Ric:
Yes we have had this discussion before, and I suspect it won't be the last either. It's important for everyone to understand that coaching advice varies widely especially when it comes to intervals. Intensity, duration, volume, pacing, etc. are only a few of the different variables that coaches disagree on.
Lower intensity zones are very useful and necessary, but I typically ride tempo enroute to an interval session for 20-60 minutes, 5-15 beats below LT, usually at 90-100 rpm. I'm nowhere close to being a professional rider, and only log about 8 or 9 hours a week on the bike, so if I can do 3-5 intervals on top of a 20-60 minute tempo block, others should be able to also, providing they have a decent fitness base to start with. The way I see it, if you went home after a 20-60 minute tempo block, you only did half your workout.
The intervals I described should actually be done with an all out 30-60 second effort to start, but I spared Redstorm the pain of an all out effort and said to just hit and hold 40 kmh for as long as possible. When going all out or very hard, watts, and heart rate are not important, effort is.
If Redstorm were using a watt meter, I would say to get up to 300 watts and hold it as long as possible instead of holding 40 kmh as long as possible, since watts are an absolute measurement of a riders output, but either will work quite well. Again, what is important is the effort not the data.
Yesterday, I was riding home with a light tailwind and was holding 26.5 mph in a 53x15 at about 84-85% of max hr. I could have gone at that pace for 60 minutes with ease. Obviously, if I were doing 3-5 minute efforts with that wind, I would have to bump the speed up to 28-29-30+ mph for the effort to be effective.
No matter who you are or what methods you use to train with, you can't fool yourself. You know when your effort is too easy.
When you are supposed to go hard, you need to go hard, and for intervals that usually means respirations of 60+/minute, or a hard breath every second. When you are breathing that fast, you are close to or at VO2 max.
The ability to recover from all out anaerobic efforts requires large amounts of aerobic power which is trained to the maximum by starting an interval all out/hard until you blow, then forcing yourself to carry the effort for 3-5 minutes. Doing intervals this way is so hard, it will take several sessions just to get to the point where you can think clearly enough to downshift and keep the effort going after the inital hard effort.
I currently start my intervals out in a 53x12 on the flats with a light crosswind, and from a 20 mph roll, I will accelerate seated as rapidly as possible to 95-100 rpm (33-35 mph)and hold it for 45-60 seconds. It's not uncommon for me to hit max heart rate (180 bpm)in 45-50 seconds. I immediately downshift into a 53x15 or 53x17 when my 53x12 cadence goes below 90 rpm, and hold 22-25 mph for a few minutes until I recover. At about 3 minutes or so, I can recover enough to hold 26-26.5+ mph for the final 2 minutes. Once you are used to training like this, holding speed at constant power output becomes much easier.
If you could only ride 24-28 mph for 30 seconds today, if you keep at it, you will start going 24-28 mph for 40 seconds, 60 seconds, 3 minutes, 10 minutes, 40 minutes, etc. The body is highly adaptable to the stresses it encounters. As long as you recover properly, you will not become chronically fatigued, overtrained, or plateu.
I'll be the first to admit these types of intervals are the hardest way to ride period, and are the most painful. But then again, we are riders, not bowlers or golfers. Who ever said cycling was supposed to be easy???
Road racing is the hardest sport on earth, and a huge part of that for all competetive/fast riders is the suffering factor. All riders will have to suffer at some point if they want to get to certain levels. There are no free rides in life or in cycling. Lots of people want something for nothing. To get fast, you have to work very hard and suffer. Don't forget to recover!!!