lol you're rediculous what I'm about to say I had to say at least a dozen times to you before.
While training HIT you can't tell that you'd be much weaker on all of your lifts when you go back to traditional training methods, and that's why I was happy with my gains at the time, which I did get. But when I stopped HIT and realized how much strength I lost (I'm still not back to my peak strength months later), I lost all enthusiasm for the training program. I value strength as much as size.
I think you definitely could use HIT for bursts of 4-5 weeks. I know Poliquin has a arm protocol that looks something like this:
4 weeks of GVT (German Volume Training)
4 weeks of traditional volume training 8-10 reps, twice a week
4 weeks of HIT
4 weeks of something else, probably heavy and low reps?
I think you're supposed to start it or end it with the 12 hour arm blitz?
You know, where you do one set of curls and french presses every half hour for 12 hour straight, with a fairly moderate weight.
Google the net or check his website for it, maybe t-mag has it too.
Anyway, as far as the Heavy Duty training goes, it won't recruit all of the Fast Twitch fibers, since you're using low weights, and slow cadence.
It does a good job of recruiting the Slow Twitch however.
To grow a muscle fiber, it needs to be trained. That's why you won't grow to your full potential if staying true to the Heavy Duty protocol. The rep cadence is too slow (especially when contracting), allowing too light weights IMO.
figgs: Do some HIT every once in a while, if you believe you get gains while on it. The loss of strength you suffer, is because of the fiber conversion, you convert from Fast Twitch to Slow Twitch. You should have more endurance these days though. Ie weaker 1RM but a stronger 10RM.
-Hedge