Written by Samuel Headley, Ph.D., FACSM
Approximately 60 million Americans have hypertension, also known as high blood pressure. An individual is diagnosed as having hypertension if their seated blood pressures on two separate occasions exceed a systolic (SBP) reading of 140 mmHg or a diastolic (DBP) reading of 90 mmHg. It is critical to treat elevated blood pressures and reduce pressures into the normal range (SBP <120, DBP < 80), since untreated hypertension is a leading cause of heart attack, stroke, and kidney failure. Hypertension is often called “the silent killer,” since a person may be unaware of elevated readings. According to the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of Hypertension (JNC7), 30 percent of the adult hypertensive population are unaware they have elevated blood pressure. This signifies the importance of regular blood pressure screenings.
In 90 percent of hypertension cases, the cause for the elevated pressures is unknown. However, we do know that blood pressure values tend to increase with advancing age; values are higher in the overweight, obese, and sedentary; and hypertension tends to be more common in minority groups, particularly African Americans. Hypertension can be successfully treated with medications. The most commonly used ones include diuretics, angiotensin-converting enzyme (ACE) inhibitors, calcium channel blockers, and beta blockers. More than 60 percent of the hypertensive population will need to take more than one type of medication to normalize their readings. Furthermore, in most cases, an individual will need to take medication for the rest of their lives to keep their blood pressure under control.
There is substantial evidence to show that lifestyle factors (such as diet and regular exercise) can play an important role in helping to reduce elevated blood pressure readings. In some cases, individuals may be able to normalize their blood pressure simply by using this non-drug approach. However, in the majority of cases, lifestyle changes help to reduce the amount of medication needed to keep blood pressures under control. According to the JNC7 report, a 10-lb. reduction in weight will reduce blood pressure in hypertensive individuals and may prevent the development of hypertension in overweight individuals. Regarding dietary factors, the Dietary Approaches to Stop Hypertension (DASH) diet emphasizes the consumption of several servings of fruits and vegetables, low-fat dairy products, a reduction in dietary cholesterol, in addition to low total and saturated fat intakes. The DASH diet leads to high intakes of potassium and calcium, which have been shown to help hypertensive individuals manage their blood pressure. Sodium intake should be reduced to fewer than 2.4 grams (2,400 mg) per day, since high sodium intake has consistently been found to lead to elevations in blood pressure. Alcohol intake should be limited to no more than two drinks per day.
Hypertensive individuals should be encouraged to exercise regularly as blood pressure can be reduced for up to 22 hours following a single exercise session. This observation of a reduction in pressure following a single exercise session is called post-exercise hypotension (PEH). The exact cause of PEH is not fully known but the fact that it does occur and lasts for so long in some individuals is part of the rationale for encouraging those with high blood pressure to exercise daily.
Hypertensive individuals who exercise regularly for several months can expect to see a 5-10 mm Hg reduction in both systolic and diastolic blood pressure readings. However, it is important to note that not all individuals may see these favorable responses since there is evidence that 25 to 33 percent of hypertensive individuals do not experience PEH. Therefore, there are some individuals who seem to be resistant to the blood pressure-lowering effects of exercise. These individuals should still be encouraged to exercise for the other health benefits that they are likely to gain from exercise training.
Exercise should primarily consist of aerobic activities like brisk walking, jogging, cycling, or swimming. These activities should be performed a minimum of three days per week for 30 to 60 minutes, but could be done daily. The intensity should be in the moderate range, with heart rates representing 40 to 70 percent of heart rate reserve. Resistance training activities should be done two times per week, with an emphasis on lower weight but higher repetitions (8 to 12 per set). Static stretching should be performed during each exercise session to help minimize the risk of musculoskeletal injury.
Individuals should have their blood pressure checked on a regular basis to make sure their values are being kept within the desirable range. In many cases, individuals will need to be medicated to achieve desirable readings; however, lifestyle modifications, including the adoption of the DASH diet coupled with regular exercise, should be encouraged. Even if blood pressure is not reduced with exercise training, the hypertensive individual should still exercise to help with weight management, lipid control and improvement in blood sugar control.
View the full spring 2008 issue of the ACSM Fit Society® Page online.