Halfman wrote:
According a friend of mine friend who is a doctor, the amount of blood you donate has a negligible impact on your performance after 48 hours. Obviously you don't want to give the day before a race, but giving blood on Saturday shouldn't slow you down by 45 seconds for a race the following Saturday. That's all mental. Some assclown at some point told you that giving blood kills you, and you bought into it.
My understanding is that your blood volume (i.e. plasma volume) returns to normal within a day or two, but your red blood cell count takes up to 4 weeks.