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Endurance training is the foundation of any endurance sport. Whether you swim, bike, run or row: the stronger the aerobic foundation of your fitness house, the higher you can build. Understanding about endurance training is confused and often endurance training is not performed optimally. How do you improve the quality of your endurance training? This blog starts with the purpose and definition of endurance training. You learn what role lactate plays in endurance training and at what intensity you do your endurance training best. Finally, you get five tips to better execute your endurance sessions.

What is the purpose of endurance training?

The aim of endurance training is to develop the best possible aerobic engine. Endurance training improves your fat metabolism, the number of aerobic enzymes, the size and number of mitochondria, your capillarization (increased blood flow means better oxygen supply!) and the ability to process lactate. Simply put: you train your body to become more and more efficient at burning diesel (fat). At the same time, you enlarge your drain to clear lactate. 

Endurance training defined

Duurtraining lopenIf you search the internet for ‘endurance training’ and related terms, you will be flooded with information and definitions. For this blog I define endurance training as the maximum effort at which you produce a maximum of 2 mmol lactate. That is the same definition that Inigo San Millan – Tadej Pogačar’s coach – uses. This definition is different from the most common ways to indicate intensity, which is a percentage of your maximum heart rate or a percentage of your Functional Threshold Power. However practical training based on heart rate or wattage is, it provides distorted insight into what exactly happens at the cellular level. Fort that, you need lactate.

Why lactate as indicator?

LactaatmetingDuring exercise you convert glucose and fatty acids into ATP, a molecule that transports energy. That process can be carried out very efficiently with the help of oxygen: your aerobic energy supply. The more energy you demand – by swimming, cycling or running faster – the more ATP you need.

Up to the level of 2 mmol lactate (per liter of blood), ATP is produced within the mitochondria – the energy factories within the muscles. This is how your aerobic energy supply works. If you need more energy, your body will supply more and more anaerobic energy (anaerobic means: without oxygen). Anaerobic energy production quickly produces more ATP, so more energy. Its by-product is lactate. That’s why I use the 2 mmol lactate limit as an indicator that your body is exceeding the capacity of your aerobic energy supply. That’s the point where your mitochondria produce as much lactate as they process. You improve your endurance training by training at the intensity that corresponds with 2 mmol.

What wattages and speeds relate to 2 mmol lactate?

That’s an interesting question. Of the athletes I tested in 2021, the best is at 2.94 Watts per kilogram of body weight. In preparation for writing this blog, I got curious, measured myself and found that I was still producing 3.35 Watts per kilo at 2 mmol. At the same time, there are plenty of athletes who can kick off ‘only’ 1.5 Watt per kilo on 2 mmol lactate. That’s half. Women produce less Watts per kilo than men, and you also see the same big differences. In running, the 2mmol limit in the athletes tested by me is between 6 km/h and 16.5 km/h. So the differences are huge. These large individual diversity is reflected in this article by San Millan and Brooks. Cycling professionals can generate around 4 Watt per kilogram of body weight on 2 mmol; a well trained Age Grouper around 3 Watts. An untrained person is between 1.5 and 2 Watts per kilo and diabetics and people with metabolic disorders can deliver 1 Watt per kilo or lower. 

Five tips to improve your endurance training 

Weaponed with this knowledge, know you want to know how to best train your endurance. The answer is simple and sober: by training at the right intensity. Not too hard and not too slow. These five tips will make your aerobic metabolism more efficiently. Or, as I sometimes put in the comments in TrainingPeaks: increase the horsepowers of your engine.

Tip 1: Train at the right intensity

The optimal intensity is the effort that keeps your blood lactate just below or at 2mmol. You prefer not to get over that. Ideally, you can determine this with an exercise test with lactate measurement. Sport-specific, because lactate values ​​can differ considerably per sport. That is why you see more and more athletes measuring lactate during their training. If you follow Lionel Sanders, Gustav Iden or Kristian Blummenfelt, you will note that they measure their lactate after almost every session. This helps them to ascertain they are providing the right training stimulus.

There are three alternative methods. The first is based on the level of perceived exertion. That corresponds with level 4-6 in the table below. It is the intensity at which you can still have a conversation. What can also approach the right intensity quite nicely is to train at the intensity at which you can still inhale through your nose and extend your exhalation to 1.5-2x the duration of your inhalation.

Rate of perceived extertion

The second method is to work with heart rate. These zones differ between athletes and lie between 65 and 80% of maximum heart rate. That is indeed a large bandwidth. To determine your individual zone, you preferably do an exercise test in which your lactate levels are also measured (this is indeed surreptitious advertising 😉 Training on wattage (cycling – or the Stryd for running), speed (walking) or time per 100m (swimming) is the third method. Ideally, you also determine these values ​​during an exercise test. Instead, you can also work with guesstimates: for cycling between 2 and 3 Watt/kilo for trained athletes. For running and swimming the individual differences (and with swimming the variation in technical skills) are too large to give any indications for this.

Tip 2: Apply the 80/20 rule (and the 90/10 rule;)

Do The 80/20 rule is the most well-known conclusion from Stephen Seiler’s study of Best Practices for Exercise Intensity in Endurance Athletes. The 80/20 rule means that eighty percent of your sessions consist of endurance training and twenty percent of other workouts. The 90/10 rule applies to the percentages in time: 90% of your training time is endurance training, 10% of your time is spent in more intensive zones. The difference is that endurance training is generally longer than intensive training. During those intensive workouts, you also do a significant part in your endurance zones – the warm-up, recovery moments and cool-down – which means that the percentage of the time that you are really intensively active is lower.

Tip 3: Endurance training = endurance training

For maximum gains your preferably do not mix endurance training with other types of training. The ideal endurance training is done at an intensity that is as constant as possible. If you do endurance training on the bike in windy conditions, in a group, or in the mountains, then you may have averaged the wattage associated with 2 mmol lactate, but that is not the way you train your endurance optimally. Especially not if you start too hard – for example into a headwind, or uphill. Or if you go hunting for Strava segments in your endurance training. Endurance training is all about maximizing the time that you train as close to 2 mmol as possible.

Indoor, on the Tacx or Kickr, is the most ideal way to do your endurance training. Especially if you quickly exceed 2 mmol lactate. Is that boring? Maybe. But this way make progress fastest. I let athletes who do these sessions indoors vary with pedaling frequencies. And you can compat the boredom by listening to a podcast or watch Netflix.

Loopband duurtrainingIf you do these training sessions outside, you prefer to leave with a tailwind, so that at least the first half of your training is in the right zone. Or you ride on a sheltered course to keep your effort as constant as possible. If you ride with a wattage meter, you can check your Variability Index afterwards. That’s your Normalized Power / Average Power: e.g. 200Watt NP / 195Watt AP = 1.0256. Ideally, your VI is below 1.05  (preferably 1.03).

The same principle applies to running: as constant as possible. If you’re one of the (many!) runners who can’t run at 2 mmol yet, the most nerdy approach is to do your endurance workouts on a treadmill. Just walk at 4-8% in 4-6km/h. Until you can run at least 8-10 km/h at 2 mmol, so that you can also run biomechanically efficient and technically decent. Then you can run outside again;)

If you still want to combine endurance training with intervals, do those at the end of the training. Then you have already given your endurance stimulus in the largest, first part of your training. You won’t lose that endurance stimulus if, for example, you go all-out for five minutes at the end to improve your VO2Max. You can also go 3 to 5x 1 minute to (almost) maximum at the end of your endurance session with three to four minutes of recovery in between, after which you do your cool-down. This way you can still combine two training types in one training. I prefer to let athletes do their intervals in a separate session. Then you have a clear focus and you run the least risk of letting the exercise-physiological training land between two stools.

Doing intervals at the beginning of a workout in which you also want to give an endurance stimulus is counterproductive. You then start by throwing ‘sand in the engine’ that ruins your aerobic training. 

Tip 4: More is more

This tip is not mine, but is credited to Nils van der Poel – the Olympic champion in the five and ten kilometer speed skating. In his foundation training period, he exclusively trained his aerobic capacity. No intervals, no sprints, none of that. Five days a week and six hours a day. His motto: more is more. He explains that the body (at least his body 😉 can be almost unlimitedly be taxed aerobically. The more you exercise aerobically, the stronger your aerobic engine.

The minimum duration for a good endurance training is 45 minutes. Elite athletes can go up to 10 hours per session, for a total of 20 to 30 hours per week. If you have many hours available, you can combine several sports for your endurance training. Triathletes already do this by nature of their sport, but in particular runners can benefit from cross-training. For example, by making extra hours on the bike. This way you can become more aerobically efficient without extra risk of injury. In the end, this will also benefit your running.

For most readers, the time you have for exercise is the biggest limitation. If so, do as much of your endurance training sport-specific. After all, these session have the highest gains.

Tip 5: Consistency and regularity

The question I often get from time-constrained athletes: do I get as much return from one four-hour training session on the weekend as from four one-hour sessions during the week? The answer: four times one hour will yield (much) more than one time four hours. So the trick is to do your endurance training as evenly as possible in your week. Consistency is the champions’ secret: a minimum of three sessions per week, spread as evenly as possible throughout the week. This gives your body a constant stimulus to make aerobic enzymes and to grow mitochondria.

Trainer Bert FlierThe goal of endurance training is to bring about a sustainable change. Just like an IV drips constantly to bring nutrition into the bloodstream as evenly as possible, endurance training is to be supplied as constantly as possible: your body absorbs and adapts best by a training consistently throughout the week every.

In conclusion

Did you know well-functioning mitochondria are anti-inflammatory and lead to longer life expectancy? Two additional reasons to take your endurance sessions seriously and to make them be the corner stone of your training program.

Endurance training takes up the bulk of your training time. If you do it right, your aerobic foundation will get stronger and you will become an increasingly better endurance athlete. Do you want to be guided in this? Then make an appointment for an  exercise test or Personal Coaching trajectory can do for you? Feel free to make an appointment.

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