What you eat, your emotions, the room temperature and your posture all have an effect on your blood pressure. When you measure your blood pressure, you are measuring the force and amount of blood being pumped through your arteries. Systolic pressure, the top number in a blood pressure reading, is the pressure exerted when your heart contracts to push the blood into your arteries. Diastolic pressure is read when your heart is filling with blood, or at rest.
How Your Body Controls Blood Pressure
Three factors influence blood pressure: heart rate, stroke volume and peripheral vascular resistance. Heart rate is the number of heartbeats during a given period. Stroke volume is the amount of blood that flows out to your body with each contraction. Peripheral vascular resistance is how difficult it is for blood to flow through your circulatory system. These factors work together to keep blood pressure in a normal range.
Heart rate and stroke volume increase when you exercise. To reduce your blood pressure, a process called vasodilation occurs. This widens your arteries and veins so blood flows easily through them. The peripheral resistance lowers, and your blood pressure is controlled. If your blood pressure were to drop too low, your blood vessels would constrict to increase the pressure and keep your blood pressure in check.
Blood Pressure Changes and Exercise
Aerobic exercise, such as jogging, swimming or cycling, uses the large muscles of your body. Aerobic activity depends on energy made from oxygen. Your heart rate speeds up to increase the flow of oxygenated blood to your muscles. Your heart rate, stroke volume and systolic pressure all increase as your heart pushes more blood out. Your diastolic pressure remains the same.
High Blood Pressure During Exercise
You can have normal blood pressure at rest and still have abnormally high blood pressure when you exercise. The medical term for this is exercise hypertension. This is because your arteries do not expand enough to allow the increasing blood flow to easily pass. Elevated blood pressure during exercise could be a warning that artery disease is developing. Notify your health care provider to have a cardiac workup if you have exercise hypertension.
Low Blood Pressure During Exercise
Your blood pressure should return to the resting measurement within 10 minutes of the end of your exercise session. It takes time for your body to adapt to reduced demand for oxygen and for your blood vessels to return to normal. If your blood pressure is lower than baseline during exercise or shortly after stopping exercise, make an appointment with your doctor to have a checkup. This could be an early signal of heart disease, or it could mean nothing.
