Disstolic blood pressure measures How fit someone is How much pressure your blood is exerting against the walls of the arteries when the ventricles relax How much pressure your blood is exerting against the walls of the arteries when the ventricles contract How sick someone is

Disstolic blood pressure measures how much pressure your blood is exerting against the walls of the arteries when the ventricles relax. It is the lower of the two numbers in a blood pressure reading, with the first number being the systolic blood pressure (pressure when the heart contracts) and the second number being the diastolic blood pressure (pressure when the heart relaxes).