When donating blood, 500 millilitres of whole blood are taken from each donor. With a total blood volume of around five to six litres, this corresponds to ten percent, which has no significant impact on everyday life. The situation is different in sport: the loss of blood results in the loss of red blood cells, which transport oxygen from the lungs to the muscles. In addition, the plasma volume also decreases, resulting in a slight overall lack of blood volume, which is compensated for by an increase in the pulse rate and thus the circulation speed of the blood. The lack of volume is compensated for by the body within a few days, but the replacement of the lost blood cells can take up to a hundred days. During this time, maximum performance is limited due to the less favourable oxygen supply, comparable to training at altitude.
It is not necessary to take a break from training after donating blood if you feel well; full performance will return after two to three months. My personal advice for you: At your age and with your level of training, you should limit blood donations to twice a year and schedule your donation dates for late autumn and winter, as you will probably reduce the amount of training you do during this time compared to summer. Taking two to three days off training is also advisable at an older age.
