Stamina

From Newerth: Savage Wiki

Stamina allows you to leap and sprint. If you run out, you can't sprint or leap anymore, this especially leaves a melee-beast very vulnerable. Jumping also uses stamina, but doesnt require stamina. Your maximum stamina increases at lvl 5. The leap improves at lvl 7.

You should never allow your stamina bar to be completely empty because when it does, it recharges much more slowly then if it were e.g. still half full. Experiment a bit to see for yourself exactly how much you can deplete it without losing the fast recharge.

To instantly restore stamina (and mana/ammo), enter a Garrison/Sublair or Stronghold/Lair and respawn. Two other ways to restore stamina, if you are beast, are using frenzy or hitting an enemy with rabid. Works on humans, enemy beasts, npc, and siege units. Does not work on buildings. Getting the replenish buff from your commander also restores your stamina to maximum. For humans, the only way to regain stamina is respawning or the auto stamina regeneration.