You finally saved enough money to buy a power meter. You’ve been hearing how using one can make you a better off-road rider and perhaps even get you to the podium. So, you got a power meter for your road bike or your mountain bike.
Regardless of which bike your power meter is on, now that you’ve got it, what do you do with it? The possibilities are seemingly endless, from managing the intensity of training, to pacing key segments of a race, to workout and race analysis – and much more.
(To get started learning the basics of how you can do all of this with your power meter read my newest book, The Power Meter Handbook. For a more in-depth discussion read Training and Racing With a Power Meter by Hunter Allen and Dr. Andy Coggan).
The most basic use of a power meter is for training to race. So let’s take a brief look at how to do that.
Many of the most important numbers that come out of your new power meter are based on a personal marker of your fitness called Functional Threshold Power (FTP). This is the average power you can sustain at race effort for an hour. Once you know your FTP you can set up your training zones. That’s the first step in actually using your new power meter.
So how do you determine FTP? There are several ways. The best would be to do a race that takes about an hour. This could be an off-road race, a 40km individual time trial or even a crit. But if you don’t have such a race handy then the next best option is to do a time trial by yourself. This is best done on the road so that the intensity can be kept steady. The most common solo time trial is a 20-minute, steady, race-like effort. Multiply your average power for the 20 minutes by 0.95 and you have a decent approximation of your FTP. Now you can set up your power training zones by using the following table.
If you use a heart rate monitor along with your power meter the first thing you’ll probably notice is that those zones don’t match up with your power zones. That’s normal and to be expected. In fact, you want to create as big of difference between them as you can. I’ll explain why.
Heart rate doesn’t change much as fitness improves. For example, when you are at your anaerobic threshold (as measured by lactate accumulation) your heart rate will be about the same whether you are in your off-season or at peak fitness. What changes as your fitness improves is that you can put out more power at your anaerobic threshold – and all other zones. In fact, this is a great way to gauge fitness improvements. The greater the separation between your heart rate and power zones, the more fit you are. As an example, when you are in HR zone 2 but your power is zone 3 then you are more aerobically fit than if your power was also in zone 2. When your output (power) for any given input (heart rate) increases, then aerobic fitness is also increasing. TrainingPeaks.com refers to this as “Efficiency Factor” (EF) and measures EF by comparing your power with your average heart rate over a given segment. If EF increases over time, you are getting fitter.
Training With Power
Now that you have your zones, the next most basic step in using your new power meter is to use it in workouts. This has a lot to do with periodization, which is nothing more than how you vary training relative to the date of your first A-priority race. All of this is discussed in much greater detail in The Mountain Biker’s Training Bible, but let’s take a quick look at it now to get you started.
There are three basic training periods in a build-up to a race: Base, Build and Peak. Their durations are usually about 12 weeks for Base, 8 weeks for Build and 3 weeks for Peak, but these can vary considerably depending on your unique situation (read the Training Bible for the details).
In Base training the purpose is to develop general fitness. There are three general goals I set for off-road racers in this period. The first is to improve handling skills. Your power meter won’t be of much help here. The second is to boost aerobic endurance. And the third is to elevate your FTP. Power is the key to these last two.
To boost aerobic endurance, do long rides of 1 to 4 hours in zone 2 heart rate (using my HR zone system from the Training Bible). This is best done on the road. What you should see happening over the course of this period is that your EF increases – you are producing more power at the same heart rate. That’s a great sign of improving aerobic endurance.
FTP can be increased by doing Coggan’s “Sweet Spot” workout. After warming up do 2×20-minute intervals at about 90% of your FTP with a 5-minute recovery between them. This can be done on the road or off-road if you have, for example, a steady, gradual climb on a fire road. By testing your FTP every four weeks or so you should see an increase throughout the Base period.
In the Build period do workouts that become increasingly like the race. This usually involves intervals that match the demands of the race for which you are training. Once you have power data accumulated from your races you’ll be able to more accurately determine the duration and intensity of these intervals and the recovery time between them.
During the Build period do a weekly aerobic endurance workout to maintain EF and a weekly Sweet Spot session to keep your FTP high. The other workouts will be racelike or recovery (zone 1).
The Peak period is when all of the above training begins to pay off. Now do a racelike workout (like those in the Build period) every third day. These should get shorter as the Peak period progresses so that you are tapering the duration of your workouts, but not the intensity. On the two days in between do recovery zone rides. Come race week do extremely short, race-intensity sessions every day – unless you experience fatigue. In that case back off. The most important thing to accomplish in this week is full recovery from fatigue so that you’re ready to go all out on race day.
That’s it for now, and it is enough to get you started down the right path of training with power on your mountain bike. But again, these are just the basics of using your power meter. The real value begins to accrue when you have accumulated a critical mass of training and racing data. You’ll learn so much about yourself as a racer once you start training with power, much more than you ever learned by using a heart rate monitor. And you’ll also race better.
For the basic guide to training with power, get Joe Friel’s new book The Power Meter Handbook.