Heat rate drop during intervals

Triathlon Forum
1

At 6x10min in TT my HR goes up to 171bpm during the first 3 intervals, then during the fourth interval it stops at 160bpm and stays there for the remainder of the intervals. My trainer is set to erg mode, the cadence is identical in all intervals and my fan is pretty strong.

Glycogen depletion or any other explanation here?

The last intervals always feel a lot easier than the first few, even though the legs obviously show some fatigue towards the end. Increased the power by 40w after the 60min in TT and did 2x5min upright and still the heart rate wouldn’t go over 160.

It is only recently that I have been able to get my HR up in the TT position but curious to this drop in HR halfway through the workout.

2

My old erg would drop resistance when it got hot, maybe that’s it?

3

That sounds like a hellish workout too
.

4

A drop in heart rate that large indicates a reduction in stress.

The first thing I would look at is if the resistance is fading.

5

At 6x10min in TT my HR goes up to 171bpm during the first 3 intervals, then during the fourth interval it stops at 160bpm and stays there for the remainder of the intervals. My trainer is set to erg mode, the cadence is identical in all intervals and my fan is pretty strong.

Glycogen depletion or any other explanation here?

The last intervals always feel a lot easier than the first few, even though the legs obviously show some fatigue towards the end. Increased the power by 40w after the 60min in TT and did 2x5min upright and still the heart rate wouldn’t go over 160.

It is only recently that I have been able to get my HR up in the TT position but curious to this drop in HR halfway through the workout.

6x10 min sounds crazy, what % of FTP are you riding at? If work set is >90% of FTP you need to re do your threshold testing.

A lack of HR responsiveness through set is to be expected although the degree that you are experiencing is extreme. Do some mile repeats on the track at 0.5:1 rest interval and see if you are experiencing similar HR decay to determine it is you or the trainer.

6

I’m not an expert, but if you can complete the set but see that as your data point…I’d also say the resistance or measuring of power is off the longer the workout goes. Or your HR strap or monitor is wonky. There’s bad data or bad trainer control somewhere.

HR is going to drift up over time with each set.

No giggling at the data…but notice for these workouts the drift in HR with each set:

3x10:
https://www.strava.com/activities/2181861970

2 1/2 min and 1:1 intervals:
https://www.strava.com/activities/2206466606

3x5min:
https://www.strava.com/activities/2215052556/analysis

A road race “opener” workout of 1:1’s:
https://www.strava.com/activities/2277152325

All those show the drift up over time. If the HR depresses with sets, then you won’t be able to finish if it’s actually fatigue. In my uneducated opinion.

7

10-min long intervals are supposed to be done at 100-105% FTP. Doing them less than 100% FTP will decrease their effectiveness.

8

10-min long intervals are supposed to be done at 100-105% FTP. Doing them less than 100% FTP will decrease their effectiveness.

caveat that “supposed to” depends on how long you rest. You could get a perfectly fine training benefit from a different intensity provided the work:rest ratio is correct.

But agree with all of the input here that heart rate drop like that seems weird and more likely a glitch with the equipment rather than a glitch with you / your body

9

10-min long intervals are supposed to be done at 100-105% FTP. Doing them less than 100% FTP will decrease their effectiveness.

I am not familiar with that rule. Your FTP is mispecified if you can do 6x 10 min @ 105%.

10

10-min long intervals are supposed to be done at 100-105% FTP. Doing them less than 100% FTP will decrease their effectiveness.

I am not familiar with that rule. Your FTP is mispecified if you can do 6x 10 min @ 105%.

Read here from Hunter Allen (scroll down to bullet point #2): https://www.hunterallenpowerblog.com/2010/12/next-level.html

“Start out with (3) x 10minutes at 105% of FTP and build up so that you are doing (3) x 30minutes at 100% of FTP”

11

10-min long intervals are supposed to be done at 100-105% FTP. Doing them less than 100% FTP will decrease their effectiveness.

I am not familiar with that rule. Your FTP is mispecified if you can do 6x 10 min @ 105%.

Read here from Hunter Allen (scroll down to bullet point #2): https://www.hunterallenpowerblog.com/2010/12/next-level.html

“Start out with (3) x 10minutes at 105% of FTP and build up so that you are doing (3) x 30minutes at 100% of FTP”

That’s one view. Coach opinion =/= rule though. Also, 3 is a different number than 6.

12

Sure, rule made by one coach will be different from rule made by another. I will always take tried and true rule made by a reputable coach. If you are not interested in making big gains, then you can do more 10-min intervals at lower intensity.

13

My old erg would drop resistance when it got hot, maybe that’s it?

It is a Wahoo Kickr 2017. I have just calibrated it, but it could of course be that erg mode is flawed. Doesn’t feel any different though.

That sounds like a hellish workout too

Oh but it is. Did it as 1x20 + 4x20 TT and added 2x5 upright afterwards which I will build up to 2x10 upright for a total of 80min at around threshold. This is a part of either double or triple interval day in accordance with AT.

A drop in heart rate that large indicates a reduction in stress.

The first thing I would look at is if the resistance is fading.

I don’t know how to check if my kickr is off. My Power meter pedals are on their way to Italy for service. Any suggestions?

6x10 min sounds crazy, what % of FTP are you riding at? If work set is >90% of FTP you need to re do your threshold testing.

A lack of HR responsiveness through set is to be expected although the degree that you are experiencing is extreme. Do some mile repeats on the track at 0.5:1 rest interval and see if you are experiencing similar HR decay to determine it is you or the trainer.

It doesn’t decay on the track, nor when I sit up and do intervals. Only when I do TT intervals.

I’m not an expert, but if you can complete the set but see that as your data point…I’d also say the resistance or measuring of power is off the longer the workout goes. Or your HR strap or monitor is wonky. There’s bad data or bad trainer control somewhere.

HR is going to drift up over time with each set.

No giggling at the data…but notice for these workouts the drift in HR with each set:

3x10:
https://www.strava.com/activities/2181861970

2 1/2 min and 1:1 intervals:
https://www.strava.com/activities/2206466606

3x5min:
https://www.strava.com/.../2215052556/analysis

A road race “opener” workout of 1:1’s:
https://www.strava.com/activities/2277152325

All those show the drift up over time. If the HR depresses with sets, then you won’t be able to finish if it’s actually fatigue. In my uneducated opinion.

This is how my heart rate normally works. And still does most of the time.

10-min long intervals are supposed to be done at 100-105% FTP. Doing them less than 100% FTP will decrease their effectiveness.

Thanks for the advice. Had I wanted coaching advice I would have asked. But to repay you your kindness: Try googling Kristian Blummenfelt, Gustav Iden, Casper Stornes or Arild Tveiten. Try to read up on how they work out and check out who has the 3 fastest time through history in 70.3 racing. I feel more confident following Arilds philosophy than yours :slight_smile:

14

Try googling Kristian Blummenfelt, Gustav Iden, Casper Stornes or Arild Tveiten. Try to read up on how they work out and check out who has the 3 fastest time through history in 70.3 racing. I feel more confident following Arilds philosophy than yours :slight_smile:

For the record, it wasn’t my philosophy. Googling Arild’s philosophy on bike training yielded this: “One will be an easy session and the rest are intervals. This could be up to 75 minutes of threshold sets.” To me, “threshold” = 100% FTP or close to it.

15

Did you see your heart rate fade when you had your powermeter?

If so the reduction in stress is from something else. Perhaps that’s what your body does, mine will do it a little but not at the magnitude you’re seeing.

16

At 6x10min in TT my HR goes up to 171bpm during the first 3 intervals, then during the fourth interval it stops at 160bpm and stays there for the remainder of the intervals. My trainer is set to erg mode, the cadence is identical in all intervals and my fan is pretty strong.

Glycogen depletion or any other explanation here?

The last intervals always feel a lot easier than the first few, even though the legs obviously show some fatigue towards the end. Increased the power by 40w after the 60min in TT and did 2x5min upright and still the heart rate wouldn’t go over 160.

It is only recently that I have been able to get my HR up in the TT position but curious to this drop in HR halfway through the workout.

6x10 min sounds crazy, what % of FTP are you riding at? If work set is >90% of FTP you need to re do your threshold testing.

A lack of HR responsiveness through set is to be expected although the degree that you are experiencing is extreme. Do some mile repeats on the track at 0.5:1 rest interval and see if you are experiencing similar HR decay to determine it is you or the trainer.

If you can’t do 6 x 10 minutes at FTP with the right recovery between you need to redo your FTP test.

17

Did you see your heart rate fade when you had your powermeter?

If so the reduction in stress is from something else. Perhaps that’s what your body does, mine will do it a little but not at the magnitude you’re seeing.

I still have a power meter. The Wahoo Kickr. It happens when I race, but I have though it to be a product of the change from horisontal position to vertical position followed by a run and then starting biking

18

Try googling Kristian Blummenfelt, Gustav Iden, Casper Stornes or Arild Tveiten. Try to read up on how they work out and check out who has the 3 fastest time through history in 70.3 racing. I feel more confident following Arilds philosophy than yours :slight_smile:

For the record, it wasn’t my philosophy. Googling Arild’s philosophy on bike training yielded this: “One will be an easy session and the rest are intervals. This could be up to 75 minutes of threshold sets.” To me, “threshold” = 100% FTP or close to it.

Well who’s philosophy was it? For categorically claiming that you have to do 10min intervals at 100% FTP (which varies a lot depending on your total training load that day, the training load leading up to the day, how you have slept and how life is treating you, which means that you probably are off regardless) without specifying the number of repeats, the rest in-between, the total training load for the day and how it all fits into a bigger picture, might be the dumbest thing I have read since the Keto thread, so please let me know.