The fitness tests are designed to measure your ability to perform under fatigue.
It’s not like pacing a 20-minute test or hanging on as long as possible on a RAMP test.
For example, the standard Fitness Test is around 30 minutes long with about 10 minutes of high strain effort. There are two all-out sprints then a series of intervals designed to pull down MPA in steps without full recovery followed by a final interval that you should fail on.
If you rode this workout under ERG control – or in Slope mode adhering to targets – you may not fully express your fitness level especially if your current signature is understated.
In Slope mode you can go all out on the sprints and keep going on the final interval until you collapse.
There are a few different versions of the Fitness Test workout. Here’s my favorite called Under Pressure. With this one there are short Ronnestad-style intervals to draw down MPA with a final interval ending with an all out sprint effort right before you are about to fail. Since you’re in Slope mode under gear/cadence control you can time that final jump as necessary. Right before you are about to collapse spin up, jump up, and hold on for at least 5-7 secs.
With the standard test the two initial all-out sprint efforts measure actual watts when you are rested. Under Pressure OTOH looks at the max watts you can produce when you are about to fail.
Both tests will calculate your PP, TP and HIE signature values. This points out a difference in how Xert derives your power duration curve. Rather than based strictly on MMP sampling, the algorithm estimates values based upon what you can generate under fatigue.
Fitness Test Version 2 looks like this –
And Version 3 looks like this –
You’ll likely discover a favorite version but keep in mind fitness test workouts aren’t necessary to generate a viable signature. Xert will recalculate your numbers after every activity.
Many users who compete are validating their signature during their events, ZRL, or hard group rides. Other workouts in the library are also candidates for producing BTs especially if you switch to Slope mode when MPA is drawn down and go for it.
Once your signature is dialed in, BTs aren’t absolutely necessary as Xert can accurately track values based upon changes in TL alone.
Reference (4 types of BTs) – Breaking Through the Xert Way! – Xert