Z2 training, optimal time, power vs HR

As I approach my last race of the season in 2 weeks (unless I race CX), I have been thinking of how to best optimize my training in the offseason (October to May). I have a trainer and trainer road but no bikes with power meters (hope to have at least one for next spring, its a priority but I’m a student). I feel rides beyond 60km, usually leave me fatigued and my power decreasing, despite my best efforts I start off too hard for a pace for long distance rides. I have done several rides ~150km but generally with 3 stops or so at like 70k, 100k, 130k (likely would be better to stop earlier, like at 50k, 90k and 120k).
What I wonder is if I should instead limit these Zone 2 endurance rides to distances I can do without stopping ~100k? I wonder if given the fact I need to stop to do the >100km efforts if I am wasting my time a bit and would be better off just doing 100km efforts with no stops.

Or as I don’t have a power meter should I try to do these on the trainer instead, to try and work up to 3 hour workouts. The longest trainer ride I have done so far is 2 hours, Boarstone -2 and I completed that without stopping but my road races are often around 2 hours so probably need to go longer to get the Zone 2 development.

Any suggestions or thoughts, I think I am both FTP and stamina limited and its made me hesitant to move up to the next Cat of road racing despite podiuming every road race I did this year (hoping to win the last one). I’m concerned that as the distance goes from ~60km to ~80kms I will get dropped from the group in the higher category. Generally on tough group rides, we will get past the 60km mark and I will crack in a spot like a railway track crossing or corner followed by a climb, when I need to surge to get back on the paceline and my legs have just lost the snap necessary to bridge that gap.

I’m planning to continue doing Low volume adaptive training in the off season with either a hypothetical May rolling road or xco race to keep Adaptive Training running. But not sure how I should approach supplemental Z2 work, whether on the trainer or outside or both.

I think the goal is to have the stamina and durability to do workouts like Boarstone +1 with late sprints Log In to TrainerRoad and Ochoco 2h30mins at 0.69 IF (which is probably more work than I would do in a 4 hour ride with stops or a 3 hour ride without stopping) Log In to TrainerRoad

I look at it in 1 month training blocks for Z2. I do maybe 3 months of fairly repetitive Z2 rides. I’ll build distance/time/TSS a little more each week. I think the prescribed increase is no more than 10%/week but, I’m honestly not sure. Someone will chime in and give a reference. Point is start with a weekly amount you are comfortable with and build on that.

As far as power vs. HR don’t over think it. Z2 is perfect for HR. You can track your drift and see when decoupling occurs. Look up decoupling if you are unfamiliar. It’s a great way to track aerobic fitness (capacity).

As far as trainer vs. outside…I’d go crazy and have gone crazy doing Z2 on a trainer. I use the trainer to supplement high intensity. People do Z2 on the trainer and nothing wrong with it. Huge point here is to stay motivated. If you are more motivated outside do it out. If more motivated inside then do it in. Or some combination. Just need to keep your eye on the work and your build progression.


Going off HR or even RPE is totally sufficient for Z2. Definitely don’t need a power metre. In terms of running out of steam what’s your nutrition/hydration like?

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When you say increase 10% per week, is that TSS or time or either sorta thing?

Will have to get a new battery for my ticker to watch for the decoupling it seems to make a spotty connection with my laptop at times so don’t trust it and on the bike can’t really correlate with power. I’m guessing I would also need to do like a long continuous tempo ride on the trainer to see this perhaps? Right now I’m 2 weeks out from my final race, an A race so its all VO2 and Anaerobic so probably tough to assess?

I understand the time spent on a trainer doing zone 2 with continuous pedalling is going to be more productive than Z2 outside with occasional coasting around corners, stopping at lights/stop signs etc but is there anything that would help me determine a sort of equivalency between the two?

I’m ~57kg and shoot for ~55-80g of carbs per hour, usually a mix of liquid and solid to achieve that. On the trainer I’m a bit more restrictive generally 50-70g per hour, also a combo of liquid and solid.

Drink every 8-15 mins depending on length and intensity and start eating solids 30-45 mins in and then every 30 mins after that.

On some of these competitive group rides though where I am hanging on for dear life, it can be harder to drink and eat however so may contribute to the cracking as these groups are at a higher intensity than my races as the majority of the riders are Cat B or A and I am generally the only Cat C in the mix (change the letters to 1, 2, 3). I do much better drinking and eating during races, on the trainer or riding on my own.

Either way I’m only now just finishing my second season of riding road and have only been using trainer road and training with power for 4 months now so should have lots of room to grow and probably don’t have much of a base developed.

I need to check. 10% actually seems like a lot no matter what your tracking. Point to keep in focus is do more work than the previous block. I’ll look for a reference…

Besides NP, TSS or Kj’sI’m not sure (you don’t have these w/o power). But even if you did
those don’t match if you’re stopping every few minutes for stop lights vs riding on a trainer. You may need to drive to some open roads or suck it up on the trainer. I do know the occasional stop or coast isn’t much to worry about. The big thing I see with new riders is they go way too hard up any grade and way too easy down. They start from stoplights way too hard as well.

I definitely have a hard time keeping my HR in the 130s range with climbs steeper than 5%, generally see it get up to 150s even when trying to take it easy.

Going by Strava trying to compare some outdoor rides and trainer rides
Boarstone -2 0.6 IF for 2 hours, Boarstone had me with an avg HR of 120, peak of 133, 905 kj of work.

My 2 hour ride yesterday outdoors, avg HR 125, max 155, estimated by strava to be 1060kj (this was also my 7th activity of the week).

My recent long ride 5:36 moving, 6:18 elapsed, avg HR 119, max 154, estimated 2238kj.

To compare, my most recent road race, 1h32m, avg HR 153, max 172, estimated 1331kj. I felt really strong, as a group of 3 we dropped the rest of the field, I think I could have won but miscounted the laps and rolled across the finish line in 3rd thinking we had another lap to go.

I haven’t been able to get out for many group rides this season but some in the spring where I struggled at times.

2h52m, avg hr 142, max 173, 1526kj

4h1m moving, 4:26 elapsed avg hr 136, max 186, 2241kj

I don’t know if any of this helps to determine what I should be targeting for Z2 workouts, like is Boarstone -2 with 2 hours and 905kj going to be productive or do I need harder and longer?

Is there a kj target I should be looking for with my Z2 endurance rides? Say working up from Boarstone -2 and its 905kj to something with 1000kj, 1100kj and so on?

I also wonder about doing long tempo work like Beard, 2h30m at 0.76 for 1416kj but have also heard that tempo compared to endurance work is overly fatiguing for similar benefit…

I found a ref only for CTL and TSS (3-7TSS/day per week) but, there is no ref to what phase of training. I’ve always assumed base/build…

I think 10% increase each week based on time or distance is probably ok. But you need to
understand where an appropriate start point is. Try searching periodization. Even if you don’t find a specific ref you’ll real a ton of good info. For example, if I start at 10 hours/week for the 1st week add 1 hour/week for the first meso block. So, basically 10, 11, 12 then rest week of 6. 2nd meso block would be 11, 12, 13 then rest week of 6.5 etc…for yo u starting at 10 might be too much. Maybe too little. IDK 3-7 TSS/day/week would be in the 10% ballpark…

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Well, it looks like 125-ish is a good Z2 HR so progressive overload using that.

I hesitate to talk about Kj’s. It just muddies the water. I have been using it more and more over the years to understand fueling for long rides/races to try and be strong late in the race. I think you should stick to being pretty simple and not get overly complex. I think it good to have an idea of what Kj’s you are doing though and how you perform at 1000 or 2000 or 3000. Fresh FTP makes for good bragging but, FTP at 2000, 3000 Kj’s is where races are won…

I think tempo work is amazing but, only after a good dose of base (Z2). This is for me though. Many guys get really hung up on thinking Z3 is grey area do to the polarized debate or misunderstanding that keeps cropping up. For me, I max out at 20 hours/week for a high volume week. Temp here would be counter productive. But, I do a lot of tempo/sst when the volume is less or when I have a week with lots of work.

But, even if you have all the time to train, tempo is essential IMO. This would be for races of 160km or less. I can’t speak for distances longer or weekly volume of greater than 20 hours.

There have been some good answers already, but I’m going to answer from my individual perspective because it may be similar to yours: I’m also a young student who was getting dropped in races. My self assessment was that I had a lack of noteworthy endurance.

  1. A little bit of background:
    I am now winding down my third season on the road bike (season equals summer time for me here in Germany). I used to smoke and drink heavily during the first four semesters at University, when Covid-19 hit I decided to change that.
    My first “season” was 2020 when I bought a gravel bike. It essentially was noodling around, even though I had tons of fun.
    Second season I bought a “real” road bike and started doing group rides, later on races. Mainly as hard as possible all the time. End of my second season I blew up hard, too much intensity all the time. After an extended break I decided to educate myself on training methods. Then I started the preparation for my third season with the main goal to build my “engine”:

  2. Off Season/Winter:
    I started Sweet Spot LV in the middle of October with added Z2 rides on two days. This accounted for a weekly volume of roughly 6-10 hrs per week. The volume variation is largely due to the weather: If I was able to ride outside, I did so. This pushed up my volume. If it was raining, I stayed on the trainer. The off-season also established my five day training pattern with two whole days off:

  • Monday: Off
  • Tuesday: Intervals
  • Wednesday: Z2 (shorter)
  • Thursday: Intervals
  • Friday: Off
  • Saturday: Intervals
  • Sunday: z2 (longer)

I added a little bit of strength training and yoga after two of my rides. This approach worked out great for me. I completed a whole base, build and specialty cycle of SS LV until the end of march.

  1. Season/Summer:
    At the end of March I switched to the experimental polarized plans, mainly because I wanted to train outside. I found the simplicity of the intervals made it easier to complete them outside. I used the TR Plans to plan my key interval sessions (1x VO2 Max on Tuesdays and 1xThreshold on Saturday), rest was easy Z2 on my other training days.
    For my endurance rides, I followed Dr. Seilers recommendations: Keep it under 70% of HRMax. I gave myself a little bit of leeway here, so mostly I kept it at 65% of HRMax. I do have PowerMeters and I did use them to double check my Z2 work: I tried to stay under 75% of FTP, but I didn’t freak out if I exceed this for short amounts of time on climbs, just as long as my heart rate didn’t climb above 70%HRMax (which happens quite fast if I push watts over my endurance zone, so it was kind of self regulating). The intervals I did by power, but with the goal to maximise the time spend at +90%HRMax. This was of course depended on the nature of the interval: for VO2Max intervals, the average power and heart rate was higher, but the intervals were shorter. Threshold intervals the other way around.
    I was able to build up to a weekly volume of around 20hrs/week, most of the time spend at Z2. I roughly followed the recommended rest weeks of the TR plans, but because of the simplicity of the polarized approach I was able to adjust my plan to my other life obligations, so sometimes I fell out of that rhythm. However, I didn’t find myself in real need of these rest weeks physically. I mostly credit that to the two whole days off.

  2. End of season/Fall:
    As mentioned in the beginning, im now winding down my season: I am not laser focused on my interval sessions anymore. I’m mainly enjoying my fitness until I take two weeks completely of at the beginning of October. But I am already able to share some main take aways:

  • Z2 is King (next to consistency): With the huge amount of Z2 I was able to accumulate over the season, I just stopped getting tired. I didn’t race this year (mental reasons, mainly fear of crashing out and ruining my summer. I’m working on that), but I set Power-PRs in all durations. But more important: I was easily able to hit my power goals even after 3-5 hour rides. I was also able to repeat my efforts more constantly, for e.g. after 3x16min@100-102%FTP I was still comfortably able to hit my power goal for the fourth interval. Next year im going to be more time constraint, so I will most likely swap out one Z2 session for a tempo/sweet sport ride, but I will have to try out what works for me.

  • No need for anaerobic work: I did not do any short intervals, e.g. 30/30s this season. This comes with two caveats: First, I’m naturally inclined to short efforts. I never struggled to push big watts up to 5min durations, it was after that when it all went downhill. Second, I didn’t race. If I found myself in need to prepare for a race, I might have switched out the longer VO2Max Intervals for 40/20s and the threshold sessions for over-unders a few weeks before.

  • Take it easy at the end: Even though I was quite successful with it, im going to switch out the SS LV plan for a traditional base plan. This allows me to start weight training and add one run per week in the off-season more easily. I will also use Christmas as a break point: Before it, there’s no need to get hyper serous with your training. Winter is long where I live and I found myself quite tired mentally when spring came around the corner. The months after Christmas leave plenty of time to get fit for the outside season.

Sorry for the lengthy answer, but it isn’t easy to fit the learnings of three whole years into a short paragraph. This is also my individual experience, im not a coach. I may or may not have broken every training principle there is, but this approach worked out great for me.

TL;DR: Prioritise Endurance work in the off-season. Slowly build up from the maximal time you can hold your endurance power (or sustain your endurance HR) without stopping to longer durations. The ultimate duration will depend on your goals, for a 80km road race 3 hours of uninterrupted Z2 riding will be a sufficient goal (I guess). Doesn’t matter if it’s inside or outside, as long as you can sustain the effort mostly uninterrupted. The easiest part is to pack on intensity.


So was thinking of increasing the intensity and length of time of zone 2 work extra workouts throughout the winter until maybe as I approach spring I would be doing longer tempo work.

Yeah right now my Strava is saying I have averaged 5h 37min a week over the last 4 weeks so feel like even if I could get that average to 10 hours per week it would make a big difference for me (but not going to start upping the volume until I get past my last road race of the season as my plan is tapering me).

In 2021 I did 290 hours, 57 mins. Hoping to exceed that this year and the big change will be compared to in the past, a large portion of it will be structured training where none of it was in 2021.

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