Originally Posted by danfoz .
Personally I don't see many gains beyond 6 weeks of structured short intervals (whatever one wishes to call them) except fatigue and loss of enthusiasm. Then again I'm usually racing many weekends back to back (and sometimes mid-week) through the season beyond the initial base and so although not a bonafide 3min, or 4 min, or 2 min, or whatever your particular flavor, I'm still hitting that intensity quite a few times a week once the racing starts.
Someone once explained this in terms or peripheral vs. central conditioning where central conditioning is the lower intensity aerobic and tempo work that correlates directly to increasing the size of the heart's left ventricle (where high intensity is not required) which allows the body to pump a larger amount of blood with a single stroke and which takes around 7-10 years to max out the potential we have been given genetically - think Indurain who's resting 28bpm must have been pumping a staggering amount of blood with each stroke! And then peripepheral conditioning, which lays down additional capillary beds and increases the number of mitochondria which has a shown to max out in various studies between 4-8 weeks depending on the individual, and the study. I don't have access to the means by which to prove or disprove the above (or footnotes to the particular studies) but it jives with everything I've picked up along the way from sources over the decades, i.e. various coaches, books, riding partners, central park boathouse bench warming experts, and other sources. Then again I've heard other paradigms that completely go against the grain.
As far as sprinting, the only reason I see to train this is learning sprinting technique which can dramatically increase the speed at which one moves the bike, but IMO has very little to do with actually increasing the speed at which one's fast twitch muscle fibers contract. In other words, you are either born a sprinter or you are not, and the specifc training simply reveals this to be evident or not. I ran the 100m, 200m, and 400m in high school. Training improved my quarter mile time bigtime - in the 10th grade I went from 62 secs to 55 secs in one year however my 100m time didn't budge a millisecond. A lot more technique goes into sprinting a bike than running a sprint.
I'm doing Battenkill later this spring and only planning on 3-4 weeks of VO2 work. I got a late start this year but sweating my basework more than my speed work as I know I can make the majority of gain to my top end in 4 weeks if needed. If I hadn't been such a slacker I would be doing 6 weeks of speedwork but that last 2 weeks would really only be to top off my tank. I'm only a Cat4 though and luckily have no income riding on my personal notions of training.
As far as energy systems I personally found simplifying things made training easier for me. I've reduced training intensities into 3 ballpark zones: aerobic/tempo, threshold, and VO2. I know this could be expounded into many more zones (zone2,3a,3b, L1-6, etc., yadayadayada) but these aren't completely disparate systems and turning training into academia, as interesting as it is, doesn't seem to yield me any better results.
Edit: One of the more interesting things I've read was a comment sometime back by either Greg Lemond or Cyril Guimard (I forget) was to avoid, in training, the 80-85% MaxHR zone as it is too hard to efficiently train ones aerobic engine, and too easy to train ones top end. With that said, I seem to spend quite a lot of time in that zone, both in training and racing. However it was for certain Guimard who said most riders train too easy on hard days, and too hard on easy days.
