Understanding and Applying FTP and Lactate Threshold

Before I get too far into this post, I think it will be important to define FTP (Functional Threshold Power) and Lactate Threshold.

Functional Threshold Power – The amount of watts someone can sustain for one hour of maximal intensity

Lactate Threshold – The rate that the body can’t remove lactate from the blood faster than it’s producing it.  The number that exercise scientists agree upon is 4 mmol/l.



The big question is, are these terms interchangeable?  The answer is yes… and no.  It depends on someones level of fitness and their ability to push themselves through the discomfort.  For the untrained individual, they won’t have the cardiovascular or muscular fitness to sustain a effort at lactate threshold (LT) for the full hour.  But for trained athletes, the numbers for wattage produced on the bike at LT and FTP should be very close.  So the sake of the article, I’m going to treat the answer to the question as yes.

The next big question is how to determine FTP/LT.  If you have a powermeter on your bike, you can look at some race data which you were going all out for an hour.  That way is the most accurate.  However, there are other ways of figuring it out:

1.  Step test – this test can be done on your own or with someone checking lactate levels.  It will be more accurate if you can have lactate levels checked, but a rough estimate can be done just by noting your breathing rate and intensity.  This test should be done on trainer that has the ability to increase wattage at specific increments.  (I suggest 25 watt steps.)  Start the watts on the trainer about 150-175 watts less than what you think your FTP/LT is going to be.  After getting warmed up, start the test and increase the watts and/or checking blood lactate levels every 2 minutes.  When you reach your FTP/LT you will notice your breathing changing from labored to “huffing and puffing.”  This is your body trying to blow off the excess hydrogen ions in your blood from the lactate acid making the pH of the blood too acidic.  When this happens, you know that your FTP/LT is somewhere between the current wattage and the previous one.  Without blood lactate levels being drawn, some guess work on your part will need to be done based the rate of perceived exertion (RPE) on the last step before the breathing changed.  If lactate levels are being drawn and recorded, the computer can estimate where LT/FTP is based on the curve of the line.

2.  20 minute Critical Power (CP) – This again should be done a trainer.  The trainer should have the ability to measure average power or a powermeter on the bike will be needed.  This test is simple and just requires the rider to go all out for 20 minutes (don’t accelerate at the end… and you should be completely spent).  Once that is done, multiply the power you have for the 20 minute average by 0.95 and you have FTP.

There are several other ways to determine FTP/LT but these two seem to be the easiest.  Of course, if you don’t have a powermeter on your bike or a computrainer, or another trainer with abilities to measure watts, be sure to wear your heart rate monitor.  It’s not as accurate (several things influence HR) but it is much more affordable than a powermeter.

So, great, you now have the ability to determine your FTP/LT… but what do those numbers mean and how do use them?

The first thing you must do is set your training zones.  I personally like Andrew Coggan’s method of setting up training zones:


Coggan’s Power Training Levels

Active Recovery: <55%  FTP or <68% or HR at LT

Endurance:  55-75% FTP or 69-83% of HR at LT

Tempo: 76-90% FTP or 84-94% of HR at LT

Lactate Threshold: 91-105% FTP or 95-105% of HR at LT


VO2max: 106-120% FTP  (3-8 minute interval pace) or > 106% of HR at LT

Anaerobic: 121%+ FTP (HR n/a)

Neuromuscular: >1000w? (HR n/a)



Now that we know our  training zones, how do we increase our FTP and/or power at LT?  As you  can see from the pictures above, the most benefit we get in raising our FTP or power at LT is to train in zones 3 and 4.  It’s important not to neglect the other zones though.  Recovery is needed to be able to the desired intensities the next day.  Endurance (zone 2) teaches the body to resist fatigue.  Zones 5 and 6, although not used much in longer races such as 70.3 and 140.6 still need to be visited occasionally to  increase stroke volume of the heart, and give us the snap we need to pass someone to avoid a drafting penalty or climbing a short hill to power over it and continue our speed.

Now… the last big question that I’m sure you’re asking:  What percentage of FTP should I race at in my triathlons.  Here are suggested ranges (these ranges are for age group athletes, pros tend to race at a slightly higher wattage.  These percentages also don’t take into account fatigue resistance/rate):

Sprint distance: 95–100%

Olympic distance: 85–95%

Half-Ironman (70.3):  75–85%

Ironman: 65–75%

I’ve told several people this and will say it again:  If your serious about getting faster, the best thing you can do is purchase a powermeter. (my personal choice would be a crank based one so you can race and train with it, such as the SRAM Quarq.)  Forget the areo/race wheels.  Save those for your next big purchase.


Lactate Threshold Testing at University of Louisville Fitness Center

Today was a very encouraging day for me.  I’m a huge numbers person, and seeing them move the way I’d like to is a huge encouragement.  But not only does it encourage me… it also motivates me to keep working harder to continue seeing the gains being made in each of the three disciplines.  It also helps me reason that the money I spent on a power meter and a coach are well worth it.

About a year ago, I did a step test on the bike without measuring blood lactate levels to get a rough estimate where my lactate threshold was to help me dial in my training.  It was roughly 300-305 watts.  Good, but nothing outstanding.  Recently, I’ve had some friends, such as Troy Shellhamer and Beau Hollis, do some testing at the University of Louisville Fitness Center to get their lactate threshold for running.  They spoke highly of it and after a little thought, I knew that it was something that I wanted to do.  But, instead of checking my threshold on the run, which I’m pretty confident that I know based on race and training data, I wanted to get tested on the bike.  Additionally, biking is my weakest link.  So, if I was going to spend the $75 to get tested, it made the most sense to do it for the bike.

I got to U of L around 11:30 and set up my computrainer in the lab so I could ride my own bike with my own power meter instead of using one of their bikes.  I also knew that the computrainer reads slightly lower than my powermeter since the computrainer reads power from a source further away from the original source (the cranks).  It was the first time that anyone had brought in their own bike, so the grad students weren’t exactly sure on how it would work.  I showed them how to increase the wattage manually and we got started.

While warming up, they said they wanted to start me at 100 watts and increase by 50 watts each time.  I looked at them a little shocked and started wheeling-and-dealing!  I suggested started at a higher wattage and increasing by 25 watts.  Increasing by 50 watts at the beginning seemed reasonable until hitting the 300 watt mark.  I felt like the numbers would be more accurate by starting at a higher wattage and doing increases in wattage in smaller increments.  With some reassurance from one of the faculty members that knew me, the grad students agreed to do the test the way I suggested.

Getting warmed up

We started the test at 200 watts… which is just above warm up effort.  We increased the wattage every two minutes and slowly entered the pain cave.  I tried not to keep track of the number of times we increased the wattage so I wouldn’t know what I was pushing so my head wouldn’t get in the way of my body’s performance.  However, I’ve been training long enough with a power meter that I can tell within about 10-20 watts of what I’m pushing just by feel.  When they drew blood and said my lactate levels were 4.4, I knew that the end of the test was close… one or two more steps at the most.

Drawing blood

Pick a finger, any finger

The students and faculty that was there (about 6-8) really started giving me some encouragement when they saw I was beginning to struggle.  I made it one more step after crossing lactate threshold (4 mmol/l).  The watts were increased to 375.  I made it through the test with a blood lactate level of 6.7 mmol/l.   I was tired enough from that effort that once they increased it to 400 watts, my cadence dropped below 85.  I just couldn’t turn the pedals anymore.

Nearing the end of the test

After cooling down, they showed me the numbers from my test.  Lactate threshold was 339 watts.  But what is more important that that is the amount of watts per kilogram, since weight is very important in cycling.  My watts/kilogram came in at 4.63.  From a year ago my power at  lactate threshold increased by about 35-40 watts and my watts/kilogram improved by 0.46!

These numbers are obviously moving in the direction that I want them to… however there is still a lot of work to be done.  They are better than last year, but still not good enough to win big races.  For example, Cameron Dye can push about 365-370 watts at his lactate threshold… not to mention he’s a faster swimming.  But all things are achievable in time with a little bit of effort.

And, I’m looking forward to putting in the time and effort!

I’m planning on doing this again before leaving for Panama for my first 70.3 of the 2013 season to see if improvement has been made and to redefine my power zones for training again.

Cya at the starting line…