Exercise may trigger stroke in people with blocked arteries

Regular exercise is good for us. Or so we keep being told.

We know that being physically active helps manage weight, strengthens bones and muscles, keeps the brain active, improves mental health and mood, and reduces the risk of developing certain diseases.

However, it seems that in some cases, exercise could actually be detrimental to our health.

New research published in the journal Physics of Fluids, has revealed that an elevated heart rate associated with exercise could trigger a stroke in patients with highly blocked carotid arteries – a condition linked to ageing most commonly affecting those in their 60s and 70s.

Contrastingly, for healthy patients and those with only slightly blocked arteries, exercise was found to be beneficial for maintaining healthy blood flow, said a team from the Indian Institute of Technology Kharagpur.

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 in the inner carotid walls, they form a plaque that narrows the artery.

This narrowing is called stenosis, and while it can be very difficult to detect the early stages of plaque accumulation, the condition 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 authors used a specialised computational model to simulate blood flow in carotid arteries at three stages of stenosis: without blockage, with a mild 30% occlusion, and with a moderate 50% obstruction.

They compared the effect of an exercise-induced heart rate at 140 beats per minute, and that of 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.

Study author Dr 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. This ruptured plaque may then flow to the brain and its blood supply, causing ischemic stroke.”

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

Many factors contribute to stenosis and stroke risk, including age, lifestyle, and genetics. For this reason, the authors recommended that people doing intense workouts should have their arterial health checked regularly.

They also suggested that those with moderate to severe stenosis or with a history of strokes, should follow a carefully prescribed exercise regime.