CdCf

Some sources claim that you shouldn't reach your threshold heart rate until the last few minutes of intervals like these, yet I am at my threshold HR about 13-15 minutes in, and 8-10 bpm over by the end.

My threshold HR has been established several times through ramp tests using an ergometer bike and blood lactate testing. It's been between 173-175 every time.

The latest attempt, earlier today, ended after the first interval. Average HR was 167 (HR ramps up slowly from warm-up levels at about 115-120 bpm) and max HR was 181.

What's the recommendation here? Is it a case of serious HTFU, or should I back off 10 W or so...?

gregf83 

'threshold HR' is not a very well defined term particularly when lactate testing is involved.

If you're measuring power and are able to complete the intervals without killing yourself then I would just continue on. If you're having trouble completing them, you'll still get plenty of benefit by backing off a little especially at this time of year.

The problem with using HR alone is that if you keep your avg HR the same in the 2nd interval your power will usually be down relative to the first one.

CdCf

I'm not using HR alone. I train on an ergometer bike, so the power stays constant throughout. Threshold in this case is estimated OBLA, based on the shape of the lactate curve.

asgelle

Well let's see what Andy Coggan who popularized these workouts said (Note there's a lot more information than a rigid heart rate zone). https://www.peaksware.com/articles/cy...ew-coggan.aspx


Level: 4
Name: Lactate Threshold
Average Power: 91-105%
Average Heart Rate95-105%(may not be achieved during initial phases of effort(s))
Perceived Exertion: 4-5
Description: Just below to just above TT effort, taking into account duration, current fitness, environmental conditions, etc. Essentially continuous sensation of moderate or even greater leg effort/fatigue. Continuous conversation difficult at best, due to depth/frequency of breathing. Effort sufficiently high that sustained exercise at this level is mentally very taxing - therefore typically performed in training as multiple 'repeats', 'modules', or 'blocks' of 10-30 min duration. Consecutive days of training at level 4 possible, but such workouts generally only performed when sufficiently rested/recovered from prior training so as to be able to maintain intensity.

gregf83 

But that definition of threshold is not the same as what most people use for threshold power. When you're riding at your threshold for a 1hr TT your lactate levels can be higher than the 4mmoL used for the OBLA threshold. How far above varies. Again, I would use power and PE to guide your workouts rather than HR.

CdCf

That's the very definition of threshold - the level at which lactate production exceeds lactate removal.

I never mentioned 4 mmol/L, did I? In fact, mine was estimated to be between 4.5 and 5.

See, that's exactly what I'm trying to do. To determine the correct power level, I need to know approximately where in relation to my threshold HR I should be at the end of an interval.

Carbonfiberboy 

I and perhaps other posters don't see what you are trying to achieve. You are on an erg and find LTHR through OBLA testing. So then don't you also know power? Can't you just run that power for the interval and see what your HR does just out of interest? Are these testing intervals, or are you using them for a particular training purpose? If the former and if you already know power and HR at OBLA, what are the testing intervals for? If the latter, what's the training objective?

When I'm TTing, I'll hit LTHR within 5 minutes and be as close to MHR as I can get at the end. If I'm training in a competitive situation, I'll hold the RPE until I hit LTHR or a few beats over and just hold it there. If I'm training alone, I'll usually hold it about 4 beats below LTHR to limit training stress. I don't use a meter, but I know what each power level feels like. Having an objective that integrates into your training plan is very important if you're going to blow that much energy.

CdCf

My threshold HR has been essentially the same for the three tests, but the threshold power has varied widely (a range of almost 50 W). My assumption is therefore that the threshold HR, for me and for this purpose, is pretty much fixed. Power at the threshold is obviously not, and since the latest test was in May, I don't think that that threshold power is representative of my current fitness level.

Different intensities do different things in terms of adaptation. That's why I want to hit the right level for this.

gregf83 

That's an odd way to train. Why do you care about your HR? If you don't have your fan set high enough and it's too hot inside your HR will be higher than normal and if you use it to guide your effort you'll be putting out less power than you should.

You're overthinking this. Just do your intervals based on power. If it gets too easy - raise the power. If you can't complete them - lower it.

Carbonfiberboy 

Ah, got it. These are training intervals, and you want to do them as close to OBLA as possible. Correct? Yes, training objectives differ. Not knowing what yours is, I can only tell you about mine.

During the season, my LTHR moves around a bit, depending on a lot of things. But I usually know pretty closely what it is at a particular stage in my training. Doing training intervals like this, I choose to ignore the starting power and just bring HR up to LTHR quite quickly, then hold it. It should not take you so long to bring it up, if you have warmed up properly before doing the intervals. Warm up just like for a TT. I want good lactate levels during the entire interval, but not so high that I bog down. I also want to be able to do the second one at very close to the same speed or V as the first, IOW not exhausted by the effort or loaded up with lactate. Maybe your objective is different. It took me a while to figure out just what it should feel like to come out the way I wanted.

For a test of this length, I ignore average HR and concentrate on my steady-state HR. Since you have power, you'll want to get your power vs. HR dialed in, and then see how that changes during the season.

CdCf

Correct! I don't expect to "use" my fitness until late March or early April next year. This is pretty much base training for me.



The HR curve in this diagram is part of what prompted my initial post. This is the HR curve for the latest interval session. Well, actually I only managed to summon enough willpower to complete the first of the intended two... If we assume that my LTHR/OBLA is at around 173-174, then I'm about 7-8 bpm over that at the end of the interval. There isn't much levelling off either. It appears as if there is an initial rapid increase in HR over the first half minute or so, then a marked deflection until about five minutes in, where there seems to be a second reduction in the rate of increase. But after that, the HR seems to increase at a steady rate until the end of the interval. That suggests to me that I'm over my OBLA level, so that no real steady state develops.
The question is, then, if my guess is correct and I should back off by 5-10 W, or if these intervals should be that hard given that they're relatively short?

Another question is how much of the increase in HR is due to cardiovascular drift, rather than lactate accumulation... I recently did a test where I warmed up for five minutes, then held power constant at about 75-80 % of my threshold power for a full hour. My HR increased slowly but surely right to the end. I started out at all-day riding levels, and finished the hour with my HR about 5 bpm above threshold, an increase of more than 35 bpm!

Yep, as you can probably guess, I'm a numbers guy!

Carbonfiberboy 

Well, you're asking yourself all the right questions, IMO.

1) You shouldn't have anything like that HR drift. Not enough base. More frequent stress, like 5-6 days a week, and at a level the leaves you capable of stressing your body again the next day, without going into overload, but nonetheless walking that knife edge. Up your volume until you find that edge, then back off a hair. You should notice great improvement in about 2 months of that. When you are in condition, your HR should hold steady state at very close to the same power level for both 20' LT intervals. Conversely, holding the power should only drift your HR 3-4 beats. That's how I know I have my base and am ready for harder efforts. Ability to repeat is the ticket.

2) Is your HR curve due to holding a steady power all the way? I'm suggesting that one purpose of LT training is to improve one's ability to burn lactate, in which case you want your blood lactate at the OBLA level the whole way. If in fact your HR predicts OBLA, then you should hit it harder at the start and bring your HR up to the OBLA level and just leave it there, ignoring your power level other than to note how it fluctuates during the interval. If you let your HR climb beyond OBLA, as you noticed, you won't feel like/be able to ride the second interval.

3) There is a competing theory among the power people who believe you should ride the entire interval at the same power level, ignoring HR. If you can't ride the second interval, the power output you chose for the first interval was over your threshold power. This is the way to find your threshold power, but I'm not sure that it's as effective training as the HR training I described in "2". My question is: "What does it do, physiologically, and why is this better than using HR?"

4) It's taking your body 5 minutes to figure out what's going on. Then you get the hit of hormones which kicks your HR up, and your interval really starts. I suggest you perform a 30' warm up as follows: 20' Z2 at normal cadence, then a 1.5' interval at TT effort and cadence or above. You should be glad when it's over. Then 3.5' of Z2 cruise at the same power level you used before, then another 1.5' interval at the 25' mark, then the last 3.5' in Z2, then immediately start your TT interval. Your HR should come up to OBLA level very quickly.

CdCf

My HR stays "flat" to a much higher degree, much like you describe, during intervals outside. I suspect that cooling is a major factor. I do have a massive fan blowing straight at my upper body, just two feet in front of me, and I don't sweat much (I never do, unfortunately) so cooling shouldn't to be an issue, but it probably is anyway.

I'm usually very challenged for time, so half-hour warm-ups are out of the question for the most part. That goes for 5-6 sessions a week as well. I only have time for three on average. Work gets in the way (I often work split shifts, and I can't make it home, do a session and get back to work in the ~4 hours I have off between shifts - on a day like that, I leave home at 6.10 in the morning and return at 11.05 at night) and due to noise concerns, I can't do them other than during daytime or early evenings.

Also, I'm not sure what you mean by "Z2". I assume that's "Zone 2", but what it means in terms of HR or power, I don't know, but if I were to guess, I'd say it's just above recovery levels.

Well, I'll drop down to 260 W for the next session and see what happens. Maybe with a more intense and progressive warm-up, it'll work better.

CdCf

I have to correct myself here. I remembered incorrectly. I did the hour at 240 W, which is about 10-15 W below my current estimated 1-hour threshold power. I wasn't really very tired during or after, except for the last five minutes or so.

Carbonfiberboy 

Yeah, that's why the power people say don't look at your HR. However, your HR did tell you that you aren't in condition yet! Good workout. A very interesting, similar workout is to go at that power, but increase the resistance until you are pedaling a 70 cadence. Start with two 15'-20' intervals with 15' Zone 2 between them, and increase over a few weeks, but only do them for 3-4 weeks in a row. Again, watch your HR during each interval.

Carbonfiberboy 

Yes, Zone 2. There are a zillion ways to calculate HR zones. I use a Z2 max of 83% of LTHR.

I don't think it's cooling as much as it is hormones. Excitement. I see a similar thing. That warmup is supposed to help. It's terrible when life gets in the way of cycling.

Have you read Carmichael's The Time Crunched Cyclist? It's very good. Basically, one substitutes intensity for time. He gives workout, training plan, etc.

gregf83 

It's normal for HR to rise when riding at threshold regardless of your fitness level. Here's a recent study ("Physiological Responses to Cycling for 60 Minutes at Maximal Lactate Steady State" by Lajoie et al) that measured changes in HR during a 1 Hr test at MLSS. Note the significant rise in HR during the course of the test.

If you're having trouble completing the intervals at this time of the year just back off a little on the power until you can complete them comfortably. Some people swear by SST training which is around 85-95% of FTP. Better to do 40min to an hour at 85% than 20min at 100% particularly at this time of year. As you get closer to racing you can increase the intensity.

CdCf

I do low-cadence intervals as well. Typically 10-15 minutes or so, at threshold power, but at around 45-55 rpm instead of my usual 90 rpm. Often followed by a slightly shorter high-cadence (115-125 rpm) interval at the same power.
Interestingly, and somewhat surprisingly, average HR for three equal-length intervals at identical power, but at 90, 50 and 120 rpm respectively, was within 1-2 bpm of each other!

Carbonfiberboy 

That is interesting. I think it shows you are a very efficient pedaler. Good on you!

CdCf

BTW, this is the ergometer I train on (not mine in the vid, of course):

koffee brown

Just cause I'm lazy, I'm gonna skip the other answers and just say God no! The long warm up is so you can spin your way up to that threshold... then you spend the 20 minutes spinning at that heart rate. That's pretty much the gist of the 2 x 20.

koffee