Blood Donation and Cycling

What is the impact of blood donation on cycling and cycling performance?

With a little internet research, I’ve discovered some helpful information. The bulk of the following information is condensed from this site on Runner’s Web, the most detailed and helpful site I found.

• Donating a pint (450cc) of blood results in a depletion of about 10 percent of your total blood volume. Of that, only about 160cc are red blood cells. The fluid component, the remaining 290cc, is replaced within hours, but the red blood cell replacement takes about two months.
• Hemoglobin delivers oxygen to our tissues, and when we exercise our muscles require increased amounts of oxygen. If we lack sufficient hemoglobin, anaerobic, or without oxygen, metabolism will ensue (producing lactic acid) at even seemingly moderate levels of intensity.
• Assuming that your cardiac output (the amount of blood pumped by the heart) remains constant, a drop in hemoglobin concentration associated with donating blood will reduce your oxygen delivery to working muscles by 10 percent. Still, when you are at rest, or even during moderate levels of exercise, oxygen delivery, even at this decreased capacity, far outpaces demand.
• However, once you reach a heart rate that is around 5 to 10 percent below your usual anaerobic threshold, your body’s demand for oxygen will outpace its supply. For example, if your metabolism typically becomes anaerobic at a heart rate of 170, then after donating blood you will become anaerobic at a heart rate of between 157 and 164 beats per minute. This value will fluctuate because your hemoglobin level will be rising slowly each day, thus the most significant effect will be felt in the first few days after donating.

(I comment: In an earlier post I suspected that a lower hemoglobin concentration resulted in reduced flushing of lactic acid out of muscle tissues.  Reading this, it is more likely that I enter the anaerobic exercise much earlier, and therefore produce much more lactic acid at lower heart rates and lower speed on the bike.  I wonder … will exercise with reduced hemoglobin and therefore reduced entry into anaerobic exercise carry over into improved fitness levels as the hemoglobin rises?)

• The key to recovery is ensuring your body has the necessary building blocks — specifically protein and iron — to replace the lost hemoglobin.

The bulleted material above, is by Dr. Jeffrey Sankoff, MD, FRCP(C), a triathlete and ER physician based in Denver, Colorado.  It comes originally from Science of Sport: The Effects of Blood Donation on Endurance Athletes
published in Inside Triathalon.

There is plenty more in the Runner’s Web link.   After reading through the material carefully, the most significant elements for me include,

1. When I donate blood, I need to hydrate the day before, the day of, and the day after in order to make sure that I keep my fluid levels up.
2. I will need to take a rest day (minimum) after donating blood.
3. I can expect that blood donation will make my cycling more of an effort and I will enter into the anaerobic threshold at a lower heart rate than normal.  This will increase my lactic acid retention and I will need to extend cool-down activities as if I have worked at a very high intensity.
4. I can expect that blood donation will have an impact on my maximum performance for longer than it will on my usual rides.  I’ll likely notice that in hill climbs and sustaining high speeds.
5. At my present activity levels (I’m not racing), there is no reason I should not continue to donate blood at my usual 4 time per year rate.  In the very unlikely event that I begin racing, I may want to time blood donations so that they occur during non-race parts of the year.
6. My diet post blood donation can emphasize foods higher in iron and protein.  Bring on the red meats, beans, spinach and other high iron foods!

Each cyclist will need to make decisions about the appropriate balance between cycling and blood donation that makes sense for them and the priorities they place on each of these elements.  Regular blood donation has been something that is important for me for decades.