FatMax Is One of the Most Unreliable Tests You Could Possibly Do! #triathlon #ironman #sportsscience

Why It Matters

If FatMax results are this unreliable, athletes, coaches and sports scientists risk wasting time and money on testing that cannot inform training decisions, and may be misled by noise rather than true physiological progress.

Summary

The video argues that the FatMax test—a measure of the exercise intensity that maximizes fat oxidation—is so noisy that it is practically unusable for tracking change. Using an analogy to cycling FTP testing, the presenter shows that if the test had a coefficient of variation (CV) of 10% rather than 1%, the smallest detectable change would be about 28%, meaning massive apparent improvements could still be within measurement error. Applied to FatMax, typical measurement error buries any realistic physiological change, so repeated testing and investment in retesting are unlikely to produce reliable evidence of improvement. The presenter concludes that FatMax testing, as commonly conducted, cannot confidently detect true change and is therefore of little practical value for athletes or coaches.