Zone 2 vs VO2 Max Training: Who Wins?

Get Fast Podcast, Ep 179, with Gerard and Jordan Donnelly

Over a few months, high-intensity training on its own can match the gains of a program built on zone 2. Over the long term, the athlete with the zone 2 base wins. That's Gerard and Jordan's conclusion from two TriVelo athletes who made almost identical improvements in their threshold power over a similar period of about 16 weeks, using very different training.

What happened in the case study?

Both athletes were experienced and started out of form, below numbers they'd ridden before. Both improved by about the same amount relative to their body weight.

• Athlete A had more time to train. They did a lot of zone 2 work, plus the key high-intensity sessions and some race-specific sessions.
• Athlete B had less time. They did three high-intensity sessions a week and very little else.

The training time each athlete had is what shaped their programs.

So do you need zone 2 at all?

Gerard's first point is that the comparison uses only one measure. Look at anything else and the two riders are very different.

• Athlete B is good for efforts up to about 30 or 35 minutes. Give them a two and a half hour ride and Gerard says they'd perform "absolutely woefully", because they have no endurance.
• Athlete A would be strong for two or three hours, and has performed very well in events of up to four hours.

Their goals were different too. Athlete A was training for endurance events of two to three hours. Athlete B wanted to get their fitness back and have fun racing on Zwift.

Gerard also suspects that if Athlete B had added some endurance work, their number would have gone up a little further. There's no way to know for sure, and Jordan is clear that a case study like this is anecdotal, with none of the controls of a lab study.

What did the two programs have in common?

• Similar hard sessions. Both athletes' high-intensity work was mostly VO2 max and upper threshold.
• Consistency. Both stuck to their program across the three to four months, even though their volume was very different. Jordan says that if you're consistent, most of the time you'll see good improvement.

Why do the hard sessions matter so much?

To keep improving, you have to train harder than your current level at some point. Gerard's example is a rider whose threshold is 220 watts who only ever trains at 220 watts. Weeks later, they'll ride well at 220 watts and no higher. High-intensity sessions provide the overload that forces the body to adapt, with recovery between them so the load can be absorbed.

Why is training only at high intensity a short-term plan?

Three hard sessions a week is tough. Many people find it harder than zone 2 work, because you're in the red zone every time. Some athletes can handle it, but Jordan says most age groupers can't, and they'll break down or get injured.

Gerard compares Athlete B's program to the 80/20 approach with the 80% taken out: 20% hard and 80% nothing. Athlete A did the 20% hard with zone 2 around it, and came out a more well-rounded athlete.

He calls the high-intensity-only approach unsustainable:

• You can make big gains over eight, 12 or 16 weeks.
• Then progress stops, and eventually goes backwards, because there's no aerobic base underneath it.
• Gerard likens it to a house with a poor foundation that stands for a while until a big wind blows it over.

He sees the same pattern in riders and runners who flog themselves in bunch rides or run groups every week and do little in between. They set big personal bests, then plateau, then start to struggle to hold the numbers they used to.

His other comparison is a bank account. Zone 2 work keeps putting money into your aerobic fitness bank week after week. Training hard without it keeps drawing money out, until there's nothing left for the next hard session or race.

What does long-term improvement look like?

Gerard says many TriVelo athletes make their biggest jump 15 to 20 months into the program, not in the first 16 weeks. A common pattern is a big early gain, such as from 150 to 230 watts over 16 weeks, then only a few watts over the next six months, then another step up. That next step comes from filling the aerobic bank with zone 2, endurance riding and strength work.

He also coaches older age groupers who are riding better in their 60s than they did in their 50s, using this approach.

Jordan adds that efficiency and economy, meaning how well you move, come from volume and consistent training. That's another benefit Athlete B is missing out on.

What's the verdict?

Don't dismiss Athlete B's result. It was a real improvement. But if you want to keep improving for years, have more options in what you can race, and avoid a plateau, build your program on zone 2 with well-placed hard sessions. As Gerard puts it, the shortcut works for the short term, and eventually you'll be found out.

Related

• How we coach triathletes
• Cycling coaching
• Real athlete results
• About Gerard Donnelly