The HTFU swim question thread devolved into a fair bit of lively discussion of whether fitness or training are more impactful on swim performance. I emphatically believe both are, but that swim training sets should be designed to improve and imprint technique, and that physiology will follow. Some technique-oriented sets are designed to "perfect" your stroke. Those are physically easier so the conditioning effect would be more aerobic. Other sets are designed to "tune" an efficient stroke to higher rates -- and thus to produce faster paces. Those place greater demands on the body's metabolic systems and could put one into the "threshold" or "anaerobic" zones.
Another philosophy advocates that it's essential to swim "hard" -- and sacrifice form if needed -- in order to get fitter or perhaps simply to HTFU.
Much of the argument for prioritizing conditioning is based on the premise that it's scientific. I related that in discussions on "energy system training" with Mike Joyner, one of the most respected human performance researchers in the country
(and a high performing athlete himself - 2:25 marathon in med school and 21-min 1650-yd swim as a 40+ Masters swimmer
) he had referred to that as "pseudo-science, at best."
As I noted in that thread, it's been an unquestioned article of faith in swimming that "energy systems" are the "scientific" way to train. Hundreds of pages in the "bibles" of swim coaching - Science of Swimming by Counsilman and Swimming Fastest by Maglischo are devoted to abstruse explanations of how these systems work at the molecular and cellular level - plus dozens of pages presenting complicated formulas for planning training sets
(how long, how fast, how much rest
) to produce these effects. Yet none of the research establishing them studied what happens with them while swimming.
Yesterday, as a followup, Mike Joyner sent me a link to the Science of Running web site, in particular a lengthy piece "The Fallacy of VO2max", which concludes: "The bottom line question that needs to be asked is why is so much of training focused on a variable that does not change in well trained athletes, barely changes in moderately trained, levels off after a short period of time, and does not even correlate well with performance? Does this sound like a variable that we should be basing all of our training off of?"
Here's the link if you'd like to read it yourself. Much of it is highly technical but there's still plenty that's thought-provoking.
http://www.scienceofrunning.com/2009/12/fallacy-of-vo2max-and-vo2ma...