Nothing new, HIT has been de-rigeur in bike-racing for as long as it's been around, over 100-years. The thing you have to consider is the goal & purpose of training. Not every athlete has the same goal. Some people want to win ultra-endurance events, others need to work on mental strategies and tactics, some need outright raw power-output, others need to lose weight.
As NoRacer's post indicated, "it depends" is typically the real answer. While doing a quick hour of HIT may lead to an extra 15% more calories being burned off over the course of 24-hours (compared to a sedentary no-exercise subject). But doing 1-hour of endurance-pace riding is for recovery isn't an accurate comparison like they did in that study. A real 3-4 hours of LSD endurance ride at 10% below LT will have burned off 150-200% more calories than the sedentary subject AND the sprint/interval workout.
Doing sprints and intervals all the time isn't the "ultimate workout" and neither is doing pure LSD either. No one can do these rides exclusively day-after-day and not burn out physically and mentally. You have to do ALL the various types of workouts possible, sprints, intervals, tempo, LSD, hillclimbs, recovery, etc in order to improve fitness as quickly as possible. The science in training is developing just the right mix of these workouts on an optimized schedule.
However, it is true that a lot of beginning riders get trapped into "no mans land" of training where they're not riding hard enough and not riding far enough. Doing 1.0-1.5 hours of steady-state riding right at your LT isn't the most effective training possible You sacrifice quick improvement in max- and anaerobic-power as well as recovery from those efforts and you won't have any endurance either. The magic formulae for a lot of people is to do more intensity and more distance, just not at the same time on the same day....
Last edited by DannoXYZ; 11-09-06 at 12:09 AM.