Currently more than 50 million Americans—and more than 50% of the American population over the age of 60—have hypertension, or high blood pressure (Hagberg 2005). Worldwide, the number of people with hypertension is estimated to be 1 billion! Furthermore, because blood pressure tends to increase with age, the number of people with hypertension is likely to rise significantly as the U.S. population continues to age. Unfortunately, due to a lack of symptoms a large number of individuals are unaware that they have the silent killer, as hypertension is called, and do not realize their hypertension is placing them at a higher risk for a heart attack or stroke. Although hypertension affects nearly every organ, its lack of symptoms means that many individuals do not realize the damage that may be occurring even at modest elevations of blood pressure.
Physical activity is considered one of the mainstays in the nonpharmacological treatment of hypertension. This chapter discusses the current definition of hypertension and introduces the physiological relationship between exercise and blood pressure, as well as provides some background and mechanistic details. Then it presents both nationally and internationally issued activity guidelines for individuals with hypertension. Also, because of the close and causal relationship between hypertension and CAD, this chapter also includes guidelines that pertain to CAD.
Benefits of Exercise for Hypertension
The definition of hypertension has changed over time. Currently, the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7: NHBPEP 2003) defines normal blood pressure as a pressure less than 120/80 mmHg (see table 10.1). Elevated blood pressure, which at one time was diagnosed only when in excess of 160/100 mmHg, is a primary cardiac risk factor and also increases the risk for stroke, type 2 diabetes, kidney disease, and vascular disease. According to the JNC 7, the risk of CVD begins at only 115/75 mmHg and doubles with each incremental increase of 20/10 mmHg. People who are classified as prehyper-tensive have twice the risk of developing hypertension. Even individuals with normal blood pressure have a high lifetime risk of developing hypertension—an estimated 90% risk for individuals with normal blood pressure at age 55 (Vasan and others 2002)!
For people with prehypertension, exercise is one of the primary recommended lifestyle changes that can lower blood pressure to a normal level. In fact, even in individuals who have a normal blood pressure, regular aerobic exercise may lower resting blood pressure, although the extent of lowering is less than that seen in individuals with frank hypertension. In the JNC 7, physical activity compares favorably with the other recommended lifestyle changes when it comes to reducing resting blood pressure—table 10.2 gives examples of these changes and their relative effects. Also, physical activity may contribute to weight loss, which can reduce blood pressure even further.