Usually, only 80% of the blood in the human body participates in the normal circulation, and the other 20% of the blood is stored in tissues and organs such as the liver and spleen, which is in a state of rest and preparation. Once there is massive hemorrhage somewhere in the body, this part of blood will be replenished in time, and the information of blood loss will be immediately transmitted to the bone marrow hematopoietic organs, informing the bone marrow to accelerate hematopoiesis and replenish the "inventory".

Generally speaking, a normal person weighing 50 kg donates 200~400 ml of whole blood at a time, and the red blood cells in the blood donor can recover to the original level within 5 ~ 10 days after blood donation, and platelets, plasma proteins, carbohydrates and water will also recover to the original level soon.

Therefore, proper blood donation will not affect muscle growth and will not cause other health problems.

However, if you exercise regularly, it is suggested that you stop exercising on the day and the second day of blood donation, and slowly recover on the third day according to the intensity of sports and your feelings. You may be more professional than me.

It's the first time I've met someone asking about blood donation and muscle growth. I wonder if this answer will satisfy you.