It appears as if exercise is not always good for all people, as the increased heart rate could make exercise dangerous for those with certain conditions. This study found that an elevated heart rate could induce a stroke in those with highly blocked carotid arteries, but in those that are healthy with slightly blocked arteries exercise remains healthy for maintaining blood flow.
The carotid arteries are located on both sides of the neck, and they supply blood flow to the brain and facial tissues. They can become narrowed when fat, cholesterol, or other particles build up in their inner walls and form plaques, this is called stenosis. Stenosis can be difficult to detect in the early stages of plaque accumulation, but it is still dangerous because it limits blood flow to the brain, and when the brain lacks oxygen the possibility of experiencing a stroke increases exponentially.
An elevated heart rate can increase and stabilize the drag force that blood exerts on vessel walls to reduce the risk of stenosis in healthy people, but for those with stenosis, it may not be as beneficial.
Using specialized computational models to simulate blood flow in carotid arteries at 3 stages of stenosis the researchers compared the effects of exercise-induced heart rates at 140 beats per minute and resting heart rates of 67 and 100 bpm. The three stages of stenosis were: without blockage, mild 30% blockage, and moderate 50% blockage.
According to the researchers, for healthy and mild cases the induced exercise condition improved the health of the simulated carotid, however, the results for moderate blockage were more concerning.
“Intense exercise shows adverse effects on patients with moderate or higher stenosis levels,” said author Somnath Roy. “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.”
While many factors contribute to stenosis and stroke risk the researchers recommend regular arterial health checkups for those participating in intense workouts, and based on their findings, for those with moderate to severe stenosis or those with a history of strokes they also recommend a carefully prescribed exercise regimen.
