Exercise for Hypertension
Guidelines for the management of hypertension recommend lifestyle modifications, in particular, a combination of and exercise. Nonpharmacological strategies are aimed to change the lifestyle and should be instituted in hypertensive and pre-hypertensive patients. Supervised exercise, and weight reduction, combined with pharmacological therapy, are effective treatments for normalization of blood pressure. This statement is based on the knowledge that exercise is a landmark in primary prevention and coadjuvant in the treatment of hypertension . Exercise is considered as a polypill and, thus, is necessary to know the optimal dosage (posology) in order to obtain maximal benefits . Specifically, the response of blood pressure to exercise aims to ensure adequate blood flow to active muscles. BP depends on cardiac output , which varies depending on myocardial contractility, heart rate , blood volume, and peripheral vascular resistance. During the development of training, changes occur at the cardiovascular level, including increased systolic blood pressure, diastolic blood pressure, and mean arterial pressure .
The possible mechanisms of the antihypertensive effects of exercise are not fully clear but may include reduction in sympathetical-induced vasoconstriction and reduced catecholamine segregation; increased insulin sensitivity; (c) anti-inflammatory effects; and vascular structural adaptations.
Different international organizations such as the American Heart Association, American College of Cardiology, American College of Sports Medicine, European Society of Hypertension, European Society of Cardiology, or the Canadian Hypertension Education Program have developed their exercise prescription guidelines for adults with hypertension (for a review, see the original statements or Pescatello et al. ). Because the ideal dose is still unknown, the emergence of new modalities of exercise, in this chapter updated exercise strategies for managing and preventing hypertension, is presented. The modalities of exercise that have shown a relatively stronger supporting evidence are aerobic exercise (Class I, level of evidence A), dynamic resistance exercise.
7.1. Cardiovascular exercise
Low aerobic fitness has been proved to be a strong predictor for future cardiovascular disease and all-cause mortality in people with hypertension . Not surprisingly therefore, there still seems to be a consensus that aerobic exercise should be prescribed as the primary type of exercise for the prevention, treatment, and control of hypertension . Aerobic training can be performed either at continuous intensity or by short intervals of high-intensity exercise.
7.1.1. Continuous aerobic
The most extensive evidence with endurance training for hypertension is available for the continuous modality, understood as exercise of a constant sustainable intensity that is carried out over a given period of time, usually long.
7.1.1.1. Benefits of continuous aerobic training for hypertension
An acute session of continuous aerobic exercise can lower BP during the post-exercise period, known as the post-exercise hypotension . PEH is considered a prolonged decrease in resting blood pressure in the minutes and hours after an acute bout of exercise . This decrease is more pronounced in hypertensive patients and has also been shown in very old adults .
Chronic exercise results in more sustained reductions in BP, known as the exercise-training response . According to different reviews and meta-analysis, aerobic exercise reduces BP in 5–7 mmHg . However, it should also be noted that there is a considerable heterogeneity of the individual response to exercise training, attributed to environmental and genetic factors. About 20–25% of hypertensive patients could be nonrespondents to exercise .
7.1.1.2. Mechanisms of benefits
PEH is mediated by both central and peripheral factors. The fall in blood pressure seen after exercise seems to be caused by a reduced signal transduction from sympathetic nerve activation into vasoconstriction, and also local vasodilatator mechanisms. Recent evidence suggests that muscle afferents may play a major role in this response .
aerobic exercise in hypertensive patients may lead to a reduction in left ventricular mass [16], although results are not always conclusive. Decreased oxidative stress and inflammation levels, as well as an improved autonomic function, have been described as key mechanisms that contribute to the physiological benefits obtained with exercise. However, further research is needed to elucidate the exact mechanisms involved in the adaptations to chronic aerobic exercise [16].
7.1.1.3. Dose of exercise
When it comes to prescribe physical activity, the dose-response question is a very relevant issue. It refers to the relationship between different doses of physical activity and changes in a defined health parameter. The total physiological load is calculated for continuous endurance training as the product of the intensity, duration, and frequency of the exercise. There is still an ongoing debate about the optimal training dose, frequency, duration, and intensity of exercise for hypertensive patients.
In regard to intensity, few studies have actually compared the effects of different intensities of endurance exercise in blood pressure. Cornelissen et al. , using a randomized crossover design, compared the effects of two different programs of endurance training in BP, HR, and heart rate variability in a group of 36 healthy sedentary older adults (mean age: 59 years, range: 55–71 years) with SBP of ≥120 mmHg or DBP of ≥80 mmHg. The study was composed of three 10-week periods. In the first and third period, the participants exercised at 33 or 66% of HR reserve (3 days per week, 50 min per session) in random order, with a sedentary period in between. The results of this study showed that endurance training at both lower and higher intensities reduced SBP significantly (P < 0.05) at rest, before exercise, during exercise, and during recovery to a similar extent. The effect of training on HR was more pronounced (P < 0.05) with higher intensity, whereas HRV was unaffected by the intervention.
However, more recent evidence suggests that moderate to high intensities produce higher BP reductions than low-intensity endurance training (<40% of heart rate reserve or <55% of maximum heart rate) .
On the other hand, the most appropriate duration and frequency of the exercise programs is not fully clear either, but most evidence is in line with the American College on Sports Medicine’s recommendations of performing aerobic exercise most, preferably all, days of the week. The duration of each exercise session should range from 30 to 60 min .
The possible mechanisms of the antihypertensive effects of exercise are not fully clear but may include reduction in sympathetical-induced vasoconstriction and reduced catecholamine segregation; increased insulin sensitivity; (c) anti-inflammatory effects; and vascular structural adaptations.
Different international organizations such as the American Heart Association, American College of Cardiology, American College of Sports Medicine, European Society of Hypertension, European Society of Cardiology, or the Canadian Hypertension Education Program have developed their exercise prescription guidelines for adults with hypertension (for a review, see the original statements or Pescatello et al. ). Because the ideal dose is still unknown, the emergence of new modalities of exercise, in this chapter updated exercise strategies for managing and preventing hypertension, is presented. The modalities of exercise that have shown a relatively stronger supporting evidence are aerobic exercise (Class I, level of evidence A), dynamic resistance exercise.
7.1. Cardiovascular exercise
Low aerobic fitness has been proved to be a strong predictor for future cardiovascular disease and all-cause mortality in people with hypertension . Not surprisingly therefore, there still seems to be a consensus that aerobic exercise should be prescribed as the primary type of exercise for the prevention, treatment, and control of hypertension . Aerobic training can be performed either at continuous intensity or by short intervals of high-intensity exercise.
7.1.1. Continuous aerobic
The most extensive evidence with endurance training for hypertension is available for the continuous modality, understood as exercise of a constant sustainable intensity that is carried out over a given period of time, usually long.
7.1.1.1. Benefits of continuous aerobic training for hypertension
An acute session of continuous aerobic exercise can lower BP during the post-exercise period, known as the post-exercise hypotension . PEH is considered a prolonged decrease in resting blood pressure in the minutes and hours after an acute bout of exercise . This decrease is more pronounced in hypertensive patients and has also been shown in very old adults .
Chronic exercise results in more sustained reductions in BP, known as the exercise-training response . According to different reviews and meta-analysis, aerobic exercise reduces BP in 5–7 mmHg . However, it should also be noted that there is a considerable heterogeneity of the individual response to exercise training, attributed to environmental and genetic factors. About 20–25% of hypertensive patients could be nonrespondents to exercise .
7.1.1.2. Mechanisms of benefits
PEH is mediated by both central and peripheral factors. The fall in blood pressure seen after exercise seems to be caused by a reduced signal transduction from sympathetic nerve activation into vasoconstriction, and also local vasodilatator mechanisms. Recent evidence suggests that muscle afferents may play a major role in this response .
aerobic exercise in hypertensive patients may lead to a reduction in left ventricular mass [16], although results are not always conclusive. Decreased oxidative stress and inflammation levels, as well as an improved autonomic function, have been described as key mechanisms that contribute to the physiological benefits obtained with exercise. However, further research is needed to elucidate the exact mechanisms involved in the adaptations to chronic aerobic exercise [16].
7.1.1.3. Dose of exercise
When it comes to prescribe physical activity, the dose-response question is a very relevant issue. It refers to the relationship between different doses of physical activity and changes in a defined health parameter. The total physiological load is calculated for continuous endurance training as the product of the intensity, duration, and frequency of the exercise. There is still an ongoing debate about the optimal training dose, frequency, duration, and intensity of exercise for hypertensive patients.
In regard to intensity, few studies have actually compared the effects of different intensities of endurance exercise in blood pressure. Cornelissen et al. , using a randomized crossover design, compared the effects of two different programs of endurance training in BP, HR, and heart rate variability in a group of 36 healthy sedentary older adults (mean age: 59 years, range: 55–71 years) with SBP of ≥120 mmHg or DBP of ≥80 mmHg. The study was composed of three 10-week periods. In the first and third period, the participants exercised at 33 or 66% of HR reserve (3 days per week, 50 min per session) in random order, with a sedentary period in between. The results of this study showed that endurance training at both lower and higher intensities reduced SBP significantly (P < 0.05) at rest, before exercise, during exercise, and during recovery to a similar extent. The effect of training on HR was more pronounced (P < 0.05) with higher intensity, whereas HRV was unaffected by the intervention.
However, more recent evidence suggests that moderate to high intensities produce higher BP reductions than low-intensity endurance training (<40% of heart rate reserve or <55% of maximum heart rate) .
On the other hand, the most appropriate duration and frequency of the exercise programs is not fully clear either, but most evidence is in line with the American College on Sports Medicine’s recommendations of performing aerobic exercise most, preferably all, days of the week. The duration of each exercise session should range from 30 to 60 min .