LV preload changes in normal vs heavy exercise. Why?

[Ven0m]

So Kaplan 2010 videos say that in normal exercise, heart preload stays normal, but in heavy exercise, preload increases. While in Kaplan 2016 lecture notes, they say "during exercise, preload increases" without differentiating between normal or heavy exercise.

I tried to come up with an explanation with this, can you guys tell me if there's anything wrong with my educated guess?

Here it is:

During any exercise:
Sympathetic activation -> B1 heart stimulation-induced increase in heart contractility and heart rate.
Sympathetic activation also induces a1 venoconstriction, reducing pooling of blood in the veins. So circulating blood volume is increased (so venous return increases as well)
Muscle pump squeezes veins to increase venous return.

Normal exercise:
The increased venous return would lead to increased preload if no other compensating factors were changed (preload = EDV - end diastolic volume), but since heart contractility is increased, end-systolic volume is decreased (increase in contractility increases stroke volume), which counters the increased venous return, and therefore EDV (preload) remains normal.

Heavy exercise:
But heart contractility can only increase so much (thus stroke volume will plateau). So the massive increase in venous return during heavy exercise will outweigh the possible increase in contractility/stroke volume, so ESV cannot be low enough to counteract the increased venous return to make EDV (preload) normal. So, in heavy exercise, preload is increased.

So would these be the reasons why in normal exercise, preload remains normal; while in heavy exercise, preload increases?

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[Jabbed]

I agree with you in principle, but this feels like splitting hairs to the nth degree. I think the key takeaway is actually how SV and HR change with exercise-- both increase but SV obviously plateaus early with increases in HR allowing for increases in CO. Along the same logic, I would expect the increase in preload to be noticeable at the point when SV plateaus.
Again though, we're splitting hairs.