Energy System Development

In human performance, energy system development is the rhythm guiding every move, every sprint, every enduring endeavor. It is the unseen force powering champions and the foundation on which our physical potential is built. “In this section, we’ll delve into the three primary energy systems

What Is ESD?

  1. The ATP-PC System, commonly called the a-lactic system.
  2. The Glycolytic System, often referred to as the Anaerobic or lactate system.
  3. The Oxidative System, also known as the aerobic system.


Visualizing energy systems can be simplified into three concentric circles. The innermost blue circle stands for the ATP-PC or a-lactic system. The intermediate red circle symbolizes the glycolytic or anaerobic system. The outermost green circle signifies the oxidative or aerobic system.

ATP - The Gain System

Starting with the ATP system, the principal energy source here comes from adenosine triphosphate (ATP) and creatine phosphate (CP). In well-trained individuals, this system can supply energy for up to 10 seconds. Its attributes include supplying immediate energy and fueling brief, intense activities. Activities like near-maximal weightlifting, short sprints, or cycling at maximum effort for less than 10 seconds are classic examples.


This system is often dubbed the “gain system.” When trained properly, the typical adaptation is an increase in maximal strength, power, or speed. The training emphasis should be on high intensity over a short span. The body achieves this by utilizing the tiny ATP reserves in muscles for instantaneous energy. But since these reserves are limited, Creatine Phosphate (found in muscles) donates its phosphate to replenish ATP, thereby powering short energetic bursts.

Training The ATP-PC System

Regarding training methods for the ATP-PC system, consider the analogy of a stationary bike. An individual would mount the bike and pedal with full force, exerting maximal effort for up to 10 seconds, followed by a rest period of two minutes and fifty seconds. Repeating this sequence multiple times, interspersed with adequate rest, would constitute an “a lactic training session.”


A systematic approach to a-lactate training involves gradually increasing the number of efforts at maximal intensity over the weeks, ensuring the individual maintains power without a power drop off throughout each effort.

For instance:

– Week 1: 10 seconds work, rest 2 minutes, and 50 seconds rest x 2 reps

– Week 2: 10 seconds work, rest 2 minutes, and 50 seconds rest x 3 reps

– Week 3: 10 seconds work, rest 2 minutes, and 50 seconds rest x 4 reps


– Week 4: download week – rest


– Week 5: 10 seconds work, rest 2 minutes, and 50 seconds rest x 3 reps

– Week 6: 10 seconds work, rest 2 minutes, and 50 seconds rest x 4 reps

– Week 7: 10 seconds work, rest 2 minutes, and 50 seconds rest x 5 reps



It’s crucial to remember when designing an a-lactic workout that participants must have sufficient aerobic capacity and be robust and powerful enough to attain the desired adaptation. If individuals feel that the rest intervals are too long or the 10-second work phase isn’t challenging enough, it’s a sign that they might not be ready for such a workout and are not strong or powerful enough to achieve the intended results from it.

The Glycolytic or Anaerobic Lactate System

Following the ATP-PC system, we have the glycolytic or anaerobic lactate system. This system sources its energy primarily from glucose and glycogen found in the blood and muscles. It begins to dominate energy provision from the 10-second mark, continuing up to two minutes. Essentially, as the ATP-PC system fades post the initial 10 seconds, the glycolytic system takes charge.

A hallmark of this system is its ability to function anaerobically, that is, without oxygen. For well-trained individuals, this means they can rely on it up to the two-minute mark. Events such as 400-800 meter sprints or sub-two-minute rowing bouts utilize this energy system extensively. When targeting this system in training, the focus should be on maintaining high intensity over a moderate duration.


The underlying mechanism of this system involves the anaerobic breakdown of glucose or glycogen to produce ATP. This process results in the formation of lactic acid. As lactic acid builds up, it can induce a burning sensation in muscles and contribute to fatigue. Given its demanding nature, this system is often dubbed the “pain system”. Training it effectively requires a maximal effort, similar to the ATP-PC system, but over an extended duration ranging from 10 seconds to 2 minutes. This often subjects the individual to intense discomfort, crucial for achieving the desired adaptation.


For an authentic glycolytic workout, one might opt for cross-training equipment, with rowing machines being a popular choice. An example regimen could involve rowing 300 meters in 60 seconds, followed by a 90-second break. Repeating this cycle multiple times with rest in between would constitute a “lactic training session.”


It’s paramount to ensure consistency in power output across repetitions. If an individual’s power wanes from one round to the next, it indicates a recoverability issue, possibly pointing to insufficient aerobic capacity. Such inconsistency converts the session into a high-intensity aerobic workout, negating the anaerobic lactate focus.



A systematic approach to lactate training involves gradually increasing the work intervals over weeks, ensuring the individual maintains power throughout each work interval with no reduction in power output.

For instance:

– Week 1: 60 seconds work, 120 seconds rest x 2 reps

– Week 2: 60 seconds work, 120 seconds rest x 3 reps

– Week 3: 60 seconds work, 120 seconds rest x 4 reps

– Week 4: download week – rest

– Week 5: 60 seconds work, 120 seconds rest x 2 reps – perform 2 sets of this

– Week 6: 60 seconds work, 120 seconds rest x 3 reps – perform 2 sets of this

– Week 7: 60 seconds work, 120 seconds rest x 4 reps – perform 2 sets of this



This structured progression ensures the individual garners the benefits of the glycolytic system while preserving its unique anaerobic nature.


The Oxidative or Aerobic Syste

Following the glycolytic system, we delve into the oxidative or aerobic system. This system is arguably the most prevalent, drawing energy primarily from carbohydrates, fats, and proteins. It’s an exceptionally durable energy system, capable of producing energy anywhere from 2 minutes to several hours, contingent on an individual’s athletic demands. Key features of this system include its reliance on oxygen for energy production and its support for prolonged activities. Sports such as marathon running, cycling, and triathlons exemplify the aerobic system’s endurance. Furthermore, it’s pivotal to recognize the aerobic foundation in many strength, power, field, and court sports. The training emphasis for the aerobic system centers around moderate to low intensity spanning lengthy durations. Mechanistically, the oxidative system utilizes substrates like carbohydrates, fats, and proteins in oxygen’s presence to generate ATP, albeit at a pace slower than the anaerobic and ATP-PC systems.

This system has earned its self the name of the “sustain system” because of its role in enabling individuals to maintain activities like walking, jogging, playing sports, and daily tasks. Virtually every sport or activity leans on a robust aerobic system.

To effectively train our aerobic system, we can select virtually any cross-training, resistance training, or running/cycling-based exercise. The key is ensuring the intensity remains low enough to keep our heart rate within the aerobic zone – typically 70% of the maximum heart rate for most individuals.


Delving into training methods for our oxidative system, consider a running regimen. Here, the individual might be tasked to maintain a pace that aligns with zone 2 of their heart rate max, which generally lies between 65% to 75% of their heart rate max. If this session extends beyond two minutes, it qualifies as aerobic work.


Before deepening our exploration of aerobic training, it’s crucial to note that the aerobic system’s programming can involve continuous aerobic sessions or intermittent aerobic intervals.


There are levels to this:


Low-Level Aerobic Work (Zone 1): Typically continuous, lasting 30 minutes or more, aiding in recovery.


Moderate to Intense Aerobic Work (Zones 2 and 3): Can be continuous or can incorporate interval training, where the individual operates in zone 3 for 3-5 minutes, reverting to zone 2 for a 2-minute recovery, and then repeats.


Very Intense Aerobic Work (Zones 3 and 4): Is normally performed as interval training and involves prolonged work periods in zones 3 and on the boarder of zone 4 with recoveries in zone 2. Even though zone 4 borders on the anaerobic threshold (80-85% of max heart rate), due to the extensive time in zones 3 and on the boarder of zone 4, it’s considered high-intensity aerobic activity. This can manifest as intense weightlifting circuits, strongman circuits, or rigorous interval or Fartlek training.


A vital reminder in energy system development programming is that many coaches, intending to focus on a-lactic or lactic system enhancements, inadvertently end up emphasizing high-intensity aerobic development. This misdirection stems from blurring intensity levels with work duration. Remember, all energy system development pivots on aerobic development. It’s paramount. Even if one encounters stagnation in a-lactic or lactic training, the remedy isn’t necessarily more of the same but rather bolstering the aerobic system. Enhancing the aerobic foundation can expedite recovery and boost ATP production rates.

Aerobic Programming:

  1. Long, Slow Distance (LSD):

A slow, relaxed run, ride, or swim, usually at 60% of maximum heart rate.

Duration should be 30 + minutes. 


  1. Interval Training:

This involves alternating between high-intensity bouts of exercise and rest or low-intensity periods.

3 min at zone 3 followed by 2 min at zone 1-2 min. repeat this process anywhere from 3 – 8 times.


  1. Fartlek Training: A Swedish term meaning “speed play”, fartlek involves varying your pace throughout your workout, mixing moderate and high-intensity periods in an unstructured manner.

5-25 min ranging from zone 1 to zone 3


  1. Circuit Training: This involves performing a series of exercises in succession, often with short rest intervals in between. The exercises can be purely aerobic, or a mix of aerobic and resistance exercises.

30 second on 30 seconds off

1a. Bench Press

1b. Squat

1c. Air Bike

1d. RDL

1e Military Press


  1. Cross Training: Engaging in two or more aerobic activities during the same workout or in different workouts. Examples include combining swimming, cycling, and running in triathlon training.

10 min at zone 2-3 Ski Erg

10 min at zone 2-3 Bike

10 min at zone 2-3 Rower


  1. Tempo Runs: These are runs performed at a “comfortably hard” pace, 70% effort or at a pace slightly slower than one’s race pace for a particular distance. The idea is to increase the threshold at which lactic acid builds up in the muscles.


Run 100m at 70% efforts with a 60 second recovery in between reps.

5 reps x 2-3 sets


  1. Sport-specific Training: Engaging in sports like soccer, basketball, or tennis, which have a significant aerobic component. Once movement is constant for 2 min or longer aerobic development will take place.





If you would like to further educate yourself on different training systems and methods check out the following education courses

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