The Power Meter Handbook: A User’s Guide for Cyclists and Triathletes

related—when one changes, the other changes in the opposite direction. In other words, an increase in duration causes a decrease in power. You can’t stay in zone 7 for more than a few seconds, but you can ride in zone 1 for hours and hours. How long you can stay at a given intensity level says a lot about you as a cyclist.
    One rider may be capable of sprinting for a few seconds at a very high intensity—upward of 1,500 watts—while another can manage only half of that sprint power for the same duration. However, the rider with the low-power sprint may be capable of riding for 1 hour at more than 300 watts, while the 1,500-watt sprinter can manage only 250 watts for 1 hour and is dropped long before the finish line.
    Power relative to duration is a great marker of fitness and performance. If you can increase your power for a given duration, we can safely say you are more fit for that duration. If your power for a given duration is greater than another rider’s for the same duration, then we know who will win a race of that duration (all other things being equal, of course).
    The best power you can generate for a given amount of time is called “Peak Power.” You have a personal set of Peak Power values for common durations, such as 60 minutes (P60), 30 minutes (P30), 5 minutes (P5), 1 minute (P1), and 6 seconds (P0.1). Likewise, you have a Peak Power for any duration you want to specify. Each of these values is unique to you as an athlete. Just as with FTP, the values change as your fitness changes.
    This raises an interesting issue: If each rider has unique Peak Power levels, there must be patterns, or profiles, that define each rider. This profile could tell you the durations at which you are currently best and perhaps even what type of training you need to boost power for a given duration. Perhaps your goal is to race well for 40-km events. That would mean focusing your training on P60 fitness. Or maybe your role on the team is sprinter. Your P0.1 is then critical to your performance. Wouldn’t it be nice if you could see this in a chart? What a great tool that would be.
    In fact, there is such a chart. It’s called a “Power Profile.” Each rider has a distinctive profile that helps to define who he or she is as a cyclist. Figures 5.1 and 5.2 show the profiles of two riders with varying Peak Powers. These charts represent their highest power output for every duration over the course of an entire season. To help orient you to these charts, the vertical, or “Y,” axis represents power in watts, with zero (0) at the bottom. The horizontal, or “X,”axis, is time, with 1 second on the left end. What you see here for the X axis is a logarithmic, as opposed to a linear, view that places greater emphasis on the shorter durations where most of the changes are likely to occur. Notice that the first 30 minutes comprises about 75 percent of each chart. The higher the line is, the greater the athlete’s Peak Power is for that duration.

    At first glance, these two charts look quite similar, with power high to the low-duration end on the left and low to the high-duration end on the right. But if you examine the charts in more detail, you’ll find some interesting differences that reflect the demands of the sports involved. In Figure 5.1 notice that the male pro triathlete has a 1-second Peak Power of about 860 watts; in Figure 5.2 the male Category III road cyclist shows a 1-second best of about 1,210 watts. The outcomes of Ironman triathlons are never determined by sprint power, but the outcomes of road races often are. The road cyclist trains for this, and it is obvious from his chart.
    Notice that on the far right end of the charts, at about 4 hours and 30 minutes, the triathlete’s Peak Power is about 270 watts, the roadie’s about 250 watts. Again, this reflects the unique demands of the sport. Being capable of riding powerfully for more than 4 hours is what Ironman racing is all about, especially at the pro level.
    Another obvious difference on close examination is the shape of the two curves. The roadie’s drops off sharply starting at about 30 seconds. For the triathlete the greatest decline occurs at about 7 seconds, but his decline is not nearly as steep.
    These differences are probably the result of some natural combination of genetics and training. The exact mix of these ultimate performance determiners is anyone’s guess. We can’t change genetics, but we can change training. For example,