Quote Originally Posted by Rumblefish View Post
The woman I spoke with assured me that I should be fine provided I drink plenty of fluids before the donation and afterwards, and that it's only recommended not to lift heavy things.
She's got that incredibly backwards! By donating blood, you are removing red blood cells (duh, I know), which severely limits the body's ability to transport oxygen. Your VO2 max (amount of oxygen your body can use) will be lower, as well as your lactate threshold (more likely to be a limiting factor, especially if there are hills or a headwind involved). Why do you think that blood doping is rampant? You ADD red blood cells, and you get increased performance... it works both ways!

As for lifting heavy things, the worst that could happen is some bruising. Your ability to perform one or two repetitions of a heavy lift would not, physiologically speaking, be affected by blood loss.