LTHR: how can a 30 minute all-out test measure your one-hour maximum?

Isn't it something to do with being able to run at much higher HR during a race compared to a solo effort? Runners can always run faster in a race situation compared to a solo TT due to many factors. More focused, better warm up, adrenaline from race situation and being pulled along by other runners. Also being more rested helps massively too.

Ya.. I've always been very annoyed by this LTHR test and people telling me that it is definitely correct. I have run a HM at almost 95% HRmax (tested in the lab). That's just what happens when you are pumped up and leave it all on the road.

Isn't it a math thing?

When you run all-out for half an hour, you'll run further/faster than you would in an hour.

But on the hour run you'll go out slightly slower so heart-rate will rise slower but rise higher because you're running longer and end up averaging the same.

Uhh wrote:

Isn't it a math thing?

When you run all-out for half an hour, you'll run further/faster than you would in an hour.

But on the hour run you'll go out slightly slower so heart-rate will rise slower but rise higher because you're running longer and end up averaging the same.

By that logic you should run all races from 5k to marathons at the same heart rate!

whatLogic wrote:

Uhh wrote:

Isn't it a math thing?

When you run all-out for half an hour, you'll run further/faster than you would in an hour.

But on the hour run you'll go out slightly slower so heart-rate will rise slower but rise higher because you're running longer and end up averaging the same.

By that logic you should run all races from 5k to marathons at the same heart rate!

Personally I'd never run any race staring at heart-rate.

The physiology is that you can train lactate clearance up to about an hour's worth which is why that corresponds to Threshold. So for an elite that would be any race up to half marathon but not marathon.

Uhh wrote:

Isn't it a math thing?

When you run all-out for half an hour, you'll run further/faster than you would in an hour.

But on the hour run you'll go out slightly slower so heart-rate will rise slower but rise higher because you're running longer and end up averaging the same.

wrong. average HR should be highest around an 800m race and then gradually decrease from there. It will be lower in events shorter than 800 or so because a greater percentage of the race is closer to the start.

Looking for more thoughts on this.

anima wrote:

As I understand it, LTHR is the heart rate that you can hold for about one hour.

Most of the tests however ask you to run flat-out for 30 minutes and take the average of the last 20 minutes to be your LTHR.

I don't understand how anyone can hold the same HR that they did for an all-out 30 minute effort for another 30 minutes? Shouldn't LTHR ideally be something like 95% of the 20 minute average (like you would in cycling when calculating FTP off a 20 minute test)?

I just read a test protocol for cycling, and they similarly take the average of the last 20 minutes of a 30 minute TT. I have a hunch what's going on in these tests.

It might have to do with the "slow component".

(Based on the test you describe, I'm gonna assume critical velocity == lactate threshold here. Different coaches and systems use different terms to refer to similar things, and vice versa. But I think we are on the same page)

At a range of intensities below critical velocity, there is a "slow component" of heart rate and oxygen utilization, which takes 10-20 minutes to develop. I think if you were to average the entire time trial, you would include early times where the slow component hadn't developed yet, giving you a falsely low LTHR. I think that's why cyclists also throw out the first 10 minutes of their time trials.

In general though, I hear many people speak about training who never explicitly acknowledge the slow component exists. It's hugely important if you want to train by HR.

I spoke to Joe Friel about this, and his explanation was basically that it just comes down to motivation: He thinks a solo 30-minute TT is the same intensity as a 1-hour race with competition. I think that's silly, but I also think the notion of a LTHR is silly.

The original LTHR test was different. I assume they changed to this new approach because it yielded similar results and was easier to apply the test.

In the old test, which I prefer, you ran for a couple of miles to warm up. Then, without stopping, you started your watch and started running at your one hour race pace. At the 10 minute mark, you took a split and then stopped at the 30 minute mark.

Your LTHR was your average HR from the 10 to the 30 minute finish mark. When done properly, it can be extremely accurate to within a couple of beats.

But there are three problems with this test. It takes longer. If the runner goes too slow, the last 20 minutes will be lower than actual LTHR. If the runner goes out too fast, HR will creep up the last several minutes of the run and the average will be higher than actual LTHR.

The latter problem is easily fixable. Take another split at the 20 minute mark. The split at 20 minutes and 30 minutes should be very similar... within a couple of beats. However, if the 30 minute split is a lot higher -- maybe 5 BPM -- then the runner was going anaerobic over the last 10 minutes by running too fast and the average would be higher than actual LTHR.

My guess is that through trial and error, Friel discovered that too many runners (and cyclists, remember, Friel is primarily training triathletes) had no ideal of their one hour race pace and were going too fast or too slow. Then, he realized the all-out 30 minute run yielded similar results. It's a LOT easier to tell cyclists, "Go run as hard as you can for 30 minutes."

The other question is ... why would anyone care what their LTHR is? Heart-rate training has so many flaws.

Relax, some people are just curious and won't die from bad data. You don't have to throw out everything that isn't perfect, or we would stop doing pace-based training because hills exist

Uhh wrote:

The other question is ... why would anyone care what their LTHR is? Heart-rate training has so many flaws.

Great question. LTHR gives an almost exact HR that you shouldn't exceed for tempos or until the latter half of marathons and half marathons. Yes, you can exceed it briefly on hills, but that's about it. Once you exceed LTHR, the time you can hold that pace becomes much more limited in a race AND you are switching from aerobic to anaerobic training in your tempos. In other words, you're wasting part of your tempo run.

OTOH, traditional HR zones give a range of about 10 beats, which is so wide as to be almost meaningless.

Once you know LTHR, you also know your recovery zone, which is much broader than your lactate threshold. Recovery zone using LTHR is 30-45 beats slower than LTHR.

There are some exceptions: sickness, heat, overtraining, but that's true for any HR or pace training approach.

Bump - just read about this topic and found this thread. Trying to think about how this makes sense. When I was a beginner running all out 30 min 5ks, how in the world is this my LT pace when that’s the pace i’m supposed to be able to run for an hour? In the last 20 mins of a 30 min all out time trial my heart rate would prob be in the 180s. No way I can sustain that for an hour (my max HR is in the 190s)