[quote=@Torch]
[@KahleenCuthald] Kind of, less decrepit though. Basically the Z's off 'World War Z' except running ones are rare. 
[/quote]

How about making it so that the older the zombies are, the deadlier and faster they become? As the virus matures over time. 

Young zombies = Traditional walking zombies.

Been Around For a Bit Zombies = Can go jogging pace, are stronger/more coordinated.

Old Zombies = Fast zombies. Maybe can open doors and climb things?

Just an idea.