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Warm and Cold Bloodedness

> >For a long time I have accepted the premise that prolonged physical exertion
> >is possible only for warm-blooded animals, but I have never understood the
> >reason why this ought to be true.  If the advantage lies in the muscles being
> >warm and better able to move, then I would think that warm bloodedness would
> >be most beneficial for short bursts of speed because the muscles would 
> >already
> >be warm.  This would be irrelevent for prolonged activity because the muscles
> >would warm themselves.  There must be something beyond the temperature itself
> >that supports the assertion, but I don't have any idea what it is.
> >
> >Bart Singer
> >
> I'm not a physiologist, but from observations of reptiles I wouldn't say
> that "prolonged activity" IS gained from endothermic muscle. Anacondas and
> crocodiles wrestling with mammalian prey don't seem to "tire out" that much
> quicker, if at all, than lions or tigers.
>  Endotherms do seem to have the advantage of quicker recovery rates after
> periods of exertion.  I'm fairly certain someone has worked on this subject,
> but for the life of me, I can't remember who.
> >
> Thomas R. HOLTZ
> > 
The stamina limitations of many modern reptiles are nothing to do with 
temperature (reptile muscle frequently operates at higher temperatures than 
mammalian); it is more to do with the problem of supplying the muscle with 
oxygenated blood, so that anaerobic metabolism predominates fairly quickly 
after an initial burst of activity (usually a matter of minutes depending on 
the species etc.).  Activity does not cease at this point, but the consequent 
build up of lactic acid leads to a problem of detoxification eventually, and 
requires a subsequent period of lowered activity.