High blood pressure affects about one in three adults in the U.S., and in 2006, it killed over 56,000 Americans. Chronic high blood pressure can cause reduced blood flow of the arteries that lead into your heart, enlargement of the heart, heart failure, stroke, kidney scarring and kidney failure, reports MayoClinic.com. The death rate from high blood pressure rose 19.5 percent from 1996 to 2006, and the actual number of deaths spiked by 48.1 percent, reports the American Heart Association. Exercise has varied effects on blood pressure during exercise, but a pattern of daily exercise can reduce hypertension.
Blood Pressure Basics
Each time your heart beats, it forces a surge of blood through your arteries, causing the arteries to expand, much like a balloon expands when you force air into it. Despite the increased volume of space in vessels because of the expansion, blood pressure increases each time your heart beats. Normal blood pressure ranges from 110/70 to 120/80. The first and highest number, the systolic blood pressure, represents the pressure placed on blood vessel walls when your heart contracts and pushes blood out of the heart's chambers. The second number, diastolic blood pressure, is the pressure placed on blood vessel walls between heartbeats.
Causes of High Blood Pressure
Though the causes for high blood pressure are often not known, it occurs when blood flow is restricted. This can occur because plaque has accumulated on artery walls reducing blood flow or because the walls of the arteries have hardened and lost their elasticity. When the heart pumps out a certain volume of blood, but the arteries don't expand, you increase the pressure on the artery walls.
Blood Pressure During Exercise
When you exercise, your heart rate increases in order to deliver oxygen and fuel to your muscles. Your capillaries dilate to allow more blood to reach muscle tissues. This increases the space into which blood can flow, causing your blood pressure to drop slightly when you first start to exercise. However, your cells' demands for oxygen and fuel further increases your heart rate, which forces more blood through your arteries, boosting your systolic blood pressure. In healthy persons, the rise in systolic blood pressure is limited because your arteries dilate to allow for greater blood volume. Your diastolic blood pressure tends to remain relatively stable during exercise, chiefly because the dilated capillaries provide sufficient space for your blood volume in between beats. Anaerobic exercise, such as weightlifting, can cause steep increases in diastolic blood pressure, especially when the workout is intense and the weight is heavy.
Exercise and Resting Blood Pressure
Both aerobic exercise, such as brisk walking, running, jogging and swimming, and anaerobic exercise, such as weightlifting, can lower your resting blood pressure. Moderately intense aerobic exercise done most days of the week can reduce high normal and early stage hypertension. You can expect a drop of 8 to 10 mmHg in systolic and 6 to 10 mmHg in diastolic blood pressure within a few weeks of daily aerobic exercise, reports the University of New Mexico. Resistance training, or weightlifting, can reduce systolic blood pressure by two percent and diastolic blood pressure by four percent.
Why Blood Pressure Drops
Routine exercise lowers resting heart rate because it strengthens the heart and improves the volume of blood pushed out of the chambers with each stroke. However, this does not directly affect blood pressure per se. Exercise improves resting blood pressure at least partially because it improves the elasticity of blood vessels. Though the precise mechanisms for this effect are not known, it is theorized that neural, hormonal and biochemical changes take place in blood vessel walls that allow for greater vessel relaxation, says exercise researcher Len Kravitz, Ph.D., from the University of New Mexico.
References
- American Heart Association: High Blood Pressure Statistics
- Centers for Disease Control and Prevention: High Blood Pressure
- Dr. Mirkin: High Blood Pressure During Exercise
- MayoClinic.cm: Exercise: A Drug-Free Approach to Lowering High Blood Pressure
- MayoClinic.com: High Blood Pressure
- University of New Mexico; Exercise and Resting Blood Pressure; Len Kravitz, Ph.D.
