I’ve read that it indicates your heart’s ability to handle stressful stimuli, but I don’t understand why. Seems like you’d just want a steady heartbeat. Why isn’t high variation the same as arrhythmia?
ETA: a couple of articles I’ve read on the subject. They all say basically the same (no)thing.
https://www.health.harvard.edu/blog/heart-rate-variability-new-way-track-well-2017112212789
https://my.clevelandclinic.org/health/symptoms/21773-heart-rate-variability-hrv
https://en.m.wikipedia.org/wiki/Heart_rate_variability
In: Biology
I think in this case they’re not talking about how *steady* your heartbeat is, but the difference between your “resting” heart rate and your “stressed” heart rate. (It’d be nice to link the articles you just read, it makes it easier for people to understand what you’re asking about!)
When you’re stressed or exercising, you need your heart to beat faster so blood moves faster through your body and delivers oxygen/other things to the things that need it. But heart rates higher than some amount put stress on your heart and the rest of your circulatory system, so if your heart rate can’t go below that amount when you calm down you face increased risks of a lot of bad things.
So a healthy person has a relatively low “resting” heart rate. Obviously if it’s too low you could have a lot of problems, but in general if it’s lower that means less stress on your body, which is what you want when resting. People who have higher resting heart rates are having their circulatory system go through more stress than people with lower resting heart rates. You can sort of visualize your heart as having hit points like a video game, and more stress means it loses them faster. Less stress means it loses them more slowly.
Arrhythmia is a little different. Your heart’s normally supposed to respond to increased activity by beating faster, and gradually beat slower as you rest. In either case, if you maintain the same amount of activity, it ought to hit a pretty stable rate. You’d expect that to look like a curve, as it goes from say 70 to 80 to 100 to 120 as you get more active, then 125 to 120 to 100 to 80 to 70 as you calm down. Arrhythmia would look more like 70 to 90 to 50 to 120 to 70 to 140 to 110… you get the picture. It’s more of a jagged line than a curve. It might be because the heart isn’t even beating consistently. It’s supposed to be a nice rhythm: boom boom. boom boom. boom boom. But it could also screw up and be like boom…. boom. boomboom. boboom. boom…. boom. That messes up how well it can pump blood and is a very bad thing.
Did you know your Motor Cortex is directly connected with the action planning part of your brain, in fact, it’s integrated. It’s actually quite holistically done so throughout your brain. Now, why am I saying this? Well, this process is extended to a healthy heart that can react to various stimuli to get whatever has to be done, DONE.
There’s a network in your brain called the Cingulo-Opecular Network, it is made up primarily of the anterior insula/operculum, dorsal anterior cingulate cortex, and the thalamus. This network is generally related to your overall general alertness (“OH MY GOD THERES A THREAT OVER THERE. HEART! TIME TO RUN)”. This network and your Cingulo Cortex (the headquarters of general muscle control and response) has axons and dendrites going to and from many nodes within different networks of your brain and they all collaborate to determine what your heart rate should be for THAT moment.
Have you ever wondered how your heart can respond and immediately know your muscles might need more oxygen? Maybe your feeling a little frisky.. and that entails exercise! Variable control is part of the system and a lack of control is not something we associate with a good and clean running nervous system.
If you have a handicap on that variability, it could be a bad sign. Is something preventing hormonal responses? Are the local heart cells responding correctly? Are they distressed or dysfunctional? Is there a genetic factor lowering your body’s receptiveness to particular peripheral system stimuli? Is there an issue in a neural preventing an afferent signal to your hypophysial tract? What about a neurochemical shortage somewhere in your Salience network, or an over expression, and that’s causing a lack of variability?
If your nervous system is a dance and something is literally offbeat- it’s worth checking everything is in check!
A healthy person will have more beat to beat variability because they respond better to the natural lulls and rises of activity during the day. The articles you’ve linked dumb it down into high and low HRV rather which I assume is just their way of saying “unhealthy people are chronically stressed/under active/whatever factor affects heart rhythms, so therefore day to day HRV is lower compared to healthy people.” . You can’t avoid every form of stress so it’s better your heart can cool itself down (leading to more variability) when it finds the time to.
Variation is not the same as arrhythmia. The first is a natural process that everyone’s heart goes through because of a bunch of reasons, including metabolism/hormone cycles. Arrhythmia is random gaps between beats that don’t follow a steady increase/decrease pattern, they just happen out of the blue from the perspective of an EKG.
I actually work in a neurophysiology lab that looks at the relationship between brain and cardiac health, I’m in charge of collecting and scoring HRV data. The real stuff is a bit more complex and relies on the ratios between varying frequencies.
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