Sprintong from enemies in PvE is fine. Highly mobile harrassment characters with 75 HP sprinting without a cooldown might be fine. Peashooter fleeing at 15 HP, jumping onto a roof, regenerating, and sniping you with pea gatling is not okay. It isn't fun. It especially isn't fun because of how difficult rapid, pinpoint aiming is in this game. Giving sprint even a 3 second cooldown after receiving damage would be much more fair and enjoyable. I don't get angry when I lose a gunfight. I get angry when I don't win a gunfight because my opponent ran to the other side of the map instead of finishing it. It's frustrating every time.
Maybe sprinting could slow down healh regen by speed and delay or, as suggested, could have a cooldown( or stamina bar based on remaining health percentage)
