The Equipment Guys

Energy Systems Defined


The human body runs on only one kind of energy: chemical energy. – Adenosine triphosphate (ATP). ATP is the gas in the tank. Our bodies have three different chemical systems that convert energy.

Energy Systems Defined Image

Energy System 1: Ready fuel for immediate energy
The Immediate Energy system, or ATP-PC, is the system the body uses to generate immediate energy. The energy source, phosphocreatine (PC), is stored within the tissues of the body. When exercise is done and energy is expended, PC is used to replenish ATP. This system gives athletes a readily available store of energy which can be accessed without delay.

What’s the downside? Athletes have only about 10 seconds worth of ATP-PC.

Energy System 2: Glucose-fueled quick energy
The Anaerobic Glycolysis is a series of ten enzyme-controlled reactions that utilize carbohydrates to produce ATP and pyruvate as end products. Glycolysis is the preferred energy system by the human body when any sort of exercise work is required. The process is fast, there is generally plenty of glucose available and the reactions can occur anywhere within the cell’s sarcoplasm.

What’s the downside? The two pyruvate molecules created in the very last reaction can be converted into lactate (lactic acid), or they can be carried into the third energy system and continue to produce ATP.

Aerobic fitness reduces lactate production in glycolysis. The lower the relative work intensity and the higher the athlete’s aerobic fitness, the less lactate that will be produced.

Energy System 3: Long-lasting aerobic energy
The Aerobic System resides within a specific organelle of the body’s cells. This specific organelle is the mitochondria– the “power house of the cell.” That is precisely true. The bulk of the ATP produced is via “aerobic” processes. The first two energy systems are anaerobic, meaning they do not require oxygen.

The aerobic energy system must have oxygen or the entire process will slow down and potentially stop completely. The oxygen needed by this system is provided by the cardiovascular and respiratory systems via blood flow to the tissues.

Optimal cardiovascular condition

The aerobic energy system is where we utilize all three of our fuel sources. It is within this system that carbohydrates, fats and proteins may be processed in order to produce ATP. An athlete needs a very well developed cardiovascular system to provide the oxygen for all of this to occur. The aerobic system takes one to three minutes to run when we begin to exercise. The efficiency of the aerobic system is directly related to the athlete’s aerobic conditioning. This system is capable of providing ATP for extended periods of time. If the intensity is not too high, an athlete may use this system for hours and hours of work.

The aerobic system helps to replenish and recover the first two energy systems. Most team sports are anaerobic in nature. However, all team sport athletes need aerobic conditioning so their aerobic system can provide recovery for the anaerobic systems.

Training the body’s energy systems for optimal performance

Each of our energy systems provides ATP in a very specific time and intensity range. In order to train these
systems, you need to work within these time and intensity ranges.

Immediate energy system—a training session with the goal of improving the Immediate Energy System would utilize short explosive movements or exercises.

Short-term energy system-a training session with a goal to train the Glycolytic System would require a longer session of work but still at a very high intensity level.

Long-term energy system—To train the Aerobic System, an athlete needs to do steady-state work for a minimum of 20 to 30 minutes. Generally, aerobic work occurs in the range of 65 – 85 percent of VO2max. Perform this aerobic work at least four days per week for optimal benefits.

When sports performance is at stake, training your energy systems is just as important as how much weight you can bench press or how high you can vertical jump.