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?
How Donating Blood Affects Your Running
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.
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.
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.
Have you ever donated blood? Did you notice any effects on your running?