Your IT band gets tight by being overworked, due to your gluts not firing properly. Tight hip flexors also neurologically shut off your gluts. When your gluts stop working your IT band kicks in and does the work for you. You might be wondering: why does everyone have tight IT bands? Well its because we all sit for too long or sleep on our side with our knees bent. Both of these actions cause tight hip flexors. If you are still tight after this stretch, check out my Hip Flexor and Glut stretches for more help!