[WanderSin]

Hi guys,

I followed one of the programs from evoke endurance (12 week) last march to June and as part of it I did a HR drif test.

The starting HR was 164 bpm, the average of the first 30 minutes was 167 and the average of the second half was 172 leaving the drift in around 3.5%.

Since then I have been running using nose breathing as I didn’t have any short term goals but since the new season approaches I have decided to do the test again to make sure I am running under my AeT.

Todays test data made no sense considering the test from 1 month ago and I am not sure if I made something wrong:

I started the test by warming up until I reached an intensity where nose breathing was becoming annoying, once there I slowed the speed down and wrote the speed number so I could start the treadmill for the test at that speed (timer is 60 minutes and the worm up took 10 minutes or so).

I started the treadmill again and set the speed to 8.5 km/h and run for about 2 minutes to check if it was an ok speed, stabilize the HR and then I pressed lap in the watch to start the test.

Finished the test at this speed without changing the speed at all and the data is as follows:

Starting HR 168

First 30 minutes average 170

Second half 30 minutes average 174

This gives me a drif of 2.3% which is less drift than the test I did 1 year ago while the starting HR was 6 BPM higher.

Did I do something wrong? Is this normal? I am so confused and I don’t want to mess up my training because of a mistake.

Best regards,

Ander.

[WanderSin]

The tests were done 1 year apart, the first one in march 2024 and the second one yesterday, february 2025.

[Jack Kuenzle]

Hey Ander,

Yeah that’s perfect, that’s exactly what we are looking for when looking to improve an athlete’s aerobic capacity. If I understand correctly:

Test 1: March 2024, 164 BPM, 3.5% drift

Test 2: February 2025, 168 BPM, 2.3% drift

Your aerobic capacity has significantly increased. You should retest at 172 BPM and aim for a test with 3.5-5% drift. The lower the starting heart rate and/or the greater the aerobic capacity, the lower the drift. Keep in mind that nasal breathing is usually a pretty conservative estimate for LT1/AeT. Nasal breathing for me stops around 125 but my AeT is around 155. Let me know if you have any other questions.

[WanderSin]

Yes, that is correct. My concern is whether or not I did something wrong during the test.

I am able to do 1 hour with nose breathing without problems, like it does not become super difficult to breath through my nose but it’s definitely not as easy as when I was running below 165 bpm.

Also I don’t think I would be able to hold a conversation without having to stop talking for air every sentence or so, nothing like every word but I don’t think I could carry out a conversation non stop running at 168-170, that’s mostly where my concern comes from, wondering if this sort of intensity/RPE is ok/normal while running under AeT.

Another question is due to time constraints I’ve had to split my longer sessions into 2. I’m currently running 3 days 1 hour and a third day of 30 minutes. Should I make this 4th day a recovery (Z1) day or should I keep it as Z2 (AeT)? I’m planning on slowly increasing the duration of those other 3 runs I just don’t have the time right now.

Regards,

Ander.

[Jack Kuenzle]

Those ventilatory indictors (nose breathing, ability to hold a conversation) are just not very effective for estimating LT1/AeT. They tend to be quite conservative. Nose breathing stops for me around 125, I can’t hold a conversation very fluidly above 140, but my AeT is 155. I see this with many athletes. For some, those ventilatory indicators are quite accurate, for others not so much. No reason to be concerned.

 

So the aerobic system responds quite well to high frequency stimuli. Better to more, smaller stimuli than fewer, longer stimuli. Yes there are many practical reasons to do longer runs (building fatigue resistance, training carb ingestion, improving fat adaptation….), but this is why you see elite road runners doing doubles and triples instead of consolidating all their daily mileage in a single run. For an athlete like you who doesn’t currently have a specific objective coming up, frequent shorter runs is honestly better.

 

As far as how hard to do these runs, it’s hard to say. It comes down to how aerobically fit you are, your ability to recover and handle training stress, and the amount of time you can allocate for training. An aerobically untrained athlete could do all of their volume quite close to AeT and be fine. For an aerobically fit athlete training in Zone 2 can be extremely taxing. Training closer to AeT will always be better quality stimulus second to second, but it’s way more stressful, especially for aerobically fitter athletes. Complicating this further, factors like heat and dehydration and recovery can really drive up heart rate and a run that’s quite easy RPE wise could be drive into Zone 2. I’d remember that Zone 2 is not training at AeT, but training in a zone that extends 10% below AeT (Assuming 172: 155-172).

 

Reading your comment, it sounds like you are constrained by time and not by recovery. If you had more time, you’d assign more stress to your training plan. By that, I would train in Zone 2 for most of my work. If I found I was having trouble recovering in between runs, I’d drop the training intensity. Heart rate is not a terribly precise way to assign intensity so I wouldn’t get too wrapped around whether activities are in Zone 1 or Zone 2. I’d use AeT as an absolute ceiling for base work, but guide day to day intensity based on perceived exertion. When you are eventually able to increase training time, I would decrease training intensity so you have the capacity to increase volume.

 

Let me know if you have any further questions.

 

[WanderSin]

Great Jack, thanks very much.

I will restest and use my AeT as the ceiling for my runs but keep using RPE for feeling off days, even if my heart rate is below or above AeT if a run feels too easy or too hard then lower/increase the intensity accordingly.

My current pace at AeT is quite slow (7m/km, 11:20/mile I think) so doing more AeT training should not be a problem.

Just a quick one, my main goal this year will be in august, going to the alps and doing some 4000 meter peaks with not much technical difficulty (PD or AD-), will keeping high frequency with lower duration still be ok up to lets say May/June and increase the duration for the last couple of months (I will be able to get out into the mountains more often then to do longer days).

Another thing that comes to mind, is it worth it for me to do an AnT test to know my AnT ceiling other than for information purposes? In case yes, should I wait until my recovery week to do the test in a couple of weeks?

Thanks a million again,

Ander.

[Jack Kuenzle]

Yeah of course! Still absolutely keep the base work below AeT. Where your HR falls exactly (ie in Z1 vs Z2) I would decide that based on RPE.

 

Based on that, I would retest AeT every month. If you were my athlete, I’d have you doing the AeT test outdoors on the track or other flat road loop. Heat can play a huge role in heart rate drift and I find athletes that conduct their drift test indoors often have a conservative estimate of their AeT. Of course, 172 is approaching the upper end of what I have see as far as AeT in male athletes, so you don’t have a ton of room to go up here, but it’s possible.

 

Yeah that schedule is perfect. I’d consider doing some volume weekly on the stairmaster and incline treadmill. Just easy base work. I wouldn’t test your AnT, not needed.

 

I would definitely incorporate strides. Two-three times per week, four-six strides per session. Take five seconds to come up to pace and then run for 15 seconds at like mile race pace. It shouldn’t be an all out sprint. Walk for a minute or two in between each stride, you shouldn’t carry fatigue in between reps. It’s unlikely that your HR gets too elevated during these, but don’t worry if it goes above AeT. Those strides will go a long way to improving your running economy and getting those flat aerobic paces faster.

 

Anytime!

[WanderSin]

Great, I start incorporating strides.

I did a VO2 Lactate Gas exchange test in 2022 in a lab where my max HR came out at 206 bpm and my upper Z2 was 177 bpm, I don’t know if AeT ceileing matches traditional Z2 ceiling but if so maybe I still got some more bpm to use.

[Jack Kuenzle]

So AeT is the Aerobic Threshold/First Lactate Threshold. In the zone distribution that Evoke uses, AeT is the top of Zone 2. If the heart rate drift test is perfect, and assuming the gas exchange test was accurate, you should get about 5% drift if you were to do a drift test at 177. Again, heat is a huge factor for heart rate drift so make sure to utilize a cool environment for test.

 

To be honest, I have seen some of those lab tests produce incorrect data for first lactate threshold. Not knowing the lab, I’d use the more conservative value for AeT. Either 177 or whatever value you get from a drift test (assuming lower than 177).

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