Login required to started new threads

Login required to post replies

Heart rate higher in 1h17 long zwift race than estimated LTHR?
Quote | Reply
I'm trying to make sense of the following "disrecpancy" in my Lactate Threshold Heart Rate (LTHR) in cycling and what I observed in racing:

I did the long FTP test on zwift.

Results:
Average HR for the 20' all out effort = 170bpm
Minus 5% to get an appromixation of LTHR = 161bpm
So my understanding is that "theoritically", I should be able to hold on average 161bpm on an all out 1h effort.

I rested for a few days and raced on zwift and ended up averaging 163bpm for 1h17 racing time.

Two things I can think of:
1. Shall I assume that I should/could have pushed harder/better/stronger on the FTP test to raise my heart rate higher on the 20min all out effort?
2. Taking 5% off of the average HR for the 20' all out effort is not an accurate estimation? The other field test I can think of is the 30' all out solo effort and take the avg of the last 20'. I feel this would give a better estimate but does require another field test on top of the 20' all out FTP test.
Last edited by: tamiii: Nov 15, 20 15:00
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
Your actual performance is a better indicator.

I wouldn’t over complicate it.

Use your actual performance to guide your training zones.

Most don’t want to do the all out 1 hr. effort to inform their training. So, in absence of that data they use approximations.

Use your actual until you think the approximation tells you to go harder.
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
tamiii wrote:
I'm trying to make sense of the following "disrecpancy" in my Lactate Threshold Heart Rate (LTHR) in cycling and what I observed in racing:

I did the long FTP test on zwift.

Results:
Average HR for the 20' all out effort = 170bpm
Minus 5% to get an appromixation of LTHR = 161bpm
So my understanding is that "theoritically", I should be able to hold on average 161bpm on an all out 1h effort.

I rested for a few days and raced on zwift and ended up averaging 163bpm for 1h17 racing time.

Two things I can think of:
1. Shall I assume that I should/could have pushed harder/better/stronger on the FTP test to raise my heart rate higher on the 20min all out effort?
2. Taking 5% off of the average HR for the 20' all out effort is not an accurate estimation? The other field test I can think of is the 30' all out solo effort and take the avg of the last 20'. I feel this would give a better estimate but does require another field test on top of the 20' all out FTP test.

Quite simply put, HR zones are estimates. You will never know your max HR, because, well going over Max would end badly. And FTP test is an estimate as well. Your best estimates would require a true LT test with blood prick testing to check lactate levels. From their you could get a pretty good estimate of your LTHR. But again HR can be impacted by many things. Fatigue, Stress, Diet, Caffine, etc. I would say guessing 161 and then holding on at 163, is pretty damn close from an accuracy standpoint.
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
tamiii wrote:
I'm trying to make sense of the following "disrecpancy" in my Lactate Threshold Heart Rate (LTHR) in cycling and what I observed in racing:


I did the long FTP test on zwift.

Results:
Average HR for the 20' all out effort = 170bpm
Minus 5% to get an appromixation of LTHR = 161bpm
So my understanding is that "theoritically", I should be able to hold on average 161bpm on an all out 1h effort.

I rested for a few days and raced on zwift and ended up averaging 163bpm for 1h17 racing time.

Two things I can think of:
1. Shall I assume that I should/could have pushed harder/better/stronger on the FTP test to raise my heart rate higher on the 20min all out effort?
2. Taking 5% off of the average HR for the 20' all out effort is not an accurate estimation? The other field test I can think of is the 30' all out solo effort and take the avg of the last 20'. I feel this would give a better estimate but does require another field test on top of the 20' all out FTP test.


Well, that's not really how HR works during an hour long effort. You don't average a lower HR for the entire time. You ramp up and hold over a longer period of time. You might take several miles of a 40k to settle in and get up to sweetspot HR. Then you may go 5bpm over sweetspot in subthreshold from miles 5 thru 15 and at 15 start entering your 20min HR numbers for the last 10 miles in superthreshold. Imagine an over damped control system (nerd speak). A 20min effort is more like your HR following a "critically damped" control system.

Also, benchmark the power durations that matter to you for the purpose of training and don't worry about fancy percentages. If you care about 1min and 5min power for crit or road racing or something......sure, test it. If you care about 20min power for a roughly 10mi TT........do that. If 40k is your thing, do that. Etc....

A and C are blowing your load too early and bobbing around and B and D are your 20min/10mi and 60min/40k efforts ramping to your final HR for an effort.

Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [burnthesheep] [ In reply to ]
Quote | Reply
All of the answers so far make a lot of sense, so thank you very much, I really appreciate the inputs.
I'm training for 70.3/Ironman distance so maybe the best FTP indicator would actually be a 1h all out test?
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
tamiii wrote:
I'm trying to make sense of the following "disrecpancy" in my Lactate Threshold Heart Rate (LTHR) in cycling and what I observed in racing:
I did the long FTP test on zwift.

Results:
Average HR for the 20' all out effort = 170bpm
Minus 5% to get an appromixation of LTHR = 161bpm
So my understanding is that "theoritically", I should be able to hold on average 161bpm on an all out 1h effort.

I rested for a few days and raced on zwift and ended up averaging 163bpm for 1h17 racing time.

Two things I can think of:
1. Shall I assume that I should/could have pushed harder/better/stronger on the FTP test to raise my heart rate higher on the 20min all out effort?
2. Taking 5% off of the average HR for the 20' all out effort is not an accurate estimation? The other field test I can think of is the 30' all out solo effort and take the avg of the last 20'. I feel this would give a better estimate but does require another field test on top of the 20' all out FTP test.


Cardiac drift (increasing HR for the same power output) occurs during longer indoor sessions due to dehydration. Dehydration causes reduced stroke volume (volume of blood per beat of the heart).

Thus, LTHR increases as dehydration increases.

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub
Last edited by: DrAlexHarrison: Nov 15, 20 18:34
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [DrAlexHarrison] [ In reply to ]
Quote | Reply
I really dont think I was dehydrated as I was sipping ~700mL of water during the race.
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
tamiii wrote:
I really dont think I was dehydrated as I was sipping ~700mL of water during the race.

Then you were almost certainly getting progressively more dehydrated as the race went on. Even average-sweating folks often sweat more than double that amount in such an indoor setting where evaporative cooling isn't as effective as when moving through the air outdoors.

Anecdotally: I have both female and male clients who sweat 3-4 times that much, per hour, during a hard indoor session and have seen HR above previously established LTHR for >1hr often when riding indoor.

Handy VERY approximate/simplified table for sweat rates in 85 degrees F ambient conditions while running (HUGE inter-athlete variability, even with identical body size, FYI). This data is from outdoor testing and is adapted/extrapolated. It is likely that sweat rates of equivalently-sized people would be higher than those listed here, for high-intensity indoor cycling, even with the best fan/AC setup.


Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [DrAlexHarrison] [ In reply to ]
Quote | Reply
I agree with what you're saying, but I reckon it applies for longer rides than what I did (dehydration impacts HR in longer rides than the 1h17 race I did).
I've done many sweat tests (at home) in the past and can say I was properly hydrated leading up to the race, drank 700mL of water during 1h17, and my sweat rate wasnt exceeding 1.5L/hour (as per older data points in very similar environment). So I basically "lost" (thru dehydration) about 0.7L.
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
I didn't know 95% of 20 min test HR was a thing. Where did that come from?
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
tamiii wrote:
I agree with what you're saying, but I reckon it applies for longer rides than what I did (dehydration impacts HR in longer rides than the 1h17 race I did).
I've done many sweat tests (at home) in the past and can say I was properly hydrated leading up to the race, drank 700mL of water during 1h17, and my sweat rate wasnt exceeding 1.5L/hour (as per older data points in very similar environment). So I basically "lost" (thru dehydration) about 0.7L.

Touche! Sounds like you've got good data.

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [jaretj] [ In reply to ]
Quote | Reply
jaretj wrote:
I didn't know 95% of 20 min test HR was a thing. Where did that come from?

I found "somewhere on the web" an extrapolation of the power model which does take 5% off of the average 20 power. As an example, I managed to hold 310w for 20min all out, which equates to 296w FTP (310*.95). I did the same for Heart Rate. I'm not sure of the accuracy of this approach, that's why I'm opening up about the way I used it.
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
OK, I see.

It's not one of the ways I've seen to estimate LTHR.

A common test is the average of the last 20 min of a 30 min Time Trial.
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
Heart rate is not a precise metric. Variation of 2 bpm isn't something I would worry about. That being said, I think 95% of max 20 min is not a correct estimation and your threshold hr is likely higher than 161
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [imswimmer328] [ In reply to ]
Quote | Reply
Yeah, there's no real trustworthy "formula." But I'd say while 95% of 20min *POWER* is a reasonable (assuming appropriate pre-loading) proxy for FTP (with all of the known caveats...), your threshold HR is probably closer to 100% of your 20min HR. But really, I wish the idea of LT would go away... as do others... https://physoc.onlinelibrary.wiley.com/...abs/10.1113/JP279963

"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
tamiii wrote:
I'm trying to make sense of the following "disrecpancy" in my Lactate Threshold Heart Rate (LTHR) in cycling and what I observed in racing:

I did the long FTP test on zwift.

Results:
Average HR for the 20' all out effort = 170bpm
Minus 5% to get an appromixation of LTHR = 161bpm
So my understanding is that "theoritically", I should be able to hold on average 161bpm on an all out 1h effort.

I rested for a few days and raced on zwift and ended up averaging 163bpm for 1h17 racing time.

Two things I can think of:
1. Shall I assume that I should/could have pushed harder/better/stronger on the FTP test to raise my heart rate higher on the 20min all out effort?
2. Taking 5% off of the average HR for the 20' all out effort is not an accurate estimation? The other field test I can think of is the 30' all out solo effort and take the avg of the last 20'. I feel this would give a better estimate but does require another field test on top of the 20' all out FTP test.

I think people underestimate the kind of adrenaline charge you can get from Zwift racing as opposed to solo TT/testing efforts. That definitely raises HR but doesn't really raise RPE (may lower it) and can give you a boost in power for shorter periods. Normally in fresh,full on training efforts I can hit ~175 bpm, where as in Zwift racing Ive finished stages at 188 bpm and done quite well.

Don't worry about it, HR doesn't matter much in these short races like it does in well paced long distance efforts. In road races you either can do it and make the selection or you can't-let the bpm fall where they may.

Professional Athlete: http://jordancheyne.wordpress.com/ http://www.strava.com/athletes/145340

Coaching Services:http://www.peakformcoaching.com/

Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
Thank you all. That was very nice feedback.
I actually changed my LTHR to be the average of the 20min all out effort rather than taking 95%. Makes more sense to me.
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
Looking over my last two 20 min FTP tests, the average HR over the second 10 min is closer to what I consider my LTHR.

But then I normally start off those tests conservatively so my HR in the beginning is low.
Quote Reply
Re: Heart rate higher in 1h17 long zwift race than estimated LTHR? [tamiii] [ In reply to ]
Quote | Reply
Has anyone pointed out that 2bpm is almost an irrelevance? It's probably a rounding error in the technology, or just because of a slight change in environment, or maybe even both.

But please don't dwell on HR levels that are 2 beats apart. You'll be telling everyone you monitor your bank account to the nearest cent next.
Quote Reply