Over the next several weeks, I’ll be posting a series of blog articles designed to shed some light on the metrics and the science behind power training.
Let’s start with FTP.
You may have heard the term Functional Threshold Power, commonly referred to as “FTP”, but do you know what it is or why it has become a benchmark for many athletes?
What is FTP?
FTP is commonly referred to as the power one can hold for approximately 1 hour. That definition is generally correct, but upon examining it closer, we can understand it’s truly not bound by duration, per se. As Andrew Coggan writes, “FTP is the highest power that a rider can maintain in a quasi-steady state for approximately one hour without fatigue. When power exceeds FTP, fatigue will occur much sooner, whereas power just below FTP can be maintained considerably longer.” That means FTP could be maintained for an hour, but that window could ultimately be a bit longer or shorter in duration. To understand why that is, we need to understand that FTP in many ways is actually a simplified method of tracking Maximal Lactate Steady State (MLSS). MLSS is derived from lab testing which includes a series of high-intensity efforts designed to measure the percentage of lactate accumulation in the blood of riders through samples taken by pricking a finger or an earlobe.
MLSS represents the highest exercise intensity at which the rate of blood lactate clearance matches the rate of lactate production – meaning you are clearing out that lactate as fast as you make it (hence the term “steady-state”). This corresponds to an exercise intensity that can typically be maintained for 40 to 70 minutes.
Why is FTP important?
For many, FTP is a benchmark for performance and fitness. Generally, FTP can be a seen as predictor in the success of a racer. The higher the FTP, the higher the power you can maintain while training and competing. So, all things being equal (rider weight, strengths, and weaknesses), a rider with an FTP of 300 watts should be able to ride faster than a rider with an FTP of 200 watts. I write should because other factors impact performance such as rider weight (watts per kg) or aerodynamics.
While a rise in FTP may indicate an increase in fitness, it’s also important to understand that FTP can fluctuate based on the type of training you are doing and the period of training you are in. Tim Cusick, coach and program manager for WKO4 refers to this as a “Cost/Benefit.” That cost or benefit depends on your specific event demands and when the individualized training occurs in a periodize cycle. These factors impact whether there is a loss or gain in FTP. Take mountain bike racing or cyclocross for example – both of those styles of racing require large frequent surges in power and fair amounts of time above FTP (referred to as Functional Reserve Capacity, or “FRC”, which is the number of kilo-joules of energy a cyclist can burn above threshold). For athletes like these who have switched over to riding highly anaerobic intervals, a decrease in FTP is usually seen. This simply means we may be trading off some of the work or volume and intensity we used to build FTP for race preparedness or race specificity.
How do I measure FTP?
This has become quite a popular discussion on the web, with a number of sites all claiming to have the most accurate methodology. I’m not going to get into the difference between all of those here but instead, focus on a few of the most commonly practiced methods for determination.
- The 20 minute test
In many ways, the 20 minute all-out field test and then multiplying the power number you get from that test by .95 has become arguably the most popular format for calculating FTP. The primary reason for this is because it’s generally reproducible by athletes and not as daunting as, say, doing 1 hour full-out test. There are some risks and criticisms with the 20 minute test, however. The results can be inflated slightly based on the phenotype of rider you are (time trialist, sprinter, all-arounder). This is because we don’t create power over those 20 mins by one energy system alone. There will always be some portion of the power generated aerobically and anaerobically. So if a rider has the ability to generate a slightly larger portion of the 20 minute test via anaerobic means versus aerobic, the results can be slightly skewed. The test developed by Hunter Allen and Andrew Coggan, which adds a 5 minute all-out effort prior to the 20 minute effort, is theorized to reduce some of that anaerobic contribution.
There has also been some research of late by Martin MacInnis, Aaron Thomas and Stuart Phillips looking at the validity of the 20 minute test and has directly cited the Allen and Coggan test:
“Although we cannot exclude the possibility that some cyclists could achieve an FTP equal to 95% of their 20-min TT, none of the cyclists in the present study had an FTP ≥ 95% of their 20-min MPO (Maximum Power Output). Instead, we propose that the ‘warm-up’ protocol suggested by Allen and Coggan, which included a 5-min TT, explains the discrepancy between the two estimates: performing a 5-min TT would likely reduce the MPO achieved during the subsequent 20-min TT, increasing the relative intensity of the 60-min TT (i.e., as a percentage of 20-min MPO).”
- The 25 Mile/40K Time Trial
Research has shown that trained cyclists will complete this distance in fairly close to 1 hour. Since FTP generally corresponds with approximately an hour, the “race of truth” done at full sustainable effort has been shown to be a reliable method to get an accurate threshold number. While many consider this to be the gold standard when it comes to testing, the ability to find races that are one-hour or 25 miles in length may be limited. It may also be difficult to motivate a rider to go out and just bury the hammer for 1 hour straight on a regular basis outside of race or lab testing situation.
- Race File Analysis
Similar to the Time Trial, analyzing the normalized power from a race file collected from a criterium or another race that lasts at least one hour has also been considered a reasonably accurate measurement. It’s important to use the normalized power for this analysis as it takes out the variability or power surges that may have occurred during the event and gives you the true physiological cost of the effort. Typically I like to use race file analysis to confirm testing data from shorter tests like the 20 min effort.
When considering FTP testing and which method to choose, there are a few simple rules to follow to help ensure you get accurate data: test often, make tests reproducible, and look for correlations from your tests versus your race files. The testing method you choose is less important than actually testing on a regular basis. If the right training is being applied, adaptation generally occurs for most around 6 weeks or more, so consider testing every 6-8 weeks to make sure you are on the right track with your training. It’s also a good idea that if you spend a considerable amount of time training indoors during the winter months, to retest again when you start riding outside. Power differences can also be seen between different bikes and different power meters, so when in doubt – test it out!
How do I raise my FTP?
Training to raise one’s FTP it usually is broken into two goals.
Goal 1) Increase the maximum duration at which the FTP can be held:”Extensive Increase” or maintaining the threshold power longer. In other words, if you can ride 200 watts for 10 minutes, try increasing the duration to 200 watts at 12 minutes.
Goal 2) Increase the power you produce in the steady-state: “Intensive Increase” or producing a higher power output for the same duration. Similar to the above example, if you can ride 200 watts for 10 minutes, try riding 210 watts for 10 minutes as a progression.
Keeping those two goals in mind, using a combination of intervals designed to use power zones just below and just above your FTP tends to be a great starting point for most. These may be intervals referred to as Sweet Spot Training (SST), Criss-Cross, and Over-Unders. Most well designed training programs will use a progression of both of those goals to target raising your threshold.
I hope that sheds some light on FTP. Keep an eye out for more posts soon that will help you get a better understanding power and how this data can be used to help your performance.
Sign up and join us for my webinar – Ironman Placid by the Numbers, where I will discuss how we use power to plan, race, and analyze bike and run splits.
Want to learn more about power training or how to train to raise your FTP? Drop a message to coach@bonkwerx.com