On Mon, 24 Jul 2000, Amadeus Schmidt wrote:

> The whole blood of an adult human (70kg) can hold a maximum of about 55g of
> amino acids.

This, of course, is a very rough generalization involving many
assumptions.  A more muscular person of the same weight will have
a greater blood volume, since muscle tissue is highly
vascularized.  This is why it makes sense to estimate protein
need by LBM, rather than body weight.  A "normal" adult weighing
70kg is probably 20% BF, making his or her LBM around 56kg.
Assuming a "normal" sedentary lifestyle, then your protein
estimate means about one gram  of protein per kg of LBM.

> One day will use about 0.4*70 = 28 g of the ideal amino acids for protein
> synthesis, from 20 to... high amounts for caloric usage.
> This means the 55g amino acids in the blood will have to be
> refilled in about one day.

Again, this usage estimate must vary significantly according to
exertion patterns.  High intensity exercise especially will
increase the usage rate for those amino acids, but overall
activity levels will also increase demand.  For this reason,
physiologists such as Lemon suggest that one's protein need
ranges from 1g/kg-LBM to 2g/kg-LBM.  If our 70kg person is a
bodybuilder engaging in high-intensity weight training several
times a week, things look different.  Now we imagine that his BF
is only 10%, making his LBM 63kg.  And his high-intensity
exercise pattern doubles his amino acid demand, so he needs
something like 120g/day of protein to sustain this lifestyle.

Todd Moody
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Todd Moody
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