FTP: Ultra Over-rated?
When considering the physiological demands of ultra-distance cycling events, success is determined by the ability to maintain a sustainably high effort level for hours, or even days, on end. For the purposes of this discussion, we can broadly use the World Ultra Cycling Association’s definition of ultra-distance as: ‘events not less than 200 kilometers or, for a defined time, at least six hours in duration. Most races are much longer!’
In the wider cycling world, FTP is frequently viewed and cited as a ubiquitous gauge of ‘fitness’. Conversely, FTP is just ultimately a single metric with a slightly more nuanced definition than is commonly assumed. It is essentially the power that one can sustain in a quasi-steady state without rapidly fatiguing and is associated with the second lactate threshold (LT2). This duration is usually around an hour for most people but can vary significantly for individuals.
However, our definition of ultra-distance makes it evident that athletes will be performing for durations for multiple times this duration. So the question is whether this measure of roughly one hour power translates to longer efforts. The title of this piece may somewhat give away my view, but read on to understand why FTP may be less important than you may have been led to believe for the ultra-distance cyclist.
The Wrong Threshold?
With FTP occuring around the second lactate turnpoint, LT2, maintaining an effort beyond this point becomes quickly unsustainable as blood lactate builds at a rate beyond that it can be cleared.
The lactate threshold with greatest relevance for ultra-distance though is the first lactate turnpoint, commonly known as LT1 or the Aerobic Threshold (AeT). Here the body shifts from primarily metabolising fat as a fuel source towards carbohydrates. This intensity can theoretically be maintained forever, given adequate fueling (until other factors intervene). Being able to ride at a consistently higher power around LT1 is far more important for an ultra-distance cyclist than simply focusing on an approximate power that you can produce for roughly an hour.
Nevertheless, concentrating on improving sustainable power at LT1 is likely to have some positive impact on a cyclist’s FTP, as these are both fundamentally aerobic efforts using similar physiological systems. But an improvement in FTP is incidental and not crucial to the outcome for an ultra-distance cyclist. In the reverse case, an ultra-distance cyclist focusing too much on improving FTP will find their general aerobic fitness improve to an extent, but will likely lack the specific preparation required for the demands of the longer durations.
Durability
FTP, for zone setting purposes, is ideally tested when a cyclist is fresh and prepared to give an effort representative of their best for that day. However, in many circumstances a cyclist will have to perform an effort when in a fatigued state to succeed in their event. For shorter races, this could be a 20 minute climb after 4 hours of riding, or for an ultra-distance event this will relate to an ability to maintain a higher consistent power hour after hour or day after day. So the extent to which a cyclist's physiological variables can be maintained over the duration of an event is not captured simply through measuring FTP when fresh.
This measure of the deterioration of the primary physiological determinants over time is commonly described as ‘durability’, a concept picking up a lot of attention currently in the research literature. One's FTP is not going to be the same after multiple hours in the saddle than when fresh. But, the smaller we can make this drop-off, the more fatigue resistant or 'durable' we can be.
The mechanisms behind durability are not yet fully understood but potential contributing factors include the ability to use fats for fuel, resistance to muscular damage and resistance to central fatigue (Jones, 2023).
Therefore two athletes with the same FTP when fresh, may have very different results when fatigued which will ultimately affect performance for their chosen discipline.
Beyond Pure Power
As well as FTP just being one of the measurements of physical fitness, we must bear in mind that most cycling disciplines are not just pure physical fitness competitions. Success relies not only on effectively applying that fitness, but also mastering other necessary skills. After all, the race winner is the person who can sustain a higher absolute speed for a given distance than the other competitors.
It therefore becomes crucial how one's power is applied, rather than just producing the maximum amount of power at all times, no matter the discipline.
In the context of ultra-distance, the management of one’s effort is crucial. It is no good just having a high FTP but realising that an effort beyond one hour is unsustainable. Training therefore has to be specific to the event, being used to ultra-long duration efforts and not causing unnecessary fatigue at an early stage. Beyond the physiological elements, one must also consider crucial logistics such as fuelling the effort, being efficient with rest periods and, if the event spans multiple days, ensuring appropriate amounts of sleep. A high FTP does not make up for deficiencies in these aspects so one’s approach must be all-encompassing.
Testing
One area that I do appreciate the value of FTP is as a means of setting training zones. It is indeed a measure of aerobic fitness and using a consistent testing protocol can be useful in setting and adjusting power zones for athletes who are training with a power meter. The common power zone models are determined in relation to a cyclist’s FTP (particularly the 7 zone Coggan model) and I find that FTP is a good starting point for setting power targets, particularly for high-intensity workouts.
Without access to laboratory measurements of lactate and gas exchange, FTP is commonly estimated using field tests. The most popular of these being the Allen & Coggan test, where 95% of 20 minute power is used as an analogy for FTP. This is a test that can be fairly easily repeated but is relatively taxing and requires good pacing to produce the most accurate outcome.
Another frequently employed protocol is the ramp test, where the power targets are gradually increased in one-minute steps until failure. A ramp test is however a great way to overestimate your FTP. With FTP by definition being a lactate ‘steady state’, the ramp test cannot represent this, as power is continuously increased until the cyclist cannot continue. For those primarily training for longer aerobic events, the results from a ramp test are likely to artificially inflate the power that can be produced for a much longer duration.
With all testing, the principle of specificity plays a role in the outcome. To get better at something one must practise doing that thing. This very much applies to testing protocols. A well paced 20 minute test will result in a very different FTP estimate than one which is less so, especially when this is intended to be an ‘all out’ effort. Those who have either performed a lot of these tests, or spend a lot of time training at an intensity close to 20 minute max will therefore be better informed of how to measure their effort. Those with a different focus to their training will thus naturally be disadvantaged in such a test.
One Hour Power?
It is commonly assumed that FTP, being a ‘maximal metabolic steady state’ equates to the power output that one can sustain for an hour.
However, two studies by Sitko et al., (2022) and Borszcz et al., (2018), provide some empirical evidence to make us question this ‘one hour power’ FTP assumption. In their studies, both research teams firstly made participants perform the Allen & Coggen 20 minute test, before (after a few days rest) getting them to ride at the resulting estimation of FTP to exhaustion.
The resulting time that the participants could hold this power was 50.9±15.7 min in the Borszcz et al. study and 44±9 min in the Sitko et al. study. Interestingly, Sitko et al. also found that cyclists with a higher performance level showed a longer time to exhaustion (although still less than an hour). This can be viewed to add further credence to the assertion that familiarity with the testing protocols and a better understanding of pacing can provide more accurate results.
Although experience appears to have some influence on the outcome, the evidence points towards large variability in the duration associated with FTP amongst cyclists, particularly with such high standard deviation values. Which leads us to pose the question as to whether it really matters if FTP is not truly representative of one’s one hour best?
Fundamentally, if the objective is to use FTP to set training zones then perhaps not. In all cases, a consistent testing protocol is vital, but even more so is not taking a broad-brush approach to zone setting through FTP estimates. Individuality must be respected and training zones adjusted accordingly to ensure that the desired outcome is achieved through each session.
Conclusion
For me, FTP has a place as one of the many physiological markers and for zone setting, with the constant caveat that it does not directly correlate with ultra-distance performance. Specificity is a key training principle and training specifically for ultra-distances is not designed to directly raise a cyclist’s FTP. Inversely, with too much of a focus on improving FTP neglects the more important factors which decide success in ultra-distance events.
In all, this is another reminder that FTP is not the be all and end all of cycling fitness. Focus what is important for your particular event and if you are really concerned about having the highest FTP possible you can always use the ‘Backwards Hat Dylan’ formula:
References
Borszcz FK, Tramontin AF, Bossi AH, Carminatti LJ, Costa VP. Functional Threshold Power in Cyclists: Validity of the Concept and Physiological Responses. Int J Sports Med. 2018 Oct;39(10):737-742. doi: 10.1055/s-0044-101546. Epub 2018 May 25. PMID: 29801189.
Jones, A. 2023. The fourth dimension: physiological resilience as an independent determinant of endurance exercise performance. The Journal of Physiology. The fourth dimension: physiological resilience as an independent determinant of endurance exercise performance - Jones - The Journal of Physiology - Wiley Online Library
Sitko, S. et al. 2022. Time to exhaustion at estimated functional threshold power in road cyclists of different performance levels. Journal of Science and Medicine in Sport, Volume 25, Issue 9, 783 - 786