Really complicated but 100% true: One of the HIT Jedi took you under as padwan and helped you reach knighthood. But, as HIT Jedi are want to do, they limited you with their dogme and talk of "only those who have above-average metachloreans can become master." Pish. They claim oneness with the Hypertrophy but do not understand it. Embrace the HST. Only by knowing the Dark Side of the MAPKp38 pathway can you understand the true power of Hypertrophy. Let the anger and fear of your ectomorphic state course through you and make you strong!
Really true but 100% complicated:
Mentzer's HD2 template basically had quirky frequency setups in his routine. For legs and back, he would have you work out once every 12 days. But the upper torso would be worked twice over a 8 day period, and then given a 8 day layoff.
What this usually meant was that both the back and legs were significantly deconditioned session to session. This, in addition to working with new PRs for legs and back, would guarantee significant microtrauma during each session. And because we're talking about a very low volume one-shot, it's not likely the muscle's resistance to future bouts would have been adequately developed anyway. Thus, each growth response would have been very significant and possibly sustained longer than the 36-48 hour window.
It should also be noted that cardio was strongly frowned upon with his program. The HIT conventional wisdom at the time was that cardio ate up gains, not only glycogen storage. Here, this was somewhat true. Due to HD (and 3-way split routines were designed in general) very, very strong reliance upon a significantly deconditioned state to elicit growth, any amount of serious physical activity would significantly hurt potential gains. Looking back, it's probably the rise of the MWF split in the 90s that begun really demonizing cardio as this mass-eater.
The other thing is, general arm and upper torso gains, strength or sizewise, were not that great with HD2. People usually saw great gains in the back and leg work, but the arms were the first to taper a bit. In fact, I think the static contractions were introduced mostly to bump up arm development. (Though to his credit, Mentzer recommending hitching the stretch reflex in his movements too.) And again, the conventional wisdom was that, well, arms are a smaller bodypart and need more time to grow. And some people later on reasoned that arms didn't grow that much because the frequency was higher-than-optimal in his given template. For myself, I noticed that it was harder to continuously increase my bench press on HD2 whereas the legs and backs flew right by.
The problem was two-fold in his arm exercises. He chose peak contraction-style exercises, movements like lateral raises and tricep pushdown, which can induce a lot of stress (thus slowing down strength gains), but is often no better if not inferior to the bench press and other movements in producing microtruama. This would be the equivalent of somebody doing HST twice a week and choosing 5-10% lighter weight during the 2nd session. But, because the 2nd session created significant stress, it would hamper the real-world strength gains possible with this routine. The template usually scheduled the chest session 2-4 days after the arms session. Because of the stress usually imposed by performing peak contractions movements to failure, it also hurt the real-world strength gains the trainee should have been enjoying on their chest day.
From my experience and others, the people who seemed to benefit most from HD2 were people with a (recent) athletic background and/or lengthy experience with high volume routines, such as yourself. Some of that, of course, is due to the lower frequency enabling higher loads, in turn initiating significant growth. But some of that is also part of the smoke and mirrors we all use when evaluating our weight gains.
Or to put it another way, given a sufficient bulking diet, most beginning-to-intermediate natural trainees can gain 17lbs in 5 months. The real question, then, is how much of it will be water, fat, and lean muscle. HD was particularly bad about this. Most who gained a lot of weight on HD in a short time also gained a lot of fat, usually around 1:1 muscle to fat. Those who did better than that, would store the excess calories in glycogen stores and gain a lot of water weight. Easily 4-6lbs can be gained from water weight alone over this way in a short time, but only by people who either have below-average glycogen stores or highly conditioned muscles by which more of excess carbs can be shuttled into the stores. It happens that athletes and high-volume trainees fit that bill. They can partially deflect the bulking diet by storing it in water, which would create higher LBM gains.
But, that in turn suffers due to the relatively light frequency. A person is caught in a double-dang situation with the HD schedule. If you are sedentary between each metabolically iffy session, you start to lose your aerobic conditioning, your water weight wll drop, your metabolism will drop, and in turn your ability to partition nutrients optimally drops. But if you remain active and vigorous, you hurt your potential for real-world gains session to session. The only "safe" alternative to mantain that weight is to eat a proper bulking diet everyday; bu without the exercise, you'll get fat. LBM gains taper off rapidly.
Therefore, a person who gained 17lbs in 5 months on HD may only gain 5-10lbs in fat, 7-12lbs in LBM, and 3-4lbs of that is in glycogen/water storage. That in itself is not a bad, but it tempers the rapid results from said program.
And it levies why HDers find it difficult to continue gaining signficantly on the program. The HDer is basically left with two choices if they stick with the program. They can eat significantly all the time and risk a lot of fat gain. Or they can eat smaller meals, accepting that a 10-15lbs gain (for the beginner/intermediate) is a very good year
as long as they feel very strong. The combination of their strength gains and their belief in their mediocre genetics or ectomorph metabolism soothes their doubts over whether another routine could produce better results. If you were a trainee with normal-to-average metabolism, pretty strong conditioning from previous training experience, and a desire to eat calorically significant meals, you could veer toward true bulking with less worry of fat. Those who don't, will stick to their lower calorie diets and reinforce their prophecy that "significant strength gains before real size gains." When the strength numbers stagnate, they lower frequency, which gets them stronger, but lowers their upside in LBM rate. .
But, yeah, Sith happens.
cheers,
Jules