Presented by Leanne Gravette, Jeff Gibberman, Zoe Fisher-Falk

 American Journal of Clinical Nutrition  Published in  Authors: Daniel R. Moore, Meghann J. Robinson, Jessica L. Fry, Jason E.Tang, Elisa I. Glover, Sarah B. Wilkinson, Todd Prior, Mark A. Tarnopolsky,and Stuart M. Phillips

 1 st study to measure a “dose-response relation between ingested whole protein and muscle protein synthetic rates after resistance exercise” (Moore, et al 161).  Past studies have proved a dose response at rest, but never after resistance exercise.

 There is a correlation between amino acid intake and enhanced anabolic effect of resistance exercise on muscle.

 How do specific doses of whole protein intake affect muscle protein synthesis (MPS) and albumin protein synthesis (APS)?  Does the dose intake enhance phosphorylation of the candidate signaling proteins?  Does albumin act as a protein storage system in times of excessive protein intake?  How is this possible phenomenon tied in to increase in albumin synthesis?

 mTOR Signaling Pathway  Pathway towards MPS  Contains regulatory proteins  Candidate signaling proteins  Changes in MPS may be regulated by these target proteins  “Stimulation of MPS in humans after feeding or resistance exercise is accompanied by enhanced phosphorylation, and presumably activity, of the mTOR signaling pathway.”

 Albumin unaffected by resistance exercise in young men.  Albumin synthesis stimulated by increased availability of amino acids.  Can dietary amino acids be incorporated into albumin protein in an effort to minimize their irreversible oxidation?  Feeding induced increase in albumin protein synthesis may serve as “storage’’ until amino acids are needed in periods of reduced supply.

 Mixed MPS will demonstrate a dose response to dietary protein after resistance exercise.  The maximal effective (maximally stimulated MPS) dose will be similar to what has previously been reported to be maximal at rest.  Plasma albumin protein synthesis will display a similar dose response to dietary protein as mixed muscle protein.  Above an ingested dose of protein that maximally stimulated muscle and albumin protein synthesis, amino acid oxidation will increase.

 The response of MPS to both feeding and exercise is regulated by specific protein kinases in the mTOR signaling pathway. Is there increased phosphorylation in response to increased dietary protein?  Is there a direct relationship between increased dietary protein intake and increased phosphorylation?  Can excess dietary amino acid be stored by albumin protein after increased APS?

 Six healthy, active males  Age: 20-24yrs  Weight lbs approx  Height: 5’7’’-6’3”  At least 4 months previous recreational weightlifting experience.

 Subjects performed exercise, ingested variable quantities of whole protein and then were tested for increases in MPS, APS and oxidation.  In this experiment Leucine was used as a tracer. This means that a stable isotopic form of leucine ( [1-13C] leucine), not usually found in the body was used to track what happened to the protein ingested post-exercise.  Leucine chosen b/c it is a EAA and a BCAA, primarily metabolized in skeletal muscle.

 The subjects were tested five times with at least one week between each trial.  The trial consisted of intensive leg resistance exercises that were designed to max out their physical capabilities.  After exercise a catheter was inserted in each arm, one was used for taking blood samples and the other was used to inject the leucine tracer into the blood stream.  This was followed immediately by an ingestion of an egg protein drink. The protein content for each participant varied between 0, 5, 10, 20 and 40 grams of dietary whole protein.

 In order to determine the physiological response to the ingested protein they used various methods of analyzing blood, breath, and muscle samples  Blood samples were taken from the catheterized arm  Breath was collected to determine CO2 enrichment  Muscle biopsy was taken twice (ouch!) at 1 and 4 hours from exercise  They took a ton of measurement from all these samples using many different devices.

 Isotope ratio mass spectrometry  CO2 enrichment in breath sample  Standard radioimmunoassay kit  Plasma insulin concentration  Standard glucose peroxidase enzymatic kit  Blood glucose concentration  Standard spectrophometric kit  Plasma urea concentration  Gas chromatography-mass spectrometry  Plasma enrichment

 Cation exchange chromatography  Free amino acid purification  Combustion-isotope ratio mass spectrometry  Amino acid conversion  Bicinchoninic acid protein assay  Determines protein contest of homogenates  GC-combustion-isotope ratio mass spectrometry  Liberates bound amino acids

 Direct correlation of increased dietary protein and MPS and APS up until 20 grams of ingested egg protein.  At 40 grams, no change in MPS or APS, however there was greater measure of leucine oxidation.  demonstrates that albumin does not actually store excess dietary amino acids.  No noticeable increase in phosphorylation of the protein kinases in the mTOR signaling pathway as a direct result of increased protein intake.

 Small sample size  6 people to represent the population  young and active men only.  The study is nonspecific about the level of fitness and capability of each individual.  What is the change of maximal protein utilization in people of various size (ex: Jeff vs. Leanne)

 Researchers proposed the possibility that ingesting 20 grams of protein, the peak amount for MPS and APS stimulation, five to six times daily would maximize utilization of ingested protein.  With a stronger study in this area one could provide empirical evidence to convince people to eat an optimal amount of protein.

 Detrimental effects of overconsumption of animal protein.  Ex: Met from meat  Osteoporosis  Atherosclerosis  Excess dietary AA get oxidized and stored as fat.