Turn your training zones into structured workouts: swim bike run

What to do after you calculate training zones based on threshold heart rate and lactate threshold? How to use those training zones to create structured workouts? This article covers exactly that for all three triathlon disciplines: swimming, cycling and running. Let’s dive right in!
If you did not calculate your training zones yet, perform these steps first:

1. Calculate heart rate training zones based on threshold heart rate
2. Calculate power and pace training zones based on lactate threshold

Training zones overview

If we use the aerobic and anaerobic threshold to split up training intensities, we end up with 3 training zones. This is also known as “the 3 zone model”.
To create more specific workouts, it’s common practice to split each of these 3 zones up into 2, leaving us with 6 training zones.

The corresponding heart rate, speed, power and pace differs per sport:

If these charts feel overwhelming, consider using the Aixsurge. It helps with performing a threshold test and calculates your training zones. As a result, you don’t stare at general percentages, but see your actual heart rate and intensity instead.
But once you have your triathlon training zones, how to use them?

How to use training zones

Once you have your training zones, it’s time to turn them into structured workouts. Let’s look at some examples and learn why and how often you should do them.
Jump straight to:

• Zone 1 → Recovery workouts
• Zone 2 → Endurance workouts
• Zone 3 → Tempo workouts
• Zone 4 → Threshold workouts
• Zone 5 → VO2max workouts
• Zone 6 → Anaerobic workouts

Zone 1 → Recovery workouts

As the name suggests, zone 1 is great for recovery workouts. They promote blood flow, loosen up tired muscles and accelerate the recovery process.
Think of them as active rest: not performance-driven, but performance-supporting.

Recovery workouts are best done the day after a hard session or race. But you can also use them during recovery weeks, in the days leading up to a race, or when feeling mentally or physically flat.
In fact, it’s pretty uncommon to not include zone 1 in your workout, since it can be part of the warm up, cool down or the recovery phase in between intervals.
A specific zone 1 recovery session typically takes no more than 60 minutes.

Common mistake

There are two common mistakes you should avoid when doing a recovery session in zone 1:

1. Slowly drifting into zone 2. This can cause training load instead of an accelerated recovery.
2. Neglecting technique, especially in swimming and running. Going slow can cause you to lose focus. But this can unconsciously internalize a bad technique that spills over to all exercise intensities.

Recovery workout example

Warm up: 10-20 minutes
Recovery swim, bike or run
Duration: 30 to 60 minutes
Intensity: zone 1
Cool down: 10-20 minutes

Notes: When performed well, you’ll finish the session feeling lighter and looser.

Zone 2 → Endurance workouts

Zone 2 is an intensity that you can sustain for a long time. Therefore it’s perfect for long endurance sessions that build your aerobic engine through high volume training.
You could say that these sessions are the backbone of your training program. They promote adaptations like increased fat metabolism and improved mitochondrial function. Both are key for triathletes.

It’s no secret that the world’s best triathletes train in zone 2 for the majority of their time. To be more specific, they train roughly 70% — 80% of their time in zone 2.
Proven training models for beginners and pros — like the pyramidal training model and the polarized training model — all rely heavily on zone 2.
In other words, if you don’t know what to do in training, you should probably go for zone 2 endurance workouts.
In practice, many triathletes first increase the frequency and duration of their endurance workouts before jumping to higher exercise intensities. Once you’re able to do long endurance sessions, you can continue to implement them all year long.
The ideal duration of an endurance session differs a lot per individual. It depends on your current fitness and training cycle. While some should aim for 1h, advanced triathletes can spend more than 2h in swimming, 6h in cycling and 3h in running.
If you’re not sure what’s the best intensity, duration and frequency of your endurance workouts, consider using the Aixsurge. It creates a training program that increases your endurance capacity, based on the supercompensation theory. By doing so, it helps you reach your triathlon goal.

Common mistake

It’s important to keep endurance workouts in the right zone, without drifting to higher intensities. Otherwise you end up going too fast during your endurance rides, which likely results in being too fatigued for high intensity workouts.
As a result, you end up training in the so-called “gray zone” all the time.
There’s a good reason why many coaches advise you to “make your easy days easier, and your hard days harder”.

Zone 2 endurance workout example

Warm up: 10-20 minutes

Cool down: 10-20 minutes

Swim notes: At low intensity, it’s harder to maintain streamlining and prevent your legs from sinking. Without momentum, technique control becomes more demanding, so keep an eye on your body position.

Bike notes: Explore new routes to stay mentally fresh. Want to mix it up? Try shifting cadence, alternating positions (like aero bars), or changing terrain while keeping effort steady. Because these rides can last several hours, be mindful of fueling. Bring more than you think you need.

Run notes: You may find it difficult to stay in the right zone, especially on hills or when your mind drifts toward performance. Keep an eye on your pace, heart rate and breathing to stay honest. For most athletes, true endurance pace feels slower than expected.

Zone 3 → Tempo workouts

Zone 3 is also known as the ‘tempo zone’. It’s an intensity you can sustain for quite a while, but you will burn significantly more energy in zone 3, compared to zone 2.
As a result, tempo workouts usually contain tempo intervals, with recovery in between.
While some call zone 3 the gray zone (it’s not easy, nor extremely hard), others call it the sweetspot. That is because it’s considered a relatively high intensity, that you can sustain for a long time, without accumulating too much fatigue. In other words: you can do many tempo workouts.
For long distance triathletes, zone 3 is actually (close to) race intensity.

While the famous pyramidal training model prescribes a significant amount of time in zone 3 (e.g. 10-20% of the training volume), the equally famous polarized training model almost fully ignores zone 3.
Whether you should train in zone 3 depends on your current athlete (power) profile and your goal. For most triathletes, tempo workouts are part of the key workouts, regardless of how often they are executed.
Tempo intervals usually take about 10 — 30 minutes in swimming and running, and up to 45 minutes in cycling. Depending on the interval duration you choose, you can do 1 — 6 of these intervals within a tempo workout.
Aixsurge is the triathlon training app that determines your profile and automatically adapts your training method based on it. By doing so, it helps you reach your triathlon goal in the most effective way.

Common mistake

It’s easy to underestimate tempo workouts, since they can feel comfortable at first.
Therefore, many triathletes under-fuel during the beginning of these sessions. This can lead to ‘bonking’ (running out of energy), which decreases training quality and increases recovery time.
Make sure to consume enough carbohydrates.

Zone 3 tempo workout example

Warm up: 10-20 minutes

Cool down: 10-20 minutes

Swim notes: Tempo swims are a great way to refine your pacing instincts, reinforce efficient stroke mechanics, and build the confidence to sustain effort over distance. Intervals at consistent effort help develop rhythm and teach you how to settle into race pace early.
Bike notes: Because these intensities mimic race efforts, it’s smart to ride using your race-position stance (aero bars), reinforcing both muscular and postural readiness during the bike leg.
Run notes: Because of the sustained effort, impact loading can be high. Maintaining good running technique and posture is critical. A slightly increased step frequency helps reduce stress on tendons and bones while keeping the movement efficient.

Zone 4 → Threshold workouts

Zone 4 is the famous anaerobic threshold zone. It’s an intensity most triathletes can sustain for 45 to 60 minutes. Therefore, threshold workouts are always a combination of threshold intervals with sufficient rest in between.
Some world-class triathletes swear by (sub)threshold workouts. For instance, a key aspect of the Norwegian training method is about accumulating as much training volume in zone 4 as possible.
Depending on your fitness and your triathlon race distance, the lower end of zone 4 roughly equals race intensity.

Since threshold workouts are very demanding, they are usually the key workout in a micro or meso training cycle. That means that all other workouts are there to support your threshold workout. For instance: easy recovery or endurance workouts to make sure you’re fresh before the threshold workout.
A typical threshold interval takes about 5 — 10 minutes in swimming, 10 — 20 minutes in running and no more than 30 minutes in cycling.

Common mistake

As the name suggests, threshold intervals circle around a threshold. At the lower end, you can keep lactate levels and fatigue fairly stable. However, at the higher end of zone 4, fatigue accumulates quickly.
Avoid always pushing to the upper end of the threshold zone, working closer to the lower end of the threshold zone can be just as effective and easier to repeat.

Zone 4 threshold workout example

Warm up: 10-20 minutes

Cool down: 10-20 minutes

Swim notes: These sessions should feel demanding, but not all-out from the start. Begin conservatively, settle into pace, and allow fatigue to accumulate gradually.
Bike notes: These sessions are ideal for teaching your body and mind how threshold effort feels, so you can recognize that effort instinctively, without constantly looking at data during a race. That connection between numbers and internal feel is what triggers smart pacing under pressure.
Run notes: Perform these intervals on uninterrupted routes like quiet streets or a running track to minimize stops and distractions. A consistent environment helps you accurately sense the effort and breathing cues without traffic disruptions.

Zone 5 → VO2max workouts

VO2max is the most well-known and accepted measure of endurance. Zone 5 is dedicated to this key performance metric.
Although VO2max intervals in zone 5 are not the only way to reach or improve VO2max, they are often used for these purposes. That is because at this intensity, oxygen consumption increases rapidly to (near) VO2max.
Although there are only a few scenarios in which triathletes actually race in zone 5, it’s still an effective training zone to ‘raise the aerobic ceiling’. By stressing the most important energy system for endurance sports, it’s a time efficient way to train.

VO2max workouts are a great way to sharpen your form, especially in the final weeks leading up to your race. It makes sense to include them more frequently during this period.
However, don’t get carried away with VO2max workouts. They are most effective when built on a solid endurance base. Keep high intensity workouts below 20% of your total training volume.
Typical VO2max intervals take 3 to 5 minutes, followed by at least the same duration for recovery.

Common mistake

It’s not always easy to hit the right VO2max intensity. That is because these efforts are very intense, but not all-out sprints. Often, triathletes start the first minutes of the first sets a bit too hard.
While it’s not critical to be perfect, you shouldn’t consistently undershoot or overshoot either. Aim for a strong, repeatable effort that stays within the intended range.

Zone 5 VO2max workout example

Warm up: 10-20 minutes

Cool down: 10-20 minutes

Swim notes: Long VO2max efforts allow you to raise VO2max without significantly increasing VLamax—helping you preserve a low anaerobic contribution, maintain a higher lactate threshold, and support efficient fat metabolism.
Bike notes: As you’re working near your VO2max, it’s crucial to maintain controlled, rhythmic breathing, even under pressure. For some, it helps to slightly increase breathing volume before it feels necessary, staying ahead of the effort can delay the onset of fatigue and help you stay composed.
Run notes: Since these intervals are demanding, maintaining good running form is essential—upright posture, quick turnover, and relaxed arms help you stay efficient under fatigue.

Zone 6 → Anaerobic workouts

Zone 6 intensity is close to all-out. It primarily targets the anaerobic energy system through short, HIT-like intervals.
The main goal is to increase anaerobic power (VLamax), which is especially useful for triathletes with a low anaerobic profile. A slightly higher VLamax can improve your ability to surge at race starts, close gaps, or accelerate around buoys.
So perhaps counter to your intuition, these sessions can actually be very effective for endurance athletes. That is true for both beginners and professionals.
Of course, the timing and frequency need to be carefully integrated into your training program. That’s exactly what the Aixsurge does for you. Based on your athlete profile and triathlon goals, it automatically adjusts the number of anaerobic workouts in your plan.

LT = lactate threshold, LTHR = lactate threshold heart rate

Similar to VO2max intervals, anaerobic workouts are there to help you reach peak form. The better your aerobic base, the more effective they are. Therefore, these high intensity workouts are usually added more frequently when you’re already a couple of weeks into a training program.
Together with VO2max workouts, anaerobic workouts usually don’t exceed more than 20% of your training volume.
Anaerobic intervals rarely last longer than 3 minutes.

Common mistake

Anaerobic intervals place serious stress on your body and nervous system. It makes no sense doing them when you’re not feeling fresh and motivated. Therefore the Aixsurge automatically adjusts your training program when you’re not feeling recovered yet.

Zone 6 anaerobic workout example

Warm up: 10-20 minutes

Cool down: 10-20 minutes

Swim notes: These sessions carry a high training load. Recovery between intervals should be long enough to maintain high output throughout the set.
Bike notes: Neuromuscular recruitment is high, so aim to do these intervals in your aero position. Good form ensures that the power you produce in training shows up on race day.
Run notes: Maintain a good running technique so the power you produce in training shows up on race day. This workout is not only about running fast, it’s about running fast while remaining efficient.

How to use training zones — FAQ

Can I combine different zones in one workout?

Yes! You can definitely combine different training zones in a single workout. Keep in mind though that this could change the training effect. For instance: returning to zone 2 after a VO2max interval does not mean your body is in a state of ‘endurance training’ immediately. It’s different from a continuous zone 2 training.

How to use heart rate zones?

Use heart rate zones in combination with speed/power zones. This allows you to learn more about ‘external intensity’ (speed/power) vs ‘internal intensity’ (heart rate). Fatigue or time delay could cause your heart rate zones not be in the same zone as your speed/power. Use this information to guide your training.

How do I adjust zone-based workouts if I’m tired, sick, or busy?

Simple: adjust your zone based workout by decreasing the intensity or skipping the workout all together. The Aixsurge allows you to easily move or skip workouts when tired, sick or busy, without messing up the entire training program.

How do I work out my Zone 2 training?

Zone 2 training is very popular, and very simple. Do roughly 70-80% of your training volume in zone 2, by using your heart rate, speed or power zones.

Is it better to train in zone 2 or 3?

Some say zone 2 training is better than zone 3 training. The truth is that it depends on your athlete profile and triathlon goal. Aixsurge helps you to discover what training works best for you, so you can focus on execution.

Which is better training in zone 3 or zone 4?

Zone 3 is not better than zone 4 per se. It depends on your athlete profile and triathlon goal. Aixsurge helps you to discover what training works best for you, so you can focus on execution.

What heart rate zones should I train in?

Triathletes should spend most of their time in heart rate zone 2. However, it’s important to mix heart rate zones in training. Aixsurge helps you to do that effectively, based on your athlete profile and triathlon goal.

What zone is best to train in?

Triathletes should spend most of their time in zone 2. However, it’s important to mix zones in training. Aixsurge helps you to do that effectively, based on your athlete profile and triathlon goal.