On 21-7-2010 16:26, Invisible wrote:
> andrel wrote:
>> My heart rate (at rest) is 68.5+-5.5 (62--87)
> 
> So you're fit then?
> 
>> Heart rate is also a function of size*. The longer you are the lower 
>> your heart rate.
> 
> Really? I would have thought you'd need a higher heart rate to pump 
> blood further.

I think it is more like that you need to move more mass, both muscle and 
blood. And the time for the contraction wave to move along the entire 
heart increases too, because the velocity does not change that much. 
Imagine what would happen if a big whale heart (one a meter in length or 
more) beat once a second. If it could do that its vessels would probably 
tear apart or it would not contract simultaneously, one part contracting 
while another already starts to relax again. That would not pump much. 
Yet a mouse is perfectly capable of 10 times per second.

> Also, is that why my heart rate increases significantly if I stand up 
> rather than sit down?

LOL. I guess that is for comical reasons and you do know why.

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