How big of an issue was cardio in medieval battles?

by Catctus

I can't imagine it was possible to go all out in all that armor and with those weapons all the time, was it customary to conserve energy? To take breaks?

waddahzaabi

As a quick addendum: what about potty breaks? Im sure they wouldn’t mind going in their armour but wouldn’t that cause it to rust / ruin faster? Plus m, diseases?