On 3/30/00, Anna Lee<[log in to unmask]> wrote:
<< . . . . the list is for all of us to use and learn and have intellectual
discussions and hopefully we will continue on this vein.>>
***The Starling Law puzzle emerged as one of those intellectual discussions,
so do share your views with us on the implications of this important topic,
as suggested a while ago.
On 3/30/00, M C Siff <[log in to unmask]>commented :
<Anna, the motto on your professional website (www.workready.com.au)
proclaims "Moving Muscles to get you back to work faster", so this puzzle
should be of special relevance to you. What are your views on this puzzle?
Is Starling Law based training preferable or should one rather train in the
middle of joint range where isokinetic tests show that maximum joint torque
takes place and where better actomyosin overlap would seem to occur? What
references would you cite to prove a case either way?>
In particular, Anna, what do you think about the following stimulating
contribution?
Frank Underwood<[log in to unmask]>
<<In cardiac muscle, the essence of the Frank-Starling Law of the heart is
that the heart pumps what you give it, at least up to a point. When Frank
and Starling were describing this phenomenon, they explained it using
skeletal muscle physiology, which was appropriate for the time. That is, the
cardiac muscle cells created more cross-bridges with a stretch, but at some
point, the myosin heads nearest the H-zone were not opposed by an active site
on the myosin, thus fewer cross-bridges were possible, and less force was
generated, and less blood was ejected. . . .
I think the bottom line is that invoking skeletal muscle physiological
principles to explain the behavior of intact cardiac muscle is a mistake,
even though both are striated muscle. Much of the early information we
have on cardiac muscle was obtained from the study of cardiac papillary
muscle, which resembles skeletal muscle in form and function much more than
does a ventricular myocyte.>>
Mel Siff
Dr Mel C Siff
Denver, USA
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