Let’s go back to our brainstorming (yes a real storm) about critical power and/or the use of FTP as a basis of power training.
Coggan's mathematical relationship collides with the reality of human functioning, its uniqueness. We started this demonstration with 4 questions:
- What are our capacities to mobilize an important strength and to use our phosphocreatine reserves during sprints?
- What is the kinetics of our lactatemia? Recycling lactate production?
- What is our ratio of lipid/carbohydrate use over long-term efforts?
- What is the motor efficiency of the pedaling of each of the trained athletes?
About to question # 3: we know that the aerobic metabolism works thanks to carbohydrates, but we also know that the reserves are limited: the exhaustion of muscle glycogen occurs after approximately 90 min of exercise at 75% VO2 max or after about 4 h at 55%.
At the same time, lipids (triglyceride)s at the muscular level can be degraded and allow energy production at the mitochondrial level.
The glycogen storage capacity in the liver is linked to the training level and we can easily imagine that a triathlete training 8 hours/week has lesser qualities than a pro at 25 hours a week.
Little aside, we can understand that the human body's capacity to assimilate a sudden increase in training load is limited and the training requires progressiveness.
Come back to our ability to metabolize lipids in aerobic metabolism: the “sine qua non” condition for using fats is to have a low-intensity exercise (-50% of VO2 or +/- 50% of MMP).
Thanks to the training, we will increase our MMP and we will raise our power outputs to the different thresholds and therefore by runoff, our cruising pace: remember your long training at the back of the pack, praying that the pacing will not accelerate! Thanks to your perseverance in the training, your position in the peloton has progressed and now, you are a pack leader because the pace for a LDST of 3 hours, for example, has become a low intensity, fully controlled, allowing you to use less glycogen and more fat.
In fact, the further our cruising pace moves away from FTP (Functional Threshold Power), the less our muscle cells are tempted to use sugar.
And we are not all equal genetically.
Question # 4 is a mixture of bioenergetics and biomechanics: is my pedal stroke economical? Is my technique suitable for high or low cadence? Is my material optimized (development or length of the crank) to have an efficient output?
It is simply a question of ensuring that the cyclist or the triathlete does not consume too many calories to advance!!
It’s, therefore, complicated to extrapolate performance from 2 simple power measurements or at least to lock yourself up only in this approach. A Coggan test around measurement of CP5 and CP20 can be a working basis which will be accompanied by a fine analysis of the Record Power Profile to obtain an image at time T as real as possible.
Frederic HURLIN - www.azurperformance.fr