Topical Review Section Editors: Anne Abbott, PhD, and Larry Goldstein, MD
Physical Activity in Primary Stroke Prevention Just Do It! Virginia J. Howard, PhD; Michelle N. McDonnell, PhD
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troke is a preventable disease. Well-documented, modifiable risk factors for stroke include hypertension, diabetes mellitus, dyslipidemia, obesity and body fat distribution, cigarette smoking, atrial fibrillation, heart disease, and physical inactivity.1,2 There is a wealth of information supporting physical activity (PA) as an important component of primary stroke prevention strategies. The proposed mechanism is that PA improves vascular function and stroke risk factors.3 The well-known health benefits of regular PA include reducing the risk of hypertension, type 2 diabetes mellitus, depression, and obesity, as well as control of these risk factors.4–7 Although data from multiple clinical trials support a reduction in stroke risk factors with PA,4,8–11 there are no clinical trials data demonstrating the efficacy of PA in reducing stroke incidence, partially because of the long follow-up required to achieve a sufficient number of events. The next best evidence comes from nonrandomized cohort studies where the consistency of results strongly supports the benefit of PA in primary stroke prevention (Class I, Level of Evidence B).1 The purpose of this review is to summarize the terminology and measurement of PA, synthesize the results of studies of PA and stroke risk in men and women, and describe how PA can ameliorate the effects of stroke risk factors, such as diabetes mellitus and hypertension. The challenges with PA research will also be discussed, as well as recommendations for future research.
Terminology and Measurement of PA PA is a complex behavior that can incorporate different elements, including occupational or leisure time PA, commuting, sport, walking, and exercise training. The accepted definition of PA used by most researchers is “any bodily movement produced by skeletal muscles that results in energy expenditure” (p. 126).12 This differs from exercise, a subset of PA defined as “PA that is planned, structured, repetitive and purposeful in the sense that improvement or maintenance of one or more components of physical fitness is an objective” (p. 128).12 Generally, epidemiological studies that rely on self-report intend to measure PA, but it is not always clear that participants understand the difference between PA and exercise when they complete
surveys or questionnaires. An alternative approach is to directly measure the physiological variable cardiorespiratory fitness using maximal or submaximal exercise tests but this is not feasible in large scale studies. The approach used in many longitudinal cohort studies, such as the Framingham Heart Study (FHS), the Nurse’s Health study, and the REasons for Geographic And Racial Differences in Stroke (REGARDS), is to ask about the frequency of intense PA, enough to work up a sweat.13–15 The validity of this widely used assessment is well-established16 and correlates with objective measures of cardiorespiratory fitness.17,18 Alternatively, participants are asked about moderate intensity PA, such as walking, the most common form of PA in older adults,19 often measured in terms of frequency, duration, or total time spent walking. Classification of PA is a significant limitation to epidemiological research. To quantify energy expenditure, it is necessary to have an estimate of the amount of time the participant spent on low intensity activities, such as domestic or occupational tasks, moderate intensity exercise (walking, playing golf), and intense physical activities (jogging or cycling).20 After this, a formula may be used to estimate the amount of energy expended on each activity. Although this approach is reported to be valid and reliable,21 the accuracy of these data is influenced by the ability of participants to accurately recall the durations spent on each activity in the period of interest. Furthermore, participants tend to overestimate the amount of time spent being physically active, leading to poor agreement between self-report and accelerometer-based measures in older adults.22 The approach to classifying participants into low, moderate, or high PA groups based on total energy expended or frequency of PA varies considerably between studies, making it impossible to quantify the specific amount and intensity of PA needed to confer significant stroke protection.
A Healthy Lifestyle (Including PA) and Risk of Incident Stroke Adherence to a healthy lifestyle significantly reduces the risk of stroke. Table I in the online-only Data Supplement provides
Received January 19, 2015; final revision received March 16, 2015; accepted March 17, 2015. From the Department of Epidemiology, School of Public Health, University of Alabama at Birmingham (V.J.H.); and Division of Health Sciences, International Centre for Allied Health Evidence, School of Health Sciences, University of South Australia, Adelaide, Australia (M.N.M.). The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA. 115.006317/-/DC1. Correspondence to Virginia J. Howard, PhD, Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Ryals 210F, 1720 2nd Ave S, Birmingham, AL 35294-0022. E-mail [email protected] (Stroke. 2015;46:00-00. DOI: 10.1161/STROKEAHA.115.006317.) © 2015 American Heart Association, Inc. Stroke is available at http://stroke.ahajournals.org
DOI: 10.1161/STROKEAHA.115.006317
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2 Stroke June 2015 an overview of the key studies that have investigated the effect of a healthy lifestyle on stroke risk. The key elements of a healthy lifestyle are avoidance of excess body weight, smoking, heavy alcohol consumption, unhealthy diet, and physical inactivity.23–25 Combined data from the US Nurse’s Health Study and the Health Professionals Follow-up Study (n=114 928) showed that adult women who make healthy lifestyle choices have an 80% lower risk of total stroke when compared with those who do not; for men, the risk was ≈70% lower.23 The optimal amount of PA within a healthy lifestyle was defined as ≥30 minutes/d of moderate or vigorous activity based on a self-administered questionnaire on frequency of PA over the previous year.23 In the population-based Sweden Mammography Cohort of 31 696 women, the definition of a healthy level of PA included both low and moderate intensity activities, walking or cycling at least 40 minutes/d and completing at least 1 hour/wk of structured exercise.25 The relative risk of stroke decreased with the addition of each healthy lifestyle factor, and women who adhered to all 5 low-risk lifestyle factors had a 62% lower risk of cerebral infarction than women with no low-risk factors. Another prospective cohort study of 23 927 men and women, the European Prospective Investigation into Cancer and Nutrition (EPIC-Heidelberg) study, supports these findings, estimating that 38% of stroke cases in their cohort could have been prevented if participants had adhered to the same 5 healthy lifestyle factors.24 Specific to PA, women who engaged in any level of PA compared with being inactive had a reduced stroke risk after multivariable adjustment, but for men, the multivariable adjusted risk estimates by different levels of PA were weaker and not statistically significant.24 In contrast, using a heath index (range, 0–20) that assigned scores of 0 to 4 to each of the 5 lifestyle components, the Women’s Health Study (n=37 636) found that an overall higher health index was associated with significantly lower stroke risk with a significant trend across the mean values of health index categories but for the individual component of PA defined by number of times per week of strenuous exercise, there was no association with stroke risk.26 The EPIC Norfolk study (n=20 040) used a slightly different definition of healthy lifestyle and for the unadjusted, individual component of PA, women who were physically inactive compared with not inactive had a significantly higher stroke risk, but for men there was no difference.27 However, for the overall healthy behavior score, in various covariateadjusted models, both men and women had consistently higher stroke risk with worse health behavior scores.27 In a Finnish population survey (n=36 686) with mean follow-up of 13.7 years, there was a graded inverse association between number of healthy lifestyle factors and risks of total, ischemic, and hemorrhagic stroke.28 For the individual factor of moderate or high versus low PA, there was a significant association with reduced risk of stroke for total and ischemic stroke but only a trend for hemorrhagic stroke.28 Using 7 different health metrics (glucose, cholesterol, blood pressure, body mass index, PA, diet, and cigarette smoking), that is, Life’s Simple 7, studies have shown that increasing numbers of these optimal factors are also associated with lower stroke risk.28–30 In the large China study (n=91 686), the
individual factor of PA comparing ideal (moderate or vigorous PA>80 minutes/week) versus nonideal showed a significantly lower risk of total and ischemic stroke but not hemorrhagic stroke.31
Physical Inactivity as a Risk Factor for Incident Stroke Several prospective cohort studies have collected data on PA and incident stroke (Table I in the online-only Data Supplement for details). Studies of all men32 or women14,21,33 participants have generally concurred that some PA, compared with none, offers protection against incident stroke. Studies including both men and women have also found significant risk reduction with PA, but with differing effects. Older men who were moderately active had the greatest risk reduction in the FHS, which found no such association in women.34 Low intensity exercise was not associated with reduced stroke risk in the Northern Manhattan Study, and moderately vigorous activity was only protective for men.35 This disparity was confirmed in the REGARDS study, with no association between vigorous PA and stroke risk for women when the sample was stratified by sex, despite a 20% decreased risk of stroke across the entire sample with 918 confirmed cases of stroke/transient ischemic attack.15 In the Spanish EPIC cohort, moderate intensity recreational PA was independently associated with reduced stroke risk in women but not in men.36 In all studies, the association was attenuated to some extent by multivariable adjustment for traditional stroke risk factors, such as hypertension, diabetes mellitus, alcohol, and tobacco use. A meta-analysis of 23 studies found that moderate and high levels of activity were associated with a reduced risk of total stroke, as well as ischemic and hemorrhagic stroke.37 Considering only prospective cohort studies in this meta-analysis, participants who were highly active or moderately active had a 25% or 17% lower risk of stroke incidence or mortality, respectively, compared with inactive participants. Wendel-Vos et al38 added to this literature with several more cohort studies and confirmed that both occupational and leisure time PA were associated with reduced stroke risk. A 2012 meta-analysis confirmed these findings, with leisure-time PA reducing stroke risk by ≈20% in both men and women.39 A dose– response relationship was particularly evident in women, with a relative risk for high PA versus low PA of 0.78, compared with 0.89 for moderate versus low PA.39 A 2010 meta-analysis studying differences between men and women in the benefit of PA and stroke risk concluded that although the overall benefit was similar, women may need a higher level of PA to achieve similar reduction in stroke risk.40 Precisely what a higher level of PA translates to, in terms of PA duration, frequency or intensity is unknown, as these meta-analyses classified PA into low, moderate, or high based on what was reported in the studies, but without any further detail. Overall, the literature to date suggests that all participants have a reduced risk of stroke from some PA compared with none, but the PA intensity needs to be more moderate to vigorous intensity for men to gain maximal benefit, whereas women generally benefited from longer duration PA of low to moderate intensity, such as walking, for example, >3.5 hours/wk.14,40
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Howard and McDonnell Physical Activity in Primary Stroke Prevention 3 Few studies have examined occupational PA in men or women, but rather the majority of studies measured frequency, duration, and intensity of all types of occupational or leisuretime PA. It is important to note that the majority of participants in all studies and meta-analyses were white from the United States or Europe. Only the REGARDS study used purposive sampling to ensure approximately equal numbers of white and black participants, with no racial differences observed in association between stroke and PA. Another important consideration in these studies is the heterogeneity of assessment of PA. All studies used self-report and differed in their questioning of PA characteristics, as well as the classification of participants into high or low PA groups. Data on the prevention of ischemic versus hemorrhagic stroke are sparse because of limited power from small numbers of hemorrhagic strokes. There are few studies that include serial assessment of PA levels during the long-term, so the cumulative benefits of PA and impact of changing behavior on stroke risk cannot be estimated.13 However, the evidence from several high-quality studies with large sample sizes provides a consistent message that PA, as part of a healthy lifestyle, reduces stroke risk. Future cohort studies that include stroke outcomes and objective measurement of PA using accelerometers41 will enable more accurate classification of PA levels and assist in clarifying the effect of intensity versus duration for men and women and dose– response relationship seen to some extent in all studies.
How Does PA Modify the Risk Factors for Stroke? Although the mechanisms mediating the reduction in stroke risk are not fully understood, there is substantial evidence for PA to influence stroke risk factors. When measuring the impact of PA on stroke risk, it is difficult to separate the specific role of PA when it often clusters with other healthy lifestyle factors, such as healthy diet, not smoking, and maintaining a healthy weight. Indeed, PA is believed to reduce stroke risk through the positive effect it has on these other stroke risk factors. When considering the 10 modifiable risk factors that, in an international case–control study, were found to account for 90% of the risk of stroke2 (hypertension, smoking, waist:hip ratio, diet score, PA, diabetes mellitus, alcohol intake, psychosocial status, cardiac causes, and ratio of apolipoproteins B to A1), PA can positively influence at least 3 of these: hypertension, diabetes mellitus, and body fat. Hypertension is considered to be the most important risk factor for primary stroke prevention.1 Control of blood pressure (BP) is one of the beneficial effects of PA for which specific recommendations have been made.4,42–44 A pilot randomized controlled trial of a simple walking intervention, using pedometers to increase step count, was effective at increasing PA and resulted in lower BP in a group of sedentary overweight and obese women.45 A workplace intervention conducted >1 year to increase PA in healthy office workers also resulted in a reduction in systolic BP in the PA, but not the control group.46 Both studies observed a reduction of ≈6 mm Hg in systolic BP, but larger reductions of ≤10 mm Hg are seen in studies with hypertensive participants.47 Individuals with treatment-resistant hypertension can also benefit from
PA, with reduced incidence of stroke observed in those who were involved in vigorous PA at least 4 times per week in the REGARDS study.48 It is likely that these reductions in systolic BP reflect improved endothelial function after exercise.49,50 Considerable evidence also supports the recommendation that people with type 2 diabetes mellitus should undergo structured PA because of the positive effects on glycemic control, visceral adipose tissue, and plasma triglycerides.8 A cohort study of individuals with newly diagnosed diabetes mellitus, followed up for 5 years, found that those who increased their PA had a relative risk of total cardiovascular disease (including stroke and myocardial infarction) of 0.53 compared with those who decreased their PA.51 When considering the association between stroke and PA in people with diabetes mellitus, those who participated in at least 30 minutes/d of brisk walking, or the equivalent, had a 45% reduction in stroke risk compared with those who were inactive.52 Several different variables are used in studies to classify excess weight: measurement of body mass index, waist circumference, waist:hip ratio, visceral adipose tissue, and overall body fat. Randomized controlled trials of PA interventions typically result in only modest weight loss (1–2 kg),5 but they are often associated with improvements in body mass index, waist circumference, and body fat with PA interventions,46 particularly in those with diabetes mellitus.10 Even in the absence of significant weight loss, moderately vigorous PA improves lipid profiles through lowering low density lipoprotein-cholesterol and triglycerides and increasing high density lipoprotein-cholesterol.5,53 Additional mediating factors, which may account for the reduction in stroke risk with regular PA, are likely to be related to inflammatory and hemodynamic factors. Blood samples from 27 055 participants of the Women’s Health Study were collected at baseline, along with data on cardiovascular risk factors including PA with follow-up of ≈11 years.3 Although this study did not examine stroke events separately from other cardiovascular events, it demonstrated that inflammatory/ hemostatic biomarkers, such as high-sensitivity C-reactive protein and fibrinogen, contributed significantly to lower risk of cardiovascular disease in women who were more physically active. This is consistent with previous literature attributing the anti-inflammatory effect of PA as an important factor in preventing cardiovascular disease.53,54
Conclusions It is estimated that 610 000 first strokes occur in the United States each year.1 Worldwide, it is estimated that there were 11.6 million incident ischemic strokes and 5.3 million incident hemorrhagic strokes in 2010.55 Although transient ischemic attacks can precede stroke, most strokes occur without warning. Stroke is a preventable disease, and control of modifiable risk factors plays the major role in prevention strategies. There is substantial, consistent evidence from numerous, high quality studies that higher PA levels are associated with significantly lower risk of stroke, and this evidence suggests that PA has a protective benefit in stroke prevention beyond the traditional stroke risk factors. With the high prevalence
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4 Stroke June 2015 of physical inactivity in the general population, increasing PA levels could have a significant effect on reducing stroke incidence. Given the numerous health benefits of PA, there are many public health guidelines on the recommended volume and intensity of PA for optimal health. Although separate guidelines for stroke prevention do not exist, the recommendations for primary stroke prevention are consistent with the current US guidelines: at least 40 minutes/d of moderate to vigorous intensity aerobic PA 3 to 4 days/wk.31,44,56,57 These recommendations should be stressed as part of an overall stroke prevention strategy, but even more so in persons with other risk factors. The literature suggests that men achieve a greater reduction in stroke risk when they engage in PA at a moderate to vigorous intensity, whereas women benefit from greater amounts of low intensity PA, such as walking. Further research is needed to clarify the type and intensity of PA, potential differences by race/ethnic groups, and use of more objective measurement of PA to clarify the dose–response relationship in men and women. The recommended PA level for stroke prevention is associated with a low risk within the general population, with an acceptable risk:benefit ratio.9 So to use the common motivational phraseology, just do it. And do it every day!
Disclosures Dr Howard has received research funding from National Institutes of Health for studies of physical activity and stroke risk. Dr McDonnell reports no conflicts.
References 1. Meschia JF, Bushnell C, Boden-Albala B, Braun LT, Bravata DM, Chaturvedi S, et al; American Heart Association Stroke Council; Council on Cardiovascular and Stroke Nursing; Council on Clinical Cardiology; Council on Functional Genomics and Translational Biology; Council on Hypertension. Guidelines for the primary prevention of stroke: a statement for healthcare professionals from the American Heart Association/ American Stroke Association. Stroke. 2014;45:3754–3832. doi: 10.1161/ STR.0000000000000046. 2. O’Donnell MJ, Xavier D, Liu L, Zhang H, Chin SL, Rao-Melacini P, et al; INTERSTROKE investigators. Risk factors for ischaemic and intracerebral haemorrhagic stroke in 22 countries (the INTERSTROKE study): a case-control study. Lancet. 2010;376:112–123. doi: 10.1016/ S0140-6736(10)60834-3. 3. Mora S, Cook N, Buring JE, Ridker PM, Lee IM. Physical activity and reduced risk of cardiovascular events: potential mediating mechanisms. Circulation. 2007;116:2110–2118. doi: 10.1161/ CIRCULATIONAHA.107.729939. 4. Simons-Morton DG. Physical activity and blood pressure. In: Izzo JL, Sica DA, Black HR, eds. Hypertension Primer: The Essential of High Blood Pressure: Basic Science, Population Science, and Clinical Management. Philadelphia, PA: Wolters Kluwer/Lippincott, Williams and Wilkins; 1998:295–296. 5. Marcus BH, Williams DM, Dubbert PM, Sallis JF, King AC, Yancey AK, et al; American Heart Association Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity); American Heart Association Council on Cardiovascular Disease in the Young; Interdisciplinary Working Group on Quality of Care and Outcomes Research. Physical activity intervention studies: what we know and what we need to know: a scientific statement from the American Heart Association Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity); Council on Cardiovascular Disease in the Young; and the Interdisciplinary Working Group on Quality of Care and Outcomes Research. Circulation. 2006;114:2739–2752. doi: 10.1161/CIRCULATIONAHA.106.179683. 6. Shiroma EJ, Lee IM. Physical activity and cardiovascular health: lessons learned from epidemiological studies across age, gender,
and race/ethnicity. Circulation. 2010;122:743–752. doi: 10.1161/ CIRCULATIONAHA.109.914721. 7. Reiner M, Niermann C, Jekauc D, Woll A. Long-term health benefits of physical activity–a systematic review of longitudinal studies. BMC Public Health. 2013;13:813. doi: 10.1186/1471-2458-13-813. 8. Thomas DE, Elliott EJ, Naughton GA. Exercise for type 2 diabetes mellitus. Cochrane Database Syst Rev. 2006:CD002968 9. Thompson PD, Buchner D, Pina IL, Balady GJ, Williams MA, Marcus BH, et al; American Heart Association Council on Clinical Cardiology Subcommittee on Exercise, Rehabilitation, and Prevention; American Heart Association Council on Nutrition, Physical Activity, and Metabolism Subcommittee on Physical Activity. Exercise and physical activity in the prevention and treatment of atherosclerotic cardiovascular disease: a statement from the Council on Clinical Cardiology (Subcommittee on Exercise, Rehabilitation, and Prevention) and the Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity). Circulation. 2003;107:3109–3116. doi: 10.1161/01.CIR.0000075572.40158.77. 10. Motahari-Tabari N, Ahmad Shirvani M, Shirzad EAM, YousefiAbdolmaleki E, Teimourzadeh M. The effect of 8 weeks aerobic exercise on insulin resistance in type 2 diabetes: a randomized clinical trial. Glob J Health Sci. 2015;7:34118. 11. Kamijo T, Murakami M. Regular physical exercise improves physical motor functions and biochemical markers in middle-age and elderly women. J Phys Act Health. 2009;6:55–62. 12. Caspersen CJ, Powell KE, Christenson GM. Physical activity, exercise, and physical fitness: definitions and distinctions for health-related research. Public Health Rep. 1985;100:126–131. 13. Shortreed SM, Peeters A, Forbes AB. Estimating the effect of long-term physical activity on cardiovascular disease and mortality: evidence from the Framingham Heart Study. Heart. 2013;99:649–654. doi: 10.1136/ heartjnl-2012-303461. 14. Hu FB, Stampfer MJ, Colditz GA, Ascherio A, Rexrode KM, Willett WC, et al. Physical activity and risk of stroke in women. JAMA. 2000;283:2961–2967. 15. McDonnell MN, Hillier SL, Hooker SP, Le A, Judd SE, Howard VJ. Physical activity frequency and risk of incident stroke in a national US study of blacks and whites. Stroke. 2013;44:2519–2524. doi: 10.1161/ STROKEAHA.113.001538. 16. Washburn RA, Goldfield SR, Smith KW, McKinlay JB. The validity of self-reported exercise-induced sweating as a measure of physical activity. Am J Epidemiol. 1990;132:107–113. 17. Siconolfi SF, Lasater TM, Snow RC, Carleton RA. Self-reported physical activity compared with maximal oxygen uptake. Am J Epidemiol. 1985;122:101–105. 18. Kohl HW, Blair SN, Paffenbarger RS Jr, Macera CA, Kronenfeld JJ. A mail survey of physical activity habits as related to measured physical fitness. Am J Epidemiol. 1988;127:1228–1239. 19. DiPietro L. Physical activity in aging: changes in patterns and their relationship to health and function. J Gerontol A Biol Sci Med Sci. 2001;56 Spec No 2:13–22. 20. Norton K, Norton L, Sadgrove D. Position statement on physical activity and exercise intensity terminology. J Sci Med Sport. 2010;13:496–502. doi: 10.1016/j.jsams.2009.09.008. 21. Sattelmair JR, Kurth T, Buring JE, Lee IM. Physical activity and risk of stroke in women. Stroke. 2010;41:1243–1250. doi: 10.1161/ STROKEAHA.110.584300. 22. Banda JA, Hutto B, Feeney A, Pfeiffer KA, McIver K, Lamonte MJ, et al. Comparing physical activity measures in a diverse group of midlife and older adults. Med Sci Sports Exerc. 2010;42:2251–2257. doi: 10.1249/ MSS.0b013e3181e32e9a. 23. Chiuve SE, Rexrode KM, Spiegelman D, Logroscino G, Manson JE, Rimm EB. Primary prevention of stroke by healthy lifestyle. Circulation. 2008;118:947–954. doi: 10.1161/CIRCULATIONAHA.108.781062. 24. Tikk K, Sookthai D, Monni S, Gross ML, Lichy C, Kloss M, et al. Primary preventive potential for stroke by avoidance of major lifestyle risk factors: the European Prospective Investigation into Cancer and Nutrition-Heidelberg cohort. Stroke. 2014;45:2041–2046. doi: 10.1161/ STROKEAHA.114.005025. 25. Larsson SC, Akesson A, Wolk A. Healthy diet and lifestyle and risk of stroke in a prospective cohort of women. Neurology. 2014;83:1699– 1704. doi: 10.1212/WNL.0000000000000954. 26. Kurth T, Moore SC, Gaziano JM, Kase CS, Stampfer MJ, Berger K, et al. Healthy lifestyle and the risk of stroke in women. Arch Intern Med. 2006;166:1403–1409. doi: 10.1001/archinte.166.13.1403.
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Howard and McDonnell Physical Activity in Primary Stroke Prevention 5 27. Myint PK, Luben RN, Wareham NJ, Bingham SA, Khaw KT. Combined effect of health behaviours and risk of first ever stroke in 20,040 men and women over 11 years’ follow-up in Norfolk cohort of European Prospective Investigation of Cancer (EPIC Norfolk): prospective population study. BMJ. 2009;338:b349. 28. Zhang Y, Tuomilehto J, Jousilahti P, Wang Y, Antikainen R, Hu G. Lifestyle factors on the risks of ischemic and hemorrhagic stroke. Arch Intern Med. 2011;171:1811–1818. doi: 10.1001/ archinternmed.2011.443. 29. Dong C, Rundek T, Wright CB, Anwar Z, Elkind MS, Sacco RL. Ideal cardiovascular health predicts lower risks of myocardial infarction, stroke, and vascular death across whites, blacks, and hispanics: the northern Manhattan study. Circulation. 2012;125:2975–2984. doi: 10.1161/CIRCULATIONAHA.111.081083. 30. Kulshreshtha A, Vaccarino V, Judd SE, Howard VJ, McClellan WM, Muntner P, et al. Life’s Simple 7 and risk of incident stroke: the reasons for geographic and racial differences in stroke study. Stroke. 2013;44:1909–1914. doi: 10.1161/STROKEAHA.111.000352. 31. Zhang Q, Zhou Y, Gao X, Wang C, Zhang S, Wang A, et al. Ideal cardiovascular health metrics and the risks of ischemic and intracerebral hemorrhagic stroke. Stroke. 2013;44:2451–2456. doi: 10.1161/ STROKEAHA.113.678839. 32. Lee IM, Hennekens CH, Berger K, Buring JE, Manson JE. Exercise and risk of stroke in male physicians. Stroke. 1999;30:1–6. 33. Folsom AR, Prineas RJ, Kaye SA, Munger RG. Incidence of hypertension and stroke in relation to body fat distribution and other risk factors in older women. Stroke. 1990;21:701–706. 34. Kiely DK, Wolf PA, Cupples LA, Beiser AS, Kannel WB. Physical activity and stroke risk: the Framingham Study. Am J Epidemiol. 1994;140:608–620. 35. Willey JZ, Moon YP, Paik MC, Boden-Albala B, Sacco RL, Elkind MS. Physical activity and risk of ischemic stroke in the Northern Manhattan Study. Neurology. 2009;73:1774–1779. doi: 10.1212/ WNL.0b013e3181c34b58. 36. Huerta JM, Chirlaque MD, Tormo MJ, Gavrila D, Arriola L, MorenoIribas C, et al. Physical activity and risk of cerebrovascular disease in the European Prospective Investigation into Cancer and Nutrition-Spain study. Stroke. 2013;44:111–118. doi: 10.1161/STROKEAHA.112.670612. 37. Lee CD, Folsom AR, Blair SN. Physical activity and stroke risk: a meta-analysis. Stroke. 2003;34:2475–2481. doi: 10.1161/01. STR.0000091843.02517.9D. 38. Wendel-Vos GC, Schuit AJ, Feskens EJ, Boshuizen HC, Verschuren WM, Saris WH, et al. Physical activity and stroke. A meta-analysis of observational data. Int J Epidemiol. 2004;33:787–798. doi: 10.1093/ije/ dyh168. 39. Li J, Siegrist J. Physical activity and risk of cardiovascular disease–a meta-analysis of prospective cohort studies. Int J Environ Res Public Health. 2012;9:391–407. doi: 10.3390/ijerph9020391. 40. Diep L, Kwagyan J, Kurantsin-Mills J, Weir R, Jayam-Trouth A. Association of physical activity level and stroke outcomes in men and women: a meta-analysis. J Womens Health (Larchmt). 2010;19:1815– 1822. doi: 10.1089/jwh.2009.1708. 41. Howard VJ, David Rhodes J, Mosher A, Hutto B, Stewart MS, Colabianchi N, et al. Obtaining accelerometer data in a national cohort of black and white adults [published online ahead of print October 20, 2014]. Med Sci Sports Exerc. http://journals.lww.com/acsm-msse/ Fulltext/publishahead/Obtaining_Accelerometer_Data_in_a_National_ Cohort.97885.aspx. Accessed February 18, 2015. 42. Pescatello LS, Franklin BA, Fagard R, Farquhar WB, Kelley GA, Ray CA, et al; American College of Sports Medicine. American College of Sports Medicine position stand. Exercise and hypertension. Med Sci Sports Exerc. 2004;36:533–553.
43. James PA, Oparil S, Carter BL, Cushman WC, Dennison-Himmelfarb C, Handler J, et al. 2014 evidence-based guideline for the management of high blood pressure in adults: report from the panel members appointed to the Eighth Joint National Committee (JNC 8). JAMA. 2014;311:507– 520. doi: 10.1001/jama.2013.284427. 44. Eckel RH, Jakicic JM, Ard JD, de Jesus JM, Houston Miller N, Hubbard VS, et al; American College of Cardiology/American Heart Association Task Force on Practice Guidelines. 2013 AHA/ACC guideline on lifestyle management to reduce cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014;129(25 suppl 2):S76–S99. doi: 10.1161/01.cir.0000437740.48606.d1. 45. Pal S, Cheng C, Egger G, Binns C, Donovan R. Using pedometers to increase physical activity in overweight and obese women: a pilot study. BMC Public Health. 2009;9:309. doi: 10.1186/1471-2458-9-309. 46. Pedersen MT, Blangsted AK, Andersen LL, Jørgensen MB, Hansen EA, Sjøgaard G. The effect of worksite physical activity intervention on physical capacity, health, and productivity: a 1-year randomized controlled trial. J Occup Environ Med. 2009;51:759–770. doi: 10.1097/ JOM.0b013e3181a8663a. 47. Carroll S, Dudfield M. What is the relationship between exercise and metabolic abnormalities? A review of the metabolic syndrome. Sports Med. 2004;34:371–418. 48. Diaz KM, Booth JN III, Calhoun DA, Irvin MR, Howard G, Safford MM, et al. Healthy lifestyle factors and risk of cardiovascular events and mortality in treatment-resistant hypertension: the reasons for geographic and racial differences in Stroke study. Hypertension. 2014;64:465–471. doi: 10.1161/HYPERTENSIONAHA.114.03565. 49. Sherman DL. Exercise and endothelial function. Coron Artery Dis. 2000;11:117–122. 50. Lackland DT, Voeks JH. Metabolic syndrome and hypertension: regular exercise as part of lifestyle management. Curr Hypertens Rep. 2014;16:492. doi: 10.1007/s11906-014-0492-2. 51. Long GH, Cooper AJ, Wareham NJ, Griffin SJ, Simmons RK. Healthy behavior change and cardiovascular outcomes in newly diagnosed type 2 diabetic patients: a cohort analysis of the ADDITION-Cambridge study. Diabetes Care. 2014;37:1712–1720. doi: 10.2337/dc13-1731. 52. Sone H, Tanaka S, Tanaka S, Suzuki S, Seino H, Hanyu O, et al; Japan Diabetes Complications Study Group. Leisure-time physical activity is a significant predictor of stroke and total mortality in Japanese patients with type 2 diabetes: analysis from the Japan Diabetes Complications Study (JDCS). Diabetologia. 2013;56:1021–1030. doi: 10.1007/ s00125-012-2810-z. 53. Ahmed HM, Blaha MJ, Nasir K, Rivera JJ, Blumenthal RS. Effects of physical activity on cardiovascular disease. Am J Cardiol. 2012;109:288– 295. doi: 10.1016/j.amjcard.2011.08.042. 54. Petersen AM, Pedersen BK. The anti-inflammatory effect of exercise. J Appl Physiol (1985). 2005;98:1154–1162. doi: 10.1152/ japplphysiol.00164.2004. 55. Krishnamurthi RV, Feigin VL, Forouzanfar MH, Mensah GA, Connor M, Bennett DA, et al. Global and regional burden of first-ever ischaemic and haemorrhagic stroke during 1990–2010: findings from the global burden of disease study 2010. Lancet Glob Health. 2013;1:e259–281. doi: 10.1016/S2214-109X(13)70089-5. 56. Physical Activity Guidelines Advisory Committee. Physical Activity Guidelines Advisory Committee Report, 2008. Washington, DC: US Department for Health and Human Services. http://www.health.gov/ paguidelines. Accessed January 18, 2015. 57. World Health Organization. WHO Global strategy on diet, physical activity and health. 2004. http://www.who.int/dietphysicalactivity/strategy/eb11344/strategy_english_web.pdf. Accessed January 18, 2015. Key Words: exercise ◼ physical activity ◼ primary prevention ◼ stroke
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Physical Activity in Primary Stroke Prevention: Just Do It! Virginia J. Howard and Michelle N. McDonnell Stroke. published online April 16, 2015; Stroke is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231 Copyright © 2015 American Heart Association, Inc. All rights reserved. Print ISSN: 0039-2499. Online ISSN: 1524-4628
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Physical Activity in Primary Stroke Prevention Just Do It! Virginia J. Howard, PhD; Michelle N. McDonnell, PhD
S
troke is a preventable disease. Well-documented, modifiable risk factors for stroke include hypertension, diabetes mellitus, dyslipidemia, obesity and body fat distribution, cigarette smoking, atrial fibrillation, heart disease, and physical inactivity.1,2 There is a wealth of information supporting physical activity (PA) as an important component of primary stroke prevention strategies. The proposed mechanism is that PA improves vascular function and stroke risk factors.3 The well-known health benefits of regular PA include reducing the risk of hypertension, type 2 diabetes mellitus, depression, and obesity, as well as control of these risk factors.4–7 Although data from multiple clinical trials support a reduction in stroke risk factors with PA,4,8–11 there are no clinical trials data demonstrating the efficacy of PA in reducing stroke incidence, partially because of the long follow-up required to achieve a sufficient number of events. The next best evidence comes from nonrandomized cohort studies where the consistency of results strongly supports the benefit of PA in primary stroke prevention (Class I, Level of Evidence B).1 The purpose of this review is to summarize the terminology and measurement of PA, synthesize the results of studies of PA and stroke risk in men and women, and describe how PA can ameliorate the effects of stroke risk factors, such as diabetes mellitus and hypertension. The challenges with PA research will also be discussed, as well as recommendations for future research.
Terminology and Measurement of PA PA is a complex behavior that can incorporate different elements, including occupational or leisure time PA, commuting, sport, walking, and exercise training. The accepted definition of PA used by most researchers is “any bodily movement produced by skeletal muscles that results in energy expenditure” (p. 126).12 This differs from exercise, a subset of PA defined as “PA that is planned, structured, repetitive and purposeful in the sense that improvement or maintenance of one or more components of physical fitness is an objective” (p. 128).12 Generally, epidemiological studies that rely on self-report intend to measure PA, but it is not always clear that participants understand the difference between PA and exercise when they complete
surveys or questionnaires. An alternative approach is to directly measure the physiological variable cardiorespiratory fitness using maximal or submaximal exercise tests but this is not feasible in large scale studies. The approach used in many longitudinal cohort studies, such as the Framingham Heart Study (FHS), the Nurse’s Health study, and the REasons for Geographic And Racial Differences in Stroke (REGARDS), is to ask about the frequency of intense PA, enough to work up a sweat.13–15 The validity of this widely used assessment is well-established16 and correlates with objective measures of cardiorespiratory fitness.17,18 Alternatively, participants are asked about moderate intensity PA, such as walking, the most common form of PA in older adults,19 often measured in terms of frequency, duration, or total time spent walking. Classification of PA is a significant limitation to epidemiological research. To quantify energy expenditure, it is necessary to have an estimate of the amount of time the participant spent on low intensity activities, such as domestic or occupational tasks, moderate intensity exercise (walking, playing golf), and intense physical activities (jogging or cycling).20 After this, a formula may be used to estimate the amount of energy expended on each activity. Although this approach is reported to be valid and reliable,21 the accuracy of these data is influenced by the ability of participants to accurately recall the durations spent on each activity in the period of interest. Furthermore, participants tend to overestimate the amount of time spent being physically active, leading to poor agreement between self-report and accelerometer-based measures in older adults.22 The approach to classifying participants into low, moderate, or high PA groups based on total energy expended or frequency of PA varies considerably between studies, making it impossible to quantify the specific amount and intensity of PA needed to confer significant stroke protection.
A Healthy Lifestyle (Including PA) and Risk of Incident Stroke Adherence to a healthy lifestyle significantly reduces the risk of stroke. Table I in the online-only Data Supplement provides
Received January 19, 2015; final revision received March 16, 2015; accepted March 17, 2015. From the Department of Epidemiology, School of Public Health, University of Alabama at Birmingham (V.J.H.); and Division of Health Sciences, International Centre for Allied Health Evidence, School of Health Sciences, University of South Australia, Adelaide, Australia (M.N.M.). The online-only Data Supplement is available with this article at http://stroke.ahajournals.org/lookup/suppl/doi:10.1161/STROKEAHA. 115.006317/-/DC1. Correspondence to Virginia J. Howard, PhD, Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Ryals 210F, 1720 2nd Ave S, Birmingham, AL 35294-0022. E-mail [email protected] (Stroke. 2015;46:00-00. DOI: 10.1161/STROKEAHA.115.006317.) © 2015 American Heart Association, Inc. Stroke is available at http://stroke.ahajournals.org
DOI: 10.1161/STROKEAHA.115.006317
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2 Stroke June 2015 an overview of the key studies that have investigated the effect of a healthy lifestyle on stroke risk. The key elements of a healthy lifestyle are avoidance of excess body weight, smoking, heavy alcohol consumption, unhealthy diet, and physical inactivity.23–25 Combined data from the US Nurse’s Health Study and the Health Professionals Follow-up Study (n=114 928) showed that adult women who make healthy lifestyle choices have an 80% lower risk of total stroke when compared with those who do not; for men, the risk was ≈70% lower.23 The optimal amount of PA within a healthy lifestyle was defined as ≥30 minutes/d of moderate or vigorous activity based on a self-administered questionnaire on frequency of PA over the previous year.23 In the population-based Sweden Mammography Cohort of 31 696 women, the definition of a healthy level of PA included both low and moderate intensity activities, walking or cycling at least 40 minutes/d and completing at least 1 hour/wk of structured exercise.25 The relative risk of stroke decreased with the addition of each healthy lifestyle factor, and women who adhered to all 5 low-risk lifestyle factors had a 62% lower risk of cerebral infarction than women with no low-risk factors. Another prospective cohort study of 23 927 men and women, the European Prospective Investigation into Cancer and Nutrition (EPIC-Heidelberg) study, supports these findings, estimating that 38% of stroke cases in their cohort could have been prevented if participants had adhered to the same 5 healthy lifestyle factors.24 Specific to PA, women who engaged in any level of PA compared with being inactive had a reduced stroke risk after multivariable adjustment, but for men, the multivariable adjusted risk estimates by different levels of PA were weaker and not statistically significant.24 In contrast, using a heath index (range, 0–20) that assigned scores of 0 to 4 to each of the 5 lifestyle components, the Women’s Health Study (n=37 636) found that an overall higher health index was associated with significantly lower stroke risk with a significant trend across the mean values of health index categories but for the individual component of PA defined by number of times per week of strenuous exercise, there was no association with stroke risk.26 The EPIC Norfolk study (n=20 040) used a slightly different definition of healthy lifestyle and for the unadjusted, individual component of PA, women who were physically inactive compared with not inactive had a significantly higher stroke risk, but for men there was no difference.27 However, for the overall healthy behavior score, in various covariateadjusted models, both men and women had consistently higher stroke risk with worse health behavior scores.27 In a Finnish population survey (n=36 686) with mean follow-up of 13.7 years, there was a graded inverse association between number of healthy lifestyle factors and risks of total, ischemic, and hemorrhagic stroke.28 For the individual factor of moderate or high versus low PA, there was a significant association with reduced risk of stroke for total and ischemic stroke but only a trend for hemorrhagic stroke.28 Using 7 different health metrics (glucose, cholesterol, blood pressure, body mass index, PA, diet, and cigarette smoking), that is, Life’s Simple 7, studies have shown that increasing numbers of these optimal factors are also associated with lower stroke risk.28–30 In the large China study (n=91 686), the
individual factor of PA comparing ideal (moderate or vigorous PA>80 minutes/week) versus nonideal showed a significantly lower risk of total and ischemic stroke but not hemorrhagic stroke.31
Physical Inactivity as a Risk Factor for Incident Stroke Several prospective cohort studies have collected data on PA and incident stroke (Table I in the online-only Data Supplement for details). Studies of all men32 or women14,21,33 participants have generally concurred that some PA, compared with none, offers protection against incident stroke. Studies including both men and women have also found significant risk reduction with PA, but with differing effects. Older men who were moderately active had the greatest risk reduction in the FHS, which found no such association in women.34 Low intensity exercise was not associated with reduced stroke risk in the Northern Manhattan Study, and moderately vigorous activity was only protective for men.35 This disparity was confirmed in the REGARDS study, with no association between vigorous PA and stroke risk for women when the sample was stratified by sex, despite a 20% decreased risk of stroke across the entire sample with 918 confirmed cases of stroke/transient ischemic attack.15 In the Spanish EPIC cohort, moderate intensity recreational PA was independently associated with reduced stroke risk in women but not in men.36 In all studies, the association was attenuated to some extent by multivariable adjustment for traditional stroke risk factors, such as hypertension, diabetes mellitus, alcohol, and tobacco use. A meta-analysis of 23 studies found that moderate and high levels of activity were associated with a reduced risk of total stroke, as well as ischemic and hemorrhagic stroke.37 Considering only prospective cohort studies in this meta-analysis, participants who were highly active or moderately active had a 25% or 17% lower risk of stroke incidence or mortality, respectively, compared with inactive participants. Wendel-Vos et al38 added to this literature with several more cohort studies and confirmed that both occupational and leisure time PA were associated with reduced stroke risk. A 2012 meta-analysis confirmed these findings, with leisure-time PA reducing stroke risk by ≈20% in both men and women.39 A dose– response relationship was particularly evident in women, with a relative risk for high PA versus low PA of 0.78, compared with 0.89 for moderate versus low PA.39 A 2010 meta-analysis studying differences between men and women in the benefit of PA and stroke risk concluded that although the overall benefit was similar, women may need a higher level of PA to achieve similar reduction in stroke risk.40 Precisely what a higher level of PA translates to, in terms of PA duration, frequency or intensity is unknown, as these meta-analyses classified PA into low, moderate, or high based on what was reported in the studies, but without any further detail. Overall, the literature to date suggests that all participants have a reduced risk of stroke from some PA compared with none, but the PA intensity needs to be more moderate to vigorous intensity for men to gain maximal benefit, whereas women generally benefited from longer duration PA of low to moderate intensity, such as walking, for example, >3.5 hours/wk.14,40
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Howard and McDonnell Physical Activity in Primary Stroke Prevention 3 Few studies have examined occupational PA in men or women, but rather the majority of studies measured frequency, duration, and intensity of all types of occupational or leisuretime PA. It is important to note that the majority of participants in all studies and meta-analyses were white from the United States or Europe. Only the REGARDS study used purposive sampling to ensure approximately equal numbers of white and black participants, with no racial differences observed in association between stroke and PA. Another important consideration in these studies is the heterogeneity of assessment of PA. All studies used self-report and differed in their questioning of PA characteristics, as well as the classification of participants into high or low PA groups. Data on the prevention of ischemic versus hemorrhagic stroke are sparse because of limited power from small numbers of hemorrhagic strokes. There are few studies that include serial assessment of PA levels during the long-term, so the cumulative benefits of PA and impact of changing behavior on stroke risk cannot be estimated.13 However, the evidence from several high-quality studies with large sample sizes provides a consistent message that PA, as part of a healthy lifestyle, reduces stroke risk. Future cohort studies that include stroke outcomes and objective measurement of PA using accelerometers41 will enable more accurate classification of PA levels and assist in clarifying the effect of intensity versus duration for men and women and dose– response relationship seen to some extent in all studies.
How Does PA Modify the Risk Factors for Stroke? Although the mechanisms mediating the reduction in stroke risk are not fully understood, there is substantial evidence for PA to influence stroke risk factors. When measuring the impact of PA on stroke risk, it is difficult to separate the specific role of PA when it often clusters with other healthy lifestyle factors, such as healthy diet, not smoking, and maintaining a healthy weight. Indeed, PA is believed to reduce stroke risk through the positive effect it has on these other stroke risk factors. When considering the 10 modifiable risk factors that, in an international case–control study, were found to account for 90% of the risk of stroke2 (hypertension, smoking, waist:hip ratio, diet score, PA, diabetes mellitus, alcohol intake, psychosocial status, cardiac causes, and ratio of apolipoproteins B to A1), PA can positively influence at least 3 of these: hypertension, diabetes mellitus, and body fat. Hypertension is considered to be the most important risk factor for primary stroke prevention.1 Control of blood pressure (BP) is one of the beneficial effects of PA for which specific recommendations have been made.4,42–44 A pilot randomized controlled trial of a simple walking intervention, using pedometers to increase step count, was effective at increasing PA and resulted in lower BP in a group of sedentary overweight and obese women.45 A workplace intervention conducted >1 year to increase PA in healthy office workers also resulted in a reduction in systolic BP in the PA, but not the control group.46 Both studies observed a reduction of ≈6 mm Hg in systolic BP, but larger reductions of ≤10 mm Hg are seen in studies with hypertensive participants.47 Individuals with treatment-resistant hypertension can also benefit from
PA, with reduced incidence of stroke observed in those who were involved in vigorous PA at least 4 times per week in the REGARDS study.48 It is likely that these reductions in systolic BP reflect improved endothelial function after exercise.49,50 Considerable evidence also supports the recommendation that people with type 2 diabetes mellitus should undergo structured PA because of the positive effects on glycemic control, visceral adipose tissue, and plasma triglycerides.8 A cohort study of individuals with newly diagnosed diabetes mellitus, followed up for 5 years, found that those who increased their PA had a relative risk of total cardiovascular disease (including stroke and myocardial infarction) of 0.53 compared with those who decreased their PA.51 When considering the association between stroke and PA in people with diabetes mellitus, those who participated in at least 30 minutes/d of brisk walking, or the equivalent, had a 45% reduction in stroke risk compared with those who were inactive.52 Several different variables are used in studies to classify excess weight: measurement of body mass index, waist circumference, waist:hip ratio, visceral adipose tissue, and overall body fat. Randomized controlled trials of PA interventions typically result in only modest weight loss (1–2 kg),5 but they are often associated with improvements in body mass index, waist circumference, and body fat with PA interventions,46 particularly in those with diabetes mellitus.10 Even in the absence of significant weight loss, moderately vigorous PA improves lipid profiles through lowering low density lipoprotein-cholesterol and triglycerides and increasing high density lipoprotein-cholesterol.5,53 Additional mediating factors, which may account for the reduction in stroke risk with regular PA, are likely to be related to inflammatory and hemodynamic factors. Blood samples from 27 055 participants of the Women’s Health Study were collected at baseline, along with data on cardiovascular risk factors including PA with follow-up of ≈11 years.3 Although this study did not examine stroke events separately from other cardiovascular events, it demonstrated that inflammatory/ hemostatic biomarkers, such as high-sensitivity C-reactive protein and fibrinogen, contributed significantly to lower risk of cardiovascular disease in women who were more physically active. This is consistent with previous literature attributing the anti-inflammatory effect of PA as an important factor in preventing cardiovascular disease.53,54
Conclusions It is estimated that 610 000 first strokes occur in the United States each year.1 Worldwide, it is estimated that there were 11.6 million incident ischemic strokes and 5.3 million incident hemorrhagic strokes in 2010.55 Although transient ischemic attacks can precede stroke, most strokes occur without warning. Stroke is a preventable disease, and control of modifiable risk factors plays the major role in prevention strategies. There is substantial, consistent evidence from numerous, high quality studies that higher PA levels are associated with significantly lower risk of stroke, and this evidence suggests that PA has a protective benefit in stroke prevention beyond the traditional stroke risk factors. With the high prevalence
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4 Stroke June 2015 of physical inactivity in the general population, increasing PA levels could have a significant effect on reducing stroke incidence. Given the numerous health benefits of PA, there are many public health guidelines on the recommended volume and intensity of PA for optimal health. Although separate guidelines for stroke prevention do not exist, the recommendations for primary stroke prevention are consistent with the current US guidelines: at least 40 minutes/d of moderate to vigorous intensity aerobic PA 3 to 4 days/wk.31,44,56,57 These recommendations should be stressed as part of an overall stroke prevention strategy, but even more so in persons with other risk factors. The literature suggests that men achieve a greater reduction in stroke risk when they engage in PA at a moderate to vigorous intensity, whereas women benefit from greater amounts of low intensity PA, such as walking. Further research is needed to clarify the type and intensity of PA, potential differences by race/ethnic groups, and use of more objective measurement of PA to clarify the dose–response relationship in men and women. The recommended PA level for stroke prevention is associated with a low risk within the general population, with an acceptable risk:benefit ratio.9 So to use the common motivational phraseology, just do it. And do it every day!
Disclosures Dr Howard has received research funding from National Institutes of Health for studies of physical activity and stroke risk. Dr McDonnell reports no conflicts.
References 1. Meschia JF, Bushnell C, Boden-Albala B, Braun LT, Bravata DM, Chaturvedi S, et al; American Heart Association Stroke Council; Council on Cardiovascular and Stroke Nursing; Council on Clinical Cardiology; Council on Functional Genomics and Translational Biology; Council on Hypertension. Guidelines for the primary prevention of stroke: a statement for healthcare professionals from the American Heart Association/ American Stroke Association. Stroke. 2014;45:3754–3832. doi: 10.1161/ STR.0000000000000046. 2. O’Donnell MJ, Xavier D, Liu L, Zhang H, Chin SL, Rao-Melacini P, et al; INTERSTROKE investigators. Risk factors for ischaemic and intracerebral haemorrhagic stroke in 22 countries (the INTERSTROKE study): a case-control study. Lancet. 2010;376:112–123. doi: 10.1016/ S0140-6736(10)60834-3. 3. Mora S, Cook N, Buring JE, Ridker PM, Lee IM. Physical activity and reduced risk of cardiovascular events: potential mediating mechanisms. Circulation. 2007;116:2110–2118. doi: 10.1161/ CIRCULATIONAHA.107.729939. 4. Simons-Morton DG. Physical activity and blood pressure. In: Izzo JL, Sica DA, Black HR, eds. Hypertension Primer: The Essential of High Blood Pressure: Basic Science, Population Science, and Clinical Management. Philadelphia, PA: Wolters Kluwer/Lippincott, Williams and Wilkins; 1998:295–296. 5. Marcus BH, Williams DM, Dubbert PM, Sallis JF, King AC, Yancey AK, et al; American Heart Association Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity); American Heart Association Council on Cardiovascular Disease in the Young; Interdisciplinary Working Group on Quality of Care and Outcomes Research. Physical activity intervention studies: what we know and what we need to know: a scientific statement from the American Heart Association Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity); Council on Cardiovascular Disease in the Young; and the Interdisciplinary Working Group on Quality of Care and Outcomes Research. Circulation. 2006;114:2739–2752. doi: 10.1161/CIRCULATIONAHA.106.179683. 6. Shiroma EJ, Lee IM. Physical activity and cardiovascular health: lessons learned from epidemiological studies across age, gender,
and race/ethnicity. Circulation. 2010;122:743–752. doi: 10.1161/ CIRCULATIONAHA.109.914721. 7. Reiner M, Niermann C, Jekauc D, Woll A. Long-term health benefits of physical activity–a systematic review of longitudinal studies. BMC Public Health. 2013;13:813. doi: 10.1186/1471-2458-13-813. 8. Thomas DE, Elliott EJ, Naughton GA. Exercise for type 2 diabetes mellitus. Cochrane Database Syst Rev. 2006:CD002968 9. Thompson PD, Buchner D, Pina IL, Balady GJ, Williams MA, Marcus BH, et al; American Heart Association Council on Clinical Cardiology Subcommittee on Exercise, Rehabilitation, and Prevention; American Heart Association Council on Nutrition, Physical Activity, and Metabolism Subcommittee on Physical Activity. Exercise and physical activity in the prevention and treatment of atherosclerotic cardiovascular disease: a statement from the Council on Clinical Cardiology (Subcommittee on Exercise, Rehabilitation, and Prevention) and the Council on Nutrition, Physical Activity, and Metabolism (Subcommittee on Physical Activity). Circulation. 2003;107:3109–3116. doi: 10.1161/01.CIR.0000075572.40158.77. 10. Motahari-Tabari N, Ahmad Shirvani M, Shirzad EAM, YousefiAbdolmaleki E, Teimourzadeh M. The effect of 8 weeks aerobic exercise on insulin resistance in type 2 diabetes: a randomized clinical trial. Glob J Health Sci. 2015;7:34118. 11. Kamijo T, Murakami M. Regular physical exercise improves physical motor functions and biochemical markers in middle-age and elderly women. J Phys Act Health. 2009;6:55–62. 12. Caspersen CJ, Powell KE, Christenson GM. Physical activity, exercise, and physical fitness: definitions and distinctions for health-related research. Public Health Rep. 1985;100:126–131. 13. Shortreed SM, Peeters A, Forbes AB. Estimating the effect of long-term physical activity on cardiovascular disease and mortality: evidence from the Framingham Heart Study. Heart. 2013;99:649–654. doi: 10.1136/ heartjnl-2012-303461. 14. Hu FB, Stampfer MJ, Colditz GA, Ascherio A, Rexrode KM, Willett WC, et al. Physical activity and risk of stroke in women. JAMA. 2000;283:2961–2967. 15. McDonnell MN, Hillier SL, Hooker SP, Le A, Judd SE, Howard VJ. Physical activity frequency and risk of incident stroke in a national US study of blacks and whites. Stroke. 2013;44:2519–2524. doi: 10.1161/ STROKEAHA.113.001538. 16. Washburn RA, Goldfield SR, Smith KW, McKinlay JB. The validity of self-reported exercise-induced sweating as a measure of physical activity. Am J Epidemiol. 1990;132:107–113. 17. Siconolfi SF, Lasater TM, Snow RC, Carleton RA. Self-reported physical activity compared with maximal oxygen uptake. Am J Epidemiol. 1985;122:101–105. 18. Kohl HW, Blair SN, Paffenbarger RS Jr, Macera CA, Kronenfeld JJ. A mail survey of physical activity habits as related to measured physical fitness. Am J Epidemiol. 1988;127:1228–1239. 19. DiPietro L. Physical activity in aging: changes in patterns and their relationship to health and function. J Gerontol A Biol Sci Med Sci. 2001;56 Spec No 2:13–22. 20. Norton K, Norton L, Sadgrove D. Position statement on physical activity and exercise intensity terminology. J Sci Med Sport. 2010;13:496–502. doi: 10.1016/j.jsams.2009.09.008. 21. Sattelmair JR, Kurth T, Buring JE, Lee IM. Physical activity and risk of stroke in women. Stroke. 2010;41:1243–1250. doi: 10.1161/ STROKEAHA.110.584300. 22. Banda JA, Hutto B, Feeney A, Pfeiffer KA, McIver K, Lamonte MJ, et al. Comparing physical activity measures in a diverse group of midlife and older adults. Med Sci Sports Exerc. 2010;42:2251–2257. doi: 10.1249/ MSS.0b013e3181e32e9a. 23. Chiuve SE, Rexrode KM, Spiegelman D, Logroscino G, Manson JE, Rimm EB. Primary prevention of stroke by healthy lifestyle. Circulation. 2008;118:947–954. doi: 10.1161/CIRCULATIONAHA.108.781062. 24. Tikk K, Sookthai D, Monni S, Gross ML, Lichy C, Kloss M, et al. Primary preventive potential for stroke by avoidance of major lifestyle risk factors: the European Prospective Investigation into Cancer and Nutrition-Heidelberg cohort. Stroke. 2014;45:2041–2046. doi: 10.1161/ STROKEAHA.114.005025. 25. Larsson SC, Akesson A, Wolk A. Healthy diet and lifestyle and risk of stroke in a prospective cohort of women. Neurology. 2014;83:1699– 1704. doi: 10.1212/WNL.0000000000000954. 26. Kurth T, Moore SC, Gaziano JM, Kase CS, Stampfer MJ, Berger K, et al. Healthy lifestyle and the risk of stroke in women. Arch Intern Med. 2006;166:1403–1409. doi: 10.1001/archinte.166.13.1403.
Downloaded from http://stroke.ahajournals.org/ at YALE MEDICAL LIBRARY on May 14, 2015
Howard and McDonnell Physical Activity in Primary Stroke Prevention 5 27. Myint PK, Luben RN, Wareham NJ, Bingham SA, Khaw KT. Combined effect of health behaviours and risk of first ever stroke in 20,040 men and women over 11 years’ follow-up in Norfolk cohort of European Prospective Investigation of Cancer (EPIC Norfolk): prospective population study. BMJ. 2009;338:b349. 28. Zhang Y, Tuomilehto J, Jousilahti P, Wang Y, Antikainen R, Hu G. Lifestyle factors on the risks of ischemic and hemorrhagic stroke. Arch Intern Med. 2011;171:1811–1818. doi: 10.1001/ archinternmed.2011.443. 29. Dong C, Rundek T, Wright CB, Anwar Z, Elkind MS, Sacco RL. Ideal cardiovascular health predicts lower risks of myocardial infarction, stroke, and vascular death across whites, blacks, and hispanics: the northern Manhattan study. Circulation. 2012;125:2975–2984. doi: 10.1161/CIRCULATIONAHA.111.081083. 30. Kulshreshtha A, Vaccarino V, Judd SE, Howard VJ, McClellan WM, Muntner P, et al. Life’s Simple 7 and risk of incident stroke: the reasons for geographic and racial differences in stroke study. Stroke. 2013;44:1909–1914. doi: 10.1161/STROKEAHA.111.000352. 31. Zhang Q, Zhou Y, Gao X, Wang C, Zhang S, Wang A, et al. Ideal cardiovascular health metrics and the risks of ischemic and intracerebral hemorrhagic stroke. Stroke. 2013;44:2451–2456. doi: 10.1161/ STROKEAHA.113.678839. 32. Lee IM, Hennekens CH, Berger K, Buring JE, Manson JE. Exercise and risk of stroke in male physicians. Stroke. 1999;30:1–6. 33. Folsom AR, Prineas RJ, Kaye SA, Munger RG. Incidence of hypertension and stroke in relation to body fat distribution and other risk factors in older women. Stroke. 1990;21:701–706. 34. Kiely DK, Wolf PA, Cupples LA, Beiser AS, Kannel WB. Physical activity and stroke risk: the Framingham Study. Am J Epidemiol. 1994;140:608–620. 35. Willey JZ, Moon YP, Paik MC, Boden-Albala B, Sacco RL, Elkind MS. Physical activity and risk of ischemic stroke in the Northern Manhattan Study. Neurology. 2009;73:1774–1779. doi: 10.1212/ WNL.0b013e3181c34b58. 36. Huerta JM, Chirlaque MD, Tormo MJ, Gavrila D, Arriola L, MorenoIribas C, et al. Physical activity and risk of cerebrovascular disease in the European Prospective Investigation into Cancer and Nutrition-Spain study. Stroke. 2013;44:111–118. doi: 10.1161/STROKEAHA.112.670612. 37. Lee CD, Folsom AR, Blair SN. Physical activity and stroke risk: a meta-analysis. Stroke. 2003;34:2475–2481. doi: 10.1161/01. STR.0000091843.02517.9D. 38. Wendel-Vos GC, Schuit AJ, Feskens EJ, Boshuizen HC, Verschuren WM, Saris WH, et al. Physical activity and stroke. A meta-analysis of observational data. Int J Epidemiol. 2004;33:787–798. doi: 10.1093/ije/ dyh168. 39. Li J, Siegrist J. Physical activity and risk of cardiovascular disease–a meta-analysis of prospective cohort studies. Int J Environ Res Public Health. 2012;9:391–407. doi: 10.3390/ijerph9020391. 40. Diep L, Kwagyan J, Kurantsin-Mills J, Weir R, Jayam-Trouth A. Association of physical activity level and stroke outcomes in men and women: a meta-analysis. J Womens Health (Larchmt). 2010;19:1815– 1822. doi: 10.1089/jwh.2009.1708. 41. Howard VJ, David Rhodes J, Mosher A, Hutto B, Stewart MS, Colabianchi N, et al. Obtaining accelerometer data in a national cohort of black and white adults [published online ahead of print October 20, 2014]. Med Sci Sports Exerc. http://journals.lww.com/acsm-msse/ Fulltext/publishahead/Obtaining_Accelerometer_Data_in_a_National_ Cohort.97885.aspx. Accessed February 18, 2015. 42. Pescatello LS, Franklin BA, Fagard R, Farquhar WB, Kelley GA, Ray CA, et al; American College of Sports Medicine. American College of Sports Medicine position stand. Exercise and hypertension. Med Sci Sports Exerc. 2004;36:533–553.
43. James PA, Oparil S, Carter BL, Cushman WC, Dennison-Himmelfarb C, Handler J, et al. 2014 evidence-based guideline for the management of high blood pressure in adults: report from the panel members appointed to the Eighth Joint National Committee (JNC 8). JAMA. 2014;311:507– 520. doi: 10.1001/jama.2013.284427. 44. Eckel RH, Jakicic JM, Ard JD, de Jesus JM, Houston Miller N, Hubbard VS, et al; American College of Cardiology/American Heart Association Task Force on Practice Guidelines. 2013 AHA/ACC guideline on lifestyle management to reduce cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014;129(25 suppl 2):S76–S99. doi: 10.1161/01.cir.0000437740.48606.d1. 45. Pal S, Cheng C, Egger G, Binns C, Donovan R. Using pedometers to increase physical activity in overweight and obese women: a pilot study. BMC Public Health. 2009;9:309. doi: 10.1186/1471-2458-9-309. 46. Pedersen MT, Blangsted AK, Andersen LL, Jørgensen MB, Hansen EA, Sjøgaard G. The effect of worksite physical activity intervention on physical capacity, health, and productivity: a 1-year randomized controlled trial. J Occup Environ Med. 2009;51:759–770. doi: 10.1097/ JOM.0b013e3181a8663a. 47. Carroll S, Dudfield M. What is the relationship between exercise and metabolic abnormalities? A review of the metabolic syndrome. Sports Med. 2004;34:371–418. 48. Diaz KM, Booth JN III, Calhoun DA, Irvin MR, Howard G, Safford MM, et al. Healthy lifestyle factors and risk of cardiovascular events and mortality in treatment-resistant hypertension: the reasons for geographic and racial differences in Stroke study. Hypertension. 2014;64:465–471. doi: 10.1161/HYPERTENSIONAHA.114.03565. 49. Sherman DL. Exercise and endothelial function. Coron Artery Dis. 2000;11:117–122. 50. Lackland DT, Voeks JH. Metabolic syndrome and hypertension: regular exercise as part of lifestyle management. Curr Hypertens Rep. 2014;16:492. doi: 10.1007/s11906-014-0492-2. 51. Long GH, Cooper AJ, Wareham NJ, Griffin SJ, Simmons RK. Healthy behavior change and cardiovascular outcomes in newly diagnosed type 2 diabetic patients: a cohort analysis of the ADDITION-Cambridge study. Diabetes Care. 2014;37:1712–1720. doi: 10.2337/dc13-1731. 52. Sone H, Tanaka S, Tanaka S, Suzuki S, Seino H, Hanyu O, et al; Japan Diabetes Complications Study Group. Leisure-time physical activity is a significant predictor of stroke and total mortality in Japanese patients with type 2 diabetes: analysis from the Japan Diabetes Complications Study (JDCS). Diabetologia. 2013;56:1021–1030. doi: 10.1007/ s00125-012-2810-z. 53. Ahmed HM, Blaha MJ, Nasir K, Rivera JJ, Blumenthal RS. Effects of physical activity on cardiovascular disease. Am J Cardiol. 2012;109:288– 295. doi: 10.1016/j.amjcard.2011.08.042. 54. Petersen AM, Pedersen BK. The anti-inflammatory effect of exercise. J Appl Physiol (1985). 2005;98:1154–1162. doi: 10.1152/ japplphysiol.00164.2004. 55. Krishnamurthi RV, Feigin VL, Forouzanfar MH, Mensah GA, Connor M, Bennett DA, et al. Global and regional burden of first-ever ischaemic and haemorrhagic stroke during 1990–2010: findings from the global burden of disease study 2010. Lancet Glob Health. 2013;1:e259–281. doi: 10.1016/S2214-109X(13)70089-5. 56. Physical Activity Guidelines Advisory Committee. Physical Activity Guidelines Advisory Committee Report, 2008. Washington, DC: US Department for Health and Human Services. http://www.health.gov/ paguidelines. Accessed January 18, 2015. 57. World Health Organization. WHO Global strategy on diet, physical activity and health. 2004. http://www.who.int/dietphysicalactivity/strategy/eb11344/strategy_english_web.pdf. Accessed January 18, 2015. Key Words: exercise ◼ physical activity ◼ primary prevention ◼ stroke
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Physical Activity in Primary Stroke Prevention: Just Do It! Virginia J. Howard and Michelle N. McDonnell Stroke. published online April 16, 2015; Stroke is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231 Copyright © 2015 American Heart Association, Inc. All rights reserved. Print ISSN: 0039-2499. Online ISSN: 1524-4628
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