Training with a power meter can help you work harder, reach higher, and become fitter than you would without it.
In the past decade, technical leaps have made it possible for engineers to create lightweight, accurate power meters that are reasonably affordable.
In most designs, sensors in a specially designed crank wheel or wheel hub measure your velocity and the force you're applying to the pedals and use this data to transmit a real-time power readout in watts to a display unit mounted to the handlebar.
Popular brands include the CycleOps Power-Tap, SRM, Ergomo and Polar. (There are also indoor cycles such as the CycleOps 300PT that feature power readouts.)
If you train as you're supposed to train, you do a variety of structured bike workouts, each of them focused around one or more target intensities. You do long endurance rides at a moderate aerobic intensity, tempo rides featuring a block of riding at anaerobic/lactate threshold intensity, short hill climbs at VO2max intensity, and so forth. A power meter makes it very easy to find and hold the appropriate intensity in each workout type.
Calculating power range
"The first thing you have to do is go and test," says Hunter Allen, a cycling coach and co-developer, with Andy Coggin, Ph.D., of Cycling Peaks power training software. The simplest test you can use to determine your power training intensity levels is the 20-minute max test.
After a thorough warm up, ride for 20 minutes as hard as you can. Be sure to pace yourself so that you're not fading in the final minutes of the test. After cooling down, find your power average for the 20-minute maximum effort.
Next, use this number, a calculator, and the table below to calculate your target power range for each of seven training intensity levels. The table is adapted from the Training Peaks Web site. The right-hand column provides an example based on a hypothetical athlete who averages 260 watts in the 20-minute max test. Note that power is not needed as a guide to training at Level 7 (neuromuscular power) intensity because it corresponds to absolute maximum pedaling efforts that one can maintain for only a few seconds.
Power Based Training Levels
||Target Power Range (as % of avg. watts in
20:00 max test)
|Example (based on 260 watts avg. power in 20:00 max test)
|| Active Recovery
|| Lactate Threshold
|| Anaerobic Capacity
|| Neuromuscular Power
Once you've worked out your target power ranges, use them during all of your cycling workouts, each of which (as mentioned above) should aim at one or two specific intensity levels. Don't be a slave to the numbers, however. If the target range is too hard on a given day, go a little easier, and if it's too easy, go a little harder.
As you gain fitness, you'll begin to find your target ranges consistently too easy and will therefore need to adjust them upward. You can make this adjustment in one of two ways: by informally tweaking the numbers at each intensity level to fit the "feel" of that intensity, or by repeating the 20-minute max test and recalculating the power zones based on the new result.
Crunching the numbers
You can also use power data from recent training to guide your future training. This requires that you download data from each workout onto your computer and study it for patterns and trends. Most power meters are sold with basic software that you can use to log workouts and perform simple data analysis. The most basic thing to look for is a trend toward increasing power performance in similar workouts as your training progresses. If you see this trend, your training is on target. If not, your training needs to be adjusted.
"Until we had good software that allowed us to track changes over time, the power meter was really just a toy," says Hunter Allen. "Now we can answer the question, 'Is the training that I'm doing really working?' If it's not, I can make changes quickly."
Allen's Cycling Peaks software is a deluxe aftermarket program that allows you to take the analysis to another level. With it you can track your power-to-weight ratio, monitor how much time you're spending in each intensity zone, "normalize" your rides to eliminate the sections where you aren't pedaling (i.e. descents) and much more. You can download Cycling Peaks software for $75 from www.cyclingpeakssoftware.com.
A question of cadence
Another use for power data analysis is finding your most efficient pedaling cadence and gear selection for various riding circumstances. Joe Friel does this with his athletes using a frequently repeated 30-minute time trial workout.
"The first time I have the athlete do it at their natural cadence, whatever that may be," he explains. "Then I'll have them do it again three weeks later at a cadence 10 RPM below what they did the previous one at. And then three weeks later do one at 10 RPM above the original cadence, and then we come back and do it at what they feel like again. The data we gather -- average speed versus power, heart rate versus power -- begins to tell me a little more about the athlete in terms of cadence. And sometimes you need to make changes in cadence."
There's no simple formula you can use to determine your ideal cadence, but simply by going through this process and paying attention to the numbers you'll develop hunches that, more often than not, will pay off. "It's an ongoing quest for information," says Friel. "You don't learn everything you need to know immediately because there are many variables. So you just keep playing with that stuff with a view toward answering the question: 'Would you be better off riding at a different cadence than you normally ride at?' "
Racing with a power meter
A power meter is very useful in races, but not quite in the same way it is in training. In races you're able to work harder and perform at a higher level than in any workout. For this reason it's a good idea to record your power output during races and use this data to establish your appropriate training intensities for the next period of training. But for the same reason, it's best not to rely on your power meter too heavily to control your effort in races.
The key to a successful race lies in distributing your true maximum effort over the full race distance. This is something you can only do by feel. The information you need to find your limit is available in the subjective feedback provided to your mind by your body and your brain. It takes time to learn how to fully exploit this feedback, but even a modestly developed ability to race by feel is better than allowing a power meter, speed and distance device, or heart rate monitor tell you how hard you can go.
"I don't want the athlete to use the power meter as a gauge of how to race," says Friel.
In training, a power meter helps you work harder, reach higher, and consequently become fitter than you would without it. But in a race there's a risk of your power meter holding you back. If you've trained well and tapered properly, you're probably ready to do something you've never done before -- something the numbers suggest you can't do. In this case you're better off relying on the world's oldest form of objective feedback in racing: chasing the person ahead of you.