How Donating Blood Affects Running

How Donating Blood Affects Running

Last Monday, a few hours after my run, I munched on some oatmeal raisin cookies and rolled up my sleeves to donate blood. Donating blood had been a long-time goal of mine. I dealt with an iron deficiency for several years and was repeatedly turned away when I went to donate. But thanks to iron supplementation, I was finally able to give blood (my levels were actually well above the required minimum!). In the days following, I did notice that donating blood affects running – so naturally, I had to research the topic. 

Giving blood is a highly individual decision, so do not think that I am saying you MUST give blood. This is an individual choice. What I strive to achieve in this article is to discuss how donating blood affects running, particularly since some fallacies do exist on the subject. Despite what you may hear, donating blood will not ruin your season of running – or even keep you out of training for too long. 

Running, like all sports, uses blood as a means of oxygen transportation to the working muscles. When you donate a pint of blood, you experience a brief amount of time where your body has less blood to transport oxygen – and therefore, your muscles are getting less oxygen. When you donate, you leave with the caveat of not to exercise in the few hours following donation due to the risk of lightheadedness and other symptoms. But what about how donating blood affects running in the days and weeks after donation?

The Fitter You are, the Quicker You Recover

Your level of fitness makes a difference. One study claims donating blood can reduce your aerobic power for up to three weeks. That’s a long time – but when you look at the abstract, this study was examining “moderately active” individuals with “average aerobic fitness” and assessing their peak VO2max. Moderately active is a vague term and while many of us runners would claim to be “moderately active” in comparison to the elites of our sport, there is a chance we would exceed the qualifications of this category when compared to the general population.

Meanwhile, a study performed on competitive male cyclists found that, while their maximal performance was decreased for approximately one week, submaximal performance remained unchanged. This means that realistically, you likely won’t notice a significant dip your training, since only a small percentage of running is done at maximal effort (and if you are doing all your runs at maximal effort, you need to assess more than just how a donation will affect you). Chances are, your hard efforts will feel more difficult for the one to two weeks after donating, based on your level of fitness, but your easy runs will feel normal within a couple days.

How Donating Blood Affects Running

What about Women? 

Except..a majority of these subjects studied were men. Thanks to testosterone, men tend to recover more quickly than women. Women also lose blood during menstruation and therefore struggle with fatigue, slower recovery, and iron deficiencies more. So what does research have to say about the effect of blood donation in female athletes?

This is where the research is interesting. A 2014 study from the University of Copenhagen found that healthy men recovered their athletic performance (measured by peak oxygen uptake and time trial performance) at an average of 14 days after whole blood donation. A 2017 study from the University of Copenhagen (featuring some of the same researchers) examined iron-sufficient women and found that their recovery times differed.

Compared to men, women took longer to recover from whole blood donation – in some respects. Within 14 days, the time trial performance of these women returned to its previous level. However, the peak oxygen uptake remained lower for up to 28 days after recovery – on average, twice as long as it took VO2peak to recover in men.

What does this mean in real life? For female runners, you may notice an impact on your speed workouts and races for longer than your equally fit male counterparts. You may notice slightly slower paces in VO2max workouts for a few weeks, while your submaximal efforts will feel back to normal sooner.

As with any stress on the body, what you do in the 24-48 hours after donating blood will make a difference in how quickly you recover. These guidelines will assist you in recovering from your donation: 

  • Treat Recovery as You Would for a Hard Workout: After a hard run, you would hydrate well and eat a combination of carbs and protein to start the recovery process. Follow the same routine after donating blood and focus on hydration and protein intake in the 24-48 hours following.
  • Modify Your Training Schedule: You would not do another hard workout within one to three days after completing one – and the same logic applies to donation. Avoid the temptation to complete a demanding workout too shortly after donation. If your training schedule allows, maintain an easy effort for one full week; if you can’t do that, wait at least 48 hours between the donation and your next hard run.
  • Don’t Run on Empty: In the week or two after giving blood, be sure you are well hydrated and well fueled when going into your runs. This will help you feel stronger in your workouts, since you won’t have to contend with poor hydration and low blood sugar on top of lower blood volume and lower iron levels.
  • Ignore the GPS: In your first few runs back after a blood donation, your paces may feel hard. Whether you are in the off-season or training for a race, resist the temptation to look at your watch and run by perceived effort instead.
  • Plan Donation Around Goal Races: The two to four weeks before a race may not be an ideal time to donate, particularly if you have big goals and do not race frequently. If you want to donate, consider donating more than four weeks before your goal race or after your race when you are focused on recovery and not training.

What about Anemic Runners?

For an anemic individual, especially one of low body weight, donating a pint of blood during a demanding training season could cause some health issues. But here’s the catch: in order to donate blood, you have to weigh at least 110 pounds (which many elite female runners do not weigh) and have adequate hemoglobin or hematocrit levels. If you are anemic or iron deficient, you cannot donate blood. So quite simply put, if your iron levels are low enough that you are worried about donation affecting your training cycle, you likely will not be able to donate based on the standards.

Key Takeaways

In the scope of things, donating blood affects running enough to notice a perceptible yet temporary difference – but not enough to ruin a training season or warrant significant downtime. Most of us, myself included, do not earn our livelihood based upon race times. A blood donation can save up to three lives – and to me, that’s well worth a lackluster week or two of running (you can read about my week of running after blood donation here). This story of a woman who survived a horrific hit-and-run on her bike and a coma demonstrates just how much of a difference donating a pint – and taking a week or two of your training easy – can make.

Disclaimer: I am not a medical professional. Please follow any tips with prudence and assess your own individual situation. 

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33 Responses

  1. I have never donated blood. I want to and I should but it’s one of those things that I always seem to forget about it. I’ll see the sign advertising that there’s a donation next week and think YES! I’ll do that. But then I don’t. Maybe I should put it in my calendar like an appointment so I WILL do it?

  2. I used to donate blood all.the.time and I haven’t in a really long time but I’m not sure why? Maybe because more blood drives were conveniently set up? Whatever the reason I’m glad you put this back on my radar because I love being a blood donor and there is always a need. It’s also good to know that it won’t really impact my training. Good stuff, as usual. Thanks!

  3. Thank you so much for assembling all this info into one blogpost! I gave blood last year, but chose to wait until after my first marathon training season was over, in case of any adverse effects. I remember trying to find research on this topic or a good answer and I swear, there was almost NOTHING out there that was even semi-cohesive. Thanks for shedding light on this important topic!

  4. I have been a runner and a frequent blood donor. When donating whole blood, I did notice that I’d be more easily fatigued for about a week.

    I recently switched to donating platelets. In that process, just the platelets are removed, the blood is returned to your body. I have noticed no fatigue in runs after platelet donations.

      1. You can donate platelets once a week and it helps cancer patients. Cancer patients get about 50% of all platelet donations I have been told.

  5. I have never even thought about how giving blood would affect running. I am terrified of the idea though…my dad gives blood all the time, I just cannot bring myself to do it!

  6. I haven’t given blood because there’s a high possibility I would pass out. I don’t do any strenuous exercise for 24-ish hours even just after a blood test.

  7. I haven’t donated blood and probably won’t since I faint sometimes when I have no choice but to have a blood test but this is very interesting! I love how you are able to research these topics which tend to get medical jargon heavy in those article and then you present it so well for regular people to understand in common terms. 🙂

  8. I donate blood to the American Red Cross 4 times a year. I have A- and it’s one of the less common types I’m told. I can tell my hard effort is labored slightly in the 10-14 days following a donation, but after that it’s back to normal. I usually run 3 to 4 days a week with a long run near the end of the week. I swim one day and ride my road bike one day. So, giving blood does affect me slightly, but I don’t mind. I never give right before a race but usually give right after a race. Works for me. If you can give once or twice a year it’s better than none at all.

      1. Laura: I am an experienced runner with several marathons and competitive track experience. I also donate blood regularly throughout the year (2-3x). I am here to understand how donation of a unit of blood may or may not affect a training outcome. A week before a blood donation I may run a tempo workout at X pace. And I would receive the benefit of that workout. If I then donate blood and after a day or two or recovery I try to do a tempo workout at such a pace that is either calculated to be a slower but “equivalent” pace or is based on actual perception of running “at the same effort” (not same pace) as the prior tempo run, would I not receive the same benefit from both? I may be running at just below my lactate threshold in both cases. So wouldn’t I expect the same training effect? Sure speed is not the same but is the training effect the same? Looking forward to your thoughts. My present position is that the workouts would be equivalent and thus no real loss of training results.

        1. hi!
          I am certainly no expert, but as a long distance runner and regular blood donor, I have thought about the same thing. My understanding is that your pace will drop because your VO2 max drops- because you have less blood and hence less oxygen carrying capacity. However, I wonder if you can stop looking at your pace for a few weeks, if the increased effort for the same amount of exercise might actually benefit your fitness down the line, once your blood levels are back to normal in about 6 weeks…I imagine it to be like altitude training 🙂 Any thoughts?

          1. Hey Donna, Giving blood acting as a sort of altitude training has certainly crossed my mind too. Unfortunately, there seems to be no information online about the long-term effects of donating in the middle of training season. I’m not a trainer, health care prof, etc., but it would almost seem that if you continued to exert yourself and regularly give max effort throughout the recovery process, I would think your body would attempt to adapt to the lower oxygen levels. When your blood is back to normal, I would think all of that hard training at lower oxygen would only benefit you!

  9. fantastic article – I gave yesterday in part due to the promise of getting a Covid antibody result. Foolishly thought I could get in an easy run later but even golf was tiring. One day later an easy 4 miler felt like a long run. Your article will now help me lower expectations for 2 weeks !

  10. Hi Laura,
    I used to run D1 college track competitively, and have also given just over 100 units of blood in the last 20 years. I started both at the same time with unfortunate mixed results!
    Though I have never chased the dream of running a marathon, nor even a half marathon, and my paid proression is a RN, I feel pretty well an authority on the subject of your article now. But again, like so many commenters have agreed, it is a very individual and unique perspective for each person.
    I run for my heart fitness, not for a time or place (individually), nor for any real specific runs. I run mostly causally between 4-8 miles at a time, and no more than 25 miles per week. I’m not an authority on distance running nor intensity.
    The human body continually creates and destroys red blood cells…continually. To give one’s blood up to another is an act of selflessness and this is why I give 3 double units per year. I know the need.
    Personally, I can attest a large drop in pace (and Polar running index number) and large increase in effort for the first 1-2 weeks post donation. I will not get back to my pre donation pacing / running index number for 4-6 weeks. This includes moderate ferrous supplementation post donation for nearly that next month. My pacing per mile will drop between 30-60 seconds per mile on average for the same perceived effort. My heart rate will be raised nearly 10 beats per minute for the first couple days after donating, compared to my last run pre donation. I could imagine donating blood is like a 5-8,000′ elevation climb on your next workout. If I don’t push my pace then I do okay post donation, but if I stick to some preplanned pacing workout, forgetaboutit!
    Donating blood is a personal choice, just as is running and why you run. There is no right or wrong choice to give blood, just choose what is more important to you personally, and enjoy to experience of giving blood, while also being a runner! Cheers!

  11. I donated blood on Saturday and struggled hard with my run on Monday, primarily by getting really stiff calves. I tried to run again today, Weds, and stuff calves again. I also feel like I might be getting shin splints. I’ve never encountered this issue before and now am wondering if it’s related somehow. Perhaps I just need go hydrate more.

  12. Very helpful information. I have just started donating blood recently. Was hesitant because I didn’t want to stop running (temporarily) to donate. I know this is a pretty selfish reason though. This article gave me some good information and with the right approach I think I can still run and donate. Thanks!

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