Call Of Duty : Modern Warfare 2
This perk is unlocked at the start of the game.
The pro version of Marathon is unlocked once a user has sprinted 26 miles across all games while it is equipped. The pro version allows you to climb ladders and vault over cover more quickly (you will take half the normal time). Aside from the obvious increase of action speed, your sprinting isn't affected by the upgrade.
Call Of Duty : Black Ops