Eight hours. That's what most serious amateurs actually ride in a winter week. The zone-2-only base model everyone follows was built for professionals doing 25-30. At that volume, pure zone 2 generates an enormous aerobic stimulus — mitochondrial density, capillary development, fat oxidation — through sheer accumulated hours. At eight hours, you're generating a third of that stimulus while your VO2max quietly erodes, your threshold power drops, and your neuromuscular snap disappears. Every spring, those same riders spend six weeks doing intensity work just to get back to where they were in October.
Professor Seiler's polarised model — the research most commonly cited to justify all-zone-2 winters — actually includes high-intensity work year-round. The 80/20 split means 20% of sessions are hard, even in base phase. That's not a footnote. It's a core finding. The common misread of his work has left thousands of time-crunched amateurs slowly detraining every winter while believing they're building a foundation.
The modern approach keeps zone 2 as the base but adds back controlled intensity — one sweet spot session, a short VO2max touch every 10-14 days, and twice-weekly strength work off the bike. The best coaches have been doing this quietly for years. The science now backs them up completely.
Where the traditional base model came from
The all-zone-2 winter base has its roots in professional cycling from the 1990s and early 2000s. Teams would send riders home in October with a simple instruction: ride easy, ride long, and don't touch intensity until January. Build your aerobic house before you start putting in the furniture. It was periodisation in its purest form, and it worked — because those riders were clocking 20 to 30 hours a week in the saddle during that base phase. Twenty hours of zone 2 generates an enormous aerobic stimulus. The mitochondrial adaptations, the capillary density, the fat oxidation improvements — all of that comes with accumulated time at low intensity. When the volume is high enough, the intensity takes care of itself.
The problem started when that model filtered down to the amateur world without any adjustment for the single most important variable: time. A professional cyclist doing 25 hours of zone 2 per week accumulates roughly 1,500 kilojoules of training stress every day. An amateur doing 8 hours of zone 2 per week accumulates maybe a third of that. Same model, fundamentally different stimulus. Same prescription, radically different response. You're following a recipe designed for a restaurant kitchen while cooking on a camping stove, and wondering why it doesn't come out the same.
What Seiler's research actually says
Here's where it gets really interesting, because the person most often cited to justify the all-zone-2 winter is Professor Stephen Seiler — and his research says something quite different from what the internet thinks it says.
When I had Seiler on the podcast, one of the things that struck me was how clearly he framed the polarised model as a year-round distribution, not a seasonal one. The 80/20 split — roughly 80% of sessions at low intensity, 20% at high intensity — applies across the entire training year. Not just race season. Not just the build phase. The entire year. That means even in base phase, one in every five sessions should be hard. Not medium-hard, not grey zone, but properly hard.
The common misinterpretation goes like this: Seiler says train easy most of the time, therefore winter should be all easy. But that skips the second half of his finding. The polarised model works because of the contrast between properly easy and properly hard. Remove the hard end entirely for three months and you haven't created a polarised plan — you've created a monotonous one. Seiler's published data shows that athletes who maintain the 80/20 distribution year-round outperform those who periodise intensity away during base phase. The distribution is the method, not just the seasonal starting point.
Let me be really clear about this: nobody is suggesting you race through winter. The intensity in base phase is reduced in total volume, it's controlled, and it serves a different purpose than race-phase intensity. But it's there. Always there.
How the best coaches handle the off-season
If Seiler's research is the theory, the application comes from the coaches working with the best riders in the world. And not one of them eliminates intensity in winter.
Dan Lorang, who has coached Grand Tour champions, structures the off-season with what he calls maintained stimulus across all energy systems. He reduces the total volume of intensity work, and he reduces the number of hard sessions per week, but he keeps a small dose of VO2max and threshold work in the programme throughout the winter months. His reasoning is simple: it takes weeks to rebuild an energy system that's been allowed to fully detrain, and those weeks are wasted time in a preparation that should be building forward, not rebuilding backward.
Tim Kerrison took a similar approach at Team Sky and later Ineos. The base phases he designed for riders like Froome and Thomas included structured intensity from the start — sweet spot work, controlled threshold efforts, neuromuscular activation. This wasn't the old model of easy miles until January and then ramp. It was building every system simultaneously, with the proportions shifting as the season approached. The foundation was still aerobic. The majority of time was still low intensity. But the intensity was there from day one of the off-season.
When I had John Wakefield on the podcast, he talked about how Bora-Hansgrohe programme their winters. Same principle. The riders take their break, they come back, and from the first structured week they're doing some form of high-end stimulus. Not a lot. Not race-specific. But enough to keep the engine ticking over at the top while the base rebuilds underneath.
And Joe Friel, who wrote the book that most of us started with — literally, the Training Bible — has evolved his own position on this over decades. In his later writing, Friel acknowledges that the traditional base-then-build periodisation model works best when volume is high. For the time-crunched athlete, he now advocates introducing intensity earlier in the preparation than he originally prescribed. That's the pioneer of cycling periodisation telling you his original model needs updating for riders who don't have pro-level hours. Worth listening to.
The modern base training prescription
So what does a modern winter base phase actually look like for someone riding 8 to 12 hours a week? Here's the framework.
Your foundation is still zone 2. Sixty to seventy percent of your training time should be genuine zone 2 work — and I mean genuine, not the grey zone most riders default to. If you can't hold a full conversation, you're above zone 2. If your heart rate is creeping into the mid-zone-3 range, you're above zone 2. This is the base-building work, and it still matters enormously. Mitochondrial density, capillary development, fat oxidation, cardiac efficiency — all of this comes from accumulated time at low intensity. Don't mistake "add some intensity" for "abandon zone 2." The aerobic work is still the house. Everything else is the furniture.
Once a week, you do a sweet spot session. Two blocks of 20 minutes at 88 to 93 percent of FTP, with 5 minutes of easy spinning between them. Warm up properly, cool down properly, and the total session runs about 90 minutes. Sweet spot sits just below threshold — hard enough to maintain your muscular endurance and teach the body to hold sustained power, but not so hard that it requires the recovery cost of a full threshold workout. This is the session that stops your FTP eroding over the winter. Without it, you lose the ability to hold power for extended periods, and you spend weeks in spring rebuilding something you already had in October.
Every 10 to 14 days, you add a short VO2max touch. This isn't a full VO2max block — it's a maintenance dose. A set of 30/30 intervals — 30 seconds hard, 30 seconds easy, repeated 8 to 10 times — or three sets of 3-minute intervals at 110 to 120 percent of FTP. Short. Sharp. Over in 20 minutes of actual work. The purpose is to keep the top end of your aerobic system from fully detraining. Your VO2max is the ceiling of your fitness. Let that ceiling drop and everything below it compresses — threshold drops, sweet spot drops, your ability to respond to surges on a group ride drops. A small dose every two weeks keeps that ceiling where it is.
And twice a week, you do strength work off the bike. This is the time of year when strength training pays the highest dividend, because your training load on the bike is lower and your body can absorb the gym stimulus without competing with high-volume riding. Goblet squats, hip thrusts, single-leg work, core stability — the compound movements that build force production and injury resilience. When the intensity ramps up in spring, you'll have the muscular foundation to handle it. Skip the gym now and you're trying to add strength during your build phase, when the bike load is already high and the body has less capacity to adapt to both.
A sample winter training week
Let me give you a concrete week so you can see how this fits together for someone on 9 to 10 hours.
Monday is rest or an easy 30-minute spin. Nothing more. Recovery is not optional — it's where the adaptation happens.
Tuesday is your sweet spot session. Warm up for 15 minutes with a few openers, then 2 sets of 20 minutes at 88 to 93 percent of FTP with 5 minutes easy between them, then cool down. Total session about 90 minutes.
Wednesday is a zone 2 endurance ride, 75 to 90 minutes. Properly easy. Conversation pace. Stay below the ceiling.
Thursday is strength training, 45 minutes in the gym. Compound movements, moderate to heavy load, focus on quality.
Friday is rest. Full rest. Not "active recovery." Rest.
Saturday is your long ride — 2 to 3 hours of zone 2, outside if the weather allows, on the trainer if it doesn't. This is where the aerobic volume accumulates. Fuel it properly.
Sunday rotates on a two-week cycle. On week one, it's an easy 60-minute spin plus a second strength session. On week two, it's your VO2max touch session — a short set of 30/30s or 3x3 minute intervals after a thorough warm-up, then easy spinning, then strength work if you have the time and the legs.
That gives you roughly 9 hours of training in a week, with the proportions landing close to 65% zone 2, one sweet spot session, a VO2max touch every other week, and two gym sessions. Every energy system is being maintained. Nothing is being abandoned. And the total load is low enough that you're recovering between sessions, building rather than digging.
What happens when you skip the intensity
You know the rider who does 12 weeks of nothing but zone 2 over the winter. You might be that rider. I've been that rider. Here's what happens.
Your aerobic base improves. Your fat oxidation gets better. Your cardiac efficiency ticks up. All good things. But while those systems are building, everything above zone 2 is quietly eroding. Your VO2max declines — studies show it can drop measurably within four to six weeks of detraining. Your threshold power slides because you haven't asked your body to hold sustained hard efforts in months. Your neuromuscular snap — the ability to respond to surges, close gaps, kick over the top of a climb — dulls because the fast-twitch fibres haven't been recruited at high intensity.
Then February arrives. You start adding intensity. And you spend the first three, four, five weeks just getting back to where you were in October. You're not building on your autumn fitness — you're rebuilding it. All those weeks of pure zone 2 didn't create a platform for growth. They created a platform for catching up.
The amateur who maintains a small amount of intensity through the winter skips that rebuild entirely. When February arrives, they're ahead. Their aerobic base is strong because they spent 65% of their time in zone 2. Their threshold is intact because they did sweet spot once a week. Their VO2max is still in the ballpark because they touched it every two weeks. They start the build phase by building, not by recovering lost ground. That's the difference, and over a full season it compounds.
The principle that ties it all together
Winter is for building. Nobody disputes that. But "building" doesn't mean building one system while letting the others decay. It means building all your energy systems proportionally — more aerobic work, yes, less intensity, yes, but never zero intensity. The proportions shift. The emphasis shifts. The total load drops. But the principle of maintaining the full spectrum stays.
This is what Seiler's data supports. It's what Lorang, Kerrison, Wakefield, and Friel all converge on from different directions and different contexts. The best coaches in the sport don't eliminate intensity in winter because they've seen what happens when they do — they spend weeks in spring undoing the damage. The modern approach is more efficient, more effective, and more forgiving of the limited hours that amateur cyclists actually have.
You're not a pro with 25 hours a week to pour into zone 2. You don't need to train like one. What you need is a winter that builds your aerobic base without sacrificing the fitness you've already earned. Keep zone 2 as your foundation. Add one sweet spot session a week. Touch VO2max every two weeks. Get in the gym twice a week while your bike load is low. Come into spring ready to build, not rebuild.
That's the modern base phase. It's not complicated. It's fixable. And the riders who adopt it stop losing three months every winter to a model that was never designed for them.
If you want the structure, the coaching, and a community of riders who are serious about getting faster — the Not Done Yet community on Skool is where we put this into practice. Structured plans, weekly calls, and a group of cyclists who are done guessing.