Glycogen-Free Muscle Growth - Erratum: Differences in P70K-Phosphorylation Between Glycogen De- and Repleted Leg Even Less Significant Than Previously Reported.
|Image 1: For the SuppVersity Super-Student Duong Nguyen, training in the semi-fasted state worked wonders. Want to know more? Read his guest-post and visit his blog.
Now, three weeks and a long and interesting email-correspondence with the author, Donny Camera from the RMIT University in Melbourne, Australia, later, I have to admit that (my interpretation of) the abstract was not completely correct. In the abstract it says (Camera. 2011):
p70S6KThr389 phosphorylation in LOW [glycogen depleted leg] increased in both nutrient (15-49 fold) and placebo (∼8 fold) groups 1 h and 4 h post-exercise compared to rest (P <.05) but was only different from rest 1 h post-exercise in NORM in the nutrient group (∼36 fold, P <.05).Back then (and to be honest, even now that I know what Donny actually meant), my understanding of "but was only different from rest 1h post-exercise in NORM in the nutrient group" was that there was no additional benefit from exercise in the normal leg, unless a post-workout drink consisting of 20g Whey + 20g maltodextrin was consumed. While I found that initially surprising I assumed that the absolute p70S6K response (remember the abstract provides information about the relative changes, only) in the non-depleted leg [NORM] would have been much higher than in the glycogen depleted leg, so that the addition of a protein + carbohydrate post-workout shake would not really make a difference.
|Figure 1: This graph depicting the p70k response in the glycogen depleted and the normal leg is of merely illustrative nature the data is not identical with the original material from the study (Camera. 2011), but was made up to adequately represent the most important findings.
Thus, it turns out the relative values from the abstract, on which I based my previous blogpost, did provide an initial impression, but not the whole picture oft what happens on the cellular level when you train a "fasted muscle" (which is why I usually do not even bother with abstracts, if I do not have access to the full text, but in this case, there simply was no fulltext, and the results were too interesting to keep them back). Contrary to the researchers initial hypothesis was there not only more than enough "gas in the tank" of the LOW leg even after selective glycogen depletion to for the protein synthetic cascade to be put into motion, the absolute degree of p70S6K phosphorylation and (this is only a reasonable assumption) exercise and nutrient induced protein (re-)synthesis were also identical.
|Image 2: Glycogen stores (magenta staining) in liver cells (A. Gunin)