After You Donate Blood .....

..... you can race again in about 2 weeks, according to published research.

Picture by Howard Lake from Flickr

That's about how long it takes before you regain your pre donation levels.

A group of regular blood donor runners with normal blood levels did a 3 kilometre treadmill time trial in this particular study. The time trial was repeated 2, 7, 14 and 28 days after donating blood. Their haemoglobin (Hb) levels were measured on those sessions. Hb is a protein in the red blood cells that ferries oxygen from your lungs to the rest of your body.

3 days after giving blood, the runners were about 5.4 % slower before giving blood. 2 weeks after giving blood, the runners had regained the pre donation speed although Hb levels were still 5.9 % lower.

28 days later, the runners ran as quick as pre donation, but Hb levels were still lower (even though they were higher than after 2 weeks).
This study measured 3 kilometre time trial performance, bear in mind that fif you want to race well for longer events, you may take a longer time to regain your pre donation levels.

The researchers suggest that you can resume training the next day after giving blood, but wait at least 2 weeks before you rave again.

Reference

Zieglar, AK, Grand, J et al (2014). Time Course For The Recovery Of Physical Performance, Blood Hemoglobin, And Ferritin Content After Blood Donation. Transfusion. DOI: 10.11111./trt.12926.