So which is best, SS or Z2? Of course this is a ridiculous question but one that we all seem to argue over ad nauseam. So what are we trying to do? Train for a sport where most of the time we’re aerobic with little lactate accumulation right. Within that aerobic state we want to produce as much power as possible therefore be at the very top end of the aerobic state right? SS would make the perfect sense here right? But… as we know, when we’re super fit we can be really close to threshold without too much lactate accumulation and when we’re not fit anywhere near FTP then we’re producing loads of lactate. If our glucose availability is too low then we’ll struggle to produce lactate, if we’re tired we’ll struggle. Take the other side, Z2 is the answer, how much Z2? 20 hours a week? 6 hours a week? Are both these numbers true. What if you’re 20 and have done a massive base already, what if your 50 and work a stressful job? All of this to say that for all of these neat nice sounding zones and theories are all fictions. We have to have some sort of intensity guides to start a discussion about things but zones are just stories we tell ourselves. We pretend we’re being so scientific about it all, 12 minutes at 93% followed by 6 minute rest? Really? That is just total make believe, I guess it’s a starting point and if you’re giving a beginner something to aim for it’s useful but we should all have a little humility and realise that as science-y as it seems with all this nice data, these programs with there specific intervals are a fiction. For me these best guide is a general principle, spend as much time as you can in an aerobic state as high up that aerobic state as possible without the accumulation of lactate and also allowing your body to recover so you aren’t continually suffering burnout. Maybe that’s 20 hours of Z2, maybe it’s 16 hours of Z2.5, 7 hours of SS, SS hours of Z3, I don’t know, only you can tell. Also a day or 2 of intensity…
I totally agree with you.
One hard part is „without burnout“. What may work for one week may not for three. What may work for three weeks may not work for three months. It can because fatigue accumulates or because of an external factor.
There is also the complex model of „fitness“ - however you want to define it. Some training may not directly show improvements in „fitness“ because it takes time.
I think people try to understand and optimize this complex factors.
But the main idea for training is simple (as you stated above).
Yes, it’s all super complex isn’t it, and as you say, when we’re talking about fitness, what are we even talking about!? FTP? duration of FTP, VO2 power, duration of that, repeatability of that? And yes, burnout, you go along fine then suddenly that night of bad sleep followed by not enough carbs 2 days ago and a stressful visit with your parents and you’re done! I think all this points to a pre prescribed general programme having to be the roughest guide in the world the big guide being self awareness both on and off the bike.
Just released today and at least partly related:
that one primary goal of training is to increase aerobic metabolism of the leg muscles involved with cycling. Those muscles require some level of overload and recovery. Zones establish a framework to help with the programming of structured training. Zones also establish a framework for understanding nervous system stress which may impact ability to recover and adapt.
Your cardiovascular system provides a fuel source (oxygen) to your leg muscles. The muscles use oxygen along with glycogen (sugar), fat, and protein to generate energy. The muscles are a mixed fuel machine, with glycogen as the preferred fuel as intensity increases. For a given level of cardio fitness, performance is more directly related to the metabolic fitness of your leg muscles. At higher levels of intensity your cardiovascular might become a limiter, depending on your metabolic fitness. Fundamental cardio and metabolic fitness can be established with a lot of relatively low intensity exercise. How low and how long are specific to the individual.
Where it gets interesting is applying those fundamentals to the question of programming for a specific individual.
I’ll have a look at that. I think a software based approach or AI or whatever is super limited. It’s only as good as it’s inputs, it doesn’t know what you ate, how you slept, how stressful the day was… If you haven’t recovered the only thing it can do is reduce intensity or duration of the next workout and by then you may have recovered already… It’s always playing catchup. When we have software that links up to a CGM, sleep tracker, cortisol, nutrients eaten and energy expended when not on bike then maybe an AI software type approach might work. I think the news of the death of the traditional coach have been greatly exaggerated! For me it’s a pretty straightforward, if I feel good, I push up to about SS, if I feel average, it’s around Z2, if I’m really struggling I just get off. Do that 4 times a week and 1 day of intensity.
Now GCN is getting into the zone 2 game.
Manon Lloyd, former professional cyclist and world champion, who is currently in a detrained state is going to do only zone 2 for six weeks.
It will be sort of interesting to see how far she gets. She’s probably a super high responder and would be kicking all of our butts after 6 weeks of zone 2. 
Saw part of it the other day, this comes across as an ad. Of course if you are detrained and then ride easy for 6 weeks you are going to regain fitness. Some of the easiest fitness to regain, both cardio and metabolic.
Last time I was really detrained, ftp dropped to 190 or 200 (rough estimate). Within 6-8 weeks I was back up to 240 ish, mostly riding easy with a little bit of tempo and some end of ride sprints. And 2 months after that was up to 265 ish ftp. About 80% easy riding, averaging 6.5 hours/week over those ~4 months.
More recently I detrained in November for an off-season break, here are monthly power increases around my lower aerobic threshold (self estimated LT1):
82% easy riding, 16% tempo/SS, and 2% threshold and above.
Averaged 6.3 hours/week. And 4 months later I’m within 5W to where I was for most of 2023 (now: 194W vs 199W for majority of 2023). And I haven’t even started doing vo2 work.
I thought it will be fun to watch a former world champ gain some insane fitness on just zone 2. Everybody will be “see it works”!
I took 8 months off the bike last year - I still ran, rowed and worked out but not 6-8 hours per week. Anyway, I regained 80% of my bike FTP in like 3 weeks and 90% in 4 weeks.
These people might as well be aliens. My former coach was “only” a US pro, and 2 years after retiring, and with limited training did sub-9 hour Leadville 100 (8 hours 40 min) and Steamboat Gravel 141 miles (8 hours and 20 min). Total of 17 hours in 2 days.
I’d be interested to see how this goes. I know at the end of my final year of grad school, all I really had time for was 30-45 minute Z2 runs with some strides thrown in and I was only 2 minutes slower in a local 10k than my best time set 4 years earlier when I considered myself to be at my fittest.
Not to poo poo the other intensities but while sweet spot is important… Z2 is importanter.
First 20 characters, nonsense, one does not exclude the other there is no “or”
Yes it is… so who is aguing it? No one with more than basic knowledge.
PS massive post when the premise makes no sense to start with.
I find it really annoying! I mean, we ride all these hours and do hard intervals and it nets us an extra 5%.
When I took 8 months off, I didn’t even cycle. I rowed 20 minutes a day (zone 2 equivalent) and jogged as slow as humanly possible for about 3 miles per week.
Eh, certainly for some. My FTP is about 25% higher minimum comparing some light aerobic work a couple times a week to real training
Same.
Luckily it comes back quickly for me. I can get into race shape in about 12 weeks, but that’s still far from nothing.