Quote (shane_is_a_balla @ Oct 15 2016 11:54pm)
2x/week is superior to 1x/week.
Think about it mechanistically, allotting volume of, let's just say, 20 sets/week for a given body part - doing that all in one day vs splitting that up two times is going to have markedly different effects on both protein synthesis in that muscle group and expression of a myogenic gene modality, from things like satellite cell kinetics and so on, as in the latter having more sustained levels. Most of the studies done on this topic are congruent with this, however, I will say there's a paucity of actual, reliable data out there in this or any other regard pertaining to training. That's more so a factor of how arduous and expensive it is to organize a long-term, highly controlled, human subject study, though. Sad times. This paradigm of training also makes it easier to have a higher total volume for the week, which we pretty much know is the paramount determinant for hypertrophy.
All this said.. you can still make immense progress w/ either training style. I got pretty large/strong (imo.. 18-19+" arms, 500x6 squat, etc) on purely 1x/week training before I became aware of the actual physiology of the human body. That leads back to what I also just stated about volume, I was doing quite high volume (upward of over 30 sets on a single day for a single body part at some points), and hitting failure on close to half of those sets at least, thus the intensity/effort was there, and I was eating in a caloric surplus... ergo, I grew.
Essentially this.
What people need to realize about all of this is that yes there is a difference and one may be superior to the other, but it really isn't going to be astronomically different. The fact that people continuously argue about it is ridiculous.