Diastolic blood pressure (DBP)

Diastolic blood pressure (DBP) is the pressure on the artery walls when the heart isn’t pushing blood out.^{1Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 34.} This happens during diastole, when the heart relaxes and fills with blood.^{1Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 34.} DBP is the second, or bottom, number in a blood pressure reading.^{2International Sports Sciences Association, Strength and Conditioning, p. 94.} At rest it averages about 80 mmHg.^{3Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 133.}

DBP gives a sense of how much the blood vessels resist flow, or how stiff they are.^{1Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 34.} It tends to fall when vessels widen and rise when they narrow.^{1Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 34.}

With a cuff and stethoscope, DBP is the pressure at which the tapping sounds disappear.^{4Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 215.}

Unlike systolic pressure, DBP changes very little during aerobic exercise.^{5Schoenfeld and Snarr (eds.), NSCA’s Essentials of Personal Training, 3rd ed., p. 103.} Even during maximal aerobic exercise, it stays near the resting level or drops slightly.^{6Haff and Triplett (eds.), Essentials of Strength Training and Conditioning, 4th ed., p. 134.}

In practice

• During an exercise test, no change or a slight drop in DBP is normal.^{7Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 300.}
• A peak above 90 mmHg, or a rise of more than 10 mmHg over the resting value, is abnormal.^{7Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 300.},^{8Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 301.}
• DBP above 115 mmHg is an exaggerated response. It is a reason to consider stopping the test.^{8Ozemek et al., ACSM’s Guidelines for Exercise Testing and Prescription, 12th ed., p. 301.}
• For limits during a training session, see hypertension.