How Should I Train? | IRONMAN U

How Should I Train?

Slowing down to speed up seems counterintuitive, especially at a time when high-intensity workouts like Crossfit and Tabata are all the rage and gymgoers have been conditioned to believe that gains come only through grueling work. But many coaches argue that the high-intensity trend has gone too far. The majority of recreational athletes are doing way too much high-intensity exercise for a triathlon these days. Therefore,  low intensity training is being neglected.


80/20 percent rule

In the early 2000s, an American exercise scientist based in Norway embarked on a mission to determine how elite endurance athletes really train. He found a remarkably consistent pattern: triathletes, world class cyclists, Nordic skiers, rowers, runners and swimmers all did approximately 80 percent of their training at low intensity.

The 80/20 approach was discovered by exercise physiologist Stephen Seiler , a sports scientist with Norway’s University of Agder, who spent the past decade analyzing the way elite athletes structure their training. “We started to see a pattern from different sports all converging on about the same distribution,” says Seiler. Whether they were marathoners, sprinters, rowers, or speedskaters, the majority of athletes spent their workouts well below race pace, and about a fifth of the time at higher intensities.

So, a growing body of research suggests that 80 percent of your workouts should be done at a slow speed, with just 20 percent at medium to fast. At this ratio, you’re able to get all the performance-enhancing benefits of high-intensity work while avoiding the injury risk and burnout that often come along with it.

What are Most People Doing

weak person

In fact, the most group of amateurs spend most of their time — 45 to 75 percent, according to studies — in a high-intensity. A majority of recreational triathletes think they are at low intensity, but it seem that  they  don’t have the ability to dissociate effort from other sensations related to physical exercise.

This can be explained as well by other several factors:

  • Lack of time for training due to work and social commitments
  • The fact that many people do not have a coach whom they can ask for guidance
  • Lack of knowledge of the training principles needed to improve performance
  • Even exercise applications that make people increasingly improve their times


The Physiological Explanation


muscle fiber


High-intensity workouts recruit fast-twitch muscle fibers that provide extra power late into a race.  They also boost blood vessel elasticity, build a stronger heart, and up pain tolerance. All that time in the slow zone, meanwhile, primes your muscles to be able to crush the high-intensity sessions. During tough bouts, your fast-twitch muscles rapidly burn through glucose for fuel, which creates metabolic by-products like lactate and hydrogen ions that — if not cleared from the muscles — inhibit muscle contraction and the breakdown of food for fuel. The result? You slow down. The slow-twitch muscles are responsible for recycling that otherwise toxic lactate back into energy, enabling you to stay on pace. Low-intensity training also revs the growth of mitochondria, which helps the body burn fat efficiently and fends off soreness and fatigue.

Training assembly

block mesocycle

To explain better this training session, it is necessary to understand that in this form of training plan, each modality (swimming, biking and running) has different goals in the periodization. I usually incorporate the endurance training of the bike, to coincide with the speed phase in the running.

This way, I will get better chances to reach the 80/20 rule of intensity proposed by Seiler.

In this type of training, I choose the bike portion to complete the majority volume of the session through a small chain ring . Generally, small ring sessions are to develop pedaling speed / coordination without putting too much strain on the muscles & joints. And already the session of the running, I usually prioritize interval training with speed stimulus in an active interval so that the body can achieve its complete recovery, from muscle to nervous system. Thus, since the largest volume of triathlon will always be the bike, transition sessions with this format, will promote neuromuscular adaptations, such as cadence frequency, which is an essential part of speed training, without this entailing severe energy losses to the body.


Race: Ironman 70.3

training session

This type of drill incorporates the necessary volume that a 70.3 needs, plus 1/3 (one third) of the running leg of the race with speed work, to ensure that the athlete will have the capacity to generate speed ( neuromuscular adaptation) after this long session.


For this rule to work, many coaches must face speed training for another vision. For now, studies have focused on physiological observations. And the principles of training, are still in constant discoveries. The speed work is still being studied as physical capacity, not as a motor phenomenon. And if we look at this type of training from another perspective, we still have many other lines of reasoning to put together the best training for athletes. To know more about how to understand the behavior of a velocity training properly, wait for the next article about speed training.

Joel Arantes de Bem is an Ironman certified coach and is a mastercoach of Commandos Legion.


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