Couch to 5K
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Effects of donating blood on running performance?

Hi all,

So I ran 5k last Monday which took me 40 mins without stopping, then donated blood on Weds and didn't run again until tonight when I planned to do a gentle 30 mins, but actually I felt so out of breath and heavy legged, I had to walk about 4 or 5 times during what was a very very slow jog - not had to do that for a while so was rather surprised! When I donated the nurse said I should feel fine again the next day so I assumed 5 days later my run would be problem-free. Has anyone else felt any effects on their running after giving blood?

6 Replies

My wife donates blood (I'm banned as I had cancer), and she was told that she would not notice the loss if she left it a day or so. This was the case for her, but we are all different, and we all have good and bad days for running even without visiting the vampires.

Well done for giving blood.


I don't know about giving blood but I have iron issues and that is exactly how I feel when I run. I am waiting for the iron tablets to kick in. Keep an eye on it. It could just of been one of those things or maybe your getting a little cold. Hopefully you will feel better for your next run.


I'm usually fine to run two days later, but will do an easy run. But I will find I'm a bit sluggish. Once I have the date for the blood donation coming to the village hall I try go jiggle my running days so I run the morning before donating in the evening.That way the following day is a rest day anyway.

Have you been consciously drinking plenty to replace the donated pint? And eating iron-rich foods?

As sallycycle says, most runners have 'bad' runs for no reason sometimes, and this may have been the case for you.


I've not had problems running on a Saturday morning after donating on a Friday evening. Until last time. I parkrun-ed (parkran?). I MEANT to take it easy, I'd really meant to, but my body didn't want anyone in front, each time I saw someone I had to go past. It wasn't my fastest run by a few minutes but was probably harder than I should have run, I felt quite light headed at the end, didn't quite need a sit down but come January when we go again I'll just have a trot round the streets the next day, no competitiveness.

It could just have been a bad run day for you, presumably you're not anaemic as they wouldn't have taken from you. See how the next run goes.


Although your body will make up the lost volume of donated blood after 24 hours it will take longer to replace the red blood cells lost. I can't remember how long they take to replenish but it maybe a month or so. Though cold air supposedly more dense and oxygen rich unless I'm remembering wrong. Make sure you are taking enough fluids. I'd go easy your next run but if you're still struggling maybe ceck in with your gp. The volume of blood they take a donation shouldn't be too much to make you unwell ..not if you are usually fit and well. Was it your first donation? It may be ypou are on verge of coming down with a bug or virus?


Try putting a couple of pints back in just before a competition and see what difference it makes... Worked for Lance Armstrong. *ahem*. Without knowing how much biology you know essentially your blod volume replenishes quickly but tbe red blood cells take a while to replenish. As they carry oxygen to your muscles (using a molecule called haemloglobin which contains iron) loss of blood means less oxygen going to your muscles which would make the run harder.


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