@stevemz is giving the straight story on this topic…
This is my favorite Friel post on the topic of LTHR:
I am asked yet again how to find one’s lactate threshold heart rate (LTHR) by doing a 30-minute time trial. I really don’t understand what seems to be so difficult about this. All that’s required is running (or riding) as hard as you can possibly go for 30 minutes ALL BY YOURSELF. It must be solo. Doing this as a part of a race or with training partners will change the outcome. Your number will be too high. If you want to do it with others or as a part of a race then you need to make it 60 minutes duration instead of 30.
Once you’ve captured the data in your device download it to your software and find your average heart rate for the last 20 minutes. That’s an approximation of your LTHR (also often referred to as anaerobic threshold or functional threshold heart rate). If you don’t have software all you have to do is push the lap button 10 minutes into the test. That will then capture the last 20 minutes as a standalone “interval.” Your average heart rate for that portion is close to your LTHR. Note that this DOES NOT mean that you go easy for 10 minutes and then turn it on with 20 minutes remaining. It’s 30 minutes all out.
Do not watch your heart rate during the test. You’re not trying to produce a given number. Do not be concerned with anything other than are you going as hard as you can go right now. If the answer is “yes” then you are doing the test right.
I don’t understand why this seems to confuse people so much.
I am not sure I understand your comments. Below is a chart from WKO4’s Tim Cusick webinar on fatigue resistance showing aerobic and anaerobic energy contribution to power level on a power duration curve for a particular athlete (another example athlete that he compares this athlete to has a slightly different curve, but the shape of the curves are the same). The green line is the aerobic contribution. The blue line is the anaerobic contribution. After approximately 5mins, the anaerobic contribution gets very low, hence why [likely] the Hunter Allen 20min FTP test includes an all out 5min portion of the warm up.
I think that figure might be a little bit misleading and does not represent the kinetics of how both energy systems are utilized. If AC is zero, you wouldn’t produce any lactate. Some people have really high lactate levels at LT, some people don’t (around 4 mmol), so not everyone is going to have the same curve.
I’m not an exercise physiologist, but I think you are always producing lactate during exercise at any level - aerobically or anaerobically. It’s above threshold (technically, your MLSS, not aerobic/anaerobic threshold) where you accumulate it significantly faster than you can clear it. Perhaps AC is > 0 for an extended period of time, but if my understanding is correct, it’s not “significant”, as I interpreted your comment, at FTP when the duration is 5mins+.
And depends on a few assumptions. People with higher AC and thus higher lactate levels at MLSS will have a higher percent of that power coming from anaerobic/glycolytic pathway. I haven’t read his response, but I may have been confounding my response to @bobmac a bit by lumping glycolytic together. The amount of energy from the glycolytic energy pathway is something like 2 ATP anaerobically and I think 38 once it enters the aerobic portion of the energy cycle.
Think about what kind of lactate levels we produce at certain intensities. I think we’re assuming roughly 4 mmol for MLSS, and roughly 8 mmol for a 5 minute effort, but for the two examples shown by Mikael the diesel engine is probably going to have a MLSS at lower than 4 mmol of lactate. Jonathan was stating that he had a very high lactate reading at threshold when lab tested, I think he was saying something like 8 mmol at threshold, so if that is right he has a higher AC contribution at threshold. This is all really hard to hash out just by HR and what percent of max your threshold occurs. As it would make sense that an individual who’s MLSS is closer to VO2max, would have a higher HR at MLSS, but I’m not sure it actually works out that way.
@stevemz, @bbarrera At the time of your posts refuting my reference to Joe Friel’s method of calculating FTHR, I was unable to locate his earlier work in my files as most had been purged (I started reading his books/materials almost 20 years ago). However, I am currently reading one of his more recent books, Fast after 50, published in 2015, where he repeats the suggested use of the 95% of your average HR during a 20 minute test I discuss above [for reference, at the bottom I have copied the text and provided the location from the kindle version of his book].
@stevemz Your logic about anaerobic vs. aerobic contribution makes sense, but it is the same argument that would be used to refute the use of the 20min test for estimating power [note: If you execute Hunter Allen’s 20min protocol, you will eliminate most of the anaerobic contribution (the WK04 graph I provided above shows this); TR’s 20min protocol does not do this as well]. The part of your argument that I do agree with is that it is dependent on your training state. However, I have been using Joe’s calculation for 20 almost years and the adjustments due to training state being higher/lower (i.e. measured by changes in decoupling factor that I monitor regularly) are typically only 1-2bpm.
@s Using Joe’s calculation, my FTHR is at 157 (95% of 165).
Results/comments about your 3 suggested methods:
2 years ago was the last time I did a long “TT” (90min Mt. Hamilton Race to the Observatory). The last 20min was 157 HR Ave, same as Joe’s calculation.
Intuitively this test doesn’t make sense (I’m curious where you have seen this) due to wide variations in heart rate response due to terrain (e.g. climbs vs. descents) and what’s taking place during the race (e.g. drafting vs chasing breaks) where HR goes anaerobic and then recovers; all which may happen many times during a race). But I tried using your approach on two recent (“9+s”): the Sea Otter (highest 60min HR Ave: 150) and Pescadero Coastal Classic (152). Both HR metrics are low (TR intervals and spirited group ride training data show this).
I have not done that, but the test seems to make sense. Where have you seen this? I’d love to read the analysis.
Summary: I think your 1st and 3rd suggestion make sense and perhaps offer a slight (?) improvement over Joe’s simpler metric. But, from a practical standpoint, I think the percentage of the cycling population that will regularly execute any of these protocols, if at all, is pretty small, including the TR population. It’s also not clear that any of these approaches adds much value over the simpler approach that can be calculated more regularly particularly where a cyclist uses a power meter for establishing training zones using the 20min test. At least from my experience, Joe’s calculation works well for fitness assessment (e.g. decoupling factor comparisons), determining optimal recovery periods during sweet spot and threshold interval training, and controlling pace on long sustained climbs with a wide variation of variables.
REFERENCE:
Joe, Friel (2015-01-10). Fast After 50: How to Race Strong for the Rest of Your Life (Kindle Locations 2312-2315). VeloPress. Kindle Edition.
The 20-minute test may be used to estimate your Functional Threshold Power (FTPo) or Functional Threshold Pace (FTPa). For FTPo, subtract 5 percent from your Normalized Power for the test. For FTPa, convert pace to speed by dividing 60 by your average 1-mile pace for the test. Again, subtract 5 percent to estimate FTPa. In a similar manner, you can get a good approximation of your lactate-threshold heart rate by subtracting 5 percent from your average heart rate for the 20 minutes.
Wow, refute? Better to say Joe Friel refuted himself LOL because all I did was post a link to Joe Friel’s website, where he explicitly lists out the 30 minute protocol. My go-to reference for LTHR has been the 30 minute protocol he describes on the blog, along with listing in his various books. IMHO its far easier to pull up a 30 minute effort and grab average HR, and that’s why its my go-to and the only one I committed to memory.
I did pull out a couple of books, to see Friel’s different LTHR estimates. The 30 minute protocol is in Appendix B of Joe Friel’s The Power Meter Handbook (2012). And the 2009 The Cyclist’s Training Bible has two tests, the 30 minute protocol above and another with a multiplicative factor based on length of TT, and if it was race or training (making this one more complicated than other estimates). The TT test with different multipliers based on distance is also in the 1998 Cycling Past 50. The latest Cyclist’s Training Bible has an appendix with the 20 minute protocol (multiplied by .95), along with Chapter 4 listing out the 30 minute protocol using just average HR as estimate for FTHR.
If the 30 minute test works for you, great! However, it seems that part of the motivation for TR coming up with the Ramp Test is that many users can’t/won’t execute a 20min test, never mind a 30min test.
FWIW: I’m 61. I started cycling training when I was 43. I didn’t keep records on HR data back then, but my recollection is that my FTHR was about 175/176 at the time with my max at 193 (~91%).
I’m 36 years old. Started my cycling career at 35 or last season. So this is my second season racing and training for it. Started cycling altogether 2017.
Good question. My reasoning for discussing it more thoroughly in this thread is that, with the explosive growth of power meters, it seems that focus on power metrics “at the expense of” HR data has swung too far to the left and there is some valuable use of HR info can be very useful (e.g. fitness assessment, recovery interval periods, controlling of climbing pace, etc., that I mention above).
Personally from my own HR-based interval training experience, I’ve found FTHR / LTHR to be of highly limited use as HR can be too variable and unreliable. Power is far more reliable and consistent as a training tool. While I’ve found a couple of practical uses for HR, those are rather limited and power trumps HR in vast majority of situations. My 2 cents as a data geek.
I think you may be misinterpreting my comments: this is NOT a Power VS HR discussion - it’s a Power AND HR discussion.
On the training front, and more specifically, interval-based training, I’m not talking about doing HR-based interval training. it’s all power-based training. But rather what I am talking about is that you can use your HR data to optimize your power-based training, and specifically in setting your recovery periods better to optimize the benefits of your workouts (for your age, cycling experience, and fitness level).
On the fitness assessment front, you can use the ratio of your Normalized Power to your average heart rate, known as the Efficiency Factor, and compare it to other training blocks to assess your fitness improvement. The comparison of the two blocks (e.g. 1st half to 2nd half of an interval; 1st interval to 4th interval) is called your Decoupling Factor and can very useful.
And on the training ride front, monitoring your HR can be very useful (e.g yesterday was a relatively hot day and we were doing an extended, pretty steep climb (15+%); once my HR hit FTHR I decided to hold it there as to not blow up.
Anyway, all I am trying to say is to say is that in this explosive day of power-based data, there are still some important benefits of HR data, and to your question earlier, of knowing your FTHR.
You are still pretty young and the other good news is that you have software tools to capture and track power and HR data. Presuming you remain an endurance athlete, I think you may find it useful to keep track of this over the years. I was a competitive swimmer through high school and college (NCAA) but we didn’t have tools to measure other than time clocks. My first collection of data (power and HR) came when I started cycling at 43. And you can see from the limited data I’ve provided of the decline. While physiologically we are all different, just based on your numbers, I probably wasn’t all that different 7 years earlier. Keep up the good work!
Actually I’m not misinterpreting. Been using TrainingPeaks premium or WKO4 for 4 years now, and have spent years trying to make use of power and HR data.
I stand by the words above, and to be more precise I’ve found very limited value in looking at Power-to-HR metrics like efficiency factor and decoupling. Use decoupling a couple weeks a year, and efficiency factor has too many variables to control in my experience so it hasn’t been a practical metric for me. I’ve tried using HRV for recovery planning and stopped collecting after 3 months. And to be honest I haven’t found any real value in knowing FTHR. Your mileage may vary, as they say.
HR tells me how hard my heart is working, irrespective of power output. I find it useful that its affected by other factors, because these do affect my total state of fitness.
Personally, I do see fairly consistent effects too - if its hot, HR goes up. If I’m tired (as in something affecting my fitness), it doesn’t go up as high as I’d expect for the power output, and I know something is wrong. RPE usually tells me the same thing, but HR gives me something measurable.
I wouldn’t train to HR usually, but I do find it useful to keep an eye on it.
