Polarized Training vs. Sweet Spot (Dylan Johnson video)

IMHO. Both. Track TIZ of your Z1 and Z3 (and Z2). TSS is just a side effect for macro level. Look at TIZ for the workout, and within the workout, the length of the intervals. The progression can be similar to those you see in the SS progression, just much shorter in length. Instead of 20, 30, 40, etc. minutes, you’re probably looking at 5, 6, 7, 8, and multiples of it.

As long as you regard TSS one metric among many, I think you are fine. I would not disregard it, though. I found TSS useful when creating my MV+ training plan, I used them to put myself roughly half-way between the TSS of MV and HV. Since these were very similar efforts, I think TSS between the plans is directly comparable.

Of course, if you follow a different training methodology, you might get different TSS for the same number of hours. Total energy expenditure is another one that is useful at times.

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Yeah agreed - but for me I’d be looking at it mostly as a sanity check, rather than planning to it.

I think this depends also the magnitude of the change - yes, a training block with 300 TSS per week average, when the athlete is used to 600 TSS training blocks, is unlikely to lead to improved fitness (maintenance could certainly possible, and who knows, maybe the extra recovery would provide a boost!).

But if we’re talking 600 down to 500 TSS? I’d be more inclined to think in terms of adaptions. I know it’s not how everyone views their training, but I’d be thinking about what specific adaptions (central? peripheral? muscle endurance?) I’d be getting out of the change in training focus.


Guess we are all different in that. To me TSS is the central factor for holding me accountable. It ensures that I don’t miss workouts. Other than that it also helps me to nail my progression and overall stress.

I think it depends on the athlete. If one is doing 600 TSS weeks productively over extended periods, a reduction in TSS will likely have them plateau. Whether they lose fitness or not will depend on how drastic the reduction is. But as you say from 600 to 500 likely won’t be enough for that.

Other than that I guess the only way to find it out is to give it a try. Perhaps not in preparation for an A event.

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Yes you extend the number of intervals and / or you make the intervals longer. If you’ve retested then the intensity may also go up. Intervals can go anywhere from 30 seconds to 20 mins or so and stay above FTP / in that Z3.

As you progress high intensity in polarized you increase the time accumulated at high percentages of VO2. You don’t need to increase the number of sessions to achieve that.

Similarly with the low intensity. If you’ve been doing 2 hr low intensity rides and want to progress that. Then you’ll look to extend to a 3 hr ride. If you’ve got a limited number of sessions you can do. Then you might combine a 1hr and 2hr session into one.

Having said the above about sessions. I have heard Stephen say that if you want to progress the amount of intensity you can add another session to a day you already do high intensity. So say a morning and evening sessions. What you don’t want to be doing is extending the number of days you stress your body that way.

I’ll add that my experience is that one high intensity session a week plus rest low intensity is enough to maintain Vo2 max / FTP etc. Two high intensity a week is enough to progress.

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I would say POL zones based on RPE (scale of 10)

Zone 1 is 1 to 4
Zone 3 is 7+

Therefore making Zone 2 5 -6

I’ll see if I can reference something that backs these thoughts up.

Edit: Source Highnorth.co.uk
"Ratings of perceived exertion can also be used fairly reliably to estimate the lactate threshold turn-points (Dantas et al., 2015), so it’s also worth also checking your perceived exertion during training sessions to ensure these zone boundaries feel right for you. The low zone should be around a 1-4 out of 10 in terms of effort, the medium zone will feel like a 5 or 6, and the high zone will feel like 7+’

I linked the article in this thread above I think.

Here Polarized Training vs. Sweet Spot (Dylan Johnson video) - #662 by Bbt67

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if you look at hours per week you dont need to worry about tss so much.
15hrs of low intensity riding with 2 good intervals sessions may give you less tss than 8hrs training with 5 zwift races. which do you think is better quality training stimulus? you can do rides/races which generate a ton of tss but don’t stimulate a particular training adaption very well.

fwiw low intensity/z2/polarised riding should actually generate fairly low tss if done right.

I am not saying never look at TSS, but you can apply progressive overload within individual sessions week on week and by tracking total hours/time in zone metrics.

chasing tss is a sure way to burn out imo. you should also check out the concept of minimum effective dose. which is basically about doing the least amount of work to elicit training adaptations. if anything you should be trying to maximise improvements with as little tss as possible!


Completely agree - TSS is a less than ideal metric, but we love a good metric so it’s hard to ignore that and listen to your body instead.

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