Three Options for the Functional Threshold Tests No One Likes

July 20, 2021
No one likes anaerobic threshold tests. But there are several options to measure your threshold that help determine appropriate training zones.

Three Things to Know about Testing for Your Anaerobic Threshold

  1. Unless you do a blood lactate test, all of the testing options are just estimates and reasonable guesses. 
  2. Ramp tests from Zwift and Trainer Road seem to be fairly accurate options.
  3. There are other ways of either measuring changes in fitness or gauging your intervals efforts that may be more effective.

No One Likes Functional Threshold Power Tests. Here are Three Ways to Test

Most people, including me, are not fans of a cycling FTP (functional threshold power) tests as an option to measure threshold.

They tend to be long efforts, require a big dose of mental focus, and we’re rarely ever happy with the results. 

Yet some kind of testing is usually necessary in order to understand training zones. 

There are Several Options to Measure Threshold

Your functional threshold is supposed to be the point at which your anaerobic system takes over from the aerobic system. 

The threshold test is supposed to approximate your power or heart rate at your threshold so you can use that number to set up your training zones. 

However, the FTP test has some accuracy issues as well as the challenge of completing it. 

Moreover, there’s even a lot of debate whether it’s an effective way to set up training zones.

Critical power, talk tests, and using current data on Training Peaks are other options to measure threshold.  

For runners, doing a percentage of a 5k is typically a threshold pace. 

Why We Hate 20-Minute Tests as an Option to Measure Threshold

One of my Simple Adventure Team members is coming back after a long break.

We’ve been trying to estimate his power output, but finally, I scheduled a 20-minute FTP test for him. 

He emailed me the next day and told me how much he hated the 20-minute tests. 

I agreed with him. I dislike them so I avoid doing them. 

They’re long, I can’t keep focus for that long, and the results always make me feel inadequate in some way. 

My best is never enough and I’m always feeling like there could have been more.

Options to Measure Threshold on the Bike

Essentially, there seem to be several legitimate options to measure threshold: 

1. The 20-minute test. 

Go as hard as you can for 20 minutes. That’s it. 

Here’s a few things that may help with the 20-minute test. 

  • The 20-minute session is just one interval. That’s it. It’s a marker of where you are on one day. Like a screenshot. Again, it’s just an interval. 
  • When you start the interval on your head unit, turn the screen to something like the map. 
  • Here’s one way to do an FTP from Bicycling magazine. The suggestions are a ways down the page with the headline “How to Measure Your FTP.” 
  • In the article in Bicycling, the coach also argues his position of doing the test as training as well as training for the test. 

I’m not sure I buy that since we don’t often ride for an uninterrupted block of 20 minutes!

2. Two Eight-Minute Tests. 

This is originally a Carmichael test. 

Doing the two eight-minute sessions with a 10-minute break can give us a picture into your aerobic capacity. 

You can look at the differences between the two. 

An eight-minute test is, at the very least, a good estimate of your VO2 max. 

So it’s usable as a test of fitness. 

Several science and coaching sites questioned its accuracy in measuring your anaerobic threshold.

However, doing an eight-minute test once or twice a month can simply be a good gauge of your fitness. 

If you get faster, have a lower heart rate, or use less power over the eight minutes, you’re making progress.

3. Ramp Test

Ironically, this is what we used to do back in the day as the only real option to measure threshold.

The coach would use the CompuTrainer and graph paper to measure HR as the coach increased the power by 10 watts per minute, hence the name ramp test. 

What we were looking for were the places in the graph where there were changes or flattening. Those were the first and second threshold points. 

The research seems to indicate that a percentage of the last full one-minute power is a pretty good estimation of threshold. 

Zwift has a ramp (MAP) test as does Trainer Road. 

These use 75 percent of your maximum one-minute effort as your FTP. 

That number may be a little high or low (72 to 77 percent is the range), but we’ll have a good number to start with.

4. Another option is the Sufferfest Half-Monty. Several people seem to think it’s pretty accurate.

So What Options to Measure Threshold Should You Use?

At this point, if you have Zwift, Trainer Road, or another program that has a ramp test, do that. (If you have Sufferfest, do the Half-Monty.)

If that’s not an option, go for the eight-minute tests.  

The value of the 20-minute session is both to get a slightly more accurate number (maybe), and push your tolerance for discomfort by doing a hard interval. 

But they suck. 

And there are other options that provide similarly accurate results without dealing with the 20-minute suffering!

I Tried the Zwift Ramp Test

I tried the Zwift ramp rest last week. 

The results, predictably, were miserable and not accurate at all. 

So I understand the value of repeating a certain type of interval to better understand pacing, fueling (which I hadn’t done very well), and dealing with the effort on a trainer in my warm garage. 

Unless we get a blood lactate test in a lab, nothing we do is going to be 100 percent accurate.

But once we get the estimate, your training will provide the fine-tuning. 

One of these options to measure threshold will give you at least a starting point for your training. 

Let’s Talk

Contact me to ask questions and talk more about making your endurance training effective.

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