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How To Use A Power Meter In A Race

  • By Bethany Rutledge
  • Published Apr 7, 2014
Photo: John David Becker

How to use a power meter to find your ideal race-day effort.

After the training is done and you’ve successfully arrived at the starting line, one of the biggest determinants of success is the ability to target the right power for your race. Here are some things to consider prior to selecting your goal output.

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Know your numbers.
If you’ve been training with power, then you should already know your estimated functional threshold power, or the highest sustained power you can maintain for one hour. This is an important metric but not the only one you should use to determine your pacing plan.

Review past efforts.
You should also take into consideration past efforts. If you’ve been uploading training data to TrainingPeaks or Strava, then you already have a record of what you’ve done. You can analyze your power curve to review your season’s best for different time periods. This is an important step toward figuring out your race pace as you won’t be able to do something successfully during a race that you haven’t done during training. For example, if your hardest century was ridden at 60 percent of your FTP, then riding your Ironman race at 75 percent FTP is going to be setting you up for a very long walk.

Reference established norms.
Unless it’s your first triathlon, you’ve already discovered that the optimal triathlon pacing strategy is not hammering as fast as you can from T1 to T2. The next step is determining how much to back off. We’ll use percentages of FTP to give some common ranges.

Race distance % of FTP
Sprint 90–105%
Olympic 85–95%
Half-Ironman 75–85%
Ironman 65–80%

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Get personal.
Consider what kind of cyclist you are. Are you a strong cyclist whose “could do” bike splits are significantly different from “should do” splits? Or are you a diesel engine whose max speed is relatively close to your go-all-day speed?

Then, consider what kind of runner you are. Do you regularly run well off the bike with minimal slowing, or do you have a history of doing the “Ironman shuffle” or unplanned walking? If you’re not sure what kind of athlete you are, seek the advice of an experienced coach.

Finally, look at the time of your overall splits. If you’re planning on a sub-five-hour Ironman bike, your intensity factor will be higher than someone who is planning on an eight-hour Ironman bike.

Consider the big picture.
It’s important to look at your training in the context of everything discussed. Has your training been optimal, bare minimum, or somewhere in between? Is this your first race, or your 100th? If you’re unsure about the quality of your training cycle or you’re inexperienced, then it’s always best to have a conservative strategy that will set you up for the best possible chance of a solid run.

Also, you never want to do anything in a race that you haven’t already done in training. If your goal race is shorter than Ironman, you can practice the full bike at race pace and a portion of the run at race pace. Ironman athletes shouldn’t go the full distance, but you can do a targeted race simulation to get an idea of what you can hit and still run after. Specific recommendations will vary, but one idea is to do a 3–4K swim, followed later in the day by a four-hour ride broken up into intervals with a total average power at or above Ironman watts, then a 10K run afterward building into Ironman pace.

What if I just got a power meter and know nothing?
If you just got a power meter, have no data, or have truly been using it as an expensive speedometer, your best chance at success is using your normal pacing strategy, whether by heart rate or RPE, and not even looking at your power. Use the race as the first step in collecting data to be used for your next effort.

RELATED: Training And Racing With A Power Meter

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