The PowerTap is a bee-yatch to ride with and I'm understanding why guys who take racing seriously get better with it. The thing makes even routine rides harder. Fer instance. Today's ride from Coach Bill G. involved 50 minutes at recovery pace, 50 at aerobic pace, 40 at tempo, then cooldown. Doesn't sound bad, right? Wellll... I'll set the stage. It's my last workout of the week, the legs are a little tired, and it was 52 this morning, and it started pissing down rain just as I rolled out of Crofton. So I was cold. The recovery part was okay, but I desperately wanted to go higher than 180 watts which for me, is soft pedaling so soft that I couldn't knock dust off a butterfly's wings with it. So I cheated a little, let myself hit 200 watts on occasion, but mostly kept it right at 180 or so. And froze. My teeth were chattering.
Eventually, 50 minutes was up, I was soaked to the bone, legs numb, and it was time to go aerobic. That's roughly 200 to 240 watts. No big deal, right? Well, it is when your legs are numbed and trying to lock up, and you just turned East, into the wind. For the first 20 minutes I was grinding impossibly hard trying to get my HR up and trying to keep my effort steadily in-zone. For the next 30, I was okay. But it was hard all the way. With the PowerTap, you tend to keep an eye on the power output, and you tend not to coast very much. You notice this when transitioning from heartrate training, because the PT lets you eyeball your heartrate while you track power. You can be riding along in an aerobic zone and crank out huge watts for a couple minutes going up a hill, and your heartrate won't hit a tempo level. Likewise, you can coast or soft pedal down a very long hill and your heartrate won't drop out of the endurance zone even though you do next to no work for five minutes. With the PT... it's grind, grind grind. My downtime has decreased, on average, from around 16-17% of the time (cadence of 40 RPM or less) to around 12%.
Anyhow, after a while, it was time to go tempo. Now, since I had my heartrate visible on the PT screen along with power, I figured Coach Bill wanted me to go tempo level effort by heartrate, not power. So I had to crank out a pretty heavy level of effort to get my heartrate into the high 140's to mid 150's. To do that, I averaged 298 watts for 40 minutes, a "normalized power" of 314, with an average heartrate of just 148, 3 beats over my 'aerobic' level as Joel Friel would describe it. But because I had very little or no downtime (the constant reproach of the PowerTap forbids slacking) this was a brutal level of effort. Maybe it was my head cold, maybe it was the cold, wet weather, but it was a heavy effort, maybe a dozen or 15 watts below threshold. When I eased up to start my cool-down, snot was strung all over my face, I had a huge coughing fit, and I felt not-quite-blown, but definitely badly worked, like a sweaty, foamy horse after a hard run.
The final stats on the day were a 222 watt average power, normalized power (measures only when you are actually pushing, basically) of 260 watts, 2018 calories burned, 2.5 hours riding time, 45 miles covered, Training Stress Score of 189.1 (or .0865, which means this was only a moderately hard effort for me...) and an average heartrate of 131, peak 30 minutes of 301 watts (this is tempo, mind you, not threshold...)
What does this tell me?
I don't know. I'll get back to you when I figure it out. Alls I know right now, is it wasn't quite as hard as the Coppi Sunday ride, but the last 40 minutes were on the average harder than the Coppi ride. The PowerTap can help prevent the surges that you get on group rides, which means you can train specific holes in your powerband much more accurately and efficiently. But it also means that when you train to a weakness, you can do so much more relentlessly and methodically than doing so with a heartrate monitor. Translation into English: the PowerTap lets you hurt yourself a lot worse, a whole lot quicker, than anything else. It should translate into good race results. Either that, or the development of a really highly refined masochistic streak.
Of course there is a little more to it than that and I make light of a lot of slightly complicated but useful stuff. The two most useful things that power training can do are measuring how fit you are becoming, and how fresh you are (or how tired you are). The single-workout data and tracking makes you work hard on an ongoing basis. The cumulative data (Acute Training Load and Chronic Training Load) tell you about how and when you are getting fit, and when you need a rest. In short, you are ready to race when you are fit and fresh; you need more training when you are fresh but unfit; you need more rest when you are fit but tired. If you're fresh, you can train harder and use the PT to do that. If you're tired, you can use the PT to do recovery spins, and to let your body adapt to the overload, and grow stronger. And yes, it's easy to track those fitness and freshness levels with Cycling Peaks, a fairly straight-forward software package that helps manage power data from nearly any power metering device.
(Ahhh... non-power users are now getting a little lightbulb going on over their heads... now you see how this can make you a better racer or even a stronger recreational rider?)
More on training with power here.