Heart Rate Time Trial question...

Chas_TChas_T Posts: 28
edited May 2007 in Pro race
(Yes I know it strictly speaking isn't 'racing' per se, and maybe it should be in this forum, but hey, it's still a competitive form of cycling).

Been doing TTs for a few years now. Mostly Tens, but a smattering of Hilly 25's, too.

Anyhoo, my technique for a Ten is: not to go too hard in the first mile or so, then maintain an even and steady output for the next 8 miles, then go balls-out for the last mile.

Seems to work quite well. However...

Up till now I've been 'guessing' at keeping the power output at a constant level (paticularly for Tens) and riding "just below where it hurts"...

My question is: If I were to use a HR monitor for a Ten, what sort of % of max should I be aiming to keep it at for the 'middle 8' miles?

Ta.
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Posts

  • quote:Originally posted by Chas_T
    [br. . . just below where it hurts . . .

    There is an old addage which goes "no pain, no gain".

    I rode my first time trial for around 45 years, last Wednesday (an evening 10 on the Q10/26). I used a HRM (obviously they weren't around in the early 1960's).

    Within 15 seconds of the start my pulse was up to 168 - 10 bpm above my theoretical max (I'm 63), after that it settled down to between 160 -165, maxing at 70 bpm near the top of Wrotham Hill.
    From experience I would say my range is from 60 to 180 bpm (climbing up Yorks Hill, Kent).

    I will not be wearing a HRM on my next time trial, I found its use interesting but restricting. I never at any time felt uncomfortable and at the end had 'too much left in the tank'.

    It is important to have a good warm up before the start (at least a couple of miles with some hills if possible) to oxygenate the blood and clear lactic acid from muscles. You need to time your warm up so that you are not hanging around for more than a few minutes before starting (otherwise there will be a build up of lactic acid in your legs). Hopefully this will help you to 'hit the deck running'. It may be better to go "balls out" in the middle of the race (you may be able to manage 3 or more miles at this pace instead of only the last mile).

    The older I get, the better I was
    The older I get, the better I was
  • domtylerdomtyler Posts: 2,648
    edited February 2011
    For any kind of TT event (including Tri bike split) you should aim for a dead flat power output line. And yes, this should be in training I think.

    ~~~~~~~~~~~~~~~~~~~
    Porridge not Petrol
    ________
    DC MEDICAL MARIJUANA DISPENSARIES
    ~~~~~~~~~~~~~~~~~~~
    Porridge not Petrol
  • My MHR is 172 or so.

    For a 10, I set my HR monitor to beep outside of 140-160bpm (ie if I let my pulse drop below 140 or go above 160, I get a warning).

    This is 81%-93% and seems to work for me. Like you, I try and wind it up towards the finish with my Polar beeping away merrily telling me I'm about to expire. [;)]
  • SteveR_100MilersSteveR_100Milers Posts: 5,987
    I have wondered about this also, and from what I have read, your 10 TT output should be at your LT, which is roughtly at 85% MHR, but again differes from person to person. This is why Joe Friel propses a method that is based around zones calculated from your all out 10TT pace, which should be your LT heart rate. The only way to be otherwise sure is to understake a MHR test. Some think this is OK, others not such a wise thing to do.

    So try to answer your post in % terms not absolute BPM since these will be meaningless for you: I also ride the same strategy, but bear in mind that you will see a small amount of cardiac drift especially on a warm day. I do the first mile at about 80-82%, the middle 8 or so at 85%+ and the last mile ramping up to about 90% This is all based upon my theoretical calculation of my MHR which could be wrong. I never look at my HRM when racing, and ride it purely on perceived exertion. Interestingly, when I compare my RPE to HR, there is a good correlation. Sorry its a bit of a vague answer.


    Time! Time! It's always too long and there's never enough!
  • andrewgturnbullandrewgturnbull Posts: 3,861
    Hi there.

    If you've been riding TTs for a number of years, then you'll be able to rate your perceived extertion much more accurately then a hrm will be able to. There are way too many factors that effect your heart rate to be able to rely on staying in a narrow zone.

    By all means wear a monitor, but don't look at it until the race is finished!

    Cheers, Andy

    ps If you've got anything left in the tank to go balls-out in the last mile then you rode the previous 9 too slowly.

    http://www.stirlingtri.co.uk
  • andrewgturnbullandrewgturnbull Posts: 3,861
    quote:Originally posted by domtyler

    For any kind of TT event (including Tri bike split) you should aim for a dead flat power output line. And yes, this should be in training I think.

    ~~~~~~~~~~~~~~~~~~~
    Porridge not Petrol


    Hi Dom.

    For a flat course I agree.

    However for a rolling course (which includes pretty much every tri on the calendar) then there is a lot of time to be gained from working harder on the climbs and recovering on the descents.

    Cheers, Andy

    http://www.stirlingtri.co.uk
  • Chas_TChas_T Posts: 28
    Thanks for all that. I just thought that by keeping your HR at a constant level, you'd maintain a constant and level power output? Which (I think I've heard) is the most effective way of doing a 10...?

    Will dig out my HRM and try the 85% -for-the-middle-8-miles technique just out of curiosity to see if it makes a difference.


    "...ps If you've got anything left in the tank to go balls-out in the last mile then you rode the previous 9 too slowly..."

    LOL! Yeah - If you can't taste blood, you're not trying hard enough, eh?
  • andrewgturnbullandrewgturnbull Posts: 3,861
    quote:Originally posted by Chas_T

    Thanks for all that. I just thought that by keeping your HR at a constant level, you'd maintain a constant and level power output? Which (I think I've heard) is the most effective way of doing a 10...?



    Hi there.

    Er, no - you're heart rate will drift upwards as the race progresses. So if you stuck to a level heart rate your power will drop...

    Cheers, Andy

    http://www.stirlingtri.co.uk
  • Chas_TChas_T Posts: 28
    Cheers, Andy,

    Ah.. Ok, so how can you tell if you're maintaining a constant power output??
  • quote:Originally posted by SteveR_100Milers

    I have wondered about this also, and from what I have read, your 10 TT output should be at your LT, which is roughtly at 85% MHR...
    It isn't (this is one of the commonest misconceptions among cycling coaches), and you won't be going fast enough for a 10 at that heart rate.

    A definition of "lactate threshold": the exercise intensity at which, during a progressively harder exercise task, the rate of production of lactic acid by exercising muscle initially exceeds the rate of its removal. (The only reasonably accurate way of determining this is by breath-by-breath analysis of expired gas). It's a useful "landmark" exercise intensity, but it doesn't define the exercise intensity sustainable during events lasting less than 90 mins, as all too many coaches still seem to believe.

    Let's say you are a well-trained athlete. Your lactate threshold is likely to be at no more than 70% of VO2max; yet you can maintain 90% of VO2max during a ten mile TT. The reason that you can maintain this apparently extremely high exercise intensity is that the effects of exceeding your lactate threshold are not *immediately* catastrophic. Lactate is being removed nearly as fast as it is being produced. You have a certain amount of "headroom" for accumulating lactate before its concentration in the working muscle reaches the level at which it impedes muscle function.

    You can use up this headroom quickly, in the ca. 24 mins it takes to ride a 10-mile TT; or you can use it up more slowly over the course of, say, 60 mins in riding a 25-mile TT.

    So during a 10 or 25-mile TT, you constantly tread a tightrope between
    a) going less fast than you could, and
    b) blowing up before the finish, by going too hard for the distance you have to cover.

    You may know from experience that if you try to ride a 25 like 2-and-a-half consecutive 10s, it doesn't work - you blow up before the end of the race. Physiologically, "blowing up" means (in my opinion; others may dispute this) that you have attained the muscle lactic acid concentration which is catastrophic to muscle function. A technically good time triallist reaches this point of catastrophic muscle lactic acid concentration at the precise moment that s/he crosses the finish line.

    Professional cyclists riding moderate distance (exercise time less than 90 mins) time trials maintain exercise intensities in excess of 90% of VO2max - here's an interesting paper on this subject:[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10776906]

    This agrees with my own heart rate reserve observations in ten mile TTs - not that I was anywhere near being a pro, but I did ride 10s for many years, by the end of which I knew how to "get it all out". This indicates that you don't have to be gifted to push yourself hard - you just won't go as fast as the pros.
  • Chas_TChas_T Posts: 28
    *WHOOOOOSH*

    Hear that? That's everything you just said going right over my head ;O)

    But I thank you for it anyway!
  • andrewgturnbullandrewgturnbull Posts: 3,861
    quote:Originally posted by Chas_T

    Cheers, Andy,

    Ah.. Ok, so how can you tell if you're maintaining a constant power output??


    Buy a power meter!

    http://www.stirlingtri.co.uk
  • SteveR_100MilersSteveR_100Milers Posts: 5,987
    quote:Originally posted by NickM

    quote:Originally posted by SteveR_100Milers

    I have wondered about this also, and from what I have read, your 10 TT output should be at your LT, which is roughtly at 85% MHR...
    It isn't (this is one of the commonest misconceptions among cycling coaches), and you won't be going fast enough for a 10 at that heart rate.

    A definition of "lactate threshold": the exercise intensity at which, during a progressively harder exercise task, the rate of production of lactic acid by exercising muscle initially exceeds the rate of its removal. (The only reasonably accurate way of determining this is by breath-by-breath analysis of expired gas). It's a useful "landmark" exercise intensity, but it doesn't define the exercise intensity sustainable during events lasting less than 90 mins, as all too many coaches still seem to believe.

    Let's say you are a well-trained athlete. Your lactate threshold is likely to be at no more than 70% of VO2max; yet you can maintain 90% of VO2max during a ten mile TT. The reason that you can maintain this apparently extremely high exercise intensity is that the effects of exceeding your lactate threshold are not *immediately* catastrophic. Lactate is being removed nearly as fast as it is being produced. You have a certain amount of "headroom" for accumulating lactate before its concentration in the working muscle reaches the level at which it impedes muscle function.

    You can use up this headroom quickly, in the ca. 24 mins it takes to ride a 10-mile TT; or you can use it up more slowly over the course of, say, 60 mins in riding a 25-mile TT.

    So during a 10 or 25-mile TT, you constantly tread a tightrope between
    a) going less fast than you could, and
    b) blowing up before the finish, by going too hard for the distance you have to cover.

    You may know from experience that if you try to ride a 25 like 2-and-a-half consecutive 10s, it doesn't work - you blow up before the end of the race. Physiologically, "blowing up" means (in my opinion; others may dispute this) that you have attained the muscle lactic acid concentration which is catastrophic to muscle function. A technically good time triallist reaches this point of catastrophic muscle lactic acid concentration at the precise moment that s/he crosses the finish line.

    Professional cyclists riding moderate distance (exercise time less than 90 mins) time trials maintain exercise intensities in excess of 90% of VO2max - here's an interesting paper on this subject:[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=10776906]

    This agrees with my own heart rate reserve observations in ten mile TTs - not that I was anywhere near being a pro, but I did ride 10s for many years, by the end of which I knew how to "get it all out". This indicates that you don't have to be gifted to push yourself hard - you just won't go as fast as the pros.



    OK then what is???? I have suspected that my MHR setting on my HRM is too low, but cannot and do not want to prove it. Will a flat out sprint for 1 minute on the track with someone breathing down your neck get close to an MHR? It's all academic, since I ride to RPE and not HR, but interesting nonetheless.


    Time! Time! It's always too long and there's never enough!
  • ClaireVClaireV Posts: 967
    My max is about 196 and I think my threshold is about 180. If I'm having a good time trial, I'll be up at about 186 or so from about five or ten minutes in, be breathing fairly comfortably, and feel like that's perfectly maintainable until the end (which it is). If I'm having a bad time trial, I'll feel like I'm dying almost as soon as I get a few beats over 170, my breathing will be all over the place, and I'll struggle all the way around. Perceived exertion in the second case will feel much higher than in the first case, even though my heart rate and power output are much lower. It's one of life's little annoyances!
  • Old TuggoOld Tuggo Posts: 482
    quote:Originally posted by andrewgturnbull

    quote:Originally posted by Chas_T

    Thanks for all that. I just thought that by keeping your HR at a constant level, you'd maintain a constant and level power output? Which (I think I've heard) is the most effective way of doing a 10...?



    Hi there.

    Er, no - you're heart rate will drift upwards as the race
    progresses. So if you stuck to a level heart rate your power will drop...

    Cheers, Andy

    http://www.stirlingtri.co.uk


    I try to keep a constant HR (about 92% MHR) but in the last part of a 25 I have difficulty in keeping up. I only get HR drifting upwards when I am hot on the turbo trainer.
  • quote:Originally posted by SteveR_100Milers

    OK then what is????
    Predictive formulae for maximum heart rate are statistically valid for populations but do not apply to individuals. If you have access to a turbo trainer, a heart rate monitor and a friend, you can do your own Max HR test.

    The test should be progressive, so that it incorporates a good warm-up. Start in your lowest gear; establish a good cadence of about 85-90rpm. Change up one gear every two minutes, while maintaining pedal revs. (By the time you change to the big ring, you will probably be breathing hard enough to make conversation difficult - if you aren't, there is probably insufficient resistance to elicit HRmax even in top gear, so stop, increase the resistance, and start again).

    During this, your helper should be keeping an eye on you and offering encouragement when it starts to get hard. Continue to change up one gear every 2 minutes. Eventually, you will be unable to maintain the workload demanded of you, and your pedal revs will start to flag. This is where having a helper becomes important. You need to be vigorously encouraged/bullied. When I did a lot of exercise testing, my preferred phrase was "Come on, give me one more minute - anybody can pedal for 1 minute!". Then, when you really cannot keep going any longer, SPRINT!! ...and at this moment (assuming that your HRM doesn't record for itself) your helper notes the highest heart rate achieved.

    As you can imagine, this is a fairly unpleasant business (far worse than a race). If you are over 45, or have any risk factors for heart disease, you should see your GP for clearance before doing it. And finally, to protect myself from any possibility of litigation, I am not suggesting in this posting that you do it!


    Having established your Maximum HR, if you want to emulate the pros in short time trials (and there is no reason why you shouldn't try as hard as they do, even if you won't go as fast) you need to be riding at ~90% of VO2max.

    You probably don't have access to VO2max measurement, but that need not stop you. Heart rate reserve (HRR) is linearly related to VO2 in the exercise intensity domain in question, so you can try riding at 90% of your HRR and you won't be far off.

    90% HRR = (0.9 x (Maximum HR - Resting HR)) + Resting HR

    e.g. Max HR 185, Resting HR 45:

    (0.9 x (185 - 45)) + 45 = 171bpm target for 90% VO2max

    In this example, 171bpm is 92% of Max HR

    Having said this, I do agree with a previous poster that heart rate, because of normal physiological and environmental variations, is not the last word in quantifying exercise intensity - and research shows that RPE is a surprisingly precise way of reproducing a learned level of effort.
  • quote:Originally posted by Chas_T


    Will dig out my HRM and try the 85% -for-the-middle-8-miles technique just out of curiosity to see if it makes a difference.


    Chas
    I'd reckon 85% for the middle 8 miles is WAY too low.
    I've averaged 92% - 94% for my last 3 tens and I reckon I'm still not pushing myself hard enough.
  • dsoutardsoutar Posts: 1,746
    Firstly I'm no athlete and I've never done a TT but I have thrashed myself on some training rides. My maxHR is 178 and my LT is 91% of this (had them measured in a VO2 max test) yet I can function quite happily at this level or higher for 30 mins no problem. I'm not sure how helpful HRMs are for this sort of thing as it can be a bit disconcerting. I think a previous poster had it wright when they mention perception rather than a cycle computer is the answer.
  • If your lactate threshold is at 91% of your maximum heart rate I am Ronald Reagan.
  • ClaireVClaireV Posts: 967
    Hello Ronald.
  • Congratulations. Your knowledge of exercise physiology obviously exceeds mine.
  • dsoutardsoutar Posts: 1,746
    Nick, fancy a bet ? If not, shut your gob

    I can gladly produce documentary evidence for this along with all sorts of graphs and stuff that mean nothing to me.

    Incidentally had it done by http://www.vo2fortri.com/
  • ClaireVClaireV Posts: 967
    Why do you say that? I'm not trying to start an argument here, but plenty of well trained people have lactate thresholds at 90% or above of their maximum heart rate. Why is it so difficult to believe that this might be the case for dsoutar, particularly since he's had both quantities measured?
  • Yes, you are; but you're not going to succeed, because it would be pointless.

    About as pointless as dsoutar.
  • ClaireVClaireV Posts: 967
    I'm not actually. I'm genuinely curious. You seem to have a very good level of knowledge of exercise physiology, maybe you even work in the field? I'm interested to know how unusual it actually is to have a lactate threshold above 90% of your maximum heart rate. Is it something that is purely a result of training, in which case presumably anyone could have those kinds of numbers, or is a high anaerobic threshold more of a 'genetic gift' in some sense, that only a very small fraction of the population could achieve. Also, presumably your lactate threshold isn't an absolute measure of performance, because that will depend on what your VO2max is. Somebody with a very high lactate threshold as a percentage of max HR, but a low VO2max, will presumably still not be a very good athlete even if they've trained themselves to reach their maximum potential. i.e. somebody with a much lower anaerobic threshold but a much higher VO2max would win out. I'm more than happy to be corrected if I'm wrong - apologies if I've caused any offence.
  • DaveyLDaveyL Posts: 5,167
    For what it's worth, two years ago I rode up Alpe d'Huez in 76 min and my average HR was 169. My max is 191 so that was 88% of maximum, sustained for over an hour. I could maybe even have gone a little harder. That's not very scientific but it has given me the view that I would not be surprised if other cyclists had lactate threshold HRs of 90%+. *Power* at lactate threshold is another thing entirely and that of course would be vastly inferior to most pro riders. However, I am prepared to be enlightened on a subject I'm happy to admit I'm not that knowledgeable about.... In fact I would welcome a bit of education.
    Le Blaireau (1)
  • Chas_TChas_T Posts: 28
    Thanks, NickM.

    Using your formula, target bpm would seem to be 177, then.
  • ClaireVClaireV Posts: 967
    Is NickM still speaking to us? I apologise again Nick!
  • nmcgannnmcgann Posts: 1,780
    On my last evening 10 I managed to average 97% of MHR - I'm sure this is waaaay over my LT, but it was sustainable for the distance.

    I was riding on perceived exertion with half an eye on my HRM - although my HR was higher than usual, I felt ok so just went with it. The download from the polar made interesting viewing later!

    The main thing I use the HRM for when riding TTs is a reminder not to slack off downhill or when I have a tailwind, I don't use it as a regulator of max effort.

    Neil
    --
    "Because the cycling is pain. The cycling is soul crushing pain."
  • SteveR_100MilersSteveR_100Milers Posts: 5,987
    quote:Originally posted by nmcgann

    On my last evening 10 I managed to average 97% of MHR - I'm sure this is waaaay over my LT, but it was sustainable for the distance.

    I was riding on perceived exertion with half an eye on my HRM - although my HR was higher than usual, I felt ok so just went with it. The download from the polar made interesting viewing later!

    The main thing I use the HRM for when riding TTs is a reminder not to slack off downhill or when I have a tailwind, I don't use it as a regulator of max effort.

    Neil


    Now to me this is the same possible dilemma - is this really based on a correct MHR..??? I would be amazed at anyone able to sustain this level of effort, any more than I am "only" managing 85%. Since these rates are all ratios of an estimated max, unless you have had it properly lab tested; then they are potentially meaningless. In my own case, I DO know that my HR is 147-152 for a 10TT, with the last 200 yards peaking at 155-156. Thats at RPE 7 to 8. A long climb at hard pace whilst training is around 142-146. A track sprint will see 160-161 for about 30 seconds. Because of the uncertainty of measuring your MHR, I use the Joe Friel approach which is to ignore zones based on your Max, and use the LT as a reference. His field test for determining LT is to ride 30 minutes at 10TT pace, and take your average HR for the last 20. The question I have is at what %MHR does your LT normally occur, the answer seems to be it varies from person to person. From now on, I am going to set my HRM with a MHR of 161, which is the highest I have seen. It might actually be higher, but I have no scientific way of measuring it.


    Time! Time! It's always too long and there's never enough!
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