Point is that there is adequate research, classical research (i.e. not the one conducted by Muscle-Tech in their "labs") conducted in the realm of motor learning and physiology which explicitly states that NM failure is to be avoided in the long run and muscle fatigue is to be avoided for any hope of having high frequency and high intensity (as a % of 1RM) workouts.
Now the HIT jedis will argue that only one or two intense (defined unscientifically as percentage of maximum effort, instantaneous effort etc) workouts a week are more than what the "hardgainer" can withstand. And that is true because they are prescribing a workout methodology which essentially "fries" the neuromuscular system to the point that subsequent frequent workouts become more difficult to perform. The integral of the force velocity curve is always low in the HIT workout. HIT style workouts make impressive videos, a la "blood and guts" it is more of a show of strength than true strength. If you are training your fast twitch fibers train them in the manner them in a manner consistent with the muscle physiology. Muscle failure is good if you want to do lactate interval training and are interested in pushing your speed endurance higher, for instance in a break from the pack in a road race in the Tour de France and not if you care to up your one rep max.
Good luck.
I'm not a HIT jedi - I just use what works for me. I gained 20 pounds in a little over a year following this routine. On my second set I simply lift until I feel a good pump. I also try to take a week or 2 off every month or so if I feel like the nervous system has taken a beating. Like I said, this works for me.
I try to follow this guideline when working out -
I do 2 sets of each exercise and do about 3 or 4 exercises per bodypart.
I don't workout more than 3 days a week.
I only do heavy exercises like squats and deadlifts every other week, but not both the same week.
Once every month or so I take a week off.
On the second set of the exercise I go until failure using my other hand to assist the lift.
WEEK I WEEK II
SUNDAY-Biceps,Forearms SUNDAY-Biceps, Forearms
Cheat Curls - 1 set (SAME AS WEEK ONE)
Concentration Curls - 2 sets
Outer Bicep Curls - 2 sets
Hammer Curls - 1 set
Brachioradialis(reverse curl)- 2 sets
Extensors - 2 sets
Flexors - 2 sets
Grippers - failure
TUESDAY-Chest,Triceps TUESDAY-Deltoids, Triceps
Free Weight Press - 2 sets Overhead Press - 2 sets
Dumbell Flys - 2 sets Front Deltoid Raises - 1 set to failure
Tricep Extensions grip1 - 1 set Side Deltoid raises - 2 sets
Tricep Ext. Grip2 - 1 set Tricep Extensions grip1 - 1 set
Triceps Ext. Grip3 - 1 set Tricep Ext. Grip2 - 1 set Tricep Ext. Grip3 - 1 set
FRIDAY-Back FRIDAY-Legs
Deadlift - 2 sets Front Squats - 2 sets
Shrugs - 2 sets Calf Raises - 2 sets
Fireman's carry - Failure
Bent Row - 2 sets
Single Arm Row - 1 set