# LTHR from HM?

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• #18105
ryanoelke
Participant

I’m probably going to do a 20 TT next week or the week after, but I’m curious what is possible to learn about LTHR from a half-marathon. Just did my first on Sunday using 8020, and man the plan and Matt’s new pacing book was a huge help going into it! I ran almost exactly what I thought I would π

Anyways, I noticed that my peak 1hr HR was 168 and peak 20 minutes was 171. Both was the last hr, last 20 minutes. I would assume that I can conclude that my LTHR is above 168, and maybe at least 171? Lot of reasons I assume that based on everything I’ve read on LTHR, but not sure if that would be accurate.

Of course, I know that it doesn’t matter per se since I can just go to do a 20 min TT, but wondered what you all thought π

-Ryan

#18107
arkadiuszm
Participant

The most reliable way to determine your pace threshold is to enter a recent race result for the 5K, 10K, half marathon, or marathon distance into the 80/20 Zone Calculator. The performance does not have to be from an official raceβa virtual or solo race will doβbut it should reflect your current maximum capability for a given distance, whether it comes from competition or training or is simply an estimate of how fast you could run a given distance today.

The next step is to determine your Lactate Threshold Heart Rate (LTHR) from your TP. To do this, warm up with 10 minutes of easy jogging and then accelerate to your TP on a smooth, flat path or road. Wait for your heart rate to stop increasing and plateau. The number you see after it levels off is your LTHR

So don’t try to guess your LTHR from your HM directly, but use your TP calculated from HM to check LTHR instead of doing time trail.

#18110
ryanoelke
Participant

Yeah, I have read that article many times, and agree that that method and the others listed on the page are the best way to determine LTHR π My question here isn’t about guessing LTHR, it’s about what reasonable assumptions can be made from a race. For example, is reasonable to assume that my LTHR is higher than 150, just pulling a number out of the air. If it weren’t, I wouldn’t have been able to hold 166 avg for the HM.

However, I’m still going to do a TT with to determine both my TP and LTHR because one limitation in using the calculator is I have very different TPs if I use my 1-mile time vs. HM time. This is because one, I’m very much more of a speedster and two, the longest I ran prior to the half was 9 miles, and I just have not built up great endurance for that distance. My HM pace 100% puts me at a too slow TP (inaccurate) and zones that are out of whack, but for that distance, it was pretty much all I could do. My 1-mile test puts my zones much closer, but a little too fast for my lower zones. The 20 min TT will be better for me and most accurate with regards to pacing, and I’m going to go focus on 5ks now.

I use HR anyways in my training, but I’ll need to establish a new TP and LTHR at the same time.

#18112
Charles
Participant

The problem with a 1/2 Marathon is that it may take long enough that you lose enough fluids that you are seeing a cardiac drift at some point. You are also artificially running slower earlier in the race, so trying to establish your threshold earlier in the race will probably not yield an accurate estimate.

I’m a fan of the talk test. I can keep an eye on heart rate/power/pace on every run. For example today I did a pace based RF26 run – my heart rate shot up to a tempo effort for the first 10 minutes, then settled down to Zone II for the duration. Cold weather seems to be the cause. Power and average pace aligned throughout, and heart rate caught up; the talk test awareness allowed me to keep everything under control…

My daily runs are on hilly terrain, so I see the best correlation between heart rate and power – pace can be quite erratic. For that reason I belong to the 80/20 subscription program so I can drag an drop pace, power, or heart rate programs onto my schedule based on the workout objectives.

#18113
Charles
Participant

I should have added that 1/2 Marathon is at far less than a lactate threshold effort (at least for non elite athletes).

#18114
ryanoelke
Participant

Hey Charles π Thanks for your replies! Your 2nd post is definitely something I was wondering/getting at. That was my understanding, but wanted to check. I’m definitely non-elite, and so have to assume, being very ballpark, that my 166 avg for the whole HM is quite a bit less than whatever my actual LTHR is right now. I haven’t reset it in a while, but based on the HM, thinking it’s very much due π

I need to try the talk test and get good at it, but I keep feeling doubtful I’ll be accurate with it lol. Your example of using it to keep things in check seems really helpful. I have noticed that the cold definitely impacts my HR for the first 5-15 minutes, then settles down. I also REALLY want to get a Stryd! Finally feel at a point where that would be such a handy, reliable metric during training. GPS and pacing is often out of whack where I run. I am trying to get better at feeling pace, but I’m no master π

For the 80/20 sub, are you using a plan, and then going into the workout library to swap workouts? I know you can swap intensity types at any time, but figured that was for an entire plan vs. single workouts. I’ve been tempted to do the sub as I can tell I’ll be an 80/20 lifer.

#18115
Charles
Participant

I’m always on one of the running plans, either goal based or racing plans. I am on the subscription service mainly for access to the workout library which is mind boggling huge.

I’m currently on a 5K Plan. At the start of each week is a brief introduction into the goals for the upcoming week. I will examine each of the workouts for the week and swap out workouts from the subscription library for pace, heart rate or power for what I believe is the most appropriate for where I will be running and what the workout objective is. 80/20 has done a fantastic job describing each and every workout, and I simply extrapolate that to the tools I will select for the workout. It’s really easy because the subscription workouts are the same nomenclature in each library.

As an example; I am following a pace plan and did a RHR26 (Hill Repetitions Run) last week. Pace doesn’t work, so I selected the power equivalent from the library and chose a hill incline at the low end of the recommended slope. This allowed me to hit my objectives for both power and pace for the workout (I ran power and got lucky on pace).

One note though… I always wear the Stryd Power Meter regardless of the workout metric, this gives me a consistent TSS on Training Peaks by default so I have an idea about my TSS, Fatigue and Form on any given day.

#18116
ryanoelke
Participant

Thanks for extra details, Charles π Super helpful! Feeling like I have a better handle on the power of the subscription, and man, I really wanted a Stryd before, and now it might be at the top of my Christmas list π Would love to have the consistency that power gives.

#18132
Leyla Porteous
Keymaster

So I will add that whilst taking average HR from a race can be a good way to get an initial LTHR I would be doing a field test as soon as possible to determine your training LTHR. HR is impacted by many external factors and it is not uncommon to be able to get your HR higher in a race and some training environments due to excitability. Does this mean you should train to that elevated HR – no. Find your training LTHR so do your field test in a similar environment to which you train in and now you have data that you can make better assumptions from.

L

#18138
ryanoelke
Participant

Thanks for the reply, Leyla! All that makes sense. Going to do a field test this weekend to update things π

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