This simple main set today (WHICH ROCKED!) is an excellent anecdotal example of overall gain in ‘racing’ fitness level when subjected to regular doses of short speed demands! Say What?
if you scroll back through the sets Daniel and I provide, there’s a lot of short speed expectation. If you swim even just 1 or 2 times a week I predict in the course of 3-4 weeks, your ability to manage 100’s at a quick pace-and then REPEAT it-will definitely improve.
Today I was so impressed with the speed people stepped up with on 7 x 100 at a pace I tossed at you, and I know some folks where pleasantly surprised with their own speed! Great job!
Asheville Masters Swimming 
That was the hardest I’ve worked in almost 20 years! Ouch!