Let it flow redux

The flames that raced through Victoria have well and truly gone out, but the desire to help has still remained strong. At the time of the fires I looked at what effect donating blood (see: Let it flow) would have on my cycling, and will admit I was slightly relieved when I was told there was a waiting list to donate.

Well, the Red Cross eventually called and with major races months away I put my O+ where my mouth is and parted ways with 470mL of the red stuff. Interest in the subject of donation and performance has continued, so here is the details of my experience.



Getting the stuff out turned out to be easy, I always knew I could do that, but what next. How would my body respond and what would happen to my performance on the bike?

Let's refer back to Scott Saifer's words.

In the hours after a donation your blood volume will be low with a normal hematocrit. Lowered blood volume means impaired exercise ability because lowered blood volume means less blood returning to and filling the heart, reducing stroke volume. It also means reduced blood pressure and a tendency to be light-headed when standing up which is not great for riding a bike.

Right, so the first issue is low blood volume and pressure. I treated this like dehydration at an endurance race. Fluid, consumed regularly, in moderate doses (Half to one litre per hour) before and after the event. After spending 20 minutes relaxing, eating party pies and drinking milkshakes I was able to depart for the leisurely ride home.



Home safe and sound it was time to consider the next issue, red blood cells.

Over the next couple of days your body will replace the blood volume so the low-blood pressure period passes, but the volume is made up with plasma (blood fluid) rather than the normal mix of plasma and blood cells, so your blood will be dilute at that point. That is, you're hematocrit will be low and your performance will be anaemic even though pressure will be normal.

Low hematocrit in the days after a donation will trigger your kidneys to release erythropoetin (EPO) which in turn tells your bone marrow to crank out lots of new red cells. It takes about seven days for a new red cell to develop and be released into the blood once it starts developing, so hematocrit begins to rise again about a week after you make a donation.

Now this Scott fellow sounds like an intelligent bloke, but he didn't mention if there was any way for us to stimulate this process. The best I could come up with was sleep. If your body is in a restive state more energy can go into the reparation processes, in this case red blood cell generation. So for the next couple of days I kept my riding intensity and volume low, ate plenty of iron rich foods and tried to get a good 8 hours sleep per night.



Research on exercise says that exercise performance will be back to normal about 2-3 weeks after a donation but if you are a competitive athlete, you need to think about this a little differently. Your ability to exercise will be normal after three weeks, but you won't have been able to train normally in the intervening three weeks, so the three weeks of low hematocrit are like an illness and will require a month or more of normal exercise to fully rebuild. Full recovery also requires that you have good iron stores beforehand.

The first few days my concentration levels were down a little, but my physical abilities seemed to remain at pre donation levels. I know this because over the next two weeks I put my body through the wringer. Weights, bunch rides, hill rides, racing... you name it, my body went through it in the name of science. Each time I would be concerned that my performance would be off, and each time the body was able to generate normal outputs.

At first I speculated that my tendency towards anaerobic power, meant that my oxygen stores (reduced by the the lower quantity of oxygen carrying red blood cells) weren't as heavily impacted. This can't be true through as the length of the riding means that aerobic exercise was performed. It's possible that my body holds a larger volume of blood and thus the amount removed was a smaller % of the available supplies.

As we've already discussed Scott sounds like a smart bloke, and I'm quite positive his quoted theory is sound, but I suppose it comes down to this for me. Knowing that it hasn't given me a perceived loss to performance and knowing it could change a lot for someone else gives me little excuse not to do it again. I wonder, what's stopping you from donating?

Donating of yourself (literally) is a noble gesture, but if you're unconvinced, then just do it for the free party pies! :)