The Athleticism Branch of the Skill Tree is the only skill tree with no pieces of equipment. All of these passive skills will improve your flexibility and survivability. Five are Commando skills, three are Direct Action skills, and one is a Sniper skill. Improved Sprint Recovery and Increased Endurance are strongly recommended skills, giving excellent passive bonuses for very few skill points.
Tier 1[]
Impact Damage Resistance[]
1 Skill Point, Commando, Passive Skill
This skill reduces the amount of damage sustained by falls or collisions.
Falls include jumping down from roofs and sniper towers as well as losing your parachute early from brushing against the corner of a building/tree/telephone pole. Collisions from friendly or enemy vehicles abound in Acquisition and Domination matches. This skill really isn't worth it considering that the only two deaths that this will probably ever save you from are dying when hitting something while paratrooping and being run over. However, when you die when paratrooping, you respawn in about 10 seconds and don't even lose any points, so not really worth it there. Also, when you get run over by your APC you respawn in it, and likely when you survive bein run over by an enemy they will stop, get in the turret of their vehicle, and finish you. So really, don't get this skill.
Improved Shot Detection[]
1 Skill Point, Sniper, Passive Skill
This skill increases the range at which a soldier detects enemy gun fire.
This passive skill shows the direction of enemy fire on your HUD from greater ranges than normal as well as a red indicator triangle above the enemy's head. Also, unsupressed fire will reveal the enemy's location on your minimap from greater distances. Having this skill will allow you to see the direction of incoming suppressed fire as a faint grey indicator on your HUD, but the enemy's position will not be displayed as a red triangle above their head, neither will a red dot appear on your minimap.
Improved Sprint Recovery[]
1 Skill Point, Commando, Passive Skill
This skill increases the speed at which a soldier regains his ability to sprint.
After a certain amount of time sprinting, a soldier must stop and regain their breath. This skill lowers the time before he can begin to run again. It is important to listen to your character's heavy breathing to know when to sprint again—sprinting too early will result in a very short sprint and another heavy breathing "cooldown."
Tier 2[]
Improved Stealth[]
2 Skill Points, Commando, Passive Skill
This skill enables the soldier to avoid motion detection at all speeds except while sprinting.
Normal running, crouched movement, and prone crawling will neither highlight your location on enemy minimaps, nor put a red triangle indicator above your head.
Increased Endurance[]
2 Skill Points, Commando, Passive Skill
This skill increases the amount of time a soldier can sprint without getting tired.
Sprinting duration will increase by approximately 50% with this skill for all armor tiers. (Minor testing shows heavy armor sprinting for almost as long as normal medium armor, medium armor for almost as long as normal light armor, and light armor for almost 1.5x the distance of normal light armor.)
Tier 3[]
Chemical Damage Resistance[]
4 Skill Points, Direct Action, Passive Skill
This skill decreases the amount of damage inflicted by chemical weapons, like poison gas grenades.
Damage from poison gas grenades is exponential rather than constant. This skill reduces the damage per second sustained by poison gas as well as the increase in damage over time by staying inside the gas cloud. [Needs verification and damage details]
Explosive Damage Resistance[]
4 Skill Points, Direct Action, Passive Skill
This skill decreases the amount of damage inflicted by an explosive force.
Any type of explosive damage is reduced by X%. Players may survive a medium-range claymore blast without wearing heavy armor. Grenade damage is reduced depending on the proximity of the blast (reported survival of "dark red" grenade indicator with 1-5HP remaining). RPG and turret rocket damage reduced while on foot. Incoming artillery/bombing strikes reduced especially if under cover (might reduce indirect/splash damage from large explosions). No conclusive testing on exploding objectives (bunker/AA/gates).
Tier 4[]
Increased Health[]
5 Skill Points, Direct Action, Passive Skill
This skill increases the soldier's base health.
Soldiers get a bonus 20 health points; increasing the total to 120. With this skill and Medical Kit/Resuscitate, you will revive other players to a base 60 HP instead of 50. If you resuscitate someone with advanced resuscitation and increased health, you will heal them for 120 health points. Normal healing also comes in larger increments as well. First tier increased health skill raises your health to 106, second tier raises your health to 112 and third tier raises your health to 120. This is a good defensive advantage for shotgunners and medics.