Donating Blood and Exercise: What Athletes Should Know

Do you ever give blood? According to the Red Cross, every two seconds there’s an American in need of it, requiring roughly 41,000 donations per day. In the U.S., more than 100 million people are eligible to donate, although only about 9 million do so every year (1). Blood donations help people cope with diseases like sickle cell (affecting more than 90,000 people in the U.S.), and cancer (affecting 14 million (2)), which require frequent blood transfusions. Hospitals also need a continuous supply of fresh blood for surgical patients, laboring mothers, and trauma cases (1,3).

While a necessary and benevolent act, exercisers and competitive athletes should be aware that donating blood is not without physical consequences, including a temporary reduction in endurance performance (4,5,6,7) and in some cases, iron-deficiency (8).

Blood Donation Types and Functions

When giving blood, most donors opt for the more common donation type called “whole blood” donation or some choose a partial donation in which only specific aspects are extracted: plasma, red blood cells (RBCs), or platelets (9-11). During a whole blood donation, blood is taken from the arm and then separated later into its usable parts, which can benefit up to three people (9).

A partial donation is performed nearly the same way except that the donated parts, platelets for example, are machine-separated from the blood, then the remaining parts are returned back to the donors arm (9).

Regardless of donation type, every part of your blood can be (and is, according to the Red Cross) used to help someone in need (9). Here’s how each part of the blood plays a role in your body, and in saving someone’s life. 

Red Blood Cells

Red blood cells support metabolism by delivering oxygen (O2) to working tissues, and the integrity of your O2 delivery system predicts your overall work capacity, or VO2max (5). Therefore, the more RBCs you have, the more oxygen you can deliver, thus enhancing your ability to do work. Endurance athletes who dope with erythropoietin (EPO), a hormone that stimulates the synthesis of new RBCs, know this first-hand because it gives them an edge (though banned by WADA) on their competition (5). On the other end of the spectrum, a trauma victim who’s experienced substantial blood loss relies on replacement RBCs simply to keep her organs alive.

RBCs have a short shelf-life of 42 days, which underscores the need for regular donation (9).

Plasma

Plasma is the water-based netting that contains all of the other blood parts: red and white blood cells, platelets, and proteins. Donated plasma (also called cryoprecipitate – its frozen state that can last up to one year (1)) can be used for either blood transfusions, or to manufacture products that help people with blood-deficiency diseases, like hemophilia – a genetic disorder in which a person’s blood lacks a specific clotting factor found in normal plasma (11).

Platelets

When a blood vessel is damaged, platelets gather around the injury site, and activate plasma clotting factors to stop the bleeding. Donated platelets are routinely given to burn victims, and patients who’ve undergone heart surgery, organ and bone marrow transplants (12). They’re also frequently supplied to cancer patients in chemotherapy treatment (13).

Best Time to Donate

If you’re an athlete that wants to donate blood, it’s completely feasible to do so, but probably best delayed until after your critical training periods. Consider donating during the off-season when training is lighter and performance isn’t an imminent concern (15). Heed the Red Cross’s advice to give yourself 24 hours rest afterward to allow your plasma levels to restore, and hydrate and fuel well before and after your donation (1).