Question: I guess I just still don’t understand where PA comes in. Isn’t the lifting and Plazma, Mag-10 (etc) consumption activating hypertrophy? When I read the article, it almost seemed like it was saying you could take Micro-PA, and do nothing else, and hypertrophy would be activated. Surely that’s not the case. Maybe I missed something, but I’m otherwise I’m confused.
Resistance training increases PA “within” skeletal muscle or within the intracellular environment. This occurs via activating an enzyme (phospholipase D) which lies within components of muscle that are sensitive to eccentric contractions. These components are called zlines and hold the contractile elements of a muscle fiber together. When stretched phospholipase D, which is bound to the zlines, senses mechanical trauma and reacts by producing phosphatidic acid or PA. PA then binds to and activates mTOR, the master switch regulating protein synthesis.
It turns out, however, that PA can also activate mTOR in a totally different pathway if delivered in the extracellular (outside the cell) environment (Winter et al). More specifically, extracellular PA triggers the ERK signaling pathway, which then activates mTOR via a completely separate mechanism than intracellular PA.
In fact, if you block ERK signaling when giving cells PA, protein synthesis does not increase. In contrast, if you block ERK signaling after resistance training protein synthesis still increases. For this reason you will maximize muscle growth if PA is increased both inside and outside the cell.
This explains why two studies to date have shown that resistance training combined with PA supplementation resulted in more lean body mass and hypertrophy than resistance training alone (Hoffman et al. 2012 and Joy et al. 2013).
Jeffrey Stout, PhD