Steve in Seattle
Registered
The objective factors include the donor's hemoglobin (blood) level before donation, the hemoglobin level after donation, whether volume loss was replenished, the presence or absence of heart problems (known or unknown), the health of the lungs, and the overall conditioning of the donor -- which can also include such factors as recent illnesses, medications, etc.
As for the subjective factors, in my experience as a hematologist who has worked with high performance, national-class athletes in the past, I can tell you anecdotally that the more fit someone is, the more likely that person is to notice some decrease in his/her performance after blood donation. While one might initially think that the less fit people would notice this more, the opposite actually seems to be true.
The reason, I believe, is because sedentary people never push themselves enough to be able to detect small changes in their physical capacity. If their hemoglobin levels drop one or two points, they may not even notice. On the other hand, people who push themselves with exercise or athletic endeavors often complain that they have lost some of their capacity after donating blood. And why not? It is just the opposite of blood doping, if you think about it.
Nope, I have to disagree.
A 340 pound male, healthy enough to dive, but really obese by BMI standards will see less changes in heme levels from the same donation vs a skinny 170 pound man of the same height. Why? Because blood VOLUME and hemoglobin mass removed is proportionally less in the large man if both donate 1 pint. Blood volume is not directly proportional to total mass, but its close. Surgeons and anesthesiologists actually calculate this with various formula, but it's usually about 70 mL/kg for a healthy male (BV = 70/[BMI/22]^0.5).
68 mL/kg (5.1L total) for the 170pound guy (23.1 BMI),
and 48.5 ml/kg (7.3L total) for the obese man (46.1 BMI) assuming they're both 6 feet tall.
As you can imagine, a 1L loss of blood from a 5.1L body vs a 7.3L body makes a HUGE difference in volume, but after the plasma levels return (the next day), RBC and other blood solutes with longer-replacement times are much lower in the "healthier" man.
The other issue of course is that the liver regulates a lot of blood chemistry values, and the larger man would also have a larger liver making it more likely he could produce higher levels of EPO sooner.
BTW, the lost blood volume itself is NOT a problem... a large man who donates 900cc is able to donate that amount twice a week ad infinim. Plasma, the bulk of your blood volume is NOT the issue. Erythrocyte concentration however IS an issue.
Red Blood Cells (RBC) are responsible for O2 transport from the lungs to myoglobin in skeletal muscle. The loss of hemoglobin(which is packed into RBCs) is replaced by the body when stimulated by the liver... when it releases EPO hormone. This is why EPO doping is so dangerous... it stimulates RBC growth in the same blood volume... making the blood thicker and thicker making clots and heart attacks more likely.
The reason smaller men feel the effects of blood donation more than larger men is NOT because the larger men are unaware of what real exercise is... it's that a 1 pint donation DOES have more affect on the donors blood volumes (and after plasma replaces that missing volume, until all solutes are replaced) RBC/heme concentration levels and O2 delivery ability.
Reccomendations:
- If you donate plasma or platelets... no sweat, just give it a day to get your plasma levels back.
- If you donate whole blood? I'd suggest a week if you're skinny... maybe less if you're "larger"
Outside of extreme cases I doubt its a major concern... max O2 isn't exactly an issue with diving... but decreased blood volume could be (nitrogen loading may be the same right after whole blood donation, but the next day when plasma has been replaced and there are less solutes than normal I suspect nitrogen gas diffusion rates would increase?). I'd be interested in seeing someone post a chart for such a thing. Its likely dive charts have enough cushion in them to make this a moot point, but dive computers may narrow that margin for error somewhat.