By Gerard Donnelly, head coach at TriVelo Coaching and 1988 Australian Ironman Champion, and coach Jordan Donnelly. From the Get Fast Podcast.
Zone 2 training is easy aerobic training. In the five zone model we use, zone 2 starts just above active recovery and ends at your first lactate threshold, the point where lactate starts to build up. You are working, but you can still hold a conversation. You can train there in the swim, on the bike and on the run. Zone 2 is the best zone for building aerobic fitness, because you can do a lot of it and still recover. It works best next to hard sessions, not in place of them.
Our position is different from most of what you will read. We program a lot of zone 2, and we also think it is one of the most overused terms of the last few years. How much you need depends on your sport, your level and the time you have to train. For a busy amateur with limited time, zone 2 matters much less than people say. As Gerard puts it, "if you don't have the time, then it should be the last thing you're doing." There is no fixed amount that suits everybody, so this page explains how we decide.
On this page
Zone 2 is the range from just above active recovery up to your first lactate threshold. Zone 1 is recovery. Zone 2 is where aerobic fitness is built. Tempo and sweet spot sit above it.
Three things about zone 2 are often missed:
You can see it working when your heart rate stays the same and your power or pace goes up.
Zone 2 has a limit. On its own it will not make you a better rider. It gives you the ability to do the other sessions well.
No. But for many amateurs it is not the answer they have been told it is.
Our Ep 253 is called "Zone 2 Is IRRELEVANT For Most Triathletes". The position has conditions, and the main one is how much time you have to train.
| Who you are | What we said about zone 2 |
|---|---|
| A busy athlete with very limited time | It becomes very irrelevant to your program. It should be the last thing you add. |
| An age grouper with a lot of time | Do more zone 2. If you spend the extra time in zones 3 and 4, you will be worse off. |
| An Ironman athlete | Most age groupers ride for five to seven hours in the race, so you must spend a lot of time in zone 2. |
| An elite or professional rider | You need a great deal of zone 2. Nobody can do that much riding at threshold, and the races last four to six hours, day after day. |
| Someone who has not run for six months | Zones are the wrong place to start. An absolute beginner runner may need to start with walking, so they don't get injured. |
The reason is progressive overload. If your time is short and every session is in zone 2, you build a nice base and then you stay at that level.
The opposite is also true. Jordan finished that episode with this: "if you have more time, zone 2 will absolutely work wonders for you." More time to train does not mean more time at intensity.
What we are against is the idea that zone 2 is a magic pill. Many people heard the hype and stopped doing high intensity work.
Everybody does some. The question is how much, and three things decide it: your sport, the time you have, and your level.
The principle we use: do as much high intensity work as your body can handle, and make the rest easy volume. For most age group athletes that means a couple of hard sessions in the week, endurance work on the weekend, and easy sessions in zone 1 or 2 around them.
For triathletes it is different in each sport. You can't make every swim, ride and run hard, and you can't do zone 2 across all three at once. As an example, if you are doing a lot of VO2 work in the swim, more of your bike time might be zone 2. We find that most athletes can do a hard swim one day and a hard ride the next, so some swims can be harder sessions. Long, slow swimming still has its place, because your body must cope with the race distance. How much swim training you do depends on the athlete. As a starting point, about 10 percent of the week goes to swimming, because the swim is about 10 percent of the race.
What about 80/20? The polarized model is often described as 80 percent in zone 2 and 20 percent hard. Most age groupers we coach do not spend 80 percent of their time in zone 2, and we don't think they should. We asked Dr Stephen Seiler about this when he was a guest. As Jordan recalls it, 80/20 is not a split of hours. The question is whether a session is hard or easy. A VO2 session may have only 20 minutes at VO2, with the rest in zone 2, and it still counts as a hard session.
Other guides we use:
Most athletes need both. One example: we compared two experienced athletes in the TriVelo group who were both coming back from being out of form (Ep 179). Over about 16 weeks they gained almost the same amount of FTP on very different training. This is one comparison and not a controlled study.
| Athlete A | Athlete B | |
|---|---|---|
| Training | A lot of zone 2, plus the key high intensity sessions and some race specific sessions | Three hard sessions and very little in between |
| Why | Had a lot more time to train | Had less time to train |
| Goal | Endurance events of two to three hours | Get fit again and race on Zwift in 30 minute efforts |
| FTP | 300 W to 360 W | 220 W to 285 W |
| What they could do after | Great for two to three hours, and has performed well in events up to four hours | Good for 30 to 35 minutes. A two and a half hour ride would go badly. |
Athlete B's result shows why we push VO2 and threshold work. But FTP is one metric, measured over 20 minutes. On any other measure, Athlete B would be a long way behind. We don't advise training that way. In our experience you get big gains for 8, 12 or 16 weeks and then they stop, because there is no aerobic base under them. Most age groupers would also break down or get injured.
Zone 2 alone has the opposite problem. Your body adapts, you become a great zone 2 rider, and that is all. Gerard's summary: "zone 2 has its own value but it's not a standalone thing that you should be doing all the time."
The other side is a pattern we see often. Many endurance athletes come to us good at endurance and zone 2 work, and struggle most with the high intensity sessions. Two TriVelo athletes are examples.
Nick came to us as a good rider with huge endurance. Most of his training was in zone 2, but those rides were closer to zone 3, and he was too tired to ride hard when it counted. We made his easy riding easier and his hard sessions harder. Three years later he has his highest peak power numbers from short sprints through to 90 km.
Fiona came to us to improve her cycling after 10 to 20 years as the same athlete. Her training was about 99 percent zone 2 and 1 percent high intensity. We cut some endurance volume so that she could hit her midweek sessions properly. Her FTP went up 54 W in six months.
Zone 2 ends at your first lactate threshold, called LT1. This is where the lactate curve kicks up a little, before it reaches LT2, which is your threshold.
There are three ways to find it, from most exact to least.
1. A lactate test in a lab. This is the only way to know your exact zone 2 heart rate, power and pace, and it can be done for riding, running and swimming. Without it you are estimating. A rider's guess might be within 10 or 15 W. A runner's could be out by 20 or 30 seconds per kilometre. The test gives you a heart rate and a power or pace at LT1, and in zone 2 sessions you stay under them. As an example, Gerard's numbers from one test were 136 beats and 220 W.
We don't think you need a lab test to follow a good program. But if zone 2 is going to be the core of your training, it makes little sense not to get one.
2. Field testing and FTP. A field test is less specific than the lab, but it gives you the general range. Put your FTP into TrainingPeaks and it gives you a zone 2 range from a generic equation. As a general guide in our method, zone 2 on the bike is up to 75 percent of your FTP. Regular FTP tests keep your zone 2 and VO2 sessions accurate.
3. Generic checks you can use on any ride or run (Ep 213). These are starting points and not your own numbers.
| Check | What to look for |
|---|---|
| Power | Under 75 percent of your threshold power |
| Heart rate | About 75 percent of your maximum heart rate |
| Talk test | You can talk without being out of breath. If you need two to four seconds between sentences, you are going too hard. |
| Sustained power | You can hold it for an hour to an hour and a half when you are fuelled and hydrated. If you fade at the end, it was too hard. |
| Perceived exertion | About 11 or 12 on the Borg scale, which runs from 6 to 20 |
Then check the range against how it felt. If your heart rate slowly rose over the session, the effort was probably too hard for zone 2.
Treat every percentage as a rough guide. Depending on which scientist you ask, zone 2 is somewhere between 60 and 80 percent of FTP. A very fit person can still be in zone 2 at 85 percent, and a beginner can be out of breath at 65 percent. Jordan's advice: "don't ever let anyone tell you that your zone 2 is 82% or 65% or 71%." The talk test is subjective, and we would not build a triathlon program on it.
Running costs your body more than riding. You can hold zone 2 on the bike for a long time with little consequence. The same amount of running will exhaust you.
It depends on your level and where the session sits in your week.
One progression we use for a zone 2 brick: a 40 minute ride into a 15 minute run, then 60 into 20, then 75 into 30, up to 90 minutes into 30 to 40. Get the frequency first, then the volume, then the intensity. For example, if your zone 2 power were 180 to 200 W, start at 180.
One coach we have had on the podcast wants a year of zone 2 before any intensity. That may be the safest way. We don't think it is realistic for an age grouper with a race in 16 weeks.
Joe Friel, author of the Training Bible books, was our guest on Ep 278. His emphasis is different from ours.
We agree with Joe that zone 1 has real value.
Our basic principle is to train easier so that you can train harder.
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