Before we get into how to use a power meter, let’s talk about how to establish your baseline Functional Threshold Power (FTP).
Establishing Your Functional Threshold Power (FTP)
According to Racing and Training with Power by Hunter Allen, Andrew Coggan, and Stephan McGregor, a 20-minute all-out time trial (TT) will help us determine your Functional Threshold Power (FTP). 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; then 300 x 0.95 = 285. So your FTP is 285 watts. Remember, the average watts for the 20-minute TT is not your FTP; rather, 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 your FTP would be to ride 2 × 20 minutes (or 2 × 8 miles) with a short recovery of about 2-3 minutes between each effort. The average wattage over the entire period, including recovery, would be your FTP.
A fourth option would be to ride a 20K or 30-minute all-out test. Your average for the 20K or 30 minutes 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 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 your FTP based on real-world conditions. The downside would be how often you could actually find an organized 40K. In addition, doing this test solo would be mentally draining.
For a solo rider, the 2 × 20 minutes (or 2 × 8 miles) would be a very easy test to replicate (indoors and outdoors).
The 20K or 30-minute time trial would be our choice.
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 cannot match their outdoor FTP indoors.
Once you establish your FTP, you can then establish watts for each training zone. According to the Coggan power levels, the following zones would be used:
ZONE 1 (Recovery Zone) = less than 56% of FTP
ZONE 2 (Endurance Zone) = 56-76% of FTP
ZONE 3 (Tempo Zone) = 77-90% of FTP
ZONE 4 (Threshold Zone) = 91-105% of FTP
ZONE 5 (VO2 Zone) = 106-120% of FTP
ZONE 6+ (Anaerobic Zone) =121%+ of FTP
These zones are based on a percentage of FTP. For example, our rider with the 285-watt FTP, riding in the Endurance Zone would be looking to ride at 56-76% of FTP, or 160-217 watts.
Let’s take a look at how we would ride different distances in triathlon:
- The desired watt range in a Sprint Distance Triathlon would be 0.95-1.00 of FTP
- The desired watt range in an Olympic Distance Triathlon would be 0.88-0.95 of FTP
- The desired watt range in a Half Ironman Distance Triathlon would be 0.82-0.88 of FTP
- The desired watt range in an Ironman Distance Triathlon would be 0.65-0.72 of FTP
Furthermore, using a power meter gives instant feedback from your energy output. Power equals the 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-distance triathlon you may train at 87-105% of FTP. With an FTP of 300 watts, that would give you a range of 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 heart rate 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 rating of perceived exertion (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 heart rate 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 time trial, 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, 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 heart rate is low, your watts stay low no matter how hard you push and you are crushing your legs trying to get both heart rate 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 Heart Rate
Old School (Compu Trainer) and New School (Wahoo Kickr) sessions: I set the Compu Trainer 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-minute hill repeats at FTP watts. Even over the course of 10 minutes, heart rate 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 heart rate lagging. I could push the watts, so I know it wasn’t fatigue and that heart rate was lagging. If I were doing the same workout based on heart rate only, I would have limped home with the idea in mind that I didn’t hit my goals. But in reality, I rode home fully knowing I hit the workout exactly as I wanted. So, once again, watts trump heart rate; but in my opinion, you still need to watch them along with RPE and cadence.
Power Training Terminology
Functional Threshold Power (FTP) = threshold wattage, or the wattage you can maintain for one hour or 95% of your 30-minute power test
Normalized Power (NP) = the power you held for a ride, taking out all the coasting, stopping, etc.
Average Power (AP) = the power you held taking into account all the coasting, easy pedaling, etc.
Variability Index (VI) = 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
Intensity Factor (IF) = the Normalized Power you held in the workout or race in relation to your FTP, so if your FTP is 300, and you 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 2 × 20 minutes at 84-97% with 5 minutes recovery in between. Follow up with 10 minutes of easy pedaling to cool down.
More on Variability Index (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 seconds 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.