Read time: 5min.
By Coach Yan Busset
In triathlon, precision matters. Being able to measure your effort accurately can make or break your performance. That’s where a powermeter comes handy . Unlike speed or heart rate, power data tells you exactly how much effort you’re putting in, helping you fine tune your training and racing. When you begin serious training to improve your cycling speed, training without a power meter is like lifting at the gym without knowing how much weight you're pushing. But there’s more to using a power meter than simply watching the numbers. Lets go through together the basics you need to know in order to make the best out of the great tool.
Understanding Power Metrics: Key Terms You Need to Know
When it comes to power meters, there are a few terms you’ll need to familiarize yourself with:
Watts: The measure unit of the power you generate . This power is a combination of two components: the force (Torque) you apply to the pedals and the cadence (RPM) (how fast you spin the pedals). Understanding how to generate higher watts helps you see what leverage you have to improve your speed on the bike, whether it’s increasing your raw power or improving cadence.
FTP (Functional Threshold Power): You may already know FTP by other names to define the same thing, when lactates starts to built up and your ability to sustain high-intensity effort decreases: lactate threshold, Critical Power or maximum lactate steady state. This threshold is a key marker of fitness, and finding the right FTP helps define your training zones and measure future improvement.
NP (Normalized Power): Unlike average power, NP accounts for changes in effort, giving a more accurate picture of how hard a ride actually felt. If your ride includes sprints or climbs, NP will adjust for those surges.
VI (Variability Index): It compares your average power vs your normalized power. This helps measure how consistent your effort was. The closer your VI is to 1.0, the more even your effort. Higher numbers mean more fluctuation, which can lead to wasted energy, especially in longer races.
TSS (Training Stress Score): If you are familiar with the fitness tracking appTraining Peaks you may have already encounter this term. The TSS is a way to size your effort, it combines intensity and duration to give you a complete picture of your workload. For example, a TSS of 100 roughly equates to riding for one hour at your FTP, while If you ride for two hours at 70% of your FTP, the TSS will be around 140. TSS helps you size and track how much stress you’re putting on your body on each workout, and it has equivalents in swimming and running as well, so you can manage training load across disciplines.
Calibrating Your Power Meter: Why It Matters
To get accurate data, calibration is essential, but it depends on the device you’re using. For example, wheel-based home trainers may require a spin-down calibration to measure resistance, while some pedal-based power meters adjust automatically and don’t need frequent recalibration. Even for devices that don’t need constant calibration, it’s important to set them up properly. For instance, on pedal-based power meters, you need to input the correct crank length in the setup. Failing to do so can result in incorrect readings, so always check your settings in the app to ensure your data is reliable.
FTP Testing: Finding Your True Threshold
Many athletes rely on the classic 20min FTP test to determine their threshold, but this approach can have a significant margin of error. Instead of using a single data point, I recommend a two-point critical power test, which provides a much more reliable result. By using two different test durations, such as a four-minute and a 15-minute test, you can establish two reference points. This allows you to see how your power declines with time and helps create a more accurate power curve.
One of the additional benefits of using two reference points is that it helps identify your athlete profile. Are you more of a "Diesel type", efficient in long-duration efforts, or a 'Petrol head", better at short, intense efforts with a quicker drop-off over time?
Once your FTP is set, you can establish power zones:
Zone 1 (Active Recovery): < 55% of FTP, used for easy recovery rides.
Zone 2 (Endurance): 56-75% of FTP, for building aerobic capacity and endurance over long durations.
Zone 3 (Tempo): 76-90% of FTP, a moderate intensity used to improve aerobic efficiency.
Zone 4 (Lactate Threshold): 91-105% of FTP, focused on increasing your ability to sustain high power for extended periods.
Zone 5 (VO2 Max and above): > 105% of FTP, Short, high-intensity efforts to push your limits
You may find some zones systems with more subdivisions of the Z5 but I like to keep it simple, more can be relevant for sprinters and track cyclists more than for long distance triathletes.
For aerobic threshold and zone 2, I prefer using a speech/breathing assessment or lactate testing rather than calculating them from FTP. This helps reduce the margin of error and provides a more accurate picture of your endurance capacity.
Race Pacing: Using Power for Smarter Racing
A power meter is the best toll for race pacing. One of the major benefits of power data is its real-time precision. Unlike heart rate, which can fluctuate with factors like temperature, hydration level and fatigue, power gives you a clear, steady measurement of your effort. Similarly, speed can be affected by terrain or wind, making it unreliable for pacing. Power, on the other hand, remains constant, letting you control your effort effectively.
Working with your coach, you can define a race strategy based on a percentage of your FTP. For more experienced athletes, you can push closer to your limits, but beginners should aim to stay more conservative to conserve energy for the run. One key advantage of power pacing is avoiding peak efforts, climbing too hard or surging to overtake others burns matches taht you’ll need later. Pacing with power helps you maintain a steady effort, ensuring you don’t burn through your energy reserves too soon. The precision of power data is so accurate that it feels almost like a cheat code, guiding you to better race outcomes.
The Limits of Power: Don’t Become a Slave to the Data
As useful as power meters are, it’s important not to become obsessed with the numbers. Power should be used as a tool to help you learn more about your perceived effort, not something that dictates your every move. ( Check this article for more on that topic).
Another key point: technical issues can happen. Power meters and head units sometimes malfunction, especially during races. If you’re too dependent on your power data, this can leave you scrambling. It’s essential to develop a good feel for pacing so you can adapt if your tech fails. Learn from the data, but don’t become a slave to it. Racing by feel is a crucial skill that complements your power data, ensuring you’re prepared no matter what.
Conclusion: You don't need a powermeter to begin with triathlon but when you will become more experience and if you have big goals in mind or if you have problem to breakthrough a plateau in cycling then using a power meter effectively can significantly elevate your game. From establishing accurate training zones to ensuring you pace yourself correctly in a race, power provides valuable insights into your fitness and abilities. However, it’s important to use this tool wisely, focusing on learning from the data without becoming too reliant on it. With the right balance, you’ll be able to push your limits while maintaining control, leading to more successful outcomes in both training and racing.
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