Exercise may up stroke risk in people with blocked arteries: Study

NEW DELHI: An elevated heart rate during exercise can induce a stroke in patients with highly-blocked carotid arteries, according to a study by researchers from the Indian Institute of Technology (IIT) Kharagpur.

In contrast, exercise showed to be beneficial in maintaining healthy blood flow among healthy patients and those with only slightly-blocked arteries.

The findings, published in the journal 'Physics of Fluids', come as many people, including several celebrities from stand-up comedian Raju Srivastav to TV actor Siddharth Shukla and popular Kannada actor Puneeth Rajkumar, suffered fatal heart attacks during or post their workout session.

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 difficult 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 experiences 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.

The team used a specialised computational model to simulate blood flow in carotid arteries at three stages of stenosis: Without blockage, with mild 30 per cent blockage, and with a moderate 50 per cent blockage.

They compared the effect of an exercise-induced heart rate, 140 beats per minute, to 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. However, the results for moderate blockage were concerning.

"Intense exercise shows adverse effects on patients with moderate or higher stenosis levels," said Somnath Roy from IIT Kharagpur.

"It substantially increases the shear stress at the stenosis zone, which may cause the stenosis to rupture. This ruptured plaque may then flow to the brain and its blood supply, causing ischemic stroke," Roy added.

Additionally, an elevated heart rate could increase the likelihood of another stenosis forming, the study showed.

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

They also recommend a carefully-prescribed exercise regimen for people with moderate to severe stenosis or with a history of strokes.