If you work out enough to break a sweat, and do it regularly, you are less likely to have a stroke compared to people who are physically inactive, researchers from the University of South Australia and the University of Alabama, Birmingham, USA, reported in the journal Stroke.
Dr Michelle McDonnell and colleagues found that self-reported physically inactive people have a 20% higher risk of stroke or mini-stroke (transient ischemic attack) compared to those who exercise enough to break a sweat four or more times a week.
Previous studies have suggested that physical inactivity is the second most important risk factor for stroke, after hypertension (high blood pressure). The authors said that their study was the first to "quantify protective effects of physical activity on stroke in a large multiracial group of men and women in the United States."
The authors explained that studies have looked extensively into the stroke-protecting benefits of less cigarette smoking, even down to how much people can reduce their risk by smoking one cigarette less per day. The same extensive research has been done on blood pressure.
Even though the sample population all came from one country, the USA, the researchers said their findings are relevant in other countries.
McDonnel and team followed more than 27,000 Americans for an average of 5.7 years, they were all aged 47 or more years.
The participants were part of the REGARDS study (Reasons for Geographic and Ethnic Differences in Stroke). The sample population included equal numbers of males and females, as well as Caucasians and African-Americans.
The sample population included proportionally more people from the southeast "Stroke Belt" states. The "stroke belt" is an area in the USA where strokes are significantly more common than the rest of the country (Virginia, Tennessee, South and North Carolinas, Mississippi, Louisiana, Georgia, Florida, Arkansas, and Alabama). The "southern diet", which consists mainly of fatty-fried foods rich in salt, is popular in the stroke belt. The southern diet has been linked to a higher risk of stroke.
The volunteers reported on how often they did exercise. The study did not, however, include details on how long each exercise session lasted.
Below are some highlighted data from the study:
- One third of all the people studied said they exercised less than once a week
- Those who exercised less than once a week had a 20% higher chance of experiencing a stroke or TIA (transient ischemic attack)
- The men who exercised moderately or vigorously - enough to break a sweat - four times a week or more were less likely to have a stroke
- There was a less clear association between vigorous physical activity and stroke risk among the female participants
Dr. McDonnell said:
"The stroke-lowering benefits of physical activity are related to its impact on other risk factors. Exercise reduces blood pressure, weight and diabetes. If exercise was a pill, you'd be taking one pill to treat four or five different conditions."
Why was the association not clear with women? - McDonnel believes this is because women might get benefit with less vigorous exercise, such as walking. The study did not focus on less vigorous physical activities. An article published in Stroke in January 2013 reported that walking reduces stroke risk in women.
According to the American Heart Association, people aged 18 to 65 should:
- Exercise moderately at least five times a week for 30+ minutes per session or..
- Exercise vigorously at least three times a week for 20+ minutes per session plus..
- Exercise on muscle-strengthening twice a week, involving all major muscle groups
Exercise may prevent a severe stroke - people who do plenty of exercise and experience a stroke are less likely to have severe symptoms, researchers reported in the journal Neurology (October 21st, 2013 issue).
What is a stroke? What is a mini-stroke (transient ischemic attack)?
A stroke is a condition in which the cells in the brain die because they are starved of oxygen. This can occur when there is a rupture of an artery that feeds the brain, or an obstruction in the blood flow.
When somebody has a stroke they can suddenly lose their ability to speak, one side of the face may become paralyzed, there may also be memory problems.
There are two main types of stroke:
- Ischemic stroke - approximately three-quarters of all strokes are of this type. A thrombus (blood clot) forms and blocks blood flow to part of the brain. A blood clot can form in another part of the body, break free and make its way through the bloodstream to the brain, causing a blockage there. A clot that has broken free is called an embolus.
- Hemorrhagic stroke - a blood vessel on the surface of the brain ruptures (and leaks). The space between the skull and the brain fills up with blood; this is known as a subarachnoid hemorrhage. A faulty artery in the brain may burst, filling surrounding tissue with blood, this is known as a cerebral hemorrhage.
In both types of stroke the brain does not get enough oxygen and glucose, plus the build up of leaking blood puts pressure on the brain.
The severity of a stroke depends on where in the brain it occurs and how much of it is affected. Minor strokes may cause weakness in a leg or arm, while more serious ones can lead to paralysis or death. It is common for stroke patients to end up with weakness and difficulties on one side of the body, some may have other problems, including incontinence, speaking difficulties, and cognitive impairment.
A Transient ischemic attack, also known as TIA or mini-stroke occurs when the blood supply to the brain drops temporarily, depriving it of oxygen. However, the short-lived oxygen deprivation is less serious than a full-blown stroke. A TIA only lasts a few minutes and is gone within a day.
Approximately half-a-million Americans are thought to experience a mini-stroke annually.
Although the symptoms disappear rapidly, from 10% to 15% of people who have a TIA go on to experience a full-blown stroke within three months. If you think you are having a mini-stroke, seek medical help immediately. Early treatment can significantly reduce the risk of subsequent stroke.