Getting started with a power meter
April 01, 2018

Getting started with a power meter

If you ask any triathlete about the best investments they've made in terms of gear that's had the biggest impact on their results, you can be certain that a power meter is at or near the top of that list.  As an age grouper (guilty!) juggling a full-time job, family, etc, you want to make the most out of your time and the power meter can really help maximize your training.  To get started, it's important to have some baseline information from which you can structure the rest of your training.  This article will cover the basic terminology to help you understand how you can perform a test.


All About Functional Threshold Power (FTP)

What is FTP and why is it important?

What is functional threshold power exactly and why should you care about it? The short answer is that if you want ride faster and stronger, whether it’s in the local group ride or a race of some type, then you should learn yours! Read below to learn the ins and outs of functional threshold power.

Your functional threshold power is important no matter what kind of cycling you do. In a cycling race, a thousand watt sprint may be important to take the win, but it’s the rider's FTP that keeps him in the hunt before that moment approaches. And in a triathlon, most athletes are racing against the clock so it’s the ability to have a high FTP and hold a high percentage of that number that matters. And even if you’re not racing, FTP plays an important role in whether you can stay on your friend’s wheel during a flat group ride versus getting dropped off the back.  

First, let’s discuss the terms FTP or Functional Threshold Power. FTP is defined as the average power you can sustain for about an hour. It’s an important number for you to know and track if getting faster and stronger is your goal. In this article we’ll look more in depth at  FTP, training zones, and testing frequency.

Defining the Terms

FTP relates closely to Lactate Threshold, which you may have heard about. Lactate Threshold is the point where lactate begins to accumulate in the blood, that is, when your body is producing more lactate than it can consume.  Lactate threshold is what’s happening inside the body and can only be truly measured with a blood lactate test (think someone pricking your finger while you perform an indoor time trial).

FTP on the other hand, can be measured in a field test and only requires a power meter, bike, and motivated athlete. Think of V02 max as your upper limit of aerobic energy production and FTP as the percentage of that limit that you can sustain. Both are important when predicting endurance performance. Other factors include VO2 Max (maximal oxygen consumption) and efficiency. Of these three variables, FTP is the variable that is both easily measured and trainable.

Even if you don’t train with power you’ve likely felt the moment where you’ve crossed the threshold zone. To keep things simple, when you ride above your FTP you will tire quickly, and if you’re riding below FTP you’ll be able to sustain your output for much longer. You can read more about these different factors influence cycling performance in Joe Friel’s blog.

Cycling Metrics (Speed vs. HR vs. Power)

Just as pace is the gold standard in running and swimming, power is the best way to measure cycling performance. Power is the most important cycling metric because it’s objective, literally a product of force and cadence. Speed is a poor metric for cycling because too many variables such as terrain and wind, will affect your speed on any given day.  Heart rate is a good metric but it’s only giving you a piece of the equation, your subjective effort versus a measure of the work being performed.

That said, the use of power zones is enhanced when you use heart rate zones in conjunction. Simply put, your power is the actual work your body is doing, while your heart rate is the response to that work. Power is objective and heart rate is subjective. If you use both together with zones that are properly set, you will not have to worry about overbiking in your next race! If you’re using power and heart rate in a race, it’s important to keep in mind that heart rate targets always trumps power. You can read more about Dr. Andrew Coggan’s power and heart rate zones on the TrainingPeaks blog.

Testing and Setting Zones

Setting an FTP is the first step to set your zones and monitor improvement. Beginners should test their FTP more frequently, say, every few months, while athletes who’ve been training for years should test a few times a season.

Even if you are just getting started training after a break don’t make the mistake of waiting until you’re ‘in shape’ to test! It’s best to set a baseline initially for comparison later. There is also a learning curve to testing. After experiencing the test a few times, you will find that your performance improves in part simply from learning to test better.