How Soon to Race After Giving Blood

Runners who donate blood might be able to race at their pre-donation level as soon as two weeks later, according to research published in Transfusion.

Nineteen men who were regular blood donors with normal blood values (i.e., not anaemic) did a three-kilometre treadmill time trial. Some time later, they made a standard whole blood donation.

The men repeated the 3K time trial 3, 7, 14 and 28 days after donating. The researchers also measured the men’s haemoglobin concentration on those occasions. Haemoglobin is a protein in red blood cells that carries oxygen from the lungs to the rest of the body.

Three days after giving blood, the men were, on average, 5.4% slower than before giving blood. Performance remained compromised a week later, although not by as much.

By the time trial 14 days after giving blood, the men ran as fast as they had pre-donation, even though haemoglobin levels remained 5.9 per cent lower. Four weeks later, time trial performance remained equivalent to pre-donation; haemoglobin concentration had increased in the preceding 14 days, but was still close to being considered significantly compromised.

Note that this study focused on three-kilometre time trial performance. While a 3K race is still largely an aerobic event, it does draw on anaerobic sources of energy more than longer races such as half marathons do. It’s conceivable that performance in longer races would take longer to rebound after blood donation, given the role of red blood cells in powering long-distance running.

Also, what’s possible in running isn’t necessarily always advisable. If you’re trying to race your best, a longer wait after donating blood could increase your chances of success.

“Training or physical activity can already be performed the day after blood donation albeit with an attenuated endurance capacity,” the researchers wrote. “Overall, we recommend
that in normal male recreational active blood donors at least 14 days are needed to allow full recovery after blood donation before participation in recreational sports competitions.” (Emphasis added to original.)

Concerning hard running after donating blood, Runner’s World columnist William Roberts wrote:

Most people will be reasonably recovered by two weeks and functionally recovered by three to four weeks, if the body has an adequate store and ongoing source of the required ingredients – protein and iron – to replace the lost haemoglobin. For most, eating a balanced diet with protein and iron intake is sufficient. Vegetarians and some female runners may require iron supplementation.

One solution to combining donating blood and racing is to donate a week or so after a goal race, when you don’t have important races in the near future and might be in a recovery phase of training.


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