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Beyond FTP III: Leveraging the Power Duration Curve for High-Performance Cycling

In this third installment around testing beyond using one testing metric namely the Functional Threshold Power Test (FTP), the idea is to advance another layer of complexity. 


The Power Duration Curve (PDC) is a mathematical description of a rider’s power-duration relationship. Put another way, it's a quantitative analysis of your unique physiology reflected in a work rate and time-to-exhaustion relationship that a mathematical equation in the form of a sigmoidal curve placed on top of that power output and duration, or "best fit" of your mean maximal power curve to the mathematical power duration curve.


PCD
Power Duration Curve (PDC)

PDC is a way to bolt all your power outputs across durations of time that is a layer above set durations such as those in Power Profiling (5s, 1min, 5min, and 20min+) and Critical Power (3min, 5min, 12min, and 20min+) don't necessarily do. For example, what is your strength level at 2mins or 8mins? And what relationship do they have regarding addressing the rider's strengths and weaknesses? 


To win races, the rider needs to know what the event requires and how their strengths and weaknesses match those needs (remember Phenotype discussed in Beyond FTP I blog post) 


TRAIN YOUR WEAKNESS, RACE YOUR STRENGTH. Training a weakness takes the most out of a rider regarding physiological fatigue, so it's important to understand the quantity of those levels and create appropriate targets. What makes a rider successful are their strengths so there still needs to be a focus in this area, however, physiological fatigue from training in this area is easier to recover and adapt to.


Let's examine key ideas around the PDC and an easy way to approach analysis:


  • Priority 1: Mean Maximal Power Efforts Curve below "Ideal Fit" Curve


Fig 1 MMP and PDC overlayed

Off the line, when we have two lines, one being the red line which shows the mathematically derived curve of "best fit" (Power Duration Curve aka PDC) and the broken dotted yellow line which is the rider's mean maximal curve (MMP) which is what the rider has done as a performance at that time duration. We need to look for places where the dotted line falls under the PDC and address those areas as they may be either an area where the rider has not done a maximal effort and/or a particular weakness at that time duration. Fig 1 shows areas between 1-5s, 1min45s, and around 50mins. New specific testing durations for this rider will be 5s, 2mins, and 60mins.


  • Priority 2: PDC crossing Category Curves


Fig 2 PDC Categories

The next idea that we need to consider is fatigue resistance. This is reflected where there is a sudden dip in the mean maximal power curve through the category power duration curve. Fig 2 shows this around 20s, 90s, and just after 3 hours. These areas represent places where the rider suddenly begins to lose sustainable power. The secret to this is understanding the unique physiology in that area that can be addressed by considering their anaerobic capacity, threshold level, and VO2 max. The power duration curve is not for those who like cookbook training and coaching, however, it is a powerful mathematical model that is hard to ignore.


PDC gives a rider the ability to go beyond fixed time durations for testing (5s, 1min, 5min, and 20min, etc) and uses mathematical modeling to give more objective descriptive data analytics that better informs strengths and weaknesses since a large sample of mean maximal power data is used. It's another tool in the toolbox! A toolbox that has grown unpacking different testing frameworks beyond just threshold testing or FTP.


Any help with further questions, discussions, consultations, or coaching? Please don't hesitate to reach out to darrin@thethreshold.coach

@darrinjordaan

@wattfarming


Train Hard and Prosper!


Darrin Jordaan

MSc (Med) Biokinetics WITS

HMS (Hons) Sports Science UP

BK 0016934

CSCS

UCI Level 1 Cycle Coach

IronMan certified coach