Before we get into how to use a power meter, let's talk about how to establish a baseline Functional Threshold Power (FTP).
Establishing an FTP:
- According to the 'Racing and Training with Power' by Coggan and Allen, a 20 minute all out time trial will help us determine your Threshold Power. Take the average watts from the 20 minute test, and multiply by 95%. For example, if your average watts for 20 minutes is 300 watts; taking 95% of that would give you an FTP of 285 watts. Note: The average watts for the 20 minute TT is NOT your FTP, but 95% of that number is.
- Another option for establishing your FTP would be to ride a 40k Time Trial. Riding this 40k solo would be tough, but in an organized event chasing and being chased by other riders would give you the motivation to generate a true FTP.
- A third option would for establishing an FTP would be to ride 2x20 minutes (or 2x8 miles) efforts with a short recovery of about two to three minutes. The average wattage over the entire period, including recovery, would be your FTP.
- Going into a lab and having a power test done while having blood drawn to determine lactate levels and heart rate at threshold would also be an excellent option.
Which method is best?
- The 20 minute test seems a bit short, as someone with a high pain tolerance and low endurance may find they have a skewed FTP (artificially inflated too high).
- A 40k time trial would be the optimal way to establish FTP based on real world conditions. The downside would be how often could you actually find an organized 40K? In addition doing this test solo often would be mentally draining.
- For a solo rider, the 2x20 minutes (or 2x8 miles) would be a very easy test to replicate (indoors and outdoors).
- A lab test would be a great way to test yourself and the only downside would be the cost of the test if it's done often.
Q: How often should I test?
A: In reality, power testing like all testing should be done every four to six weeks.
Q: Do I test indoors and outdoors?
A: Absolutely! Typically, many athletes can not match their outdoor FTP, indoors.
- Once you establish a FTP you can then establish watts for each zone. According to the Coggan power Levels the following zones would be used for our 300 watt FTP example:
Zone 1 Recovery Zone: less than 56% of FTP
Zone 2 Endurance Zone: between 56-76%
Zone 3 Tempo Zone: between 77-90%
Zone 4 Threshold Zone: between 91-105%
Zone 5 VO2 Zone: between 106-120%
Zone 6+ Anaerobic Zone: 121%+
These zones are based on percentage of FTP or Intensity Factor (IF). For example our rider with the 300 watt FTP, riding in the Endurance Zone would be looking to ride at .56-.76IF. Let's take a look at how we would ride different distances in triathlon:
* In a Sprint Distance Triathlon our goal wattage would be .95-1.00IF
* In an Olympic Distance race we would shoot for .88-.95IF.
* Our goal wattage for a Half Ironman Race would be about 82-87IF
* In an Ironman Race our goal wattage would be 65-72IF
Furthermore; using a power meter gives instant feedback from your energy output. Power = work done at the current time. Heart rate, on the other hand, is an 'indicator' of the work done, but you don't know how much 'actual' work you have done. I'll give examples below.
If you are training for an Olympic you may train at 87-105% of FTP. That would give you 260-315 watts. Your key workout may be 4x5 minutes at FTP - and your goal would be in that range. Some days you may push 265 and others you may be pushing 320 - the wattage that you can manage that day would give you feedback about your fitness, dehydration, and glycogen stores that day. You can monitor HR as well, just to 'see' where you are. Also check your cadence to make sure that is in line with your goals and most of all, understand your RPE as well. Let's say you can push 350 watts in this workout but it's at 55 cadence? Chances are that's not going to help you. Or maybe your HR is at 5 beats above LT - once again; that's not going to help you.
Power adds another dimension, but over a long race or a TT it allows you to literally meter out your energy. For example if you ride 112 miles, you can tell within 100 kj how much energy you are most likely to use up. Knowing this kind of information will allow you to know how much nutrition to take in - and guess what this leads to - not bonking on the run, and running to your potential as you are now racing at a more even effort, taking in the right number of calories and so on.
Chasing watts: When you are feeling tired, or maybe low on glycogen, or you may end up trying to 'chase watts' that aren't attainable on that particular day. There are a few symptoms of 'chasing watts' such as your HR is low, your watts stays low you are crushing your legs trying to get both HR and watts up. Once again, try to avoid this, and take what the day gives you.
Examples of when to watch watts and ignore HR:
Compu Trainer sessions: I set the CT to ERG mode which forces me to ride certain watts. I can set that sucker to 250 watts and ride 25 cadence or 90 cadence, and I am still pushing 250 watts. I do not think there is a better tool on the market for improving your cycling. You have NO CHOICE but to push the workload. There are days that I can't push the watts at the desired cadence, and on these days, I back off the watts.
Hill repeats: I recently rode 3x10' of hill repeats at FTP watts. Even over the course of 10 minutes, HR wouldn't rise to where I think it should have been for my FTP/RPE. So, that was either a function of fatigue or it was lagging. I COULD push the watts, so I know it wasn't fatigue, so I know HR was lagging. If I were doing the same workout based on HR only, I would have limped home with the idea in your mind that I didn't hit my goals, but in reality I did ride home full knowing I hit the workout exactly as I wanted. So, once again, watts trump HR, but in my opinion you still need to watch them along with RPE and cadence.
Power Training Terminology:
FTP = Functional Threshold Power = threshold wattage = the wattage you can maintain for one hour or 95% of your 30' power test
NP = Normalized Power = the power you held for a ride, taking out all the coasting, stopping etc
AP = Average Power = the power you held taking into account all the coasting, easy pedaling etc.
VI = Variability Index = the difference between AP and NP. For example if you rode 30 miles at 250 watts AP, and 300 watts NP; the difference is 50 watts or 20% of 200.
IF = intensity factor = the Normalized Power you held in the workout or race in relation to your FTP, so if your FTP is 300, and I hold 90% IF, that means youI held 270 NP.
More on VI: The goal to riding as even as possible, is to try to keep your VI under 12% for any given ride and I like to see the VI even closer to 5%. Riding even, means applying force to the pedals at a constant effort and not standing up or stomping on the pedals and seeing the watts spike to some crazy 500-1000 watt efforts. By riding even for a race or training ride you are metering out your energy evenly vs. hammering for 1 minute then coasting or lightly pedaling for the next. If you were to race in a criterium, you would see a huge power difference between AP and NP, with all the sprints and hard efforts.
You can 'burn a match' a few times in a race (this means riding 25% over threshold for 60" or more) but it will affect your run, and not in a good way. Steady application of pressure on your pedals will result in the best performance off the bike. If you want to push HUGE watts go ahead, but be ready for the payback on the run.