Intensity- how low is too low for aerobic development?

I would say even walking has its time and place. In between training cycles I like to do some backpacking and feel it really does wonder in strengthening my body for the next cycle of high mileage weeks with hard workouts. Don't over think it just go easy.

Check out the Norwegian method on singles thread. You will learn a lot about this put into practice but other amateurs. One of the main posters especially is an absolute aerobic monster at this point and all runs are under 70% average HR. Your easy run has the least value or impact on your aerobic development.

Really, given that easy runs are 80% to 90% of of total?

I actually agree with the other poster, it's well worth reading that whole thread over a few days. I think it's genuinely changed how I think of aerobic development and especially the slower/shorter runs as well as the long run. The guys in that thread are super helpful, you should post the question there as it's just become quite active again so they see it.

Are you saying that the easy volume has little impact because the intensity is below 70%?

Great topic. Have wrestled with this question (how slow is too slow) for years and even went through a period myself where I slowed down to 9:00-10:00 miles thinking more volume at paces that would allow me to recover would be beneficial. I’ve concluded that intensity is very important. No slower than 5K pace + 2 minutes on easy days. If you’re more of a slow twitch aerobic monster kind of runner you can still rack up the miles this way and feel good but if your profile is more speed oriented, keep the intensity and be careful with the volume.

Link?

Most diagrams depicting HR training zones start at 50% of max.

I'd say that's a good bet, and in my experience, that's roughly where zone 1 begins.

Honestly though, "aerobic development" is such a nebulous, which ignores many of the other benefits one gets from running easily.

Training isn't just about "aerobic development". If it was, you could just bike 40 hours a week and achieve 4 times the benefits you get from running 10.

For trained athletes about 50%VO2max is required to be considered as training. That is about 60%HRmax. For untrained people it is a little bit lower.

That means in practice that for most people running triggers enough stimulus, as you have to be very fit to run below 60%HRmax. So you can count any running time.

An easy run should be seen in respect to a microcycle (a week) and should not be seen isolated as you train before and after the easy run.

Not slower than 5k pace + 3minutes per mile

The 75 page thread?

Are there certain sections that are more pertinent?

Anyway, this is an interesting question. Seiler has a video nominally on this topic, but his only real answer is "it depends on duration, you can't consider intensity in isolation", which is surely true but not very helpful. I've heard him say "oh I don't know, 50% of VO2max or so" in podcasts. Alan Couzens is a giant phag, but I once saw him answer this question by citing a paper (which I can no longer find, or I'd link it here) that had guys skiing at IIRC around 45% of VO2max 6hr a day for a month and no change in various reasonably-chosen markers of aerobic performance, which is certainly a quantitative answer to the question but I don't know if I believe the study, either.

You need mostly easy runs to be steady around 70-75% of MHR . If running steady at this pace you get most aerob boost for your bucks. This easy steady pace is one of the main reasons why runners have been at the world top even if running relatively low mileage. 🇸🇪🧙🏼‍♂️🇸🇪

I am 60 years old. So my estimated max heart rate is 160. My easy runs are at 80-90 BPM which is about 55%. I run 20MPW and do 2 hours of cross training. I ran 18:02 for 5k last year.

Are you estimating the 160 max from the 220 formula, or actual max hr achieved recently? What hr do you top out at during the 5K efforts?

Absolurely wrong, as usual.

Both. 160 is the estimate and I don't exceed 160 for 5k but I can hit 165 on hill repeats.

Given your low volume, 20 mpw, presume your easy runs are very short, which must skew things.

I can run the first mile under 100 bpm, but cannot keep t there, hr then starts to drift up over the next few miles.

Looks like you eatimate MHR from the old 220- age and it's mostly not good to give your exact MHR. But if you run easy runs at 80- 90 bpm on 20 MPW it really looks you run most of the 20 MPW at a faster clipp to be able to run 18.02 @ 5 k .

🇸🇪🧙🏼‍♂️🇸🇪