Dynamic exercise, unlike isometric exercise, involves movement. Both endurance exercise, such as running, and resistance exercise, such as weight lifting, are forms of dynamic exercise. Working muscles require nutrients and oxygen, supplied by the circulatory system. To maintain adequate blood flow to muscles, changes occur in blood pressure during exercise. How the blood pressure responds depends upon the type and intensity of the exercise.
Blood Pressure
Blood pressure readings consist of two numbers. The first, systolic pressure, measures the force of the blood through the arteries as the heart contracts. The second, diastolic pressure, measures the pressure while the heart is filling between beats. Blood pressure is determined by several factors, including heart rate, the amount of blood ejected from the heart with each contraction and the resistance of the blood vessels. All of these factors change with different types and intensities of exercise.
Endurance Exercise
Systolic blood pressure increases sharply when you begin a bout of dynamic endurance exercise. The heart beats faster as working muscles pump more blood back to the heart, causing a greater surge of blood through the arteries with every heart beat. When you reach a steady pace, systolic pressure plateaus, but if you continue to ramp up the intensity, it will continue to rise. Diastolic pressure remains basically unchanged throughout, because of the dilation of blood vessels in the muscles.
Resistance Exercise
Dynamic resistance exercise, such as lifting weights, can lead to large transient increases in systolic blood pressure.The larger the workload, the more systolic pressure rises. These increases result from greater resistance to blood flow in the blood vessels within contracting muscles, as well as from from holding the breath while lifting, termed the Valsalva maneuver. The effect on diastolic pressure is controversial. Some researchers report no change, while others have found increases.
Longer Term Effects of Exercise
Exercise can help lower blood pressure, with larger reductions occuring in people with high blood pressure than in those with normal blood pressure. Doctors once worried that resistance exercise could be dangerous for people with high blood pressure, but research has not borne that fear out. However, since endurance exercise lowers blood pressure more effectively than resistance exercise, the American College of Sports Medicine recommends that those with high blood pressure emphasize moderate aerobic exercise, supplementing it with resistance training.
References
- "Exercise Physiology for Health, Fitness and Performance"; Sharon A. Plowman and Denise L. Smith; 2011
- "Exercise Physiology; Energy, Nutrition, and Human Performance"; William D. McArdle, et al.; 2007
- "Medicine & Science in Sports & Exercise"; ACSM Postition Stand: Exercise and Hypertension; Linda S. Pescatello, et al.; March 2004
