Originally Posted by Jason M Struck
I don't often do this... but I disagree with Steven.
I have direct experience with multiple clients implementing loads of 55-78% of 1RM in compound movements (predominantly the Back Squat) for very high volumes with VERY LOW RESTS, and while I think that all of those parameters are important, I would say that the most important for Hypertrophy is in fact the reduced rest periods.
So, his first two point are very correct in my mind, but on the third we disagree. I would place the emphasis first on volume, then on density. Ie, reduced rest periods. There are several research pieces regarding hormonal response and other blood work (lactate especially) showing increase endocrine response to protocols of reduced or incomplete rests. Add to this excess calories and you will see rapid hypertrophy.
That's nice but....
I stole this image off some t-nation article way back when.. but it's true wfs:
There's a couple different ways your body hypertrophies and rest times don't really matter except for increasing metabolic intensity like you said. The other two pathways don't rely so much on increasing density (volume & heavy lifting), so it really depends on what you're aiming for here.
If you're using the heavy weights and relatively lower reps for linear progression or intermediate loading like SS or Bill Starr's intermediate 5x5 or whatever else 3x5/5x5 programs novice/intermed/advanced/etc. program then you are then generally rest times will be higher..... and they will still be effective for hypertrophy (clearly).
Like I said I would defend my position that rest times don't matter (or rather should I say variable) depending on what exactly you are doing. Density work sure you're aiming for lower rest times. Volume lifting and heavy lifting the rest times will generally be a bit more. Volume is generally the most important one with heavy enough weight to do enough muscle damage to induce a hypertrophic response.