OK it feels like a dumb question, but seriously what would be your diagnosis if you can't determine your lactate threshold on a treadmill? I can get to it easily enough on a bike, I know what it feels like, but are you supposed to get that burn on a run? I get leg fatigue after enough miles, winded, sapped energy and so on, but even sprint intervals on the treadmill I never reach the point where I'm feeling that lactic burning. Sprinting for me is 80-90 second quarters

Could it be inefficient running when close to threshold? Need to work on aerobics more (which isn't great btw)? Or is it just hyperbole when you see "heart hammering, legs burning" and so on?

Why can't you figure it out? If you're used to running, just run as hard as you can for 30 minutes. That should get you close enough. A full-out 10k left me bordering right on the edge of a spectacular blowup over the last 10 minutes.

Anyway, 90 second 400s at threshold pace isn't a very effective workout. I'd say at least 15 minutes at a time would be necessary to get some good stuff out of it, especially at threshold pace. 400s would be closer to 3k pace or faster unless you're doing a lot of them with very short rests.

Only been training for about a year plus a little. I can get an aerobic threshold for 30 minute runs but that isn't the lactic threshold - and knowing the actual threshold isn't really the concern. I'm questioning whether it's symptomatic of some other deficiency, and if so I can work something out to correct it.

I know that you have a big aerobic engine. I don't, and hard quarter mile intervals are recommended by some trainers as very effective for more quickly improving Vo2Max. Also half miles, miles, even short all-out sprints ... I think that it does help. I mentioned 400 meters as that's where people seem to say reaches their LT. It could be 5 miles, 11 miles, 200 meter sprints, I am nowhere getting the feeling of lactate let alone accumulating. I run out of wind first.

I'm doing 6-8, with about 1-1 rest/run ratio. It would be tough to stretch it to even one mile, actually even a half in under 3 minutes would be pretty good for my level of conditioning.

I think it's asymptomatic of you not running full-out for a long enough time. You do that and you'll get that full-body burn of "this sucks and I have to stop". Of course, that's a lot harder to do in running, and generally requires a sufficient amount of time to build up to that without feeling like you're going to break in half for the next few days.

Hard 400s to improve vo2 max aren't run at AnT. Like I said, they're run at 1 mile to 3k pace and they're done with short rests. And even then, it may not be long enough to really obtain a sufficient amount of time at vo2 max, which generally requires about 2.5 minutes at a minimum.

If you can't run long enough then you'll not experience it.

Put it in cycling terms:

If I have an ftp of 200w on the bike, and I just ride at 200w for 90 seconds, it's not really going to feel anything like doing 200w for 15 minutes, which won't feel nearly as bad as doing it for 45 minutes.

Duration is a big component when you're working at lower intensities.

Those quarters are way beyond AnT, unfortunately because it means AnT isn't so hot either. I know that I'm doing those faster than are recommended for my 5K pace, but I'm also interested in improving the sprinting paces.

I did kind of a field test yesterday in fact, 20 minutes @ 7 minute pace on the treadmill, and while possibly I could have pushed it more it wouldn't have been much. Supposedly AnT would be at 5% lower HR, and that's close enough to LT, generally speaking, for setting zones. Some physiologists tend to use them interchangeably. Keep in mind I'm 59 and hadn't run since track in HS, so just mentally scale these numbers back from "normal" performance.

It could well be, as you said, not able to run long enough full out, and that's kind of the basis of the question. The limiter is not LT obviously, it could be too low anaerobic threshold, could be something else, I'm looking for best guesses as to why. Why no lactate at AnT for example?

Only if you're sprinter. And even then I wouldn't expect too much of a burn from slow-twitch muscles.

Apologies for a somewhat OT question, but I will keep it brief:

Does high altitude (eg 7,000 ft) significantly change lactate threshold?

Oh, sorry, i misunderstood. Thought you were doing the 400s at threshold pace to improve threshold.

I don't know. I raced 5ks and 10ks and had all encompassing body death at the end of all of them. I did a 400m race once and felt the same way. Towards the end of an all out effort it's just overwhelming fatigue and saturation of...whatever it is that makes you feel like you're about to physically melt. Same in cycling, though I rarely do efforts like that outside of a finishing hill because of drafting and tactics and all.

I don't really do much, if any, training at threshold pace. As far as I know, which circles back to the original question. You can determine AnT HR easy enough just by running until you're winded, for a decent amount of time. But if you don't feel the lactate specifically, and it sounds like you don't, how would you derive the LT short of a lab test? Does it even matter?


The challenge is, you can't just work on one thing and let everything else catch up, or circle back to them later, which might have worked 30 or 35 years younger. You have to hold back, and build from whatever is the weakest. That's my operating theory, and it's working so far, but it means that being a little OCD about details and data may be beneficial.

How much are you running during the week? At my age it takes a long time to slowly build up my running muscle/tendons etc to the point where I can stress them properly. I usually end up injuring my calf long before I can actually run a hard 10k. I like running but it's frustrating to have to build up so slowly.

20 miles usually, except sometimes reducing the weekend run when something doesn't feel right so it varies 16-20, less than half of it outside. It has been several months since I have increased the weekly mileage, or long run but I have increased the pace targets, worked on form and stride, etc. I've been trying to apply changes on the treadmill first, and then the road if they feel stabilized, it seems more incremental that way.


When I first reached the initial goal of just being able to run for 30 minutes on the treadmill, I thought yay that's it, take it all outside now, speed up, add some miles, and that lasted 2 or 3 weeks until I damaged an ankle. I finally got that lined out, repeated the general idea almost a year later and then it was shins, though not as severely. The last 8 or 9 months though I've been more cautious in the build up. It may take 3 years, much slower than we'd like but it is what it is. I skipped both the long run and the ride this weekend - maybe I didn't need to, but with two fast workouts this week (instead of the usual one) I wanted to ease off the overall stress.

I wouldn't use that as a gauge. I don't "feel the lactate" when I determine my LTHR on the bike either, its more the pacing. Same would apply running, and IIRC LTHR running is generally higher than cycling due to the ability to process more lactate due to the larger proportion of muscles involved.

Sounds reasonable but "more the pacing" - how? How do you distinguish it from anaerobic threshold by using pacing?

Joe Friel - Determining your LTHR
By pacing a mean simply going by feel for a metered effort that you can sustain for 30 mins max. Your HR should peak after 3-5 mins, then plateau and only climb a couple bpm over the last 20-25mins.

But isn't that essentially the same method (it's for cycling) as finding the anaerobic threshold when running?

Honestly, I swear I can get the cycling LTHR by feel. I can feel when I start getting the lactate, and when it starts building. Running, no way. I'm pretty sure that they're going to be different numbers between running and cycling, and different numbers for AnT and LT.

Not sure what your question is, aren't you trying to find the anerobic threshold/lactate threshold HR? What I'm saying is ignore whatever feeling you think you should expect and run as hard as you can for 30 mins, as suggested above. If after 30 mins you keel over because you can't run anymore, and your pacing was relatively steady, then that's probably close to your LTHR. Then look at the HR plot afterwards and see if it climbs and plateaus.

Lactic buildup is a byproduct of an anaerobic activity. Given that I'd say no. At least not directly.

You consider them the same thing then, which granted appears to be the established terminology. I may be using outdated definitions, but

aerobic threshold: below which energy is almost entirely aerobic
lactate threshold: above which blood lactate accumulates faster than it can be cleared

and anaerobic threshold: where blood lactate suddenly increases, the inflection point

I've been saying LT is not necessarily equal to AnT since after all the lab tests measure different quantities, and perhaps lactate may be cleared in some interval beyond the inflection point, which would make the LT HR higher. I could live with it if the distinction is pointless.

Seems like a bit of a semantic arguement if you are trying to use HR to determine the breakpoints since MLSS is defined as 4 mmol or <1mmol rise in blood lactate that has to be measured via sampling.to further continue down the semantic rabbithole, lactate doesn't cause muscle burn so it's not a good measure either. In terms of at home training it doesn't matter, just use any of the established protocols for determining or LTHR or semisteady state HR or whatever you want to refer to it as to use to base your training on.

Well, I said earlier that it's not about finding the number or defining zones.

Maybe it is too much of a rabbit hole to further into, without lab equipment anyway.

Lactic buildup is a byproduct of an anaerobic activity. Given that I'd say no. At least not directly.

UPDATE: Okay, this seems like a fascinating subject so I did a little research and found that there are varying ideas, opinions, and understandings on LT (not to mention the varying terminology), so this could take some time. And although I couldn't find an exact answer to this question, based on what I found so far, that answer seems to be an emphatic yes. I'll check more once my head clears of all the charts and graphs.

Running into the same thing I'm asking. Anaerobic threshold deals with oxygen/co2 balance. Lactic threshold deals with change in blood lactate concentration. Two different things, although "threshold" is where some condition applies to both of them, generally at the same heart rate.

Maybe some control mechanism regulates both of them directly, all neat and tidy. Maybe it's a locally stable state from a whole slew of feedback control mechanisms. I don't know, but the answer to his question would depend on how that "lactic threshold" actually works.

I've always used the two interchangeably.

There's a new understanding that's been slowly unfolding, which says lactic acid isn't what causes the burn. It being heavily concentrated in your blood isn't the issue, it's everything else going on.

I never done a lactate threshold test yet...Am I missing something ?...Is it really necessary and important ?...What's wrong with using heart rate monitor and just going by the heart rate or going by feel ?.

In running, it's more usual and IMO more accurate to go by pace than by heart rate, since a difference in pace is pretty solidly a difference in power, for a given person. So you'd use a threshold pace, rather than a threshold heart rate. HR being highly variable due to factors you're not as concerned about when structuring workouts. In cycling that power/pace relationship doesn't hold true, but if you know your threshold heart rate you can watch the HR monitor and know where you are relative to the threshold effort.

My interest is from the other direction, I want to know instead if the capacity to clear blood lactate is lagging, or if the ability to absorb oxygen is lagging, and so on. I theorize that there are different things you can do to address these relative deficiencies, but to get there you'd have to measure first. Setting HR zones based on LT may be useful, but it's not where I personally am coming from here.