"The ancients knew" is always a good start.
> The heart, an organ weighing about three hundred grams, is supposed to 'pump' some eight thousand liters of blood per day at rest
Or 92 mL/second. Or 46-92 mL per beat.
> through millions of capillaries
I read 10 billion capillaries elsewhere, but let's go with '5 million' capillaries.
This would mean the heart pushes 18.2 nanolitres through each capillary per second.
The amount of blood that descends to your legs is the same amount that the heart has to lift...
I know the name Rudolf Steiner for a kind of cultish school of child pedagogy, so I'll admit I was a little wary going in.
Even Ted Stevens knows that.