Geschatte leestijd: 4 minutenThe ATP-PC System, also known as the phosphagen system, is one of the energy systems of our body. Our body requires a constant supply of energy to function properly and to stay healthy. When we exercise, the body naturally has a greater demand for energy than when the body is at rest. The body receives energy from what we eat and drink in the form of carbohydrates, protein, and fats.
Table of Contents
Energy Systems of the Body
Carbohydrates provide us with energy for daily activities, including sports activities. Carbohydrates are converted into glucose (blood sugar) in our body. This glucose is transported in the blood where it may be taken up by cells (with the help of insulin) and used. Additionally, it can be stored as glycogen in the liver and muscle cells.
Another major energy reserve comes from fats. Most of the fat in our body is in the form of triglycerides, also called body fat (under the skin and around the organs). When we consume an excess of both protein and/or carbohydrates, this excess energy (positive energy balance) can also be stored as triglycerides in the fat cells of our body. An advantage of fats as an energy source is that most people have an inexhaustible amount they can use. Glycogen stored from carbohydrates, on the other hand, can only provide energy for about 30-40 minutes of high intensity.
Proteins are primarily building materials and are used to a lesser extent as an energy source. This actually only occurs during a negative energy balance (low-calorie diet) or for example during starvation. For this, a conversion to glucose must take place. This process, where glucose does not come from ingested carbohydrates but is produced by the body from other nutrients, is called gluco(neo)genesis. The (amino acids from) proteins can be used for this, as well as previously stored glycogen and fats.
So, we mainly use carbohydrates and fats as forms of energy in the body. The energy contained in these substrates is released in various ways in the cells and stored in a high-energy compound called adenosine triphosphate (ATP). Basically, we need ATP to achieve muscle contractions (as well as muscle relaxation). Therefore, the body has different ways to generate ATP.
There are three different ways cells can generate ATP: These energy systems are all described in separate articles.
1. The phosphagen system or ATP-PC system
2. The anaerobic system or lactate system
3. The aerobic oxygen system
The ATP-PC System
The first way (ATP-PC system, or phosphagen system) is the easiest and fastest way to generate ATP and this happens without the presence of oxygen (“anaerobic”). The name Adenosinetriphosphate implies that it involves adenosine linked to three phosphates. The release of one of these phosphates produces energy. When ATP is used to supply energy (about 7.3 kcal per ATP), what remains is ADP (Adenosinediphosphate, adenosine with two phosphates) and a free phosphate molecule. CP stands for creatine phosphate that is stored in the skeletal muscles. Before ADP can release energy again, this phosphate group must be replenished, which is provided by the stored creatine phosphate in the body. In this process, carbohydrates, fats, or protein are not used.
This way of generating ATP mainly occurs during very intensive, short-duration forms of training. Think, for example, of short sprint activities (100m), powerlifting, but also in high and long jumps. Through this method, only 10 to 15 seconds of energy can be supplied to all muscles, after which exhaustion occurs. It is also not possible to store large amounts of ATP in the muscles, only a small amount for a few seconds of intensive activity. This system is immediately ready to supply energy and is thus always the first to be active. This is also the case, for example, when you get up from your chair, although this (for healthy people) is naturally not an intense action. Nevertheless, the energy supply then mainly comes from the ATP-PC system.
Training and the ATP-PC System
Through training, you can, for example, become faster in the 100 meters. But it is not possible to increase your ATP stores. Well-trained athletes need about 3-5 minutes of rest, after which the entire ATP supply is replenished. This allows them, for example, to perform the second 100 meters almost as fast as the first sprint during training.
Also in team sports such as soccer, basketball, and hockey, you often use this energy system during the most active highlights. Think, for example, of an explosive and fast dunk action. Or a short quick sprint with a hard shot aimed at the goal during soccer. It is not the only energy system that is active, however. All three systems are always active together, but the duration and effort determine which system is the most active. Almost all of the energy for these short, strenuous activities comes from the ATP-PC system.
ATP-PC training is a good way to train strength and speed. You can do this, for example, by performing explosive exercises (up to a maximum of 15 seconds and resting at least 2 minutes in between). Rest between exercises is important because time is needed to rebuild the ATP levels. Sprints, jumping exercises, and throwing exercises with medicine balls are forms of training that mainly stress this energy system.
Summary
The body has various ways to supply energy: The phosphagen system or ATP-PC system, the anaerobic oxygen system or lactate system, and the aerobic oxygen system. The extent to which these different energy systems are used depends on the duration and intensity of activities. For activities of short duration of about 10-15 seconds and high intensity, mainly the ATP-PC, or “phosphagen system,” is used. This system can deliver energy the fastest and is always the first to be deployed. Training focused on this system mainly improves performance in short-duration, high-intensity activities.
In the following parts, I will further elaborate on the other energy systems: The anaerobic oxygen system or lactate system and the aerobic oxygen system.
Sources
- Van Loon LJC. The effects of exercise and nutrition on muscle fuel selection. Maastricht:
Universitaire Pers Maastricht, 2001. - NASM Essentials of Personal Fitness Training
- The Three Metabolic Energy Systems by Jason Karp PhD
- All About your Metabolic Energy Systems by Andrew Heffernan
