FTP - Valid or Not?
by George Blackwell
A recently published paper explores the legitimacy of using common FTP Tests (20 min TT) and the 95% predictive model as an indicator of your maximal metabolic steady state (MMSS). For many coaches and researchers, this model is used as a means of differentiating between the “heavy” and “severe” domains of exercise intensity, or – in the language you’ll have heard more commonly from TMR – the boundary between Zone 4 and Zone 5. In layman’s terms, this means that, at or below ‘FTP’ intensity, your body should be able to find its way into a (temporary) homeostatic steady state, where blood lactate and oxygen consumption stabilise. Above this threshold, oxygen consumption should continue to increase to VO2Max values (as per the concept of the VO2 Slow Component). How this threshold is estimated can have a profound impact on the training load athletes are prescribed and the effectiveness of programmes.
Methods:
Thirteen cyclists were recruited for this study, with participants classified into four categories based on their relative and absolute VO2 peak (their maximal oxygen consumption, taken from a ramp test prior to the trials). The inclusion criteria were: at least three years of cycling experience, a minimum of four hours of training per week, and previous experience with the FTP determination test. This study examined the blood lactate and VO2 response when exercising at FTP and 15 W above FTP.
Key findings:
The VO2Max found during testing was not reached at either intensity.
Oxygen consumption stabilised at both intensities.
There was no significant difference in the VO2 slow component between either intensity.
46% of the participants reached task failure before 40 minutes when exercising at FTP.
Conclusion:
It was noted by Wong et al., that, despite the study not setting out to examine the validity of FTP and hour performance, the results demonstrated that the FTP determined using 95% of a 20-minute TT performance is not a valid estimation of maximal hourly performance. They also concluded that FTP and FTP+15W are both within the ‘heavy’ intensity domain and, therefore, should not be used to represent the physiological threshold between the heavy and severe intensity domains. Wong et al., noted that future studies should examine the value of FTP, other than a valid 20-minute TT indicator, and whether it can be used as an alternative to conventional and modified maximal lactate steady state.
Understanding the pros and cons of such a measure is important from a coaching standpoint. Equally, it is important for athletes to understand it, too. Many correlate these tests to potential performance in upcoming races, which may (or may not) be relevant, depending on the event you’re training for. Furthermore, it is often used to base training intensities - such as setting your FTP in Zwift. Irrespective of this, it’s important to maintain a balanced view of testing measures so that you can use the information they give you as effectively as possible.
References:
Wong, S., Burnley, M., Mauger, A., Fenghua, S. and Hopker, J., 2023. Functional threshold power is not a valid marker of the maximal metabolic steady state. Journal of Sports Sciences, pp.1-7.