Nouvelle méthode de mesure Hi-tech des besoins en protéines chez le bodybuilder
Pour un bodybuilder, les besoins en protéines triplent
Protein requirement of strength-trained athletes determined using the indicator amino acid oxidation technique is several
fold greater than the current DRI
Arash Bandegan Appl. Physiol. Nutr. Metab. Vol. 40, 2015 pS4
Despite a number of studies indicating increased protein needs in
athletes using the nitrogen balance technique, the Institute of Medicine
(2005) has concluded, based largely on methodological concerns,
that “no additional dietary protein is suggested for healthy adults
undertaking resistance or endurance exercise”.
The indicator amino acid (AA) oxidation technique (IAAO) is based on the concept that
when dietary protein is insufficient, all AA, including the indicator AA
will be oxidized. With increasing dietary protein, oxidation of the
indicator AA will decrease incrementally. Once the requirement is
met, the oxidation of the indicator AA plateaus, despite the increasing
protein intake and the inflection point or ‘breakpoint’ is the estimated
requirement.
For the first time, we have determined the
protein requirement in strength-trained athletes (≥3 y training
experience; n=8) by measuring the oxidation of ingested L-[1-13C] phenylalanine
to 13CO2 in response to graded intakes of protein (from 0.1 to
3.0 g·kg-1·d-1) in a total of 32 studies. The isoenergetic diets provided
energy at 1.5× each subject’s measured resting energy expenditure.
Protein was given as an AA mixture on the basis of the egg protein
pattern, except for phenylalanine and tyrosine, which were maintained
constant across the protein intake quantities.
For two days
prior to the study day, the subjects were adapted to a dietary protein of
1.5 g·kg-1·d-1. The mean breakpoint was determined by applying a
mixed-effects change-point regression analysis to F13CO2 (label tracer
oxidation in 13CO2 breath).
The mean estimated average protein requirement
(EAR) for these strength-trained athletes was 2 g·kg-1·d-1,
which exceeds the current N balance determined EAR for untrained
individuals (0.66 g·kg-1·d-1) by 3 times.