For how long can you sustain heart rate above 90%?

I’d say delusional, coming from someone who spent a long time frustrated about not being able to run easy and always “jogging” in the 90s HR percentages for 30-60 minutes, getting injured, and what not. I understand and can relate to the instinct to think of a high HR as a great workout or effort but it’s an unproductive view and, to the extent HR has a place in training, the lower the better.

It's not quite clear what circumstances you were doing it. What was the specific training ?

Yes, it was a good effort. Was it smart or a good training effort? Hard to say based on what we know. You could have gone anaerobic, which negates some of the benefits of a tempo workout. Or, your real MHR could be higher than what your device is using.

Is your Polar device using 220-age to estimate your max HR? That formula can be way off. For example, it would have shown my most recent trail run to average 93% MHR for 42 minutes and a peak of 116% of max HR! However, I've tested to determine my current MHR. My actual numbers were 75% MHR average and a peak of 92% MHR for this run.

Does anyone know how the Polar HRMs determine MHR?

I forgot to mention...

Since the 220-age formula is way off for me, I have to override my Timex and Garmin devices to manually set my HRM.

The OP might need to do this. Just guessing, I'd guess that his MHR is 10+ beats higher than his device thinks.

First thing I would say is you need to know your true max heart rate. If you wear a wrist based monitor the values can at times be erroneously high or low. I’ve been wearing a HRM since they were first widely available, maybe 1996 or so. I remember once running in a group of 6 who trained together frequently and were all capable of running a 7:00 pace for longer runs. We would periodically compare heart rates during workouts and at the same pace, various ages they would vary from 160 to 210 when we were all running together. Heart rates vary an awful lot from person to person as does each individuals ability to hold a high percentage of max for a long time. I’m 62 years old and my max has dropped from 193 down to about 185 over 30 years. In a marathon race I can run between 90% and about 92% for maybe 90 minutes. One beat above that and I’m toast almost immediately. I think if you know your body very well you can operate right at redline for quite a while. Or, maybe I just don’t know my real max HR

Yeah I know the 220-age is not accurate. I established my max HR by the hill sprint test, which I find the most precise.

It was a workout in the sense that it was not a race but a race pace simulation. Or you could consider it a time trial.

But I think it was the most all-out effort I've ever endured. I think I MAYBE had one more minute at this intensity.

Your experience is almost exactly the same as mine, except you were a much better distance runner than me. I could never hold 90%. If I hit 90%, I'd be anaerobic and my HR would continue to go up so I'd have to slow down a lot and soon.

I did notice that one beat above what I could hold (HR 162 or 85% of MHR) and I'd be toast, just like you said.

That doesn't sound crazy to me. Quite common to hit max HR in a motivated, fast-finishing 5k. Highest HR I've ever recorded was in one such (204) and I averaged 190 for the whole thing (~20min) so, yeah, checks out.

I'm primarily a cyclist these days and on the bike I can sustain 90% max HR for roughly 45 minutes at my peak fitness. My max HR (~185bpm) was figured by testing a few different manufacturers chest straps I wore in various road and mtb races over a years time and estimating the average.

During racing season my primary training focuses on sustained uphill threshold efforts followed by high tempo pace recovery when the road flattens out (I live near Lake Tahoe so lots of huge hills to go up/down). Two years ago I did an uphill effort near Downieville which averaged 165bpm for 43 minutes averaging ~400 watts. Strava makes it super easy to see average heart rate measured over time with power. Super useful training tool.

That sounds as all-out as it can be. DAMN.

Were you dizzy at the end, or near to puke? That hr is crazy high unless you are -or were- very young.

I'm 41 and hit my max at 185.

I figure cycling and running physiology is quite different, but this sounds amazing.

I was 28 at the time. I didn't throw up and don't remember feeling dizzy. I pretty much never throw up from exertion absent both an obvious food-related cause and mechanical agitation of the guts via situps or planting trees or something.

I don't think it's all that remarkable. On the high side but not wildly so if you're comparing to athletes who have field-tested maxes as opposed to randos using 220-age. But maybe I'm wrong.

I can hold 90% HRmax for 100 minutes.

No, you're not delusional. I've tracked my HR data carefully for 15 years, and when I'm racing my best and pushing very hard, I sustain a HR of 94-95% for that long. I remember seeing figures for sustainable HR at distance that goes like this:

5K: 95%

10K: 92-93%

1/2 mara: 89-90%

mara: 85%

That's consistent with what I've run.

Same here.

93% is a good effort, but it also depends on if it was cool conditions or not. The HR can creep up if for instance you do treadmill in normal room temp for a while. It is not the heart rate that is stopping you, it is the processes that drive the need of blood that are.

But, HR is not good at all to judge if you race to your limits for as short as 20min. I think rather splitting up the distance in 3 is better. You need to know roughly how fast or how hard you should set out running to be able to run 20min, but if you think about the first 1/3rd part (7min) as being fast, but controlled, the second part a little more work, but still in control, and the last 3rd as hard and progressing towards max at the end, I bet you can race well. You know 20 is controlled so you can set out at a 4 per km for the first 2k, then try to keep or even go a little faster the next 1.5k and then gradually go for it the alst 1.5k and get whatever pace you can achieve.

Up to threshold (approx 90% for well trained), HR can be quite well at indicating (even if it varies day by day too much). This works well some strokes above 90% as well, but quickly become a balance between the anaerobic and aerobic and lactate.

Thanks everyone for your insight.

Now I'm really curious about what the heart rate of the top long distance athletes can be during their best races.

Komen's 3k. Kiplimo soloing a 57:31. Chep's 5000 & 10000 WR. Kipchoge's INEOS.

Is there any data available on that?

You had me nodding my head in aggreement until the 45 minutes at around 400 watts.

Are you racing any of the spring classics?