Her er en kommentar angående denne studien som du viser til (Tipton et al) av Kumar et al (2009):
"There is disagreement as to whether amino acid feeding before or after resistance exercise promotes MPS to a greater extent. It has been reported (114) that ingestion of essential amino acids taken with a carbohydrate supplement immediately before resistance exercise resulted in greater leg uptake of amino acids, but the results are quantitatively difficult to believe, given that they were made under non-steady-state conditions, and the increases in uptake were physiologically unlikely to represent increases in MPS, given their size (20-fold!), but, more likely, some artifact, such as pooling of amino acids within muscle. Furthermore, it has been recently shown by direct measurement of FSR in humans that feeding 1 h before an acute bout of high-intensity resistance exercise did not further enhance MPS during the 2-h postexercise period (43). Thus, once again, the leg tracer dilution method appears to yield qualitatively and quantitatively different results to those obtained by incorporation of tracer amino acids."
Alan Aragon har kommentert studien og vektlegger følgende:
Table 3. Mean arterial insulin levels during 4 time periods for PRE and POST trials
Rest Exercise 1 H Post-Ex 2 H Post-Ex
PRE 4.560.5 18.565.7 22.066.2 6.262.0
POST 4.160.8 8.562.4 27.065.8 6.661.2
Values are means 6 SE, expressed in IU/ml. Both PRE and POST
were significantly different across time, but individual significant
differences were not identifiable.
Han kommenterer: "However, upon closer examination, insulin levels during exercise and 1 hour postexercise in Tipton's trial were 18mU/l and 22mU/l, respectively. Both of these values are within the range of 15-30mU/l, which has been shown to maximally stimulate net muscle protein synthesis (this includes maximally inhibiting muscle protein breakdown) in the presence of elevated amino acids."
Så det du kan muligens konkludere med er at:
1) det viktigste er makroernæringsforholdene over tid (hva du har spist tidligere om dagen, om du trener på faste, hva du spiste i går og forholdene mellom protein / karb / fett i den dietten).
2) det er vanskelig å si om protein timing (enten whey, EAA eller BCAA) gir ulike utslag om det tas før eller etter trening. Min spekulasjon er at det vil være spesifikt etter energiinntaket til individene, hva slags trening som utføres, intensiteten på treningen osv....