Blood pressure is the measure of the pressure of blood exerted upon the walls of the vessels. As a key measurement in the overall state of the heart, it is also a potential indicator of health and mortality. If blood pressure remains consistently high, then immediate treatment is needed, usually in the form of medication or a change in lifestyle. Measuring the changes in blood pressure before and after exercise is another way to discern the state of your health.
Measurements
Blood pressure is measured by two main figures: systolic and diastolic pressures. Systolic is the type of pressure that occurs when the heart contracts. Diastolic is the type of pressure that occurs when blood fills the heart in between beats. Blood pressure is written in such a way that the systolic pressure comes first and the diastolic pressure comes second. It is also measured by a unit known as mmHg, or the fluid pressure exerted by a millimeter of mercury. For example, normal blood pressure at rest is a measurement of no more than 120/80 mmHg. High blood pressure is defined as a measurement of at least 140/90 mmHg.
Exercise
During upright exercise, the systolic pressure will greatly increase to about 200 mmHg, and the diastolic pressure will tend to stay at or slightly below 80 mmHg. If your diastolic pressure does decrease slightly during exercise, then it is nothing to be alarmed about. It will begin in the recovery phase to return to your resting pressure. Generally, however, there should be no significant changes.
Causes
Diastolic pressure is intractable in response to exercise due to the fact that, in between contractions, blood is exerting very little pressure upon the vessels, even when the demands from physical activity are great. The state of a diastolic heart is similar at rest as it is in motion. However, the tendency of diastolic pressure to decrease, if it does occur, is actually caused by a widening of the arteries. The widening occurs when the smooth muscles surrounding the vessels automatically and unconsciously relax, allowing a greater volume of blood to flow to and from the skeletal muscles. This is a phenomenon known as vasodilation. Blood is the transportation mechanism that carries oxygen through the body. Oxygen is used to synthesize energy. Widening the vessels, and therefore lowering the overall diastolic pressure, will create a greater capacity for physical activity.
Warning
An increase in diastolic pressure of more than 10 mmHg after exercise is considered to be abnormal. It is usually a sign of hypertension, which is defined as consistently elevated blood pressure, and may also sometimes be associated with coronary heart disease. Hypertension may be difficult to diagnose on its own, so you should have regular checkups with your doctor. If you suspect that during or after exercise you are exhibiting signs of hypertension -- headaches, dizziness, nausea -- then you should see a doctor immediately.
References
- National Heart, Lung and Blood Institute; What Is High Blood Pressure?; April 2011
- Dr. Mirkin; High Blood Pressure During Exercise; Gabe Mirkin; September 2006
- "Journal of Applied Physiology"; Autonomic Control of Skeletal Muscle Vasodilation During Exercise; John B. Buckwalter, et al.; August 1997
- University of New Mexico; Exercise and Resting BP; Len Kravitz, Ph.D.; 2001
