Sufferlandrians everywhere are trying to make some sort of sense out of all these complicated training metrics. You can search for deeper explanations on FTP®, TSS®, IF®, LTHR®, and NP® on the internet. We will cover some of the Sufferlandrian basics when it comes to these numbers and what they mean to you, the Sufferlandrian Speed Demon.
Functional Threshold Power (FTP)®
Your Functional Threshold Power (FTP) is the maximum average power that you can sustain for one hour. The Sufferfest has a specific video, "Rubber Glove" that can be used to determine your FTP and Lactate Threshold Heart Rate (LTHR). More info on LTHR below. If you want more information on your FTP test and Rubber Glove, you can read our blog about Virtual Power and Rubber Glove.
Basically, if you have an FTP of 270 watts, this would mean you could sustain that power for 1 solid hour. We calculate your FTP in the video Rubber Glove by multiplying your 20 minute effort by .95, or 95% of your 20 minute effort. Athlete's FTPs may be anywhere from 90 to 95 percent of their 20 minute power. It is just a general gauge of your fitness level so we can set the appropriate suffering zones for each one of our workouts.
Training Stress Score (TSS)®
Your Training Stress Score is a calculated by the duration and intensity of your workout. Each Sufferfest video has a corresponding TSS. The TSS score alone doesn't dictate how hard the workout is. Some of our workouts like Extra Shot have a TSS of 40 in a matter of 22 minutes. That is because this workout holds you near and just above your FTP for the entirety of the workout. Our video To Get To The Other Side only has a TSS of 78 over 91 minutes and is meant to be a bit easier on the legs (if that even exists in Sufferlandria!).
TSS is primarily used to measure workload over extended periods of time. It helps identify your training volume over weeks and months. This will help Sufferlandrians gauge recovery while doing The Sufferfest Videos or Training Plans. However TSS alone cannot replace how you feel after completing a workout. The difference between completing To Get To The Other Side with a 78 TSS and the video Revolver with a 66 TSS are quite different. Even though the TGTTOS holds a higher TSS, you may need an additional 24 hours of recover after doing the video Revolver. Revolver is meant to destroy your legs like you are being chased by a large dinosaur named Fluffy!
Intensity Factor (IF)®
Intensity Factor is nothing more than the ratio of your normalized power for your workout against your FTP. For instance, if your FTP was 270 watts, and you rode your bicycle for one hour at exactly 270 watts (or your NP was 270 watts), your IF would be 1.0. IF is only a number that compares relative intensity against your training session. IF is an important consideration if we are see values above 1.05. This is an indication that you are riding higher than your set FTP. It may be time to revisit the video Rubber Glove for another round of testing.
Lactate Threshold Heart Rate (LTHR)®
Lactate threshold heart rate is similar to FTP in that it is the maximum Heart Rate you could hold for one hour. We don't focus on LTHR as much as we focus on power. We use LTHR in the App to set your Heart Rate training zones.
There are many variables that effect a Sufferlandrian's heart rate. How many intervals have you done up Mount Sufferlandria? Did you have too many glasses of Real Pagne the night before? Did Grunter Von Agony keep you up late at night feeding "Fluffy and the Pain Suckers" (Sounds likes a rock band)? So many things can affect a Sufferlandrian's Heart Rate. The only thing we look for is trends over time. An increase in LTHR can signal an increase in the bodies ability to clear the muscles during heavy work. A lowering in LTHR can signal an increase in Sufferlandrian heart stroke volume, allowing you to work harder at a lower heart rate.
The main benefit of analyzing heart rate and LTHR, is our ability to spot overtraining and the need for more rest. If a Sufferlandrian cannot raise their Heart Rate into the appropriate zones, it is a sure sign that more rest is needed. Don't worry, Mount Sufferlandrian is going nowhere but up! Take the rest days.
I hope this answered some of your questions about these training metrics. We do adjust FTP, TSS, and IF in the App when you change your workout intensity. These numbers will be reflected in your passport and on your shared links like Strava and Training Peaks. Please email TheMinions@TheSufferfest.com if you have any other questions.