I recently had a terrible disagreement with someone and everytime I think about it I start shaking and my heart starts pounding from adrenaline, which according to Google is unhealthy. But our hearts are accelerated when exercising, which is supposed to be a good thing – so what is the difference?
In: Biology
Lot of misleading information here – the truth is there really ain’t a good way to make this ELI5 – but I’ll try my best. (Credentials – I put people to sleep for a living).
From a functional standpoint elevated heart rate is no different on the heart wether it’s from stress or exercise when it comes to rate.
Elevated heart rate is dangerous with an already diseased heart for two reasons. First, pumping fast requires more oxygen and if you have a problem delivering oxygenated blood at baseline (coronary artery disease), increasing the requirement of oxygen will make the muscle ischemic (injures due to lack of oxygen). Second, the heart is perfused (blood flows into the muscle) during the resting period of the cardiac cycle (diastole). The faster your heart beats, the less resting and the less blood that flows to the muscle.
The body releases a chemical when stressed (epinephrine and norepinephrine) that both increase heart rate (stimulate beta-1) and increase blood pressure (stimulate alpha-1). Making your heart use even more oxygen as it has to push against a higher pressure.
This happens with exercise and stress – so it can be dangerous to exercise with already very high blood pressure. There is nothing magical about stress on the heart when it comes to exercise vs stress.
Long term exercise leads to demand changes in the heart that make it better able to deal with the increased oxygen demand of expected continuous exercise. Stress also releases a host of other inflammatory hormones that are contributory you high BP and heart disease.
The main idea here is overtime the cause of the stress matters but in a Single session there is little difference.
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