Xert Claims my FTP (Functional Threshold Power) Sits At 265 Watts. Is It Accurate?
I’ve always wondered if calculated Functional Threshold Power Values are accurate. Since 2017, however, I have relied on the Xert FTP value.
For years, we relied on the “20-Minute” Test. Riders would perform a 20-Minute effort, all out, and then subtract 5% from that value. The new number was considered “Threshold”.
Later, physiologists looked at 90% of a 3-Minute Maximal Effort.
There’s the 5-1-5 test….
Step Tests (25w steps every 3 minutes)…
Ramp tests (15-20w every minute)…
The latest ‘Testing’ asks for a 20-minute, 5-minute, 1-minute, and 5-second effort.
NO MORE TESTING.
Xert removes that testing, and claims that ANY effort to exhaustion, performed within a general ride, can accurately determine Threshold.
My favorite efforts? Billat 30-30’s. I perform them to exhaustion, every two weeks or thereabouts. It resets my Xert FTP, my High Intensity Energy (HIE), Peak Power, and Lower Threshold. If I don’t perform the workout, my Xert Fitness Signature will decay. When I don’t achieve a breakthrough, that’s fine as well. The Fitness Signature remains accurate.
But does it? Is my Xert FTP Correct?
Xert FTP Tested – Physics VS. Physiology.
In order to accurately determine whether my Xert FTP of 265 Watts was accurate, I programmed my PerfPro Studio for a workout. The workout included my standard Muscle Oxygen Vasodilation Warmup. Then, I attempted four separate 5-minute intervals. They started at 85% of FTP, then 95% of FTP, 100% of FTP, and 105% of FTP.
The instruments used to measure my body included:
- A heart rate strap that records Heart Rate Variability (HRV).
- A Moxy Muscle Oxygen Sensor that transmits Saturated Muscle Oxygen (SmO2) and Total Hemoglobin (ThB).
- A Vo2Master Portable Gas exchange analyzer.
Here’s a Video explaining the workout and the results.
CONCLUSION – XERT FTP
Honestly, I am really impressed. Xert accurately measured my FTP. The information from my Heart Rate Monitor, Moxy Monitor, and Vo2 Analyzer, confirmed that I could sustain 265 watts under stress for at least 5 minutes. But when I attempted it at 105% of 265 Watts, I was not able to make it for the 5 minutes. Vo2 crept higher, SmO2 crept lower, and heart rate got close to max.
Later this month, I’ll be performing more intervals with this combination to further prove just how accurate Xert is with my physiology.
Thanks for watching, and ENJOY THE RIDE!
