Fortitude increases chance to resist knockdown effects and increases the shield recharge rate of a Warframe.
This mod can combine with Sure Footed for an 80% chance to resist knockdown, and also combine with Fast Deflection to increase shield recharge rate by 170%. The knockdown resist mechanic does not affect the speed at which you recover from a knockdown (Handspring does). Shield recharge modifiers affect the rate at which you gain shields, but does not shorten the 3-second delay between taking damage and initiating the recharge.
Players will perform a blocking animation along with an energy effect if a successful resistance to knockdown occurs. This animation does halt your movement briefly.