Good question! I’ve noticed more variability in heart rate at Zone 2 than at higher intensities.

e.g. for sessions when the breathing test and virtual power on the rollers suggest I’m at zone 2 I’ve seen heart rates anywhere between 135 and 145.

But ultimately if Z2 is all about measuring work done by muscles then that’s just a measure of power isn’t it? Heart rate is secondary.

I would try to get better at RPE but it just seems so dependant on external factors like motivation/mood/temperature etc.

HR is affected by other things not just getting oxygen to muscles. It drifts upwards during the session, for starters, and could be affected by ambient temperature probably and what you’ve eaten or something.

I think that’s the biggest (only?) revelation in what drISM has been saying…
On the days you are really pushing your z2 on, you need to be at the “talk test” rather than an arbitrary percentage of either HR or power.

Then power just helps you see your progress (you’ll be pushing more watts at the same lactate) and your HR will probably not change too much but you will see your decoupling (how far apart your power and Hr become over time) improve.

But ultimately- you can do his protocol with neither power or heart rate data just as effectively 👌🏻

you need to be at the “talk test” rather than an arbitrary percentage of either HR or power.

My fundamental issue with this is how inaccurate I think the talk test is. I’ve even found myself wondering if singing is different from talking? does it matter how loud you are talking? what about talking to yourself, is that different because there are no pauses while the other person speaks?

I’m sort of joking but sort of not, I don’t like the talk test, was really hoping there was a more repeatable, accurate alternative.

For me though, I think the benefit of Z2 will always be that I’m not panning myself in midweek then getting sick or injured, so long as I’m reasonably close to Z2 without going over I’ll probably be doing well.

That’s it- to be honest it’s more important as a cap than an absolute.

I find I get to know my talk test / ease of breathing through nose levels and HR level match up pretty well and from there I work to that level or just under – you have good or bad days, you have higher HR a day or 2 before getting ill, HR does change Vs output after 3hrs or so at steady Z2, etc. But all in all, agreed, it’s mainly about keeping a lid on it 80% of the time so you can go all-out the other times, which seems to be an effective way to be quicker.

But ultimately if Z2 is all about measuring work done by muscles then that’s just a measure of power isn’t it?
Heart rate is secondary.

I thought Z2 was more about O2 demand level and thf HR and breathing rate were more of a guide than muscle power output on that day. Could be over-simplifying or wrong though.

So following on from my preivous post… I upped the wattage from 185 to 200w, and held that for an initial 60 min.
It seems that’s the wattage required to keep my HR in zone 2:

Will up the time to 80 min, then 100, then aim for 120 min…

Needs a good film, tbh!

DrP

You don’t know what your Z2 is in power or HR without a lactate test.

You also can’t really ride to it without a power meter. You can find yourself punching out extra efforts without seeing your HR change much, but as above that would be affecting the oxidative stress on your body and making it a different workout. If you’ve never used one you will be astonished at how hard it is to get your effort down to z2 on a climb and up to z2 on a descent.

You don’t know what your Z2 is in power or HR without a lactate test.

True I guess…but you can, like the vast majority of the population, figure out that you likely sit somewhere in the middle of a bell-shaped-curve of likely power and heart rate bands…

DrP

Well, I have to say that I’m really looking forward to racing against folks that have spent all winter doing 7hrs of ‘zone 2’ + one interval session per week…

Good luck all!

Lolz @Jamz 🤣🤣

I feel absolutely amazing on it to be fair. Even got away in a zwift race last night. Big attack and then just ‘made it say 400’ until the gap was 8 seconds. Ended up averaging 330w for ten minutes until I got caught.
That was after an hour ticking off route badges beforehand and 90mins on the mountainbike at lunch time.

The other day I averaged over 300 in a 55min race… at low tempo HR!

It’s partly just insane levels of freshness but also you can feel yourself coping with the lactate. The blocked legs never arrive- your HR just keep going up instead.

Looking at intervals.icu I’m on 72% Z2 or under for the year so could afford even more Z2 yet.

I’m looking forward to starting a sweetspot progression next Spring (goal is 2h @ 300w) but summer is a looooong way away so I’m also determined to stay patient.

Means I can lose weight too- 10lbs and counting…

Well, I have to say that I’m really looking forward to racing against folks that have spent all winter doing 7hrs of ‘zone 2’ + one interval session per week…

😂

To be honest 7hrs + 1 interval session a week is currently about 3 extra hours over what I manage now, so I’d probably be flying!

Although 7hrs + 1 interval session isn’t really 80/20, if you’re doing 8hrs a week that’s time enough for 2 interval sessions 😎

There is some debate over whether it’s 80/20 by sessions or time in zone 😉

I’m pretty sure Seiler’s original description was sessions….

I had my “beginning of season” meeting with my coach today and he laid out in an evidential way how zone 2 had allowed me to catch up with people of very long durations by maintaining or recovering back to circa 200w for much longer than they can, then add the cherry on top. For example, the national 12h within which I came 9th I averaged 196w over 10:25 of actual pedalling, with a “power on” average of 231 w which is low Z3 for me.

For ’23 for a change / rest / because the Marathon scene seems to be fraught with cancellations I shall be having a bash at XCO, and while this means intensity starts early, he then showed how training in Z2 will support higher efforts and be “stronger for longer”.

Hences, 2.5 months of Z2 work incoming….

@crosshair … 2 hours at 300 watteroonies is impressive! Whacha weigh dude?

DrP

Too much 😭 🤣 Down to 94kg at the minute…

I’ve dabbled a little bit with zones and stuff, having always raced by feel in the past and done well. I do a 6 week training plan before a race that has a lot of zone 2 stuff, often at high cadence.

What exactly is the point of it? Is so much zone 2 work really aimed at people who are not particularly fit and need to get fitter, rather than people who are already race fit? Is it meant to be rest day stuff (although I’ll admit it does feel like my legs have had a work out)? Active recovery?

When I’m not doing the training plan almost all my training rides are just reasonably hard rides with the odd interval and that’s always got me up the front at races in the past.

@munrobiker I suppose you could call it non-specific aerobic conditioning. Whatever level you are at, the idea is to try and move your aerobic threshold higher. Basically make your Diesel engine bigger.
However.. the fitter you are, the more of a stimulus you will need to progress. For world tour road pro’s, that could mean multiple 6/7hr rides a week during the ‘base’ season when they are looking to nudge that aerobic threshold up a small amount.
Likewise, a type 2 diabetic with obesity may only need 3 brisk 30 min walks at zone 2 to see massive gains.

If you are able to maintain a large enough aerobic base on your current training program then there may not be much benefit to changing what is working.

However, you may find that by switching to doing less generic intensity, you can smash your odd interval session much harder. So you get gains at both ends. (Aerobic gains by upping your weekly volume of diesel work and Vo2 Max gains by being fresher when its time to whizz the turbo!)

Active recovery should be sub 1h and really easy but I do sometimes alternate long Z1 sessions with harder Z2 sessions.

Is so much zone 2 work really aimed at people who are not particularly fit and need to get fitter, rather than people who are already race fit?

No. See: Pogacar 😎

But also, I guess if you’re already race fit then you possibly already have a big aerobic engine so could maybe spend more time developing the high end? Or like Crosshair says, maybe you’re doing more Z2 than you think because you’re already fit?

Either way, the point for me is still being able to do worthwhile structured training without smashing hard sessions all the time, I’m currently nursing a minor sniffle after 3 week’s Bronchitis, and now Norovirus is doing the rounds in our 5 year olds school, it pays not to be constantly recovering from hard training sessions!

I also did all my indoor sessions last week at Z2, so when I got out on the gravel bike at the weekend I pootled along at Z2 for an hour or two (call it an extended warm up to the coffee stop) then got to play segment chasing and pushing hard on the muddy bits on the way home. So the benefit of Z2 indoors for me is that I can save the hard efforts for the fun bits outdoors. Win-win

suppose you could call it non-specific aerobic conditioning. Whatever level you are at, the idea is to try and move your aerobic threshold higher. Basically make your Diesel engine bigger.

This x 100

For me I wasn’t very efficient and would often bonk on rides (from my post earlier in the thread i was awful at utilising fat) . I realised if i needed to race i need to improve this area. My weekly training plan would change as this area improved and i did less and less of zone 2 specfic training. I guess it also depends on your physiology how well you respond to training.

Since we’re making car analogies, your body is more like a hybrid car, with a diesel engine and an electric motor as well*. You cruise along using the diesel engine but it’s only got so much power – when you really boot it the electric motor kicks in. But the batter’s not that big so it drains quickly.

Training can improve the efficiency and power of either or both motors but it’s far better to train one at a time. If your diesel engine becomes more powerful you can go faster before needing the electric motor, so for a given pace you can go further before the battery runs out; or for the same amount of battery usage you can go faster because your total power is the sum of both motors.

Now the thing often overlooked is that we’re born with different diesel or electric motors, and different training potential for each. And the way we choose to ride when we are just riding for fun affects the training each one gets. If you’ve got a naturally powerful diesel engine but your electric motor is trainable, then you may end up with a good profile that matches your preferred racing with your preferred riding. Other people may really need to focus on one thing because it’s weak but trainable. But other people (like my mate) might be all diesel, so trying to train the electric motor is a waste of time.

I’m a sprinter (mostly electric) genetically, and like Trickydisco I was terrible at burning fat aka diesel until I did some base training.

I’m doing more now, having neglected it for many years, and my RHR has dropped in the last few weeks. And I can ride every day without being fatigued if I stick to z2.

* actually it has diesel, electric and one of those flywheel systems for small amounts of instant energy but that’s not that relevant unless you are a track sprinter, really.

I tried. I’ve done 4 Z2 this week and an outdoor, but today I had to play at short circuit racing. It’s so much more fun

That’s perfect then. Nobody said don’t do any intensity 😀

and one of those flywheel systems for small amounts of instant energy but that’s not that relevant unless you are a track sprinter, really.

Or ride like Bernard Kers…

DrP

IGMC

Isn’t zone 2 training for people with lots of spare time like the pros?

I use sweetspot training with a longer ride and indoor HIIT session instead as I’ve not got the time for zone 2 (well not enough that I think would make a difference).

A 1 hour Sweet Spot focused workout (.9 IF intervals) produces 69 TSS, or roughly 30 TSS/hour more compared to Zone 2. Said another way, Sweet Spot training can produce roughly 40% more training stress per hour compared to Zone 2 with similar physiological changes and benefits

Reference:

Sweet Spot vs. Zone 2 for ⬆️ Aerobic Capacity

I’ve not got the time for zone 2 (well not enough that I think would make a difference).

I’ll let you know. I’m attempting to do at least 90 mins per day this week. I spend more time than that pissing about on the internet so I think I can fit it in.

Re that sweet-spot article.. interesting, because the Zwift races and TTTs I do constitute about 40 mins in that sweet-spot, as long as I don’t go for the sprint points.

To be honest- I find TSS to be a bit of a con job because the calc is based on NP which, as Mr Blobby of this parish always says to me- is technically made up nonsense 🤣🤣

The other benefit of staying in zone 2 is that you don’t stress the autonomic nervous system in the same way as you do when you cross that aerobic threshold. So a Sweetspot workout imparts the same physiological stress as if you’d done vo2 intervals.

So.. if you look at the work you are doing in kj’s (Ie a product of the straight average power not NP) the amount you burn for a sweetspot interval session (which will include a warm up, cool down and recovery intervals) won’t be massively more, if at all than for a high Z2 session. (DrISM Z2 is probably low tempo watts for a well trained person at Z2 HR).

So put another way, if you have 8 hours and five sessions a week to train, you are better off doing the maximum aerobic work you can do without triggering the high level stress for 4 of those sessions and then when you do decide to add stress- make it really high quality, high power stress.

Sweetspot is muscular endurance rebranded as an aerobic hack.

Note/ in that article I think he deliberately leaves the KJ field blank in the illustrations 😉

As my slightly contrived but indicative illustration shows…

OP here

Some very useful contributions to this thread, so thanks all!

I’m still injured, so not getting outside as much as I’d like but I have been doing Z2 sessions on the turbo but was finding it difficult to keep in Z2. The efforts seemed very low and I’d usually drift up into Z3.

Anyway, somewhere up thread, someone mentioned crickles.casa so I connected that to my Strava account and crickles calculates my HR zones quite differently (higher) than the usual 50/60/70/80/90% of max HR. Consequently, when I thought I was straying upwards into Z3, I was still in the crickles Z2.

I’ve now adjusted my Garmin/Strava to use crickles values and I’ll try a few more Z2 sessions this week to see how it goes.

Anyway, I did manage to ride outside yesterday and can’t say I felt any better for two weeks of Z2 work (and minimal high intensity stuff) but I am curious about the fat burning potential of Z2 work.

Throughout my life (I’m 59), I’ve been fortunate to be able to eat what I like and not put on any weight. But in the last few months I’ve developed a pronounced gut which I’d like to shift (Ideally I’d convert 2kg of gut into 2kg of muscle mass in my shoulders, arms and pecs 😃).

So…given I ain’t gonna turn fat into muscle, will Z2 work actually burn off fat that Z3/4/5 won’t? Or does it follow that, for instance, a 30 minutes Z4 session will burn off the same amount of fat as a 60 minutes Z2??

(Going back to my original post, I tilted the saddle down slightly and now use Vaseline as a chamois cream and that has drastically reduced the “painful” element of being sat in the same position for a long time. My mind seems to have adapted to watching Netflix so the “boring” side seems more tolerable as well – though having done Mt Ventoux on Zwift once, I’m pretty certain I don’t have the fortitude to do multiple hours on the turbo anymore)

So put another way, if you have 8 hours and five sessions a week to train

In my book that’s not time-crunched!

can’t say I felt any better for two weeks of Z2 work

Base training takes a lot longer than that. Couple of months to see results I reckon.

@vlad_the_invader

That’s got to be one of the biggest minefields on the internet 🤣

Ultimately a calorie deficit is what burns fat…

At higher intensity, you are burning some fat still but fat max peaks even lower than Z2.
The problem is, even with a big FTP, it’s not massive kj’s we’re talking about in short sessions.
140w for an hour is 500kcals. So you’d need 7 hours of that to burn 1lb of fat even if you were running on 100% fat….(which you wouldn’t be).

Longer, un-fuelled endurance work is a massively helpful tool for me to burn fat at the moment but some people are the opposite and find that leaves them starving.

@molgrips The point still stands at lower weekly hours… as ISM said with Peter Attia- stress is stress. If you’re time crunched you’re likely already in a highly stressed state many days of the week so it’s perfectly possible to be overtrained on single digit hours.
Basically- Sweetspot is all the bang stress wise (as one of the best interval sessions like 30/30’s or 4×8) for not much buck.

will Z2 work actually burn off fat that Z3/4/5 won’t?

Ultimately a calorie deficit is what burns fat…

Hmm I don’t think it’s even that simple, it’s the appropriate hormones (glucagon?) that cause fat to be converted into glycogen, and those hormones might be released by certain exercise.. it’s pretty complicated and it depends on you a lot. A calorie deficit might result in low glycogen stores which stimulates appetite or makes you tired.. I mean there’s a lot of things that need to be balanced. And many ways to balance them.

But otherwise you’re right – the point about Z2 is that you might burn up fewer calories overall, say 25% fewer per hour, but you can do it (and really you need to be doing it) 3-400% longer. I can do a 4hr ride at 200W, about 90 mins at 250W on a good day, and about 30 seconds at 400W so clearly 200W is better for burning more calories. The relationship between duration and power isn’t linear.

For losing mass, I find longer fasted easier rides (at the weekend) are more effective than shorter higher intensity rides (normally in the evening).

Also I can be ravenous after an evening sweetspot/hiit session where I’m only mildly hungry after a weekend fasted morning ride 🤷‍♂️

That’s the thing for me- I have to get glycogen depleted to lose any fat. Otherwise I just go up and down over about a 5lb range.

And then when I do eat carbs, my body grabs hold of them for dear life 🤣
Did Brass Monkeys yesterday on 100g carbs/hour, still left a 750kcal deficit for the day but I put on 1.5lb this AM thanks to wheetabix and all that rocket fuel 🤣🤣

I have to get glycogen depleted to lose any fat

Yeah. Being glycogen depleted raises glucagon which then promotes lipolysis. I find that I can go low carb for a couple of days early in the week, then when I start to feel crap I can eat more carbs, and do more exercise but still be not be at 100% and weight loss continues. But it’s a very fine line and I’m mostly playing a guessing game based on feel. I could try pee sticks though – apparently lipolysis produces ketones which can be picked up, so you can get an idea of how much fat you’re burning, in theory.

I can’t seem to eat enough for long easy rides, massive bowl of porridge for breakfast then the first hour or so unfuelled then approximately 60-90g carbs for the remaining 2-3hrs.

What I notice most afterwards is extreme crankiness and that slight feverishness I recognise from really long rides.

But if anything Z2 should leave glycogen reserves intact?

No, if it’s there (exogenous carbs)- your body will use it.

Try one relatively fasted. My hunch is that you’ll be amazed how un hungry you are (assuming you stay disciplined).

I built up to 6hr easy fasted rides last year. Only 150w so 3000kjs. Felt fine.

https://strava.app.link/XFDyk56ykvb

I can’t seem to eat enough for long easy rides

Oh now that’s weird, I find I don’t really need to eat that much. I can do (and did yesterday) 3 hours on 2 scrambled eggs.