Energy System Training (EST) is a bit of buzzword in the fitness industry at the moment; it’s what all the cool kids in CrossFit are doing to develop overall fitness by isolating each energy system and training them specifically. This usually involves breaking longer workouts/distances down into repeatable intervals, and to monitor the rest and duration of the exercise in order to control intensity.

For example, think about the intensity profile of a 2,000m row vs. the intensity profile of 4 x 500m rows.

What are these energy systems you speak of?

In order to function, the body must convert the energy derived from the food we eat into fuel. Here is a very quick overview of the three pathways available, and how they relate to our training:

1). The Anaerobic A-lactic energy system is responsible for converting energy into useable fuel quickly to supply very short, powerful bursts for short periods of time. This is the one you’d use if you were trying to lift something heavy very quickly, for example, the Clean and Jerk or the Snatch, or for any intense effort lasting up to 10 seconds, like a 25m sled sprint.

2). The Anaerobic Lactic energy system lasts slightly longer than the first but is still considered a “sprint” energy system. This pathway kicks in when doing intervals over 10sec (when the Anaerobic A-lactic ES can no longer fuel you) but will only sustain you for up to ~2 minutes. Think about how much you lose your “sprint” effort towards the end of a longer interval, like a 400-800m sprint, or a 500m row - you can literally feel yourself slowing down as your body is no longer able to supply enough energy for you to sustain the same intensity. However, should you wish to continue running/rowing past the threshold of your anaerobic lactic ES, you could slow right down and find a new pace that could be fueled by the third energy system…

3). The Aerobic energy system, where oxygen is the primary fuel, is used for sustained activities. We are talking about anything upwards from 2-3 minutes, for example, an 8k run, 60min row, a marathon etc. This ES has a slower turnover rate, hence the lower intensity output, but, can last for very long periods of time so long as oxygen is available for utilisation.

Ok great, science and bla bla bla…but…

 How is this information useful?

As we have already said, EST is a great tool to isolate energy systems and train them independently. This not only allows coaches and athletes to target and develop areas of fitness required for their specific sport, but to also pinpoint and develop the weaker areas of an athletes arsenal.

When implementing EST, there are a few variables to consider.

 The Intensity / Effort Level

This will be directly related to the response you are looking for, and will help to guide the athlete on how to attack each interval.

·       Very very hard (VVH) 110%
·       Very hard (VH) 100%
·       Hard (H) 90-100%
·       Moderate (M) 75-95%
·       Easy (E) Below 75%

The Duration

The duration will be dependent on the effort. If you want your athlete to hit a VVH effort, they will not be able to hold that effort for very long. Here is a broad summary of the durations in each energy system

·       Anaerobic A-lactic = up to 10 seconds, for more than 10 rounds
·       Anaerobic Lactic = 10 seconds to 2 minutes, for up to 10 rounds
·       Aerobic = longer than 2-3 minutes, for 1-5 rounds

The Rest

The rest should be representative of the work; the harder the effort, the shorter the work, and the more rest required in order to be able to repeat the same effort at the same intensity.  

·       10 seconds of work at VVH = 10-12:1 rest to work
·       1:30 minutes of work at H = 5-8:1 rest to work
·       10 minutes of work at M = 0.6-1:1 rest to work

The Movement

It is important to understand when to use certain movements when prescribing EST. There is a direct correlation between simple movements and higher work output, meaning, the shorter/harder the section of work the simpler the movement needs to be. Think about the difference in work output between 60sec max effort Assaut Bike vs. 60sec max effort handstand pushups. Basically, imagine the aftermath of an Assault Bike sprint...have you ever seen anyone that bad after HSPU?!


The workout should be designed in a way that allows the athlete to repeat multiple rounds with similar outcomes. In order to do this you need to abide by the variables mentioned above when creating workouts.  

Ok, now I know all about EST when do I use it?

EST can be and is used across any and all sports. For example, a marathon runner would not train for a marathon by running 42km repetitively; their training program would also include shorter distances at different (faster) paces. Similarly, an NBA player would not show up to practice and play basketball for 48 minutes. Instead they would run shuttles, do skill drills, run lay-ups, and shoot 3s; the game would be broken down into sections so that each section could be trained individually.

Let’s bring this back to a workout at BASE 3.

My aim is to improve my performance for the following workout:

200m run
10 front squats
10 pull-ups

What type of training will give me the best results so that I can get another round or two?

A). Repeating the 15min workout multiple times until I get a better score.
B). Breaking the workout down in to sections, and manipulating work:rest ratios and intensity level. For example:

10 RNDs
200m run
10 front squats
10 pull-ups
Rest 2-3mins

Option A will allow for some adaptation by teaching you to become better at that workout. This will, of course, allow for some improvement, but intensity will most likely continue to drop at similar points each time you attempt the workout.

By using forced rest between rounds, Option B allows me to perform each round at a higher intensity than the rounds I performed back-to-back in Option A. This teaches me to be able to access and work towards maintaining this level of performance throughout the entire 15-minute work period. As I start to improve my times, I could play around and decrease the amount of rest time whilst still trying to maintain intensity. Imagine if I were able to get the same times with only 1-minute rest compared to the 2-3 minutes I needed at the start! Now how about with 30 seconds rest...can you see where I’m going with this?

I am a big fan of EST and have been using it in my programming for a couple of years now. From experience, I no longer believe that you should only practice the sport to get better at the sport, but that it is also imperative to train the energy system. And the options are endless. And fun. Simply by using the variables mentioned above and a little creativity, there are so many angles to take that will manipulate training to get a desired and more well rounded response. But this only skims the surface, and I could talk about this stuff for hours. So, if you’d like to know more or you think you could benefit from some EST in your program, bring me a coffee and I would be happy to help.