My workout called for a total of 1300 yds, with the main set being 5 X 100 fast. Somehow, I managed to do the first one in 1:35. That's 5 seconds faster than I've ever done it before, even at a lower altitude! I thought it might have been a fluke, but the second one was 1:36. I slowed a bit after that, but my 5th, and slowest, was still only 1:40. I'm thrilled!