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breckenridgeback t1_j6eb2n0 wrote

Your blood pressure is higher while you're exercising at first, but it becomes lower on average as a result of exercise (in much the same way that exercise raises your heart rate during exercise, but lowers your average heart rate).

The reason is that exercise:

  • Causes your body to store and carry oxygen more efficiently, by improving oxygen storage in your muscles, increasing the density of of red blood cells in your blood, and increasing the amount of hemoglobin in those red blood cells. This reduces the amount of blood flow required to support your body's operation.

  • Increases the size and strength of your heart, which no longer has to work as hard to pump.

  • Stretches out your blood vessels, making them more flexible to blood flow. The stiffness of blood vessels is a big part of high blood pressure, and contributes to the buildup of deposits on the sides of the blood vessels that contribute to e.g. heart attack or stroke.

When your body is storing oxygen more efficiently, your body doesn't have to "ramp up" to handle everyday tasks. You feel this as being less out of breath from small bits of exercise, like jogging for a moment to catch a bus or climbing a flight of stairs. It can also run quieter when you're stationary, because fewer, gentler heartbeats are needed to sustain your body's background oxygen usage. That reduces the overall stress on your body, and lets your body heal itself under low stress in between bouts of heavy exercise in a way that it can't if it's constantly under stress.

For example, I find about 30 minutes of relatively strenuous exercise a day drops my resting heart rate from ~100 beats per minute to ~60. Even though it spikes up to like 150 bpm during that exercise, that's only for 1/48th of the day, and it's running half as hard for the other 47/48ths. My low-fitness heart has to beat about 144,000 times a day, while my high-fitness heart has to beat 4,500 times during the exercise (using the 150 bpm number) and 84,600 times for the other 23.5 hours of the day, for a total of 89,100 beats - barely half as many.

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ninetentacles t1_j6g0xnh wrote

Wouldn't your heart need to beat more forcefully to move the same volume of blood completely around your body at 60bpm than at 100bpm, though?

And are these your own actual numbers, or are people more likely to see a more modest decrease in resting heart rate, like from 70bpm to 60? 100 seems awful high for "resting"!

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breckenridgeback t1_j6g31kd wrote

> Wouldn't your heart need to beat more forcefully to move the same volume of blood completely around your body at 60bpm than at 100bpm, though?

No. You don't need as much blood flow when your blood is more efficiently carrying oxygen, and it doesn't have to push as hard when it's not getting as much resistance from your arteries.

> And are these your own actual numbers, or are people more likely to see a more modest decrease in resting heart rate, like from 70bpm to 60? 100 seems awful high for "resting"!

It is high, yes. It's typical of someone with poor physical fitness, but not healthy. 60 bpm is a fairly normal healthy resting pulse. But the thrust of the explanation - that the heart does less work by having mild stress during exercise and less stress the rest of the time - stands either way.

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ninetentacles t1_j6g4hqr wrote

Ah, was just wondering because it's often at lower heart rates when I feel my heart pounding particularly forcefully, but I think my oxygen transfer may be a bit out of whack cause rona.

Will deconditioning cause your resting heart rate to go back up? Or if you're less active will you still maintain your low RHR past the point where whatever damage people think you're going to cause yourself by not pushing yourself to exercise til you drop through something like long COVID?

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breckenridgeback t1_j6iecay wrote

> Will deconditioning cause your resting heart rate to go back up?

Yeah, because your body won't keep putting in the resources to maintain the higher level of fitness.

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ninetentacles t1_j6l45vy wrote

After how long, would you say? Weeks, months, years?

And does that mean that if your RHR stays the same around 60ish, you're getting adequate cardio in to avoid deconditioning?

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breckenridgeback t1_j6l5e79 wrote

> After how long, would you say? Weeks, months, years?

Well, empirically, I notice it after a few weeks and have mostly reset after a few months, but this is deeper than my knowledge goes. (The rates probably vary by a lot of factors, like sex and age among others.)

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ninetentacles t1_j6l8k3v wrote

Excellent, thanks! I don't have a normal control to test, so I had to ask...

I've maintained my resting heart rate over the last few months of actively trying to rest and pace myself to try and help my long COVID. This has caused much hand wringing about deconditioning from every single person (not to mention what all of their friends say!) who knew me before I got sick! Despite me telling them I'm still hitting my Fitbit (now switched to Garmin!) cardio goals, they are thoroughly convinced that deconditioning is something you'll never notice until one day you get up to make a coffee and your legs crumble into dust. Which you can then supposedly never recover from. A presumably healthy person like you, your description of deconditioning and your knowledge of your own body and what's going on inside it isn't questioned as much as...anyone within a 10 mile radius of the 'rona.

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breckenridgeback t1_j6nh5qc wrote

I wouldn't take my personal experiences as some sort of proof. If you're looking for guidance on your own health, talk to your doctor. (Notably, I have not, to my knowledge, had covid.)

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ninetentacles t1_j6ogcx6 wrote

No, I was just looking for a healthy, fit control that didn't have COVID, but also had familiarity with their own heart rate.

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breckenridgeback t1_j6olj9s wrote

I'm not a healthy, fit control. Even in the more-fit of those two states I was still way overweight and not particularly fit.

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