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:
Which method is best?
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.
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 a percentage of FTP. For example, our rider with the 300 watt FTP, riding in the Endurance Zone would be looking to ride at .56-.76 percent of FTP. Let’s take a look at how we would ride different distances in triathlon:
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 4×5 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 stay low no matter how hard you push and 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. 'Chasing watts' is a common practice, but not one that will lead to race day success.
Examples of when to watch watts and ignore HR:
Old School (Compu Trainer) and New School (Wahoo Kickr) sessions: I set the CT or Kickr to ERG mode which forces me to ride certain watts. I can set that trainer 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 way for you to improve 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 and keep the cadence in my desired range (which is another conversation!).
Hill repeats: I recently rode 3×10′ 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 HR 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% of FTP, that means you held 270 NP.
Sweet Spot: To perform 'Sweet Spot' interval, ride between 84-97% for at least 20 minutes, with 2 reps, and 5 minutes in between. The workout would look like this: After a thorough warm-up, ride 2x20' at 84-97% with 5' recovery in between. Follow up with 10 minutes of easy pedaling to cool down.
More on VI: The goal of riding as even as possible, is to try to keep your VI under 10% 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 your threshold for 60″ or more) but it will affect your run, and not in a good way. The 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.