FTP, MAP and percentages: the endurance factor

Following our recent article on calculating the FTP required for using different training apps, we received some very good questions. To share them with everyone, we are publishing one here that sums up the questions many people have quite well. Along with Coach Bru's answer, of course.

Your blog posts are always so interesting! Regarding the MAP test (PAM test), it seems to me that subtracting 15% would give an FTP that is too high, wouldn't it? I thought that FTP corresponded to 75% of MAP, so you would subtract 25%. For me, it works pretty well and corresponds roughly to 95% of my CP20.

Hello,

Thank you for your kind words about the Vélo Cartel blog! We share useful information for cyclists who take their training seriously, without necessarily taking ourselves too seriously! ;)

If we wanted to find the ideal percentage to subtract from the estimated maximum aerobic power (MAP) (following the simple protocol I propose) in order to accurately estimate the critical power over one hour (PC60min, often mistakenly referred to as'Functional threshold power (FTP)'), we would need to subject a very large number of subjects to MAP and PC60min tests.

This would give us an accurate picture and allow us to appreciate interindividual differences. But it would require a lot of work. To my knowledge, no researcher has undertaken such a project to date.

It is unclear whether such a tedious task would confirm or refute my hypothesis that this percentage averages 15%. But in any case, this is what my observations in the field, and those of my colleague Guy Thibault, indicate.

While this percentage is not extremely accurate, it is clearly accurate enough to inform the planning of training sessions, where extreme precision is not necessary, given the imperfect accuracy of intensity measurement instruments and the vagaries of motivation.

This is also indicated by the following logical reasoning.

• For cyclists, MAP is roughly the power that can be maintained, on average, during a maximum effort lasting approximately five minutes. 
• The intensity that a cyclist can maintain for 60 minutes is obviously lower than their MAP. 
• The decrease in the percentage of MAP that can be maintained during a maximum test lasting five to 60 minutes depends on a physical quality known as endurance. 

However, and this is where the data that may lead us to modify the percentage mentioned above comes in:endurance is a quality that is independent of maximum oxygen consumption (VO₂max) and MAP.

What is endurance? To be distinguished from basic endurance (which is the ability to rides long rides), endurance (or aerobic endurance) is the rate of decrease in relative intensity as the natural logarithm of the duration of the events increases. Endurance varies between 3.5 and 12.5% VO2max/ln(Tlim). It is more commonly defined as the ability to maintain a high relative power output for a given period of time, or as the ability to maintain a given relative power output for a long period of time. Source Thibault G (2009) Cardio training. Endurance sports and performance, Vélo Québec Éditions; Collection Géo Plein Air, 264 p. www.velo.qc.ca/magazines/guides-livre/423-0/

 The endurance standards established by my colleague Guy Thibault among 2,464 subjects indicate that the percentage decrease in power between MAP and critical power over 60 minutes varies greatly: some have high endurance, others low endurance, regardless of their performance level.

Therefore, the percentage to be applied to the MAP to find the critical power over 60 min varies according to the subject's endurance, as shown in the following table.

Endurance		% of MAP corresponding to critical power over 60 min
Lower than average	-9.3% VO2max/ln(Tlim)	74%
Slightly below average	-8.6% VO2max/ln(Tlim)	77 percent
Average	-7.6% VO2max/ln(Tlim)	81 percent
Slightly above average	-6.6% VO2max/ln(Tlim)	85 percent
Higher than average	-5.8% VO2max/ln(Tlim)	88%

So you are not wrong in thinking that in some cases, the percentage to be subtracted from the MAP to estimate the 60-minute critique is not 15%. It all depends on the subject's endurance! In general, athletes with below-average endurance have above-average anaerobic capacity; their MAP test results overestimate their true MAP.

I still think that estimating critical power over one hour by subtracting 15% from the MAP remains valid for most cyclists, as many have above-average endurance.

That being said, this method is not perfect either. Because there is no such thing as a perfect method.

Professionals who are very data-driven regularly perform 20-minute tests, which are more demanding but more accurate. They say that depending on their level of fitness, stress, fatigue, or other factors, the results can vary considerably. We're talking about tens of watts. 

The same goes for your PAM test, which is done alone, without encouragement from peers or support from a coach who would undoubtedly push you to do one more minute. 

The solution? 

You can retake the test when you feel in good shape.

You can also take the number you obtained from your PAM test and do a 20-minute test, trying to maintain that value. You will get the correct time.

You can also simply play around with the numbers in your app (TrainerRoad, Zwift, Sufferfest, etc.) and adjust them if you find that you are completing demanding workouts without being completely exhausted. Take it slowly, adding 5 watts at a time. Or remove some if the number is too high.