Energy System Development

A Brand New Day
CC Photo Credit: Thomas Hawk

As far as I know, Energy System Development is a term coined by Mark Verstegen, Founder of Athlete’s Performance.

Mark’s a smart dude, but also the term obviously describes the intent, much the same way Neuromuscular System Development encapsulates training for the nervous systems and muscular systems.

Most people only know about ‘Aerobics,’ or ‘Aerobic Training,’ or what I often hear people talk about in terms of ‘cardio,‘ and maybe a few refer to as ‘conditioning.’

Aerobic simply means, ‘with oxygen,’ and only compromises one of three energy systems.

Two are actually Anaerobic Pathways — which if you’re wondering, basically means, ‘without oxygen.’

We are capable of producing energy in an oxygen environment and in an environment exclusive of oxygen.

Oxygen is a catalyst for energy production, your aerobic energy system is actually far more efficient at generating energy via the production of adenosine triphosphate (ATP) — the most basic component of energy that your body utilizes — but at the expense of speed and a lower power output.

You can’t sustain a high level of energy output for too long, before the aerobic system must kick in to cope with the energy demands.

The other obvious drawback is that exclusive training of the aerobic system won’t really contribute much in the development of the other two energy systems, while training the other two energy systems leads to dramatic improvement of the aerobic system, as shown most notably in the Tabata Study.

Too much time spent in the mythological ‘fat-burn zone‘ or too much low-level aerobic training also often leads to degradation of muscle tissue, making your body less metabolically active throughout the day. [toc]

1. The Quick System

AKA: ATP-CP Phosphagen System (Alactic Anerobic Energy System)

This is your immediate or shortest duration energy system, lasting roughly no longer than 10 seconds.

You’ll find this energy system heavily involved in sports like javalin, shot-putting, American Football, Baseball and short sprints.

It basically uses the ATP stored directly in your muscles, to produce energy quickly.

It’s actually a pretty powerful energy system, but the obvious limitation is endurance.

A lot of NMSD is actually geared to this system and strength training, particularly explosive strength, with less than 5 reps is often within this system, but in terms of everyday health and performance an ESD day of training geared to this system most likely has sprint variations of an exercise with longer periods of rest.

For example, a 10 second sprint followed by 30-60 seconds of rest. Sprint intervals like this are often characterized by quick or short duration work periods, with longer rest periods as high as ten times the duration of the work portion.

Often energy system work in this realm is characterized by 3-6 times the amount of recovery relative to your work period, or enough time to allow a chemical process to restore ATP again within the muscle.

For example, 40m, 60m, 80m and 100m sprints are mostly geared to this energy system, and are among my favourite protocols for maintaining cardiovascular fitness via this system.

Often I’ll just do a quick sprint, walk back slowly and repeat.

The nice thing about this type of training, is that you can do significantly less but get great results, while preserving metabolically active muscle tissue, so they are time efficient.

The more work you do in this realm, the more muscle mass is also likely to be preserved (by comparison to the other two), but in my opinion shouldn’t be at the expense of occasionally working on the other two energy systems.

2. The Medium System

AKA: Glycolytic System (Lactic Anaerobic Energy System)

The glycolytic system or your sugar system, still requires energy expenditure in an environment without oxygen like the ATP-CP system, but after about 10-12 seconds the body basically starts utilizing simple carbohydrates or glucose as a fuel source, rather than ATP.

Sugar requires some breakdown and chemical changes to occur for this system to be effective and training this system leads to a better utilization of glucose and a greater duration of exercise at a higher intensity.

This system is predominantly used in Power Sports like Soccer, Basketball, Hockey, Rugby, and 200m, 400m, 800m track events.

The downside?

Lactic Acid build-up, which isn’t as bad as most people think, however, it still creates a burning sensation as your body produces the acid  — which is actually a fuel source, basically your body in an anaerobic state produces lactic acid  — and eventually will disallow you from continuing at that intensity.

This is also often referred to as the Lactate Threshold, but your body is good at dealing with it for about 90-120 seconds, depending on training, before it has to start utilizing the aerobic energy system and your power output has to drop.

It’s maintaining this intensity past your initial threshold, that makes training this energy system so vital, in so many activities.

The nice thing about this system though, is that with a little bit of rest, you can tax it pretty heavily and actually train your aerobic system at the same time — as a side note, these energy systems actually have a bit of a cascade effect in that ATP-CP can contribute to Glycolytic System development, which can lead to Aerobic system development, but the opposite is not true, you can’t train your aerobic system and significantly develop your ATP-CP system.

A good example of training protocols that develop this system would be 30 seconds on, 60 seconds off intervals or basically anything where the work is less than about 2 minutes and characterized by at least an equal amount of rest but upwards of three times the amount of rest to work, in terms of a ratio.

15 seconds on, 45 seconds off, is still an example of Glycolytic Interval Training.

*Note more rest is needed when training the quick energy system, less for the medium, and even less for the long system.

One of my favourite and according to Dr. Steven Boutcher at the University of South Wales, perhaps the most effective for fat loss (per time spent, and if using a bike for comparison), is an 8 seconds on, 12 seconds off protocol. 

A major advantage to this protocol, is that the rest permits you to keep your output high. Try it for 4-5 minutes.

One very popular interval training method, 20 seconds on, 10 seconds off — or Tabata Intevals, probably popularized through Crossfit — falls into the the Glycolytic Realm too, though not exclusively.

Interval training in these zones, has been shown to make significant improvements in markers for aerobic and cardiovascular health.

You can also limit training in this area significantly, perhaps even to only 20 minutes or less in a training session, while getting similar results (or better) to the typical long-slow distance aerobic work that many people still do for fat loss and weight loss.

3. The Long System

AKA: Aerobic System

This system is predominantly used in endurance sports such as long, typically slow (relative to their power sport counterparts) distance cycling, triathlons, marathons, kayak racing, and swimming.

The aerobic system can handle medium intensity activities for about 90 minutes in duration, depending on training.

If you’re ever heard the term ‘bonking’ or are familiar with the practice of ‘carb-loading’ in endurance sports, then you are probably aware of this limit, in that your body can only store so much fuel.

Once you run out of this fuel you can make yourself feel rather sickly.

Typically the average human being stores enough fuel for about 20 miles worth of activity.

Obviously through training you can increase this, and if your goals are suited to endurance sports, then you will want to do a considerable amount of training this system still.

Aerobic energy system training also what most people think of when they hear the term ‘cardio,‘ but it’s also the one style of training that typically falls short of expectations in my experience.

Unlike the Anaerobic pathways, training your aerobic system yields little improvements in speed, power or strength and actually leads to a degradation of muscle tissue, the latter of which we know improves body composition and increases basal metabolic rate.

However, you are mostly in a state of aerobic energy expenditure all day, every day.

Walking, is predominantly  aerobic, and yields numerous health benefits, not to mention provides many people a much needed break within the day.

I’m not saying Aerobic training is evil, just that for fat-loss, you are better off focusing your energy on the other two systems in your training, and using the Aerobic system for other purposes.

Like what?

Mostly recovery purposes.

Going for a walk or light hike between workouts is a great activity for ‘active recovery‘ days and low level blood flow has been shown to reduce muscle soreness from previous workouts,

Even if it’s only a placebo effect, light swimming and cycling (notice non-weight bearing endurance activities…) have also been shown to reduce muscle soreness when done between harder workouts.

My recommendation though, is to use this sparingly, for no more than 20 minutes at a time (with the exception of walking), and if done on the same day, place it after your other training sessions or workouts.



It is important to remember that these are more like guidelines, than rules.

We know that all three energy systems work interdependently, so it’s not exactly cut and dry.

For example, working your quick or medium systems, means your aerobic system is in use during the recovery period.

If you want to optimize your training, it’s important to order any energy system work within a training session or workout appropriately, so that the quick energy system is developed first, then the medium system, finishing with the long system.

This is of course assuming that you plan to train 2 or more energy systems within a given session.

Also you are better served utilizing some form or combination of interval training in your weight loss efforts, instead of typical aerobic exercise.


  • Train all 3 energy systems on a semi-regular basis.
  • Place emphasis on the Anaerobic System over the Aerobic System if weight loss is your goal, but not at the exclusion of any and all aerobic training.
  • Your Quick Energy System means anything less than 10-12 seconds, with up to 6 times the rest, between bouts.
  • Your Medium Energy System means anything lasting 10-120 seconds, with typically up to 4 times the rest, but more often a 1:2 or 1:3 ratio.
  • Your Long Energy System will last roughly up to 20 miles which is typically where people bonk in Marathons without adequate training, or about 90-120 minutes (depending on your level of training) before your carbohydrate stores are depleted and additional carbohydrates must be consumed. 
  • Intervals done in the Long Energy System typically have an inverse work to rest ratio (think walk-run protocol), often the rest is considerably shorter than the work phase, often 1:1, 2:1, 3:1 or even up to 10:1 or higher.
  • If training more than one system within a given workout, train the systems from quickest to longest.
  • All 3 systems work interdependently, not exclusively, so take most recommendations with a grain of salt.

16 thoughts on “Energy System Development”

  1. This was a great overview of the different systems and various types of interval training. One thing that I think should be noted though for the “more is better” crowd – if doing high intensity intervals they should remember to cut back on their longer duration/steady state. Overdoing intense intervals is a sure way to burn-out. 

  2. Thanks for the comment, I completely agree.

    For the “more is better crowd,” better is better, not more…  😉 

    Actually I’m going to be making more specific recommendations in an upcoming Interval Article, this was mostly just an overview of the energy systems (in following with the overview I did for neuromuscular training the week before) but might as well throw in the recommendation that typically I don’t recommend High Intensity Interval Training (HIIT) for more than 30 minutes 2 or 3 times a week.

    This all kind of ties into an upcoming article that aims to simplify a modular system of training though too.

    However, I feel it is noteworthy that I used to play basketball and volleyball for up to 3 hours a day, 5-6 days a week, on top of 2-4x a week weight training. It is essentially interval training, and while I’m sure it hit my immune system from time to time, and sometimes led to injury, you’d be surprised what the human body is capable of.

    It’s been my experience that there is a fine line between too much exercise and not enough.

    Provided there is a sensical progression leading up to more duration of higher intensity energy system work, it is possible to add a fair bit of interval training in place of long slow aerobic training, depending on desired outcomes. However, recovery and mobility work also need to increase to combat it.

    Lastly, proper nutrition goes a long way towards helping you recover from any kind of exercise, but especially intense exercise.

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