Excerpt from POLARIZED TRAINING AND HYPOXIC MUSCLES: Highlights of the ACSM Annual Meeting http://www.sportsci.org/jour/9902/wghacsm.html
A high point was Stephen Seiler's contribution to the symposium on practical aspects of lactate measurement (#2041). On the basis of his experience with elite cross-country skiers and rowers, he argued that top endurance athletes do comparatively little training at or near lactate-threshold intensity (blood lactate concentrations of ~4 mmol/L, corresponding to intensities of ~85% of maximum oxygen consumption). Instead, their training is "polarized" around this intensity, in the sense that they do a few sessions per week at intensities well above 4 mmol/L and the rest at <2 mmol/L. He described the lactate threshold as the "lactate black hole", to emphasize his idea that too much training at this intensity tends to reduce the quality of higher intensity work-outs and ultimately leads to training monotony and overtraining. Carl Foster, who chaired the symposium, then outlined running programs of the famous Jack Daniels. Most of the training in Daniels' programs is below threshold intensity and the rest is at or above, which could be considered polarized training. Axel Urhausen, one of the speakers at the symposium, commented afterwards that he and his co-workers induce an overtrained state for research purposes by prescribing daily training at the lactate threshold.
Periodization--the structuring of a training program throughout a season--was the subject of only two free communications. One of the perennial problems of periodization is whether you should do base (low-intensity) training before quality (high-intensity) training in the months leading up to a competition, or whether you should do both together. In a 12-week training study in which the event was a simulated 80-s cycling time trial, sub-elite cyclists were randomized to sequential or concurrent training programs with the same total volume. The slowest cyclists gained more from the sequential approach, whereas the fastest cyclists did better with concurrent training (#789, Reid and Sleivert). Incidentally, world-class cross-country skiers and rowers use concurrent training for 10 months of the year, according to Seiler. Another periodization problem is how best to taper the training load in the days immediately before a competition. Sub-elite cyclists training exclusively at 85% VO2max tended to get a bigger improvement in a 20-km time trial following a 7-day taper in which volume was reduced to 50% rather than 30% or 80% (#387, Neary et al.).