HR during 4DP test

I’m a little bit surprised, how high my heartrate is during the 4DP test.
During the MAP part it reaches my maximum heart rate, which seems to be plausible. But during the following 20 min test its only a few bpm lower and higher than 95% of my HRmax.
From the 1 hour test duration, 27 min are above 90% HRmax!!

This leads to a very high cTHR, which is 10 bpm higher than the one from the Half Monty test, where FTP and MAP were nearly equal to the one from the 4DP.

Do you have a similar experiences?

My fear is that this behavior could be quite risky, especially at my age of 67. There is literature, saying that heartrates above 95% HRmax should be avoided or at least minimized.
So it is probably better to do regularly half monty as test and only once or twice per season the 4DP test.

What is your opinion?


Has this happened every time you’ve done the 4DP? Reason I ask is that if your heart rate is suddenly out of sync with your effort/RPE it could mean that something isn’t right - over training, fatigue, illness, hydration for example

it happened every time I’ve done 4DP. I would not say, that heart rate has been out of sync with effort/RPE, those tests have been really hard.

How have you determined your max HR? I find I don’t hit mine except in relatively extraordinary circumstances where I repeatedly go all out. For me, the only time has been riding in very tough competitive situations.

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@andih I have hit all of my max HR records in Full Frontal. Looks like I am around 92% of max for the 20 minute and 95% for the 5 minute. Sometimes it is lower and that is generally when I get better cooling and hydration. Caffeine can also interfere with the readings.

Do you use a HR strap or wrist monitor for HR? The strap will give a more accurate reading but it is also important to listen to your body.

Apart from FF, do you experience this in any other workout (cycling or other?)

Another suggestion could be doing a 15min open ride or igniter prior to FF in order to give your body more time to warm up.

Ultimately though if you are seeing abnormally high HR numbers. I recommend seeking medical advice.

Thank you all for your comments and advice.
@Coach.Rupert.H I so use a strap.
Such high heartrates I see only during tests and sometimes on hillclimbs when I try to gain a PR.
What’s special during 4DP ist the long time in this heartrate range. Shouldn’t this be avoided?
The other issue is the big difference of cTHR between 4DP and Half Monty.

As others have mentioned, if something seems odd it’s good to get medical advice.

My experience is that getting to your max HR is hard on the bike, I’ve only achieved it in competitive situations with for example a hard crit and a sprint at the end of it.

Having said that, I just checked my last FF results:

  • Avg MAP HR: 93.5%
  • Max MAP HR: 97.5%.
  • Avg 20m HR: 93.5%
  • Max 20m HR: 96.8%

My HR threshold from HM is also lower (166bpm) than the one I get from FF (174bpm). I’m 38yo.

I said very similar in my earlier post. I never hit it working out my own, only in after repeated closely spaced very hard efforts in competitive situations.

Thanks for the extra detail, I recommend getting medical advice on this to make sure you do not have any underlying health issues.

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Here are the cTHR guidelines: “Cycling Threshold Heart Rate (cTHR) is your expected heart rate when riding at FTP. It’s calculated from your Full Frontal results (98% of average 20-minute test heart rate) or Half Monty (88% of peak 1-minute heart rate during Ramp). cTHR can vary on a daily basis, so while we set a specific value, it can vary within a range of +/- 3 beats/minute.”

Thank you for your data. That looks quite similar to my results. Maybe my real HRmax is also slighly higher, I did no special test estimating it, but use simply the highest value I see in my rides.

Like others have already written - maybe time to get checked by medical experts BUT I would just like to suggest that you’re heart monitor belt might be at fault. I had one that as it aged used to “stick” at stupid high - even sometimes above my measured max! It was also very sensitive to static built up by cycling clothing…needless to say a replacement belt was needed…ALSO how do you know your max? I’m 61 year old female with a recently measured max of 177 - which is miles off the old 220 minus age guestimate of 159!! which is 2 below my cTHR.

The strap has been heavily used, so there could be a problem.
I did no extra test for HRmax, the highest during training and rides.
Mine is 180 and I’m a bit older than you. The 220-age seems to be not usefull.

I have a ~12 year old original non-deluxe Garmin HR strap that’s been totally reliable (AFAIK). I wet the contacts (spit) before putting it on, particularly in cool dry weather, which prevents it from giving wack very high rates before I start sweating. FWIW, my max rate was 181 at 63. As of late, I don’t have a good solid number.