The role of physical activity in the prevention of stroke is of great interest due to the high mortality and significant impact of stroke-related morbidity on the individual and on healthcare resources. The use of physical activity as a therapeutic strategy to maximise functional recovery in the rehabilitation of stroke survivors has a growing evidence base. This narrative review examines the existing literature surrounding the use of exercise and physical therapy in the primary and secondary prevention of stroke. It explores the effect of gender, exercise intensities and the duration of observed benefit. It details the most recent evidence for physical activity in improving functional outcome in stroke patients. The review summaries the current guidelines and recommendations for exercise therapy and highlights areas in which further research and investigation would be useful to determine optimal exercise prescription for effective prevention and rehabilitation in stroke.
Stroke is a leading cause of mortality and morbidity worldwide. In the UK stroke is the third most common cause of death and the main cause of acquired disability. Approximately 130,000 individuals experience a first ever stroke per annum [
Exercise and physical activity have an increasing evidence base in the primary and secondary prevention of stroke and in stroke rehabilitation. The interface between physical activity and cerebrovascular disease is complex and of broad interest to clinicians, therapists, and epidemiologists. The importance of the relationship is becoming clearer: physical inactivity has been implicated by the INTERSTROKE study as one of the 5 key risk factors which account for more than 80% of the global burden of stroke [
A computer-assisted literature search was performed using the database Ovid MEDLINE (1950–June Week 4 2010) and the database EMBASE (1980 to 2010 Week 25). Briefly, we sought to identify studies examining the relationship between exercise or physical activity and cerebrovascular risk and studies examining the effect of exercise or physical activity in populations with cerebrovascular disease. Reference lists of all identified relevant articles and reviews were screened to identify other potentially eligible studies.
Hypertension is recognised as the most important modifiable risk factor for both ischaemic and haemorrhagic stroke [
The mechanistic basis of the effect of exercise on stroke risk is likely to be multifactorial. Regular exercise is known to increase the activity of nitric oxide synthase improving endothelial function, reduce left ventricular hypertrophy; stimulate elevations in plasma tissue plasminogen activator and HDL concentrations, and reduce fibrinogen and platelet activity. Aerobic conditioning has been shown to enhance glucose regulation and promote reductions in total serum and LDL cholesterol, triglycerides, total body fat, and systemic inflammation (Figure
Putative pathophysiological benefits of exercise [
Exercise and physical activity have a well-established evidence base for their benefits in reducing cardiovascular risk factors through the mechanisms described above. Observational studies have found an inverse association between physical activity and stroke risk [
Characteristics of studies investigating physical activity and stroke risk.
Study | Year | Methodology | Number of participants | Population Characteristics | Followup (years) | Number of stroke events | Relationship between physical activity and stroke |
---|---|---|---|---|---|---|---|
Abott et al. [ | 1994 | Prospective cohort | 7530 | Male (Honolulu Heart Program) 55–68 years | 22 | 537 | Inverse association |
Agnarsson et al. [ | 1999 | Prospective cohort | 4484 | Male (The Reykjavik Study) 45–80 years | 10.6 | 249 | Inverse association |
Ellekjær et al. [ | 2000 | Prospective cohort | 14101 | Female (Nord-Trondelag Health Survery) ≥50 years | 10 | 457 stroke deaths | Inverse association |
Evenson et al. [ | 1999 | Prospective cohort | 14575 | Male and Female (The Atherosclerosis Risk in Communities Study) 45–64 years | 7.2 | 189 | Inverse association |
Hu et al. [ | 2000 | Prospective cohort | 72488 | Female (The Nurses’ Health Study) 40–65 years | 8 | 407 | Inverse association |
Kiely et al. [ | 1994 | Prospective cohort | 4196 | Male and female (The Framingham Study) 28–62 years | 32 | 427 | Inverse association |
Gillum et al. [ | 1996 | Prospective cohort | 7895 | Male and female (National Health and Nutrition Examination Survey I) 45–74 years | 11.6 | 623 | Inverse association |
Haheim et al. [ | 1993 | Prospective cohort | 14403 | Male (Oslo Study) 40–49 years | 12 | 81 | Inverse association |
Wannamethee and Shaper [ | 1992 | Prospective cohort | 7735 | Male (British Regional Heart Study) 40–59 years | 9.5 | 128 | Inverse association |
Sacco et al. [ | 1998 | Retrospective case control | 369 + 678 controls | Male and Female ≥39 years | — | — | Inverse association |
Shinton and Sagar [ | 1993 | Retrospective case control | 65 + 169 controls | Male and female 35–74 years | — | — | Inverse association |
You et al. [ | 1995 | Retrospective case control | 203 + 203 controls | Male and female 20–85 years | — | — | Inverse association |
You et al. [ | 1997 | Retrospective case control | 201 + 201 controls | Male and female 15–55 years | — | — | Inverse association |
Hu et al. [ | 2005 | Prospective cohort | 47721 | Male and female 25–64 years | 19 | 2863 | Inverse association |
Williams et al. [ | 2009 | Prospective cohort | 41402 | Male and female (National Runners’ Health Study) | 7.7 | 119 | Inverse association |
Lee et al. [ | 1999 | Prospective cohort | 21823 | Male (Physicians Health Study) | 11.1 | 533 stroke deaths | No clear association |
Lee and Paffenbarger Jr. [ | 1998 | Prospective cohort | 11130 | Male (The Harvard Alumni Health Study) 43–88 years | 13 | 378 stroke deaths | U-shaped association |
Fossum et al. [ | 2007 | Prospective cohort | 9193 | Male and female Left ventricular hypertrophy and hypertension patients (Losartan intervention for endpoint reduction in hypertension (LIFE) study) 55–80 years | 4.8 | 541 strokes | Inverse association |
Lindsted et al. [ | 1991 | Prospective cohort | 9484 | Male (The Seventh Day Adventist Study) ≥30 years | 26 | 410 stroke deaths | No inverse association |
Menotti and Seccareccia [ | 1985 | Prospective cohort | 99029 | Male (Italian Railroad Workers Study) 40–59 years | 5 | 187 | No clear association |
Simonsick et al. [ | 1993 | Prospective cohort | 4840 | Male and female (Established Populations for Epidemiologic Studies of the Elderly) ≥65 years | 6 | — | Inconsistent relationships between physical activity and stroke |
Key: — = Data not available.
Differences in methodology, patient populations, and exercise interventions are likely to have contributed to this disparity. Studies generally, have been limited by their observational design and variations in adjustment for residual confounding. Some of the studies are retrospective and case control, which may have introduced selection and recall bias. Many of the studies use subjective measures to quantify the frequency and intensity of exercise, incorporating reporting bias. The lack of standard definitions of exercise intensity and the wide variability of exercise undertaken by participants into these studies introduce significant complexity to the meta-analysis and the clouds interpretation of the results. Populations studied differ in terms of ethnicity, age, and gender. In some prospective studies which have examined the effect of exercise on various cardiovascular endpoints [
A meta-analysis by Lee et al. included 18 cohort and 5 case control studies and concluded that moderately and high physically active individuals have lower stroke incidence and mortality. The relative reduction in stroke incidence observed in moderately and highly active individuals was estimated at between 20 and 27% [
Further evidence in support of a beneficial effect of exercise on stroke risk can be found in a meta-analysis of observational data from cohort and case control studies which investigated the effects of occupational and leisure-time physical activity on the risk of stroke [
Findings from further studies have been broadly supportive of the evidence that physical activity has an independent protective effect on the risk of cerebrovascular events [
A meta-analysis, including data from 33 prospective cohort studies and 10 case control studies addressing the effects of physical activity on stroke-related morbidity and mortality, found that the risk of an ischaemic stroke was reduced by 24% in women and 27% in men. However, they reported the effect to be statistically significant only for men [
A prospective cohort study of participants in the Women’s Health Study [
More recently, Sattelmair et al. investigated the effect of physical activity on stroke risk in 39315 women from the Women’s Health Study (WHS) with a mean followup of 11.9 years [
Many of the studies have not included women; therefore, there is less evidence on exercise in the prevention of stroke for women from which to draw conclusions and formulate guidelines and recommendations.
The Northern Manhattan Stroke Study [
In order to maintain the cardiovascular benefits and stroke risk reduction associated with exercising, patients must continue to participate in regular physical activity. If indeed a large proportion of the benefit of exercise on stroke risk reduction is mediated through its effect on reducing blood pressure, as some have suggested, then it is important to note that the positive effect of blood pressure reduction is reversible with cessation of exercise [
Evidence suggests that regular physical activity reduces the incidence and the mortality associated with stroke. The relative risk reduction appears to be somewhere between 20 and 30%. Some studies, though not all, report a trend for higher risk reduction with higher intensity physical activity [
In summary, published evidence favours an association between exercise and cardiovascular health. Beneficial effects of exercise on cerebrovascular risk reduction seem likely; however, definitive controlled trials are justified to establish the intensity and the frequency of exercise required to achieve benefits.
Approximately 30% of strokes are recurrent in nature [
With recent improvements in the care of patients presenting with an acute stroke and wider availability of pharmacological treatments, the majority of patients are surviving the initial insult [
Physical fitness is greatly reduced in people after stroke when compared to their age-matched counterparts [
The American Heart Association’s scientific statement from 2004 concluded that training-induced cardiovascular health and fitness benefits seen in the general population may be extrapolated to stroke survivors [
A meta-analysis assessing the effect of aerobic training on aerobic capacity by reviewing results from nine articles (seven randomised controlled trials) found that aerobic training achieving 50–80% of heart rate reserve, for 20–40 minutes, 3–5 days per week results in improved aerobic capacity as determined by peak oxygen consumption and peak workload. Most of the studies involved in the meta-analysis used the treadmill, cycle ergometer, or functional activities such as brisk stepping as a mode of aerobic training, and the analysis did not find that combining aerobic with resistance training resulted in improvements in aerobic capacity in this poststroke population [
Current stroke rehabilitation guidelines [
The loss or reduction in motor function is the most common and widely recognized impairment resulting from stroke [
Previous advice to avoid strength training in stroke patients in order to decrease the chance of developing spasticity has not been substantiated [
A recent meta-analysis by Langhorne et al. reported on a wide range of interventions that have been shown to improve motor function after stroke [
The Copenhagen Stroke Study reported that 22% of stroke survivors are unable to walk at the end of rehabilitation programmes [
There is limited evidence that the use of technological devices improve gait in stroke patients. The use of electromechanical gait training to improve walking after stroke was evaluated in a systematic review of seventeen randomised controlled trials. Results indicated that electromechanical-assisted gait training in combination with physiotherapy after stroke enhances patients’ chances of achieving independent walking. No benefits were found to walking speed or endurance [
Biofeedback [
Participation in regular physical activity can be beneficial to patients who have had a stroke. Aerobic training has been shown to enhance physical fitness and reduce cardiovascular risk factors in stroke patients who are generally less physically active than age-matched counterparts, and physical activity guidelines now recommend dedicating more time to aerobic activity as part of stroke rehabilitation programmes to optimise cardiovascular and cerebrovascular benefits and reduce the risk of recurrent events [
Despite the potential benefits, in reality the implementation of exercise for stroke patients is complex; there are often significant barriers to exercise prescription. Clearly the nature and severity of the neurological deficit will influence the range of activities deemed suitable for the patient. Further, previous studies have highlighted that, even in the optimal setting of an acute stroke unit, the time devoted to each individual’s physical and occupational therapy is limited by economic constraints, such as limited resources and personnel. As stroke is predominantly a disease of the elderly, many patients have significant comorbidities which may make regular physical activity less feasible [
Further trials are required to provide robust evidence to enable the design of exercise regimens, which can be implemented into stroke rehabilitation programmes to maximise functional outcomes in patients after stroke.
Exercise and physical activity are useful tools in the rehabilitation and the functional recovery of patients who have suffered a stroke. In addition, physical activity potentially provides protective benefits in the prevention of stroke, which may extend beyond the positive effects on traditional cardiovascular risk factors.
Based on the available evidence, the American Heart Association (AHA) recommends that stroke survivors should undertake: strength training to increase independence in activities of daily living, flexibility training to increase range of movement and prevent deformities, and training to enhance balance and coordination. The AHA advises that each of these exercise modalities should be carried out twice or three times per week with the view to improving functional outcome after stroke. Aerobic exercise of moderate intensity should be carried out on at least three days of the week for twenty to sixty minutes at a time, in order to increase physical activity capacity, improve walking and independence, and reduce the risk of cardiovascular disease [
Limitations highlighted in previous studies which have investigated the benefits of exercise in the prevention of stroke inhibit definitive conclusions regarding the type, frequency, and intensity of exercise that is required to confer a protective effect. Although some trials have included data on haemorrhagic stroke, the main body of evidence is for ischaemic stroke, and data on physical activity and haemorrhagic stroke are lacking in comparison. Profitable topics for further investigation should focus on defining the optimal intensities and durations of exercise required to provide the most substantial reduction in stroke risk for use in both primary and secondary prevention, the frequency of exercise sessions, the effect of gender on risk reduction with exercise, and the duration of observed benefit. For patients with previous stroke, identification and targeting of barriers to exercise delivery could lead to more widespread implementation of exercise prescription in this population. The long-term effect of regular physical activity on recurrent stroke risk in patients with previous stroke merits further study.