Dave Luscan wrote:
When my 40k power was 350-360 watts, and my :05 sprint was 1200, I would hit 600 initially, but just for literally a few pedal strokes. By :05 - :07 I was down below 500 and by :15 I was down below 400. I made a point to NOT be at top speed for about :40 - :50 into the race. This is how I had my highest averages ands fastest times.
I've tried it both ways, and ^^this^^ is the way that has worked best for me for TTs that last longer than 20 minutes...especially the 40k. My last 40k I held 281 watts, and my first 5 seconds I averaged 489, peaking at 550. The first 33 seconds I was averaging 326, but my real time power was already in the 270-280 range. I let my avg power drop all the way down to 275 the first 3 minutes into the race, and then got into my groove where avg power remained pretty steady at 279-281 the rest of the race.
I've done TT's where I would blow 700+ watts for the first 15 seconds and my HR would just get all jacked up...and I couldn't settle in at my goal avg power. Usually meant riding 10-15 watts below goal avg power for 10-15 minutes before my HR would settle...and by then it was too late to get the avg back up to goal. End result would be either a blow up, or salvaging my race by ending with an AP 6-8 watts below goal average.
I suppose if you're trained to do that explosive burst and still stay in control afterwards to stay at goal AP then you can pull it off. But most interval workouts don't call for that type of effort. Such as a 2x20' where you're supposed to do the first 25" of each 20' interval at 250% of FTP.