Assuming that by “blood during motion” you mean blood during sexual intercourse, you might be experiencing a state of mucosal rupture caused by increased friction. The rupture is usually very small and cannot be seen easily. The amount of blood is also small (a couple of drops of blood perhaps).


The friction might be caused by insufficent lubrication. The lubrication during intercourse is mainly provided by the female. However, in the case of insufficient lubrication, artificial lubricants might be useful.


You might want to visit a urologist to check if another condition might have caused the mucosal rupture. The physical examination might help to find the mucosal tear. A urethral swab might be needed to rule out the presence of bacteria that might cause an infection and additionally make the mucosa more susceptible to friction and tearing.