle. "Therefore, oftentimes a 'tight IT band' is not because the IT band is actually tight or tense, but rather the chronic load and impact absorbed by the IT band and surrounding muscles — like the quadriceps, hamstrings, and hip abductors — leads to irritation or inflammation of the area," Martinez told POPSUGAR.

No matter the cause of your IT band issues, both experts agreed they shouldn't be ignored. "If unaddressed, the pain can continue to increase, which can make it difficult to do any activity involving your lower limbs," Martinez said. He recommends stretching — try these targeted stretches [7] after your workouts — as well as corrective exercise to strengthen the muscles surrounding your IT band. As always, if you're concerned about the pain you're experiencing, talk to your doctor.