Everything You Think You Know About LTHR is Wrong

THE APEX LTHR Rationale  

Since APEX Coaching first partnered with The Sufferfest we have continued to refine our training philosophy. Some of this has been in response to feedback and questions from the close-knit community of Sufferlandrians toiling tirelessly in their torture chambers and Embassies around the world. A common question from those concerned about maximising their Return on Suffering is how best to set up heart rate training zones based on Lactate Threshold Heart Rate (LTHR)

What is LTHR and How do you Use it?

First let's define what exactly Lactate Threshold Heart Rate is, and why it is useful. If you were to do a sustained, maximal, one-hour effort your average heart rate during that effort is your LTHR. Just like maximum heart rate, LTHR can vary widely from person to person. Knowing your particular LTHR is vital if you want to get the most benefit out of your workouts. The key to maximising your training is to make sure you are Suffering at the correct intensities for the correct amount of time. Knowing your LTHR will allow you to tailor your training zones to your specific heart rate and maximise your Return on Suffering.  

For subscribers to The Sufferfest Training Centre App, you have the ability to input your LTHR into your profile. The app then uses this value (in parallel withor Functional Threshold Power (FTP) if you’ve determined that) to automatically set recommended heart rate zones for each section of the workouts. This functionality shows you, in real time, what zone you should be in at any given moment. But in order to take advantage of this feature you first have to determine your LTHR.  That’s where the head scratching often begins.

The Old Way of Calculating LTHR

Enough digital ink has been spilled on the “correct” way to measure LTHR to fill the crater of Mt. Sufferlandria. The old, traditional method is to take your average heart rate for the last 20 minutes of a 30 minute all-out effort, or alternatively, your average heart rate for a 20 minute max effort. This value would then be used to set up your training zones. At APEX Coaching we feel there are some downsides to using this method. The main issue is that your heart rate during a 20 or 30 minute all-out effort will give you a higher heart rate than you could hold for an hour long effort. That’s like saying, “I can average 1,000 watts for a 10-second sprint, so I should be able to average 1,000 watts for 10 minutes.” While optimistic, this isn’t realistic. Let’s look at why.  

Physiologically when you ride at intensities above your FTP your body starts releasing stress hormones, such as norepinephrine and epinephrine (commonly referred to as adrenaline). Your heart rate increases in response to the epinephrine in your blood. As the levels of epinephrine rise so will your heart rate. That is why it is tricky to base your LTHR off of a test where your average effort is greater than FTP. All that epinephrine is muddling the results, making it seem like your LTHR is higher than it actually is.  

Our observations and empirical studies at APEX Coaching have led us to believe that there is a better, more effective way to calculate LTHR and use it to determine the appropriate training zones to give you the greatest Return on Suffering.  

The APEX Method for Determining LTHR

If you have a full hour to do a maximal effort, you certainly have that option. Just make sure you don’t have anything strenuous to do for the next two days. Like walking. There is, however, a quicker way. It’s not going to be pretty, but it will get the job done. It’s time for some Tough Glove.

The aptly named “Rubber Glove” is a Sufferfest fitness (ahem) “examination”, a workout designed specifically to help you determine your FTP or your LTHR. On its face it seems harmless enough: one hour on the bike consisting a solid warm-up, some high-cadence drills and then a 20 minute maximum effort, but it has been the undoing of many a Sufferlandrian.

A few words of advice before you step into the doctor’s office. The key is not to go too hard too early. The more evenly paced you can complete this maximal effort, the more accurate your LTHR will be. Perfect pacing can take time to master, so don’t fret if you struggle with your pacing during your first few cracks at Rubber Glove. If you have your heart rate monitor connected to The Sufferfest Training Centre during the workout the app will take care of calculating LTHR for you, and then set heart rate zones for all subsequent workouts based on that value. If you don’t yet have a subscription to The Sufferfest app, find your peak average 20 minute heart rate from this ride (please note this is not the same as your average heart rate for the 20min of Rubber Glove, your heart rate will remain elevated after finishing your effort, and we want to make sure that is taken into account). Once you have that peak 20 minute heart rate you will want to subtract 12 beats per minute from that number, and Voila! You now have your LTHR. Since individuals vary in LTHR, if your peak 20 min heart rate is under 155bpm then we suggest subtracting 10 beats per minute instead of 12.

How APEX Developed a New Way of Calculating LTHR

The APEX philosophy of LTHR and training zones is based off of APEX founder Neal Henderson’s years of experience as the head of Sports Science at The Boulder Center for Sports Medicine (BCSM). During his tenure he performed over 10,000 physiological tests in the lab. By comparing the results of these tests with data collected from athletes in the field, he was able to refine the testing protocol to create a new, more accurate method. It’s important to note that everyone’s heart rate will respond differently to the same workload, and no one method for calculating training zones will be universally applicable or yield results that are 100% accurate for every single individual.

If you have previously set up LTHR based on your average heart rate from a 20 or 30 minute test it is likely that the LTHR you get by using our method will be a little bit lower. To accommodate this we have adjusted the Recommended Perceived Exertion (RPE) values and how they equate to HR zones on The Sufferfest LTHR mapping sheet. A good example of this change can be seen in the HR Z2, or “Endurance”, pace. Previously the upper limit for Z2 was 83% of LTHR. Based on the APEX method we have increased Z2 to 87% of LTHR. But don’t worry. Despite the change, you haven’t gotten slower. You’re training has only gotten more effective.

Keep in mind that your heart rate can vary quite a bit from day to day. Things like hydration, fatigue, and stress can have a profound effect on heart rate. That is why when determining how hard to go during a given effort it’s best to combine heart rate with RPE (and power data if you have the ability to measure it through a power meter of via virtual power). By comparing multiple factors like heart rate and RPE you can adjust efforts accordingly. You will also want to ensure your Torture Chamber has adequate cooling by using a good fan. Your body produces a lot of heat when exercising, and if you start to overheat your body responds by diverting some blood closer to the surface of your skin where it can be more readily cooled. Your legs still need the same amount of blood, though, so the only way your body can simultaneously provide blood to your legs and divert it to the surface of your skin is by increasing your heart rate. This can cause of what is called “heart rate drift”, which is when your heart rate rises above your LTHR despite the fact you are doing an effort under your FTP.

If you’ve used the old standard method of determining LTHR you might feel that this new method results in an LTHR that is “too low”, meaning that longer efforts—particularly sustained climbs like those in Hell Hath No Fury and Thin Air— are now “too easy”. Physiologically speaking, a sub-threshold effort gives your body 99% of the same training stimulus as a full on threshold effort. However, the total stress on your body is higher after threshold efforts compared to sub-threshold efforts. In practical terms this means if you’re using the heart rate zones based on the APEX LTHR method as part of a complete training plan, going “easier” isn’t necessarily a bad thing. In fact, quite the contrary. Staying right below threshold will leave you fresher to smash tomorrow’s workout.  Hitting two workouts back to back is a much better training stimulus than hitting day one at full gas but falling apart on day two.  If you aren’t as concerned with being fresh the next day, then by all means, see what the weather’s like up there above your LTHR and Suffer like there’s no tomorrow. You won’t hear the Minions complain.

Read more from Mac Cassin

Mac Cassin has been coached by Sir Neal Henderson since 2009 and is a coach at APEX Coaching, with a focus on masters and junior racers. As an elite cyclist who also has to balance the demands of ‘life’ with his goals as an athlete, Mac has a deep understanding of how to get the most out of those who have limited time to train. Mac has raced at the World and PanAmerican championships and holds several US national and state titles. His studies were in Integrative Physiology from the University of Colorado and has worked as a research assistant in the CU Neurophysiology lab.

Did we miss anything? Make sure to ask a question or leave a  comment in the space below.

Mac Cassin
Mac Cassin


1 Response

Gerry Stephenson
Gerry Stephenson

January 25, 2017

Good article and I think I understood most of what you said. Now did you write this after your Knighthood and your mind was, how shallow I say not right? Just Kidding and congrats on the KoS.

So in summary is going to the Dr. create the right LTHR? this was where I got a bit lost in what to do.

Thank You

PS. I am in week 10 of the Intermediate Road plan so my Dr. visit is scheduled for the end of this week. Any info will be greatly appreciate.

Leave a comment

Comments will be approved before showing up.

The Sufferfest App - Free 7 Day Trial

Get unlimited access to 37 Sufferfest videos, 20 yoga for cyclists videos, 10 different training plans and more. Train to specific fitness targets by connecting your power meter, HR strap and trainer using real or virtual power. Control your smart trainer. One subscription works across Windows, Mac, iPad and iPhone devices. Try it for free for 7 days. Cancel easily at any time. If you continue, it’s just $10 USD/month.