How the 80/20 approach can improve your endurance performance

Kelsey Brown, BSc


March 30, 2023

Defining endurance

Endurance in a sporting context refers to a person's ability to sustain a certain velocity or power output for as long as they possibly can. This ability is demonstrated when an athlete, for example, completes a marathon or continuously lifts weights. 

Intensity, duration and frequency of endurance training sessions contribute to improvements in an athlete’s performance, and it is important to explore different methods to achieve this. 

What is 80/20 training?

One endurance training method is known as the 80/20 rule, it is also referred to as polarised training, where athletes will perform roughly 80% of their training at a low intensity and 20% of their training at high intensity. This concept was introduced following research on the training habits of elite rowers. 

Over a 4-week training block involving 5 sessions a week, an 80/20 split would include 16 days of low-intensity training and 4 days of high-intensity training over the period. 

Low-intensity training typically comprises aerobic endurance training at around 62-82% HRmax (maximum heart rate). This may involve continuous running at a sustainable 10k pace. Carrying out a higher proportion of low-intensity training is linked to better success in endurance performance as outlined in research comparing the training volume in six elite long-distance runners. 

High-intensity training may consist of interval training (HIIT) carried out at 82-95% HRmax. For example, in repeated sprint training, you may sprint as fast as you can for 7 seconds, have a less than 60-second rest period, and then repeat the sprint. Interspersing sprints with short recovery periods in this way allows you to reach higher heart rates compared to continuous running. 

Some evidence also suggests that HIIT induces greater or similar physiological adaptations (such as VO2max) than continuous training. However, HIIT is physically demanding and requires more recovery time. Therefore, high-intensity workouts should make up a lower proportion of your overall training compared to low-intensity. 

What are the benefits of 80/20?

Performing both high-intensity and low-intensity endurance training has been shown to improve endurance performance by 2-4% more than carrying out low-intensity training alone. As a runner, for example, it is important to incorporate HIIT sessions, which you may not normally think to do, alongside more conventional, continuous running.

When using the 80/20 method, adding additional high-intensity sessions does not appear to improve performance further, and may lead to overtraining symptoms, so it is best to keep the percentage of these sessions at around 20%. 


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Kelsey Brown, BSc

Kelsey holds a BSc in Sport and Exercise Science (University of Winchester) and works as a part of the science team, carrying out research for trait and action creation and blog content. She plays netball for her local team and after enjoying learning her wedding dance so much has started Latin and Ballroom dance classes with her husband.

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