One reason forefoot running prevents IT band injury is that several studies have connected forefoot running to producing two mechanical outputs that effectively safeguard the IT band from injury. They are: reduced stride length and increased step-width. These two mechanical outputs naturally occur when you land with a forefoot strike, and were found to have a corrective effect on mechanical entanglements of the leg, thereby preventing bending strain and tensile stress on the IT band. Read more here!
