Zombies drag their feet, stumble over rocks, moan loudly and effectively play pinball with their own limbs. Everywhere they go they leave body parts and drippings. When they eat people, they grunt like little piglets and chew with their mouths open. How do victims fail to hear them? They should never be able to sneak up on anyone, unless that person is sleeping. Even then, the disintegrating balls of rotten meat would probably fall down fifty times beforehand and the sleeping victim would awake. Arguably, the zombies in 28 Days Later would be better at catching prey than other zombies of lore, because of their speed and agility. However, they still careen into whatever is in their way and growl incessantly. Also, they are not technically zombies since its a rage virus that infects them and they are not dead. While cardio training would be useful to escape those fast, little creepers, all you need to do is take a brisk walk or listen for grunting to avoid other zombies. If something is growling in the dark, just walk away. Chances are, the lumbering fool isnt fast enough to get you anyway.
