Is a constant power output the best way to pace for race performance?
In this latest blog, Coach Alan answers the question ‘Is a constant power output the best way to pace for race performance” by looking into pacing strategy using dFRC.
Pacing
Standard racing advice is to “not go off too hard, aiming to maintain a steady effort along the course”. But is this the only way to race?
Those who go off too hard accumulate too much lactate, oxygen debt, and general stress and constantly work to clear these consequences while still maintaining an effort. This little bag of fatigue has to be carried with you for the duration of an effort, and it can take its toll on the effort you can produce. This is the basic premise of an even pacing strategy. But recent work has shown that not so even pacing can be beneficial. So does that mean we should negative split linearly? Again, evidence suggests that this linearly negatively splitting is also not the answer!
But why is this? Efforts accumulate stress in many forms of oxygen debt, heat, heart rate, cognitive load, and lactate to be processed. All of these factors have an accumulation rate and a maximum capacity. This means that a linear approach to pacing only builds and never lets them decrease or clear. Our performance in all areas is limited by our capacity to work at that intensity and our ability to process the work; this processing is rate limited. Capacity and rate are the keys to all systems.
Psychological pacing is also key
Psychology is why some athletes do better on specific courses relative to themselves. Athletes strong on the bike can often overcome the challenge of a long straight road with confidence in their ability. Their relative comfort zone offsets the cognitive load of the challenge; they go deeper. The same athlete’s comfort zone may be reduced on a long alpine climb, the cognitive load is higher affecting their cognitive reserves to push themselves physically, and they don’t go as hard relatively as on the flat road. The same can be said physiologically, and technology and data analysis combined with our understanding of exercise physiology have led us to dFRC. To some degree, it can show how deep we go.
What is dFRC?
Firstly, we must understand FRC. Functional Reserve Capacity is a quantification of your anaerobic capacity that is calculated within the WKO training analysis software. This anaerobic capacity is quantified in joules or kilojoules. The best analogy for this quantification is to think of your anaerobic capacity as a rechargeable battery, much like the batteries in a Formula 1 car, your anaerobic battery can be used for a boost or you can ease off a bit and recharge that battery. dFRC is the real-time representation of the discharge of that anaerobic energy we can effectively watch the discharge of a battery. Think of it as the battery starting to discharge when you go above FTP and recharging when you drop below FTP. By calculating the size of an athlete's starting capacity, we can then use power data to provide a ‘live’ line that shows discharge and recharge
1 Watt = 1 joule per second
500W for 1 second = 500J of your battery used up
BestBikeSplit
Best Bike Split is something I and all coaches at Tri Training Harder have been using with athletes for quite some time now, and within that programme, variable pacing is a factor in riding your best performance. Often with athletes, I will talk about going up or down one or two zones based on the average speed; when the race is moderately hard or slow, go up one zone; when it is extremely slow or hard, you can go up two. In effect, this advice squashes the pacing profile of a novice rider using power from extremely variable to deliberately variable at certain points. Importantly this means variable in both directions, so when you are above race pace, you relax! Often for athletes, this would be a 10%window in either direction above or below their average power. This wasn’t a bad suggestion as research has shown this to be a helpful number. Crucially going low on power allows the cognitive load to be reduced and the perception of effort to decrease, but the real trick is looking at a course and knowing where to punch those efforts. Even more so we can use our knowledge of dFRC to understand how hard to punch and precisely work out where it won’t cost us in recovery. Let’s look at a couple of examples.
A Hill Climb (26min)
In the image above, you can see an example of a hill climb effort made by an athlete. The red line represents the gradient, the yellow shaded area power output and the purple line dFRC.
Lower slopes of the climb where the athlete holds a steady effort after an initial acceleration at the foot of the climb. The second half of this section sees a steeper section, and FRC starts to deplete where the athlete is above FTP (340 - 400W)
A flatter section follows, and a small recharge occurs at higher speeds before a very short sharp, high gradient section where the athlete surges at over 900W, this is a huge discharge of energy, and the athlete works incredibly hard after it to maintain their power output as harder gradients persist.
The rider continues a strong effort just below FTP (300-330W)
The climb starts to plateau, and as the speed rises, the athlete drops further below FTP with occasional efforts at some junctions where the rider slows (the graph really can’t show corners or junctions, so don’t forget a map in your analysis)
Final rise to the finish, the athlete uses what cognitive energy they have to push the discharge button again towards the line.
Looking at this effort, you would say that the big effort in section two was too early in that it didn’t allow the rider to carry that effort into the next section of the ride.
25m Time Trial (53min)
Now let’s compare this to an effort over a severely rolling 25m Time Trial Course by the same athlete. In the image below, I have highlighted where the rider pushes into their battery in red, where they recharge in green and relatively consistent sections have grey arrows. On this out and back course, you can see that the ride starts with a downhill section and goes up a rolling climb with a short climb up and over a bridge at the turnaround. The rider then climbs again on the return leg before descending before the final drag up to the finish. The more squashed version of this rider’s dFRC represents a strongly paced ride for this duration: it is less aggressive than the hill climb but still very much variable.
This effort at almost every point sees the rider carry their anaerobic effort over the crest of each climb. It sees the rider carry that investment of energy, that investment of speed into the recharge sections on the downhills. The decisive factor in analysing these efforts is whether or not the momentum from that effort is carried forward or if simply that bag of fatigue is carried forward. If you have an opportunity to recover at a high speed (higher than average race pace) dig in if you don’t hold back.
Cost-benefit
So going back to linear versus variable pacing, we can then start to use course information to look at cost-benefit analysis for individuals. The race distance and the racecourse you are preparing for will command how important including an element of variable pacing and FRC into your training is. However, the approach of retaining some variability but squashing it will remain. Even on the flattest long-distance course, the wind will demand subtle changes (and subtle changes are good for the cognitive load). Of course, if you are racing draft legal on a hilly course, you best be ready with a big battery and some strong bike handling skills.
It is also important to note that athletes with a higher dFRC will be able to punch harder into a bigger battery but only if they can then recover in conjunction with a high FTP. If the cost of punching into that anaerobic battery is dropping below a low FTP then the best approach would be to ride a less aggressively anaerobic component of the ride. Understanding how big your battery is, how deep you can go and when to use the battery most effectively for overall speed can add another weapon to your pacing on the bike. You must, however, remember one thing and that is to ensure you recharge on the way into T2!
Use your great power responsibly.
To end, I will say that every discipline in a triathlon race requires a micro warm up and also a micro cooldown. Use the swim start, swim end (T1), bike start, bike end (T2) and run start to ease your body through the physical transitions whilst focussing on excellent technical execution for your best race day performance. Then mid swim/bike/run, choose your point to discharge your secret weapon, be it out of the buoy turn that sees you turn into the wind, over the last kilometre of that long climb before you descend or out of that last dead turn onto the red carpet finishing line.
Alan has worked with Tri Training Harder since 2014. During this time working with a wide spectrum of athletes from beginner, to youth and junior elite athletes through to 70.3 and Ironman AG winners and Ironman Kona Qualifiers.
An active Triathlon coach since 2007 Alan has been fortunate enough to work with athletes, peers and support staff who have continutally challenged him to evolve and develop. Building on a solid foundation in swimming teaching, Alan has specifically developed swimming coaching experience having worked in High Performance Swimming environments. Alan's other passion is all things fast on a bicycle!
Since 2015 Alan has worked in conjunction with the other Tri Training Harder Coaches to significantly develop collective coaching practice both on camp and online.
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