Scientists warn exercise may trigger stroke in people with blocked arteries

Exercise is an important part of staying healthy, even if it’s considered low-intensity such as walking.

It typically appears as one of several recommendations made by health bodies to reduce your risk of various issues, alongside lifestyle changes such as eating a healthy diet and giving up smoking.

However, there are some cases in which exercise could actually be detrimental to your health.

New research has revealed that it could trigger a stroke among people with blocked arteries.

A team from the Indian Institute of Technology Kharagpur found that an increased heart rate can induce a stroke in patients with highly blocked carotid arteries – arteries that supply blood to the brain.

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However, for healthy patients and those with only slightly blocked arteries, exercise is still beneficial for maintaining healthy blood flow, they said.

Carotid arteries supply blood flow to facial tissues and the brain and are located on both sides of the neck.

When fat, cholesterol, and other particles build up the inner carotid walls, they form a plaque that narrows the artery.

The narrowing is called stenosis, and while it can be very hard to detect early stages of plaque accumulation, stenosis is dangerous because it limits blood flow to the brain.

Without the necessary blood, the brain lacks oxygen, and the patient suffers a stroke.

In healthy patients, an elevated heart rate increases and stabilises the drag force blood exerts on the vessel wall, reducing stenosis risk.

But for patients already experiencing stenosis, it may not be as beneficial.

As part of a study, published in Physics of Fluids journal, the team used a computer modelling to simulate blood flow in carotid arteries at three stages of stenosis.

These stages were: without blockage, with a mild 30 percent blockage, and with a moderate 50 percent blockage.

They compared the effect of an exercise-induced heart rate, 140 beats per minute, and resting heart rates of 67 and 100 bpm.

As expected, for healthy and mild cases, the exercise condition improved the health of the simulated carotid.

But the team said the results for moderate blockage were “concerning”.

Study author Doctor Somnath Roy said: “Intense exercise shows adverse effects on patients with moderate or higher stenosis levels.

“It substantially increases the shear stress at the stenosis zone, which may cause the stenosis to rupture.”

He added: “This ruptured plaque may then flow to the brain and its blood supply, causing ischaemic stroke.”

Dr Roy said an elevated heart rate could also increase the likelihood of another stenosis forming.

Many factors contribute to stenosis and stroke risk, including age, lifestyle, and genetics, but they recommend checking arterial health regularly for people doing intense workouts.

The team recommended a carefully prescribed exercise regime for people with moderate to severe stenosis or with a history of strokes.

A stroke can be identified using the acronym FAST:

• Face – the face may have dropped on one side, the person may not be able to smile, or their mouth or eye may have dropped
• Arms – the person with suspected stroke may not be able to lift both arms and keep them there because of weakness or numbness in one arm
• Speech – their speech may be slurred or garbled, or the person may not be able to talk at all despite appearing to be awake; they may also have problems understanding what you’re saying to them
• Time – it’s time to dial 999 immediately if you see any of these signs or symptoms.

If you suspect someone is suffering a stroke you should call 999.