Last Updated on December 23, 2020 by Heather Hart, ACSM EP, CSCS
Confession: I put off donating blood for the last decade because I was concerned it would negatively affect my running and racing. And frankly, I could never find a window of opportunity where training or racing wasn’t a concern.
But at some point this summer, when training and racing wasn’t a concern (thanks 2020), I decided to quit being so selfish and to go donate. In doing so, I did a lot of research about running after donating blood, and more importantly, I experienced running after giving blood.
And guess what? It wasn’t as huge of a deal as I anticipated.
That said, donating blood CAN have an impact on your running, so it’s important to understand how and why, so you can plan accordingly.
What Runners Need to Know about Giving Blood
In order to best understand how donating blood affects your running, we’ve got to first understand exactly what role blood plays in our body. Yes that’s right, I’m about to dive into some anatomy and physiology – one of my favorite things to do around here. So let’s start with a brief refresher, and stick with me, we’ll answer the question of how blood donation affects your running soon enough.
How Blood Works
Blood is responsible for transporting oxygen and nutrients around the body, and also for transporting cellular waste to the lungs, kidneys, and digestive system to be removed from the body. Oxygen is a necessary component of cellular respiration, which is the process by in which our bodies break down sugar (from the foods you eat) and turn it into adenosine triphosphate (ATP). Think of ATP as the body’s useable form of energy. ATP is then used to perform work at the cellular level (i.e. “do” all of the things your body needs to do to continue living).
In short, we NEED oxygen to function. And runners rely on this process ever more, as the act of running places a greater demand for oxygen on our bodies.
So what is blood made of? Blood consists of approximately 55% plasma, and the other 45% is made up of red blood cells, leukocytes, and platelets.
Plasma is essentially the “liquid” portion of your blood. It’s main purpose is to be the transport system for blood cells, and it plays a critical role in maintaining normal blood pressure. Plasma consists of 92% water, and the remaining 8 percent consists of carbon dioxide, glucose, hormones, proteins, vitamins, fats, and mineral salts.
Red Blood Cells
Red blood cells (also referred to as RBCs, or erythrocytes) contain hemoglobin, the protein that binds to and carries oxygen throughout your body.
White Blood cells
Also know as leukocytes (or WBCs), these cells are responsible for fighting germs and making antibodies. Blood contains far fewer WBCs than red blood cells, although the body can increase WBC production to fight infection.
Also called thrombocytes, platelets are responsible for the clotting process within the body. When an injury occurs, platelets work with proteins called clotting factors to control and stop bleeding.
Types of Blood Donations
Donating blood is exactly what it sounds like: a needle is placed into a vein in your arm, and blood is removed. While that sounds – uncomfortable – whole blood donation is actually a quick and painless process.
According to the American Red Cross, there are four types of blood donations.
- Whole Blood Donation: whole blood (typically a pint per donation) is removed from the donor. This is the most common type of blood donation, and removes your red blood cells, white blood cells, platelets, and plasma.
- Power Red Donation: Also referred to as “double red”, this type of donation is where red blood cells are separated from the other blood components, and then your plasma and platelets is returned back to you. This results in donating a more concentrated amount of red blood cells compared to a whole blood donation.
- Platelet Donation: an apheresis machine collects your platelets along with some plasma, returning your red cells and most of the plasma back to you.
- Plasma Donation: Plasma is collected through an automated process that separates plasma from other blood components, then returns your red blood cells and platelets to you.
Running After Donating Blood
Now that we’ve done an “anatomy and physiology 101” lesson regarding blood and blood donation (thanks for sticking with it), let’s talk about what happens to your body after you donate blood. And more importantly, what to expect when running after donating blood.
What Happens After You Donate Blood
Let’s assume you’ve donated a pint of whole blood, as this is the most common type of donation. You are now down – you guessed it – one whole pint of blood. For reference, on average there are:
- about 9 pints (4.3 liters) of blood in an average-sized female (5 feet 5 inches tall and weighing 165 pounds)
- about 12.2 pints (5.7 l) in an average-sized male (6 feet in height and weighing 200 pounds)
(Sharma R, Sharma S. [Updated 2020 Apr 25])
So on average, you are down about 10% blood volume after a standard whole blood donation. Now after you donate, your body gets to work to quickly replace what was lost. The first thing it does is replace plasma levels, to help stabilize your blood pressure. This happens within hours, and is usually complete within 24 hours post donation.
Next, your platelet and white blood cell numbers begin to climb, returning to normal over the course of a few days.
Red blood cells, however, take longer to replace. It can take up to 6 to 12 weeks before RBCs are back to their previous levels.
How Does This Affect My Running?
At this point, I hope our anatomy lesson has clicked, and you’re already figuring out how donating whole blood can affect your running. After whole blood or double red donation, you have a lower volume of red blood cells, which also means a lower hemoglobin count. Lower hemoglobin equals reduced oxygen carrying capacity to your muscles.
In layman’s terms: running after donating blood is going to feel more difficult.
But how much harder, and how long does this side effect last? There’s a lot of varying research. For example:
- One study using time to exhaustion on cycle ergometer tests demonstrated that VO2max (the maximum amount of oxygen your body can take in and use during exercise) dropped by 15% and time to exhaustion decreased by 19% during the exercise test two hours after a blood donation. VO2 max was still 10% and 7% lower than pre-donation levels at two and seven days post-donation. (Hill, Vingren, Burdette, 2017)
- Another study focusing on female donors, found that peak oxygen uptake in women remained lower for up to 28 days after blood donation. (Stangerup, I., et al, 2017) The slower recovery of performance in women is likely due to menstruation, which can also negatively affect hemoglobin levels. (Ofojekwu et al, 2013)
- What’s more, it appears that repeat donations can have a greater detriment to your running. Studies show that 25-35 percent of regular donors develop iron deficiency. Since iron is needed for red blood cell production, low iron can cause fatigue and anemia, a condition in which the blood has a lower than normal number of red blood cells, and can take many months to recover from.
Ultimately what you need to understand is that donating blood will lower your oxygen carrying capacity temporarily, thus making running feel harder. How long that effect lasts, and to what extent it is actually felt, varies from person to person, and may even vary from donation to donation.
What about Plasma or Platelet Donation?
Because plasma and platelet donation both return red blood cells back to your body during the donation process, any negative effects due to loss in hemoglobin in standard whole blood or double red donation do not apply here.
When donating plasma, running can be effected upwards of 24-72 hours, until plasma levels stabilize. Studies show that the time to exhaustion for those who donated plasma (as opposed to whole blood) was back to their baseline after just two days (Hill, Vingren, Burdette, 2017).
The recovery time for donating platelets is less than whole blood, but it’s probably best to donate platelets in the beginning of your training season or when you know you’ll be able to take a small break.
How Can I Minimize the Effects of Donating Blood on my Running?
Hopefully all of the above information didn’t completely scare you out of donating blood. Because here’s the thing: blood donation is incredibly important. It’s estimated that every year in the United States, 4.5 million people will need a blood transfusion. Yet only 37 percent of the country’s population is able to donate blood. So if you are able to donate, it’s a great and selfless thing to consider doing.
You can minimize the effects of donating blood on your running by taking the following steps:
Plan to donate during off season, or early in a training cycle
Since there’s no denying blood donation can affect your running, plan to donate either during off season, when running goals are not as imperative, or early in your training cycle, when volume and effort is still on the lower end. If you have a goal race coming up, plan to donate at least 4 weeks before (to allow hemoglobin levels to return to normal), or 4 weeks after (to allow your immune system to recover before donation) your race
Plan Your Training Week Around Your Donation.
Plan to donate on a rest day. Further, plan to follow your donation with several days of short, easy effort workouts. When you do return to running, try to train by perceived effort for the first week or so, rather than stressing over pace.
As we’ve discussed, blood is made up of 55% plasma, and plasma consists of 92% water. Staying hydrated before and after blood donation will help prevent your blood pressure from dropping too low, and will help stimulate the post donation increase in plasma levels.
Prior to, and after donation, make sure your diet includes plenty of healthy, iron rich foods. The iron will help your body with hemoglobin production. Examples include: spinach, red meat, fish, poultry, beans, and iron-fortified cereals.
A 2012 NHLBI-supported study measured the effect of low dose daily iron supplementation on the time to recovery of lost hemoglobin and iron after donating a unit of blood. Compared to donors who did not take iron, the donors taking iron supplements returned to pre-donation hemoglobin levels faster in both the lower iron (five weeks versus 23 weeks) and higher iron groups (four weeks versus 11 weeks).
Similarly, donors taking iron supplements recovered lost iron more rapidly than those not receiving supplements (11 weeks versus more than 24 weeks). Without iron supplementation, two thirds of the donors did not recover the iron lost from donating blood after 24 weeks.
As always, please check with your physician first to see if you are a candidate for iron supplementation, as over ingesting iron can come with health risks.
Avoid running 24 hours post donation
Because plasma levels are low, causing lower blood pressure, running immediately or within hours after donation can cause dizziness or even fainting. Further, harder intensity workouts may increase the risk of excessive bleeding from the area where the needle enters your skin. Therefore, the American Red Cross recommends waiting to exercise until your plasma levels normalizes (approximately 24-72 hours).
Ultimately, blood donation is a personal decision for runners.
Personally, I do not regret donating blood. If anything, I regret waiting so long to sign up. While I have certainly experienced a little more lethargy in my runs immediately post donation, overall, I haven’t noticed a huge impact on my running. But then again, I’m not training for the Olympic trials, or anything where a slight decrease in performance will ruin my plans.
Blood donation is an important, selfless gift. However, as mentioned above, not everyone is a great candidate for giving blood (you can read about some of the blood donation requirements HERE). If you’re not sure if blood donation is right for you or your body, or you have added concerns about recovering from blood donation, talk with your doctor first.
Heather Hart is an ACSM certified Exercise Physiologist, NSCA Certified Strength and Conditioning Specialist (CSCS), UESCA certified Ultrarunning Coach, RRCA certified Running Coach, co-founder of Hart Strength and Endurance Coaching, and creator of this site, Relentless Forward Commotion. She is a mom of two teen boys, and has been running and racing distances of 5K to 100+ miles for over a decade. Heather has been writing and encouraging others to find a love for fitness and movement since 2009.