Lifestyle Modification as a Prescription for Hypertension: Physical exercise, stress management
Lifestyle Modification as a Prescription for Hypertension: Physical exercise, stress management Simon L. Bacon, PhD Montreal Behavioural Medicine Centre Concordia University, Hôpital du Sacré‐Cœur de Montréal Montréal Heart Institute Sept 2010 Practice Challenges 1. Physical activity is a good treatment to reduce blood pressure and prevent the development of hypertension, but for how long and how often do people need to exercise? 2. When exercising, do patients really need to work hard? Should I be pushing them to really work‐
up a sweat? 3. Does stress management really help reduce blood pressure? 4. There are many kinds of stress management, which is the best at reducing blood pressure? Learning Outcomes By the end of this document you should be able to: 1. Provide patients with appropriate details of how much exercise they should do to reduce their blood pressure. 2. Distinguish between different kinds of stress management techniques and evaluate their impact on blood pressure. 2010 CHEP Recommendations Physical Exercise  For nonhypertensive individuals (to reduce the possibility of becoming hypertensive) or for hypertensive patients (to reduce their blood pressure), prescribe the accumulation of 30 to 60 minutes of moderate intensity dynamic exercise (such as walking, jogging, cycling or swimming) four to seven days per week in addition to the routine activities of daily living (Grade D). Higher intensities of exercise are no more effective (Grade D). Stress management  In hypertensive patients in whom stress may be contributing to blood pressure elevation, stress management should be considered as an intervention (Grade D). Individualized cognitive behavioural interventions are more likely to be effective when relaxation techniques are used (Grade B). 1. Hypertension and physical activity In the late 1960’s evidence started to emerge that low levels of physical activity were associated with an increased incidence of hypertension. This subsequently lead to a growing interest in physical activity and exercise interventions to reduce blood pressure and incident hypertension. In 1990, Hagberg report the 1st meta‐analysis of 25 studies assessing chronic aerobic exercise interventions in patients with mild hypertension.1 This analyses suggested that a standard exercise intervention, built on the cardiac rehabilitation model was associated with a systolic blood pressure (SBP) reduction of 10.8 mm Hg and a diastolic blood pressure reduction (DBP) of 8.2 mm Hg. In effect, this meta‐analyses Simon Bacon, CHEP 2010 – www.hypertension.ca
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Lifestyle Modification as a Prescription for Hypertension: Physical exercise, stress management
formed the basis for most of the hypertension guidelines in the 90’s and the 2000’s. However, this study was criticized for its lack of adjustment for control groups and as such, an overestimation of the impact of exercise on blood pressure. In the early 2000’s a series of updated meta‐analyses were published, culminating in Whelton et al’s study of 54 randomised controlled trails (RCT’s), which included nearly 2500 individuals.2 Analysis of this data reported a more conservative control group adjusted reduction in SBP and DBP of 3.8 and 2.6 mm Hg, respectively, in those engaging in an aerobic exercise program. This finding has been replicated several times, with slight various but general agreement in the findings.3‐4 In summary, when patients start to engage in a structured aerobic exercise program, it can be expected that the effective reduction in their blood pressure should be in the region of 4/3 mm Hg. However, any individual may have a reduction as high as 11/8 mm Hg, which is equivalent to many 1st line pharmacotherapies. 2. How much aerobic exercise is enough? Whilst the initial meta‐analyses were focused on demonstrating the efficacy of aerobic exercise, the more recent studies have attempted to explore some of the nuances of which factors contribute to a greater reduction in BP. Of particular note both the Whelton et al2 and Wallace5 reviews tried to uncouple those factors which provided optimal outcomes. Interesting, both studies used the same empirical studies as the backbone of their analyses, with each author taking a slightly different tact. Whelton et al assessed the impact of the weekly cumulative amount of aerobic exercise on BP reductions and found a non‐significant trend for a greater reduction with increased exercise for SBP, but not DBP (see Table 1). Table 1: Cumulative exercise and BP changes from the Whelton et al study. Cumulative Exercise Change in SBP Change in DBP < 120 min/wk ‐2.8 ‐2.2 120‐150 min/wk ‐4.7 ‐2.1 > 150 min/wk ‐5.1 ‐2.8 In contrast, Wallace assessed the impact of the number of aerobic exercise sessions per week and the duration of each session on BP change separately. In both cases she found a negative linear relationship with SBP, i.e., with more sessions and longer sessions there was a greater decrease in SBP. This relationship was also true for DBP and the number of sessions, but not for the length of sessions. However, it should be noted that the maximum number of sessions and length of sessions reported in the studies were 7 session per week and 60 minutes, respectively. From this literature, it would appear that the more exercise the better. It is unclear where the plateau effect comes for benefit, or even if there is one. Though from a practical stand point, there is only so much time in a week that most people will dedicate to exercising. In summary, the more aerobic exercise sessions per week and the longer the session are the likely greater reduction in SBP will be. However, due to the limitations in the data, we do not know if there are any benefits in exercising more than 7 times per week and for longer than 60 minutes per session. Simon Bacon, CHEP 2010 – www.hypertension.ca
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Lifestyle Modification as a Prescription for Hypertension: Physical exercise, stress management
3. Exercise intensity and blood pressure Exercise intensity refers to the amount of work that is being done during a session. It is most often reported as a percentage of a person’s maximum exercise heart rate or oxygen uptake. From the preceding section one might expect that a greater intensity of aerobic exercise would result in a larger improvement of BP. However, the evidence does not support this. Whelton et al, found a trend for a greater SBP and DBP reduction in those that engaged in moderate intensity exercise compared to those that engaged in high intensity exercise (see Table 2). Table 2: Exercise intensity and BP changes from the Whelton et al study. Exercise Intensity Change in SBP Change in DBP Low ‐4.1 ‐2.7 Moderate ‐4.3 ‐3.6 High ‐4.0 ‐1.5 Wallace found a positive linear relationship between intensity and change in BP, indicating that lower intensities were associated with better BP reductions. Of note several recent studies in non‐
hypertensive populations have found that moderate and high intensity exercise were equally good at reducing BP. Of course, caution needs to be taken when separating the number, length, and intensity of sessions, as invariably they are linked. To account for this, Wallace ran a 2 length X 2 intensity analyses on BP change. Long duration equated to session of approximately 45 min, with short duration equating to a 15 min sessions, and intensity was split into moderate (50% VO2 max) or high (70% VO2 max). Those who exercised for a long duration at a moderate intensity had significantly greater SBP reductions (ca. 7.5 mm Hg) than those in the other 3 groups (ca, reduction of 2‐4 mm Hg). In summary, to obtain the most out of aerobic exercise, patients need only to exercise at a moderate intensity. The positive practical implication of this is that at lower intensities, people tend to be able to exercise for longer and more often. 4. Future areas of research in physical activity and hypertension All the information above focuses on aerobic exercise. There has been a recent influx of studies assessing the impact of resistance exercise on blood pressure, including a couple of review articles.3,6 Initial evidence suggests that there is a potential benefit of such exercise, especially for reducing DBP. However, at the moment we need more literature to be sure as to what the effects truly are. Another area which requires urgent attention is the efficacy of non‐supervised exercise interventions for BP. Once again the initial evidence is promising, but still relatively scarce. This kind of intervention is critical to get to the point of delivery effectiveness trials and ultimately improving population level health. Simon Bacon, CHEP 2010 – www.hypertension.ca
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Lifestyle Modification as a Prescription for Hypertension: Physical exercise, stress management
5. Stress Management Simply put, stress management is a process where by stress, and especially chronic stress, is reduced, with the ultimate goal of improving everyday functioning. There is a very well established link between stress, both acute and chronic, and BP.7‐8 As such, it is unsurprising that the potential treatment capacity of stress management for BP has been a target of considerable investigation. Though there are over 100 articles reporting on stress management interventions and BP, the waters are somewhat muddied by the fact that stress management interventions are quite diverse. For example, relaxation training, cognitive restructuring, communication skills, and problem solving can all be considered forms of interventions to reduce stress. In addition, some stress management programs will quite often include more than one of these techniques. This provides some degree of complexity when trying to evaluate the impact of such interventions on BP reductions. In summary, stress management is a process whereby stress, and especially chronic stress, is reduced, with the ultimate goal of improving everyday functioning. Stress management interventions generally include one or more of the following techniques relaxation training, cognitive restructuring, communication skills, and problem solving. 6. Stress management to reduce BP Two relatively recent review articles provide nice summaries and perspectives on the impact of stress management on BP changes. Linden et al,9 reviewed 8 previous meta‐analyses, accounting for over 100 trials, and Rainforth et al,10 conducted a meta‐analysis of 17 trials, which consisted of 23 treatment comparisons. The main conclusion from the Linden et al review was that there is a moderate effect of stress management interventions on BP reductions, accounting for a drop in SBP of 6‐10 mm Hg. When multi‐component or individual interventions were considered then the effect size got larger and a greater reduction SBP was seen (7‐15 mm Hg). However, the authors did also note that there was considerable variability in the data BP with SBP changes ranging from +3.6 to ‐14.1 mm Hg, and DBP changes ranging from +2.6 to ‐11.1 mm Hg. It should be highlighted that these changes were not adjusted for control groups. Suggesting that though they may reflect potential individual benefits they are not reflective of the real efficacy of such interventions. In contrast to the Linden et al study, Rainforth et al, utilized control adjusted BP changes in their assessment of stress management on BP. Furthermore, Rainforth et al, provided summary for different classes of stress management interventions. Of the 5 categories that the authors constructed (biofeedback, relaxation‐assisted biofeedback, progressive muscle relaxation, stress management training, and Transcendental Meditation), only Transcendental Meditation was associated with a significant reduction in BP (see Table 3). Table 3: Stress management interventions and BP changes from the Rainforth et al study. Exercise Intensity Change in SBP Change in DBP Biofeedback ‐0.8 ‐2.0 Relaxation‐assisted biofeedback +4.3 +2.4 Progressive muscle relaxation ‐1.9 ‐1.4 Stress management training ‐2.3 ‐1.3 Transcendental Meditation ‐5.0 ‐2.8 Simon Bacon, CHEP 2010 – www.hypertension.ca
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Lifestyle Modification as a Prescription for Hypertension: Physical exercise, stress management
A few points need to be highlighted from the Rainforth et al study. Firstly, whilst there are some good rationales to support the breakdown of groups in the study, other could argue that due to inherent similarities certain groups should be combined. Another important aspect is that there is no estimation of the impact of multi‐component interventions with this study, and as seen in the Linden et al study, these may provide the strongest effects on BP. Finally, it should be noted that Transcendental Meditation is a registered service mark licensed to the Maharishi Vedic Education Development Corporation, and that Dr. Rainforth is faculty member of Maharishi University of Management, Maharishi Vedic City. In summary, stress management may be a useful intervention to reduce BP, however, the specific technique or techniques used may need to be matched to individual requirements. 7. Relaxation and BP There is a very recent Cochrane review update which has assessed relaxation in the context of BP reductions.11 The meta‐analysis used 25 trials which included nearly 1200 participants. The authors reported a control group adjusted significant reduction in SBP (5.5 mm Hg) and DBP (3.5 mm Hg) with meditation. However, further interrogation of the data revealed certain notable issues. For example, when adequate blinding was taken into account (SBP reduction of 3.2 mm Hg) and a sham therapy was used as a control group (SBP reduction of 3.5 mm Hg), the effects of meditation were no longer significant. As such, the collective evidence would suggest a weak effect of meditation on BP. Finally, it should be noted that when relaxation was combined with another form of stress management there was a consistent positive effect of the intervention, compared to the control group, on BP reductions. In summary, relaxation has a significant, but weak effect on BP reductions. The combination of relaxation with another stress management technique may provide a more optimal intervention. 8. Future areas of research in stress management and hypertension The information above provides an encouraging basis for further exploration of stress management in the treatment of hypertension. What is lacking from the current literature are studies which include well defined control groups. Furthermore, it seems that different treatment strategies probably provide individual specific benefits. A greater understanding of how best to match the intervention to the individual is needed, as well as, better comparisons of the different potential strategies and their combinations. Simon Bacon, CHEP 2010 – www.hypertension.ca
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Lifestyle Modification as a Prescription for Hypertension: Physical exercise, stress management
References 1. Hagberg JM. Exercise, fitness, and hypertension. In: Bouchard C, Shephard RJ, Stephens T, Sutton JR, McPherson BD, eds. Exercise, fitness, amnd health: A consensus of current knowledge. Champaign, IL: Human Kinetics, 1990:455‐466. 2. Whelton SP, Chin A, Xin X, He J. Effect of aerobic exercise on blood pressure: A meta‐analysis of randomized, controlled trials. Ann Intern Med 2002;136:493‐503. 3. Fagard RH, Cornelissen VA. Effect of exercise on blood pressure control in hypertensive patients. Eur J Cardiovasc Prev Rehabil 2007;14:12‐7. 4. Kelley GA, Kelley KS. Efficacy of aerobic exercise on coronary heart disease risk factors. Prev Cardiol 2008;11:71‐5. 5. Wallace JP. Exercise in hypertension ‐ A clinical review. Sports Med 2003;33:585‐598. 6. Kelley GA, Kelley KS. Isometric handgrip exercise and resting blood pressure: a meta‐analysis of randomized controlled trials. J Hypertens 2010;28:411‐418 10.1097/HJH.0b013e3283357d16. 7. Bacon SL, Ring C, Li Saw Hee F, Lip GYH, Blann AD, Lavoie KL, Carroll D. Hemodynamic, Hemostatic, and Endothelial Reactions to Psychological and Physical Stress in Coronary Artery Disease Patients. Biol Psychol 2006;72:162‐170. 8. Blumenthal JA, Sherwood A, Gullette EC, Georgiades A, Tweedy D. Biobehavioral approaches to the treatment of essential hypertension. J Consult Clin Psychol 2002;70:569‐89. 9. Linden W, Moseley JV. The efficacy of behavioral treatments for hypertension. Appl Psychophysiol Biofeed 2006;31:51‐63. 10. Rainforth M, Schneider R, Nidich S, Gaylord‐King C, Salerno J, Anderson J. Stress reduction programs in patients with elevated blood pressure: A systematic review and meta‐analysis. Curr Hypertens Rep 2007;9:520‐
528. 11. Dickinson HO, Campbell F, Beyer FR, Nicolson DJ, Cook JV, Ford GA, Mason JM. Relaxation therapies for the management of primary hypertension in adults: a Cochrane review. Cochrane Database of Systematic Reviews 2009;CD004935. Simon Bacon, CHEP 2010 – www.hypertension.ca
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