A character can be winded from a Critical Hit to their torso, received in either hand-to-hand or ranged combat. If winded, a character's movement is reduced to a walk, as one cannot run when afflicted with the winded condition.
If a character has low doctor skill and tries to use the doctor's bag, it may result in a loss of health and they will be winded.
Fallout 3 and Fallout: New Vegas
Characters can be become winded by having their torso crippled, making them flinch more from damage taken.