If you press the Sprint Button while running Lara will dash forward.
She can turn left or right while sprinting. (Although some keyboards will keep PC users from doing so. Remapping will help.)
By pressing the Crouch Button Lara will either do the same but end up crouching, enabling her to get into a crawspace much quicker. (Tomb Raider 4, Custom Levels) Or she will come to a sliding halt. (Tomb Raider 3)
You also have to use the sprint button to swing a rope.