|Image 1: Glycogen depleted or not,
post-workout protein, preferably from a
leucine-rich, fast digesting and nutritionally
complete source such as whey, is a must.
Dr. Connelly, who talked about this issue at length in the past installments of the BodyRX Show, was kind enough to remind me that back in 2007 Coffey et al. from Stuart Phillips' group at McMaster University, in Hamilton, Ontario (Canada), conducted a study that was based on an antithetical hypothesis, i.e. whether or not commencing resistance exercise with low muscle glycogen would enhance the encoding of genes implicated in muscular hypertrophy (Coffey. 2007). Yet, while there were significant differences at rest for the glycogen depleted vs. the normal leg of the subjects, both the increased GLUT4-MRNA expression, which is a sign of an increased capacity for glucose uptake, as well as the reduced expression of atrophic atrogenes (responsible for proteolysis, i.e. protein degradation) were overridden by exercise. Now, four years later Donny Camera from the University of Melbourne presented the results of a recent colloberation with the scientists from McMaster at the American College of Sports Medicine Conference in Denver, this year (Camera. 2011). The intention of this 2nd study was to elucidate the "effect of divergent glycogen content and subsequent post-exercise nutrition on anabolic signaling target p70S6 kinase during the early recovery period" after the completion of a standardized resistance training protocol.
|Illustration 1: Very simplified illustration |
of the role of mTOR and p90S6K
in protein synthesis.
|Figure 1: Increase in p70S6K phosphorylation in 16 resistance trained males after unilateral leg press exercise in normal and glycogen depleted leg relative to baseline (data adapted from Camera. 2011)|
Note that the baseline levels of the LOW and the NORMAL leg were probably different and the 8x increase could thus have lead to an absolute level of p70S6K phosphorylation that was still lower than in the NORMAL leg..These results do not only contradict the initially raised hypothesis that well-stocked glycogen stores would be a necessary or at least facilitative prerequisite for the muscle anabolic response to exercise to take place, they also (re-)raise the question whether "training on empty" may not after all be advantageous if ...
- the training performance is not effected by the lack of muscle glycogen and
- the muscle anabolic response is augmented via appropriate post-workout nutrient-replenishment