the rise and fall of an adventurous heart

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Harald Motz

Level 8 Valued Member
Certified Instructor
Hello community,

We all know that a set of hardstyle swings skyrockets the heart rate really fast very high.

I made the following observation: after the set is done I shake my limbs a little bit, try to belly breathe and my heart rate rises almost 5-15 sec. after the completion (very pronounced in later sets) and/or goes a little bit down and up and down again.

Another experience I made in many sessions is this: when I do my “passive” rest I go down in the deep squat position, back straight and erect, my elbows pressed on the inside of the knees, my palms pressed together like in a prayer gesture. This is a really stable posture (braced in myself) but I still can belly breathe (my thighs are outside my torso).

Now the following happens: after a short time (in later sets it takes a little longer) my heart rate skyfalls, 5-20bpm suddenly, and I can get to 90-100bpm in maybe a minute. When I stand up it will rise 10-20bpm and stabilizes. I ponder this effect has something to do that the heart does not need to work all the way up when Iam in the deep squat position. But the drop rate it produces really amazes me...
 

Bryant W

Level 6 Valued Member
When squatting, preload (the amount of blood returning to the heart per stroke), increases. The left ventricle is therefore filled with more blood, resulting in a larger stroke volume. Since (cardiac output = heart rate x stroke volume), the heart rate won't spike as much because cardiac output is already augmented by increased stroke volume. When you stand back up, preload decreases, and the heart rate spikes again to maintain cardiac output.

Maybe you've had a physical exam where the doctor asked you to squat while listening to your heart. By increasing stroke volume, certain heart murmurs become more intense. The same physiology explains both phenomena.
 

slot canyon

Level 1 Valued Member
Following up on essentially what Bryant said. When you deep squat you essentially squeeze blood out of your lower extremities and into the pool that returns to your heart resulting in that increased pre load and increased cardiac output. In this environment, there is decline in the heart rate. There are some "sensors" in the vicinity of the aortic arch which adjust your pulse based on the requirements. When the sensors get the message that your cardiac output is decreased/falling then it increases the pulse rate to compensate. There would also be some constriction of some of the small arterial vessels in order to "squeeze" more blood into the circulatory system and contribute to the increase in cardiac output. When you stand, the opposite occurs. There is suddenly an empty space created in the vessels in the lower extremities which are now not being squeezed. Blood now begins to "pool" there and there has to be an increase in pulse rate (and peripheral resistance/arteriol constriction) in order to maintain cardiac output. If this did not happen or if you had a sluggish autonomic nervous system then BP would drop and you would also. Not unusual for someone who has been in the squatting position for a while and suddenly stand to experience a temporary light headed or dizzy feeling due to a decrease cardiac output and drop in BP.
 
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