Triathlon Base Training 101

 January 10, 2016

By  Mikael Eriksson

It's all too common to hear the phrase "base training" being thrown around carelessly with no other meaning to it than "it's whatever random training I happen to be doing when my goal race is still a looong time from now".

And understandably so. There's a lot that goes into structuring a good base building phase for triathletes.​

​But that doesn't mean that you should fall into the trap of believing that anything goes when it comes to the training you do before you get to your serious race build.

In this post, we'll take a look at how base training is defined, what schools of thought there are on how to structure it, and of course, help you structure it the way that I believe is the best for most age-group triathletes. 

As a special treat, I've made an infographic laying out the basic ingredients of a successful base training period from start to finish for you. It provides a cheat-sheet of what to do during the triathlon base training phase. For the why, make sure you stick around and read the whole post. Here we go!

​Triathlon base training defined

​Triathlon base training, or base building, is a specific period in the triathlon season. As you know, effective triathlon training must be periodized.

If we look backwards from a ​goal race, the preceding periods are 

  • Taper
  • Peak
  • Build
  • Base

Since we pretty much know for how long the build, peak and taper should last for optimal performance, although there are variations for different race distances and some individual variations as well, it's easy to calculate when the base training ends.

For example, a typical progression to an Olympic distance goal race would be an eight-week build, two-week peak, and one-week taper. The base phase then ends 11 weeks before the race.

So when does it start?

That depends on the time available to you before your race and on​ how much fitness you have lost in the off-season. 

But as a rule of thumb, if you have enough time, a 12-week base building phase is pretty much ideal.​

Okay, so now we know when the base training comes in the season in relation to your goal race. But what is it all about? What's the purpose of base training for triathletes?

It's all in the name!

The purpose of base training is to lay a base for performing the training necessary later in the build and peak phases to have an optimal race performance.

That is, you train to train.​

Different schools of thought on base training

As with most anything in triathlon, there are a couple of different opinions on how to best structure the base phase, and what its objectives should be. 

On the one hand, there is the camp prescribing high-intensity work like lactate threshold and VO2max intervals in the base phase. The theory behind this is that your limiting factors for optimal performance are most likely your pace or power at VO2max and lactate threshold intensities. (By the way, if you find the terminology challenging, you can check out this glossary.)

Another reason to do base training like this is that improved capacity at high intensity levels also leads to improved capacity at lower intensity levels. Win-win, right?​ 

Finally, proponents of this way of training say that many athletes have maxed out their aerobic endurance already with the time they have available to train.​

I'll say this right away - I'm not a fan of this way of training for several reasons:

  • ​You can typically only make significant improvements in VO2max and lactate threshold for a limited time period of 8-10 weeks. If do them already in the base phase you'll plateau early, and you'll have to keep doing this high-intensity work consistently until your race, or you lose the improvements.

    If you start doing these intervals 5-6 months out, that's a long time to get overtrained, burned out, or injured.

  • It removes focus from aspects of training that are more important right now - like technique work for improved efficiency and strength training.

  • It doesn't prepare you to train at your best in the all-important build phase. That means that you won't be able to peak for your race.

    If you do the most challenging training in the build and not the base phase, you'll be able to do it at a much higher level, since your work leading up to it has improved your technique and efficiency, your maximum strength and force, and importantly, you're still healthy and motivated!

  • In short, sure, intense training in the base phase will make you much fitter faster and get you ready to race in February and March. But that's not when you want to peak!

    Patience is the key here. Wait to be a rockstar until the races are just around the corner. You won't regret it.

As you might have guessed by now, the other camp prescribes mostly lower-intensity aerobic zone - the opposite of the high-intensity school we saw above.

But there's more to it than that. With this base training philosophy, your training will become more and more specific the closer you get to your race. This might look like race simulation workouts in the peak phase, intense interval sessions in the build phase, and so on working backwards to less and less specificity.

In the base phase, you'll start your work towards race-specificity from the two extreme ends:

  • Low-intensity, aerobic exercise
  • Very intense maximum strength work

Within the base phase, you'll slowly ramp up the aerobic workouts in intensity to more moderate intensity and tempo work, so you're then prepared for the workouts to come in the build phase.

From the other end, the maximum strength work ​will turn into sport-specific maximum force, then force endurance and so on.

In my opinion, if there's someone that's got their base training philosophy absolutely spot on it's the great triathlon authority Joe Friel​. He uses a three-part base phase (Base 1, 2 and 3) of progressively more volume and more intense training, that will prepare the athlete for the most challenging training in the build phase. You can check out some of his thoughts in this blog post series (Base 1) and this (Base 2 and 3).

I'm a big proponent of this type of base training for triathletes. There are absolutely no flaws in the logic of it. It serves to set you up for your best training when it really matters, which is what well-structured base training is all about.

How to structure your base training

So with the theory behind us, lets move on to the implementation. How should triathletes structure their base training?

First, click the image below to get to a zoomable version of our base-training infographic. It is essentially a simple timeline of what to do when during a a 12-week base period.​ Then you can better follow along in the discussion.

Triathlon Base Training

Click image to go to a zoomable version of the infographic.

Let's first review the objectives of the base phase:


  • Develop aerobic endurance
  • Develop biomechanical efficiency (technique)
  • Develop maximum strength
  • Develop sport-specific maximum force (alactate training)
  • Transition into build phase by gradually inserting muscular endurance and lactate threshold work.

These objectives are achieved through a dynamic base phase where priorities shift. This is why Friel's three-part system is so good.

​As you can see in the infographic, different types of training are performed in all or part of the base phase to achieve these objectives. 

Also, the training is done in the right order, moving from less race-specific training (such as weight training) towards more specific training (transitioning to the higher-intensity trainng of the build phase).​

So, let's take a quick look at each of these periods within the base phase. What should we do in each and why.

Weeks 1 to 4​

  • For most age-groupers, there is some catching up to do on the aerobic endurance side of things after the off-season. Even sprint-triathlons are 95% aerobic events so a strong aerobic base is a must.

    These first few weeks we'll start building this base.

    That doesn't mean that you should jump right into massive volumes. Instead, you should gradually increase your volume, which will prepare you for larger volumes in the later parts of the base phase, so by the time the build starts, your aerobic endurance will be excellent.

  • One thing that is often overlooked by triathletes is their biomechanics, or technical skills, in each discipline. Still, the potential rewards are huge! Become more biomechanically efficient, and you'll be faster without becoming fitter.

    There's no better time to focus on these skills than now, when there's little else in terms of training that demands your attention, and the volume is still not too big, so you can do your drill-work when you're really fresh and make it count.

    What drills to do is beyond the scope of this post, but there's a number of great resources for swim, bike and run drills on the internet. For the run, I strongly recommend also implementing strides.

  • Something that triathletes often shy away from is strength training. But if you really want to make your intense workouts later in the season maximally beneficial, doing triathlon-specific maximum strength (high-weight, low-rep) work now will increase your potential benefits in those later workouts.

    To clarify with an example, if you increase your maximum strength, you'll have an easier time achieving higher power outputs on the bike, since your power is limited by your strength. Improve your strength, and you'll be able to improve your power more than you would have otherwise later.

Weeks 5 to 8​

  • You'll keep working on aerobic endurance and technical skills in this period. The volume will be larger now, so your aerobic endurance is really emphasized.

  • Strength training will move into more of a maintenance mode, and instead, alactates (short, 20 seconds or less, maximum efforts like sprints or hill reps) are used to work on your sport-specific maximum force.

    This is a great example of how your training becomes more and more specific. Yeah, I know, 20-second hill-reps are not really triathlon specific, but compared to 4 x 4 reps of squats and lat pull-downs it sure is!

  • Some of your easy aerobic workouts become a bit more intense in this period, since some tempo-work at around 90-95% of your lactate threshold intensity is thrown into the mix.

    These are still not very hard workouts (they're not threshold workouts, but just below threshold intensity), but they prepare you for the harder workouts to come.

Weeks 9 to 12

  • Aerobic endurance is still emphasized in the sense that the volume of your training is now at its highest (even slightly higher than it will in the build phase), but there are fewer pure aerobic endurance workouts relatively speaking, since you're now properly transitioning towards the build phase and doing some work around lactate threshold intensity.

    Your technical skills should also be coming along nicely by now, so the amount of drill-work is decreased and moved into maintenance mode.

  • Strength training is cut back properly now, so you can perform well in your other, more specific workouts. You can maintain the strength gains you've made pretty easily with just one shorter session a week.

  • Your workouts increase in intensity once again, and now your doing work around your lactate threshold. This will make you prepared for workouts of even higher intensities, or for threshold work of longer duration, coming at you very soon!

And there you have it! Your base training is all wrapped up, and what follows are the 8-10 weeks when you will see very significant gains by doing high-intensity work. And with a base training phase like this behind you, many a triathlete will envy the progress you make in the build, just because you trained to train, and not to win non-existing races in February. BOOM!

Many a triathlete will envy the progress you make in the build, just because you trained to train, and not to win non-existing races in February.

I hope that this post helped you learn how to structure your base training appropriately, and also that you understand the reasons why. 

​If it did help you, I'd really appreciate it if you took a moment to share it, and subscribe to our e-mail newsletter if you're not already on it.

If you have any further thoughts or questions, leave a comment below!​

Mikael Eriksson

I am a full-time triathlon coach, founder of Scientific Triathlon, and host of the top-rated podcast That Triathlon Show. I am from Finland but live in Lisbon, Portugal.

Please contact me if you have feedback on the podcast or want to make suggestions for improvement or send in a question for a Q&A episode.

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  • To my understanding the base phase targets in part the same physiological adaptations that are associated with aerobic capacity: mitochondrial number/volume, efficiency of metabolism, capilarisation of muscles and stroke volume to some degree. Since those are the targeted processes in the base phase why not add a little bit of HIIT to it to maximise gains? For example 1-2 HIIT sessions per week (per sport) embedded in an otherwise zone 2 workout?

    You mention that “You can typically only make significant improvements in VO2max and lactate threshold for a limited time period of 8-10 weeks”. There are a couple of points that I don’t understand here: 1) If this is true shouldn’t you already plateau in the base phase since you are basically targeting VO2max? 2) How does this match up with the fact that elite athletes have such massive VO2max? Surely they don’t go down to amateur level every season. So does that mean if you go through a whole season cycle the next time around you can get to a higher VO2max? Do you happen to know any scientific literature discussing this plateau effect?

    It is also mentioned that high intensity work removes the focus from technique work etc. But do you think a small HIIT load would really prevent you from still training those aspects?

    I’m genuinely trying to understand this. Thanks!

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