I want  to change the speed of players and zombies.  something like:
 
Players Walk Speed      5
Players Sprint Speed    8
Zombies Walk Speed    7
 
And then if possible have a sprint cooldown for players, so that overtime the zombies would outrun the player. maybe 5 seconds of sprint followed by a cooldown where they couldnt sprint.

Where would I look or change values to achieve this?

The sprint cooldown is a mechanic already in the game. You can have up to four seconds of sprint and if you use all of your sprint you have a cooldown of one second.
If you want the zombies to be able to catch up to the player easier, you could lower the players move speed.

players = get_players();
for( i = 0; i < players.size; i++ )
{
     players[i] setMoveSpeedScale( 0.9 );
}

Thanks man, that should work, though I cant figure out exactly where to place this script

that isnt going to work, that changes the players "max move scale" not current, you also need to factor staminup if your using it, also from the above, its not being corrected or set back ever at all

that isnt going to work, that changes the players "max move scale" not current, you also need to factor staminup if your using it, also from the above, its not being corrected or set back ever at all

SetMoveSpeedScale changes currently applied scale.
weaponfiles have a set number but in script you can scale it using this function.

i.e.
PTRS = 0.85 speed, SetMoveSpeedScale = 1; movement speed = 0.85.
PTRS = 0.85 speed, SetMoveSpeedScale = 2; movement speed = 1.7, double this for adsMoveSpeed as well.

it does?

huh, handy, that fixes something i was working on then... 

You can notice it in my stalker script.