About Power, FTP, CP, ECP, training load and efficient workouts.
Resources:
e-book "The future of training and racing with a power meter"
www.typhooncycling.org
www.sportim.be
INTRODUCTION
Thanks to power meters, cycling training evolved from conservative to groundbreaking. In early stages we focused on measuring the actual training intensity, now attention is shifting to the physiology behind power. Being able to map the metabolism of endurance athletes - purely on the measurement of mechanical work and exercise tolerance - is now one of the greatest challenges of scientists.
FTP, CP, ECP
· FTP
An important threshold, the boundary between maintainable and not maintainable efforts, could and can be determined quite accurately in the lab by measuring lactate, oxygen consumption and/or monitoring ventilation. Quite invasive methods and difficult to achieve in training practice so the use of power meters in cycling came as a godsend. "Functional Threshold Power" was born. Initially, FTP was defined as "a load - expressed in watts - that can be sustained over 60 minutes." Later, this definition was modified as "the highest power a rider can maintain in a quasi-steady state without becoming fatigued." Moreover, since a rider can very easily determine his/her FTP himself/herself by going 20' full blast and multiplying that value by 0.95, it goes without saying that in no time the concept of FTP became an all-important concept for training with a power meter. Consequently, all training zones were calculated based on % FTP.
So the FTP protocol is simple to use but modern training methodology is increasingly moving away from this approach because FTP does not reflect any physiological process and, moreover, is determined in a debatable way. Only if a rider accepts an error of nearly 10%, the use of the value FTP as the limit between whether or not to become fatigued can be used. But even if FTP correspond to the actual metabolic limit, deriving other training ranges remains problematic. In other words, expressing training zones as a % FTP is highly inaccurate. There is only one key number, FTP, and this does not allow any conclusions as to how the performance achieved came about. Therefore, it remains unknown which energy sources the athlete tapped into in a given zone and to what extent.
· CP
Every athlete knows that the more intense an effort is, the less long it can be sustained, and thus there is a kind of inverse relationship between the intensity of the effort and the sustaining time. This observation was - a long time ago - behind the creation of the scientific Critical Power Concept. This model defines the hyperbole intensity-time relationship using only two parameters: CP being the horizontal asymptote of the curve and W' the anaerobic energy reserve. The asymptote identifies the maximum metabolic steady-state intensity. Below this value, muscle metabolism remains in "steady-state," above it is no longer possible so that after a certain time, exercise at this level will come to an end. In this context, steady-state means that the effort can be maintained indefinitely.
· ECP
However, this point of view is correct only within the measured limits 150 to 900 sec. The major error in thinking, according to C. Dauwe D.Sc., is that we should be allowed to extrapolate this relationship indiscriminately to shorter and longer endurance times or to higher and lower power. It is therefore imperative to also use actual values for exhaustion during longer efforts and consequently establish a new and extended CP model: the Extended Critical Power model (ECP). The most striking thing about the graph below - which shows performance with the inverse of time on the X-axis - is that it is clearly impossible to describe all performance with a single law. In fact, there are 2 distinct areas of performance!
The above 1/T analysis shows several things that require our special attention. They are very important because they delineate zones of great physiological significance. Moreover, they play a key role not only in calculating the type and amount of energy consumed but also in calculating the amount of anaerobic energy that can be replenished: the W' balance.
The points of interest are as follows:
- The intersection of the blue dotted line with the vertical axis corresponds to Critical Power CP.
- The slope of the blue line is equal to the anaerobic energy reserve W'
- The intersection between the two lines is the Super Critical Power SCP, a term first used by Mike Puchowicz.
- The extension of the orange line also gives an intersection with the vertical axis, the Recovery Threshold RT.
BETTER ANALYSES - MORE EFFICIENT WORKOUTS
· It follows from the above observations that RT and not CP indicates the boundary between recovery and depletion of the anaerobic reserve. In this view, CP is actually equivalent to the Maximum Aerobic Power MAP. Professor Dauwe's ECP model is therefore able to delineate physiological effort zones more precisely and, moreover, to define load indices that quantify effort levels much more accurate. The Training Stress Score TSS - originated from the FTP vision - and a widely used but very general value to calculate load, is replaced in the ECP concept by 3 much more precise load indices: Aerobic load index, Slow Death load index and Fast Death load index. Competitions and training can be better analyzed through these indexes, making it possible for the coach to perfectly align competition and training goals. The graphs below show an analysis of a race and an interval training with the corresponding indexes.
Thanks to the new approach, three of the five conditions for making training as effective as possible have already been met:
o Being consistent with the objectives
o Taking into account the capabilities of the athlete
o Being able to use the "most relevant" parameters
- The fourth and not least important condition: providing feedback "in the action," is Prof. Dauwe's second great achievement. In collaboration with Osborn Technologies Inc. an "anaerobic reserve widget" was added to the existing SuperCycle app and displays live the amount of anaerobic energy you still have available.
· Training zones catalog the efforts but they do not calculate the physiological impact! This is especially true for interval training in the higher zones where the incredibly large number of possible combinations of the variables makes it a lot of smoke and mirrors whether the desired goal has been achieved. HIIT training until now was a real nightmare for the rider or his coach, but the ECP model now offers the possibility to calculate the training load in detail and create the almost perfect training. This also meets the fifth condition.
Training modules can be used from the “member area” on www.sportim.be
