[Patrick]

Let’s suppose AeT is 130.
In a long session I start at HR 120 then after two hours HR rises above 130 with the same pace as in the beginning and continue for 3 more hours and end at 140. Do the last 3 hours count as Z3?
It seems that eating rises HR. Has HR still to be below AeT to count as Z2?

Topic

[JGwartney]

JGwartney on March 3, 2020 at 6:46 am #39164

Yes, the last 3 hours count as Z3. You’d need to keep your HR below 130 to stay in Z2.

Jon

[javier.marin.loeches]

javier.marin.loeches on March 4, 2020 at 9:41 am #39233

Well, I am not a coach nor a sport’s scientist, but in my point of view, since what your main target with your endurance training is metabolic adaptation I don’t see reasons for metabolic changes of pace and general perception is the same, I try to use HR only as a guide for training and don’t use thresholds as a fixed thing. HR varies from one day to other depending on things like recovery status, general stress etc. So for me your described training is mainly z2 training time, since as I said before I think your metabolic state remains more or less the same during the whole training.

[Anonymous]

Anonymous on March 6, 2020 at 7:19 am #39303

I think both responses are somewhat correct. Heart rate training is fudgy at best. A certain BPM will mean different things at different times.

When you’re fresh, fueled, and hydrated, 130 BPM means one thing. When you’re tired and dehydrated, it means something else. If you have a nasty fight with your spouse and then go for a run, it probably means nothing (training-wise).

The effort level is the key thing. Think about it as if you were doing squats in a gym. The weight you’re pushing is the stimulus. It doesn’t change, but heart rate and fatigue will.

In general, it’s best to be conservative. So there’s less disadvantage in using heart rate as a limit than perceived effort. With years of experience, RPE may work, but for most of us, self-serving bias kicks in and we think we’re going easier than we are. Heart rate is a good way to guard against that.

[Anonymous]

Anonymous on March 6, 2020 at 7:21 am #39304

Rather than squats, a treadmill session is a better example. If your AeT pace is 10 kph, then heart rate will drift less than 5% within the first 60-90′. However, if you stayed on the treadmill for six hours, heart rate would rise above 5% for most people. The load hasn’t changed, but the cumulative stress has increased.

[maforbes2000]

maforbes2000 on March 6, 2020 at 11:01 am #39335

Hi Scott,

Cardiac Drift is one area that particularly interests me, as I am finding it difficult to stop my HR drifting upwards. I have been running at Low HR for a couple of years now, so should be well adapted, but apparently not?

My target max Hr is 125. I start off running at about 100 bpm, and it rises to say 120ish after about 3 miles. From this point onwards I have to keep a close eye on it as it rises very easily (eg a small hill, speeding up to cross a road etc). I have to keep slowing down to stop HR going above my target of 125. If I ignored the HRM and maintained same RPE, HR would probably drift up to about 135bpm (say on a 12 mile run).

Some reference sources suggest that if you are truly running aerobically, cardiac drift should be minimal, or less than 5%. Mine rises by more than this.

Some say that you should slow down (walk if necessary) to keep to target, otherwise fatigue will increase and negate part of the reason for running at low HR.

I am running 50 miles per week, so volume shouldn’t be the issue. However, I am more naturally a sprinter than a distance runner, and wonder if genetics could be an issue?

I am reasonably happy slowing down as distance/duration increases, but am I then “under training”?

[Anonymous]

Anonymous on March 6, 2020 at 3:08 pm #39348

I don’t have much faith (i.e. zero…) in drift calculations that aren’t on a treadmill. But I’m also kinda OCD… 🙂

I start off running at about 100 bpm, and it rises to say 120ish after about 3 miles.

That sounds normal. I’d say that you start out at a 120 BPM pace and it takes three miles for your heart rate to catch up. Again, totally normal.

Some reference sources suggest that if you are truly running aerobically, cardiac drift should be minimal, or less than 5%.

Those recommendations usually come with a duration attached. I’ve only read the 5% rule with respect to one-hour durations.

Think about it. What if you were going at a constant pace for 60 hours? Your heart rate would probably get really high because it measures stress (which is constantly accumulating), not intensity (which is constant).

However, I am more naturally a sprinter than a distance runner, and wonder if genetics could be an issue?

Not sure.

I am reasonably happy slowing down as distance/duration increases, but am I then “under training”?

…only if one intensity (the speed you start at) were responsible for increasing aerobic capacity. It doesn’t work that way. You just need to stimulate mitochondrial biogenesis. That happens best at or just below the aerobic threshold, but the stimulus is still high even below aerobic threshold.

[maforbes2000]

maforbes2000 on March 7, 2020 at 4:15 am #39363

Many thanks Scott.