Extreme Conditioning

Extreme Conditioning is a Tier 3 perk in Call of Duty 4: Modern Warfare, Call of Duty: World at War and in Call of Duty: Black Ops (Nintendo DS) that doubles the user's sprint time. It returns in Call of Duty: Modern Warfare 3 as a Tier 1 perk, with the same effect. This perk was replaced by Marathon in Call of Duty: Modern Warfare 2 and Call of Duty: Black Ops. Extreme Conditioning does not increase the sprinting speed of the player.

Call of Duty 4: Modern Warfare
"Sprint for longer distances."

- Perk description

This perk allows a player to gain a significant field advantage, such as reaching sniping points or objectives before the other team. Sprinting longer or more frequently disrupts any opponent trying to gain a long range firing advantage. This perk can also be considered as a fallback when being chased or ambushed, sustaining the sprint to take cover and regenerate health.

Combining this perk with an M21 or P90 makes the player sprint for much longer, but this is now only possible on the PC version and Wii version as the Xbox 360 and PS3 versions were patched to remove this bug.

Call of Duty: World at War
Extreme Conditioning is exactly the same in this title as it was in its precursor. Like its Call of Duty 4 predecessor, it is often beat out by more commonly used perks such as Steady Aim and Deep Impact. Extreme Conditioning in World at War is vastly superior compared to the Call of Duty 4 perk. The reason behind this is that the maps in World at War are usually three to fives times bigger than Call of Duty 4, making the doubled sprint time very helpful to people who tend to favor using SMGs on bigger maps (like Cliffside) allowing the player to close the distance against people trying to snipe.

Call of Duty: Black Ops (Nintendo DS)
Extreme Conditioning is in the DS version of ''Call of Duty: Black Ops. ''It is unlocked in Multiplayer by getting kills on the opposing team.

Multiplayer
Extreme Conditioning returns in Call of Duty: Modern Warfare 3 as a Tier 1 perk. It allows users to sprint for eight seconds instead of the usual four. The Pro variant allows users to climb obstacles faster. It is unlocked at level 22, and the Pro version being unlocked after sprinting 20 miles.

Survival
Extreme Conditioning is obtained from the Air Support Armory as a Perk Care Package. It costs 4000 and is unlocked at level 36.

Call of Duty: Black Ops II
Extreme Conditioning makes a return in Black Ops II as a tier 2 perk. It can be stacked upon and it'll become Dexterity.

Trivia

 * In Call of Duty 4: Modern Warfare and Call of Duty: Modern Warfare 3, the perk has an image that resembles an emergency exit sign.
 * A typo appears in Call of Duty: Modern Warfare 3 in which once the first stage of the challenge has been completed on the screen it will say "Extreme Conditioning I: Sprint 0 miles". It should be just 1 mile.
 * In Call of Duty: Modern Warfare 3, Extreme Conditioning can be paired with the USAS 12, MP9, or Skorpion (which gives a unique 75% increase in sprint duration) for 14 seconds of continuous sprinting.