Triathlon Theory: Training Intensity Distribution

December 21, 2020
Triathlon Theory: Training Intensity Distribution

For triathletes planning efficient training is a challenge. Triathlon (Ironman) combines swimming, cycling and running. The right training intensity is key so you don’t overtrain and constantly improve. There is a lot of science and theory to getting your body ready for long, demanding races. However: We believe even elite athletes should get a focused, efficient overview of the underlying concepts—but then concentrate on training, rest and life instead of reading 30 studies. 

What is Training Intensity Distribution?

Training intensity distribution (TID) is the theory about an optimal combination of low, moderate and high intensity training for elite and recreational endurance athletes. There are three often-discussed approaches: threshold, polarized and pyramidal. Polarized and pyramidal are what scientists have found to be most effective. The threshold model (a lot of middle intensity, no high, less very low intensity) also builds endurance and is often chosen instinctively but in the end it has less impact on the athletes’ endurance. 

TID’s Impact on Building a Training Plan

TID is just one piece of the puzzle. But it does determine many nuances of the planning steps that follow. We’ll compare the three popular TID models that have been discussed and scientifically tested in the last 50 years after shortly looking at at four levels of training planning to show TID’s role in this.

For Context: Four Levels of Professional Training Planning

The following levels are a simplification and don’t happen just once and in a linear way. But they are part of any good training plan. Performance, freshness and life or career events further determine how the plan is reconfigured and updated to improve the athletes’ endurance consistently and not overtrain. 

Choosing a Fitting Training Intensity Distribution Model: Picking the one (or a combination) of the popular TID models should first and foremost focus on whether the athlete can actually follow the chosen distribution consistently. This and the target race distance (e.g. Ironman, 70.3, Olympic Distance) and desired finish time lay the foundation of how to combine low, moderate and high intensity sessions.

Planning Training Phases (Periodization): It’s important to structure training phases and ramp up intensity correctly as you near a race (2-3 times per year). While the exact phase length (e.g. 6-week preparatory phase) should be determined by your progress, phases must be outlined in advance to set realistic goals and allow enough time to peak, rest and ramp up.

Planning Training Sessions: Determining which chunks of training availability will be spent on swimming, cycling, running, strength / regeneration sessions—and off-days is an ongoing process. Scheduling the intensity and type of workouts you’ll do and when, like endurance or threshold or interval training, is also done on this level.

Performance Monitoring: Finally it’s key to analyze what happens throughout a set of completed workouts (instead of singles) and draw conclusions for future training by monitoring freshness and physiological parameters. This happens via wearables during workouts as well as feedback in between and can take into account many more parameters like nutrition or sleep.

Athlete running

TID Approaches use Three Training Zones

In conversations by coaches, athletes and support staff concerning the types of training performed by the best athletes in the world TID often is mentioned. Various TID models have been discussed and researched. It was found that the ”correct” TID seems to improve athletes’ performance significantly. While it’s possible to break up training zones in more detail (and an app like TRIQ constantly just picks whatever makes sense out of an infinite amount of ”zones”) all common approaches use three training intensity zone demarcations for simplification. 

  • Zone 1: ”Low intensity” at high volume (slow, long distances, below aerobic threshold)
  • Zone 2: ”Threshold intensity” (moderate yet ”uncomfortable“, between aerobic and anaerobic threshold)
  • Zone 3: ”High intensity” (mostly interval, intermittent interval, or short sprints above anaerobic threshold)

Polarized Training Intensity Distribution

This model gets its name from focusing on the ”poles” (zone 1 and 3) and mostly skipping the middle (zone 2). Polarized TID was first described as part of endurance training in East Germany between 1970-80. Professional athletes that train many hours use it and avoid threshold work to not tire the body too much. This particular training intensity can be very stressful as it falls in the sweetspot between intensity and volume, both of which are high. A high volume of low-intensity training is ”balanced” (though low-intensity takes more time) with regular application of high-intensity training to stimulate adaptation processes.

Polarized Training Intensity Distribution

This has been shown to be effective in elite level athletes and an observational study by Fiskerstrand & Seiler in 2004 supported this when they described the training and performance characteristics of 28 international Norwegian rowers developing across the years 1970-2001. The polarized model usually consists of 75-85% at low intensity, no more than 5% at threshold intensity, and 15-25% at a high intensity. Several other studies (however mainly focused on elite athletes) provided evidence to support the importance of this model for endurance athletes striving to be the best. It subsequently has been adopted by many elite endurance athletes across the world and was also confirmed via experimental studies in trained cyclists.

Pyramidal Training Intensity Distribution

There have been newer studies that show a pyramidal approach (e.g. zone 1: 77.9% / zone 2: 18.8% / zone 3: 3.3%) to TID can also work and keep up with a polarized TID in certain scenarios. Elite athletes trying to squeeze out the final few percentage points almost entirely skip zone 2 training. But for recreational and amateur athletes who can’t spend 20+ hours training per week a more pyramidal approach seems to also work for certain “shorter” race distances like a 70.3. For example, one 2019 study conducted in a controlled environment by Spanish scientists hints at this. It was published in the Journal of Sports Science and Medicine (18, 708-715) and found that recreational athletes training about 13 hours per week actually improved slightly more in certain areas of speed and performed a bit better in a 70.3 than the group using a polarized TID.

Pyramidal Training Intensity Distribution

Threshold Training Intensity Distribution

This classic way to train is what many recreational athletes with a good fitness foundation might pick intuitively. The name stems from the fact that in this approach a large portion of mid-zone threshold work is thought to be optimal. (e.g. 57% low intensity, 43% threshold intensity, 0% high intensity training). But while including high intensity training (zone 3) might seem counterintuitive, there is more and more evidence that it should be part of any endurance training plan looking to maximize improvement.

Threshold Training Intensity Distribution

TRIQ and Training Intensity Distribution

At TRIQ we’re well aware of the latest studies and developments in regard to TID. We constantly incorporate them into the way our algorithm plans endurance training. The TRIQ algorithm usually operates in a range between polarized and pyramidal TID. We believe it’s important to provide our athletes with infos like this to form a solid, well-founded knowledge basis. Understanding some of the theory behind the plan is important to trust the process and feel in control, while letting our app do most of the planning.

At TRIQ we find it totally normal for plans to change all the time as every human and every season is unique. Doing this manually and keeping all of the science in mind is too stressful. That’s why we built the TRIQ algorithm to adjust training in real-time taking into account much more information than a human can. Unlike a remote coach TRIQ is always available and can take into account just about every piece of information there is. It reacts immediately to constantly give you a functional and updated plan at any moment of your journey and it explains changes. If informs you referring to classic training zones so you know what is happening and why. But really, the algorithm fine-tunes your training sessions infinitely in a way that actually goes way beyond 3-7 training zones.

If You’d Like to Read More About TID…

…we recommend the following articles that we find very helpful:

If you would like to join our team, please have a look at our openings.