From Lane 9 News: "... To look at what can happen shortly after altitude training, one just has to look at Kate Ziegler's world record in the 1500 free set just days after coming down from Colorado. ..."
Nineteen Japanese swimmers were in Flagstaff, Ariz., training for the Japan International Grand Prix meet in August. Two of the top swimmers in attendance were Tomomi Morita, who won a pair of bronze medals at the 2004 Athens Olympics, and Hanae Ito, who won the women's 100 back at the 2006 Pan Pacific Championships. ..." [Link]
If you click on the link there is an interview with the coach of the Japanese team as well. Here is where they will be training I believe: [Link]
The above photo was taken by Erik_found. His image is hosted by Flickr. Ibelieve the Japaanese willl be swimming there.
The results are mixed that high altitude training works yet the Japanese team, the French team and even Kate Ziegler who broke the great grandmother of all swimming records had just finished training at high altitude before setting the new world record in the 1500m.
All right, so how do I know the results are mixed? In the 1993 Scandinavian Journal of Medicine & Science in Sports; (Volume 3 - Issue 4 Page 256-262 - December 1993), found that High-altitude training does not increase maximal oxygen uptake or work capacity at sea level in rowers. An abstract of the article with numbers and figures is here: [Link]
In 1998 A.Baker & W.G. Hopkins, Altitude training for sea-level competition In: Sportscience Training & Technology. did a study stating it was best to live up high but train down low. Here is a snippet:
"...Training near sea level while living at an altitude of 2500m (8000 ft) for a month enhances subsequent endurance performance, probably by increasing the oxygen-carrying capacity of the blood through an increase in production of red blood cells. A small proportion of athletes shows no improvement or even reduced performance with this "live-high train-low" strategy, but the enhancement for the average athlete is 2-3%."
The difference between the live high, train low versus the live high and train high goes as follows:
"...The difference in performance between these two groups after altitude training averaged 2.5%. But it's important to note that the altitude group showed only a marginal improvement in performance, and only at three weeks after the return from altitude. In contrast, the control group performed worse and had not recovered fully by the end of the study. ..." [Link]
I think it's high altitude training is questionable. The increase in ability appears to be barely barely measurable unless you live at 7,500 feet and train at sea level